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Chandipura virus (CHPV) is an arthropod-borne virus linked to encephalitis in humans, primarily in India. Its evolutionary dynamics and transmission pathways remain poorly understood due to limited genomic data. This study analyzed 23 publicly available CHPV genomes, including isolates from humans, sandflies, and a hedgehog, retrieved from GenBank. Phylogenetic analyses were conducted to explore host-specific and geographic evolutionary patterns. Phylogenetic analysis revealed distinct evolutionary lineages. Human-derived genomes collected in India between 2003 and 2024 formed a well-supported monophyletic clade, suggesting a unique evolutionary lineage. In contrast, sandfly-derived genomes exhibited diverse clustering patterns. Notably, Kenyan sandfly isolates from 2016–2017 were phylogenetically closer to human-derived sequences, suggesting possible shared evolutionary pressures. These findings provide preliminary insights into CHPV evolution and emphasize the need for enhanced genomic surveillance in both human and non-human populations. Expanding genomic data is essential to validate these observations and inform public health strategies. [ABSTRACT FROM AUTHOR]

The Western equine encephalitis virus (WEEV) is a globally relevant vector-borne pathogen that causes encephalitis. The role of environmental variables in the epidemiology of WEEV has become greater in the context of climate change. In December 2023, a significant resurgence of WEEV began in South America, with major ongoing outbreaks in Argentina and Uruguay. In this study, we employed a machine learning algorithm to model the distribution of WEEV in South America, considering both present and future scenarios. Ecological retrospective study. We conducted a modelling study to identify areas with the highest prevalence of WEEV in South America, based on confirmed human and equine cases during the 2023/2024 outbreak and climatic variables. Our analysis utilised Maxent software, a machine learning algorithm for species distribution modelling. Our results indicate that environmental variables, particularly thermal seasonality and annual rainfall, can directly influence the occurrence of WEEV, leading to increased virus incidence. Consequently, high-risk areas may shift in the future. Countries, such as Paraguay, Venezuela, Colombia, and various regions in Brazil, particularly the Northeast, Midwest, and the Pantanal biomes, will be significantly impacted, drastically altering the current distribution of WEEV. The ongoing WEEV outbreak in South America is concerning because it coincides with migratory bird stopovers. These birds are natural hosts that can spread the virus to unaffected areas. Our results will help to identify priority areas for developing preventive measures and establishing epidemiological surveillance. Occurrence of WEE in South America during the last 20 years. (A) Records of outbreaks by year. (B) Maxent model showing the probable current distribution and bird migration routes. The maps were built using QGis version 2.10.1. [Display omitted] [ABSTRACT FROM AUTHOR]

Objectives: Tick-borne encephalitis (TBE) is an infection caused by the tick-borne encephalitis virus (TBEV) that can lead to symptoms of central nervous system inflammation. There are five subtypes of TBEV, three of which – European, Siberian and Far Eastern – occur in Europe. As it is thought that different subtype infections exhibit varying clinical courses and outcomes, serological differentiation of the virus subtypes is clearly important. However, to date, this has proved difficult to achieve. Methods: An ELISA format was developed based on TBE virus NS1 antigen against the European, Siberian and Far Eastern subtype. The three NS1 antigens were biotechnologically produced in a human cell line and used for ELISA coating. Sera from German (European subtype) and Russian (Siberian and/or Far Eastern subtypes) TBE patients with positive TBEV IgG were used to test the reactivity against these three NS1 antigens. Results: Testing of 23 German and 32 Russian TBEV IgG-positive sera showed that the ELISA was able to differentiate between TBEV European subtype and TBEV Siberian and Far Eastern subtype infections. Conclusions: In geographical areas where two or more TBEV subtype infections can occur, the NS1-IgG ELISA developed here constitutes an important diagnostic tool to differentiate between European subtype infections and Siberian/Far Eastern subtype infections and to use the new assay for epidemiological studies to clarify the importance of particular subtype infections in an area. Consequently, it may help to better describe and anticipate the clinical courses and outcomes of particular TBEV subtype infections. [ABSTRACT FROM AUTHOR]

BackgroundMethodsResultsConclusionChronic neurologic deficits from traumatic brain injury (TBI) and subsequent infectious encephalitis are poorly characterized.Using TriNetX database we queried patients 18 years or older with a confirmed diagnosis of encephalitis between 2016 and 2024. Patient cohorts included those with a diagnosis of TBI at least one month before encephalitis (N = 1,038), those with a diagnosis of a TBI anytime before encephalitis (N = 1,886), and those with encephalitis but no TBI, (N = 45,210; N = 45,215). A murine model of controlled cortical impact (CCI) injury and Venezuelan equine encephalitis virus (VEEV) infection was used to reflect the clinical model, followed by extracting hippocampal tissue for bulk RNA sequencing and analysis.Patients with a TBI history at least one month before infectious encephalitis have an increased risk of mortality, epilepsy, and dementia or delirium. Bulk RNA sequencing of the hippocampus from mice subjected to CCI injury and VEEV infection demonstrated that key pathways, specifically those involved in granzyme mediated cell death, were enriched compared to VEEV infection alone.Our findings reveal that infectious encephalitis in patients with TBI history portends worse neurologic outcomes, and the hippocampus may be vulnerable to granzyme mediated cell death under these conditions. [ABSTRACT FROM AUTHOR]

We report the genomic analysis from early equine cases of the Western equine encephalitis virus outbreak during 2023-2024 in Uruguay. Sequences are related to a viral isolate from an outbreak in 1958 in Argentina. A viral origin from South America or continuous enzootic circulation with infrequent spillover is possible. [ABSTRACT FROM AUTHOR]

Enteroviruses (EVs) and parechoviruses (PeVs) are common pathogens of childhood. Enteroviral infections cause a range of clinical syndromes from mild illness to neurologic manifestations of meningitis, encephalitis, and acute flaccid myelitis. Disease manifestations are driven by a combination of viral replication and host immune response. Despite ubiquitousness and clinical importance, there are no approved targeted therapies for these viruses and most are without an available vaccine. Studies of EV neuropathogenesis began with poliovirus and are ongoing for other nonpolio EVs and PeVs. Many unanswered questions remain with regard to cellular tropism, mechanisms of dissemination, receptor usage, immunologic control, and cellular death. This review describes what is known about epidemiology, clinical presentations, and neuropathogenesis of these important pathogens. [ABSTRACT FROM AUTHOR]

Objective: Rare disease Background: Varicella-zoster virus (VZV) encephalitis is a commonly reported form of encephalitis that clinically manifests as skin lesions, fever, headache, and neuropsychiatric symptoms. We present a case of a patient with VZV encephalitis complicated by cerebral hemorrhagic transformation, characterized by high levels of inflammation and protein in the cerebrospinal fluid. The aim is to highlight the risk of hemorrhagic transformation associated with VZV encephalitis. Case Report: The patient exhibited scattered herpes lesions on the head, neck, and chest. Notably, the cerebrospinal fluid (CSF) protein concentration was markedly elevated at 9049.3 mg/L, with a CSF white blood cell count of 950×106/L, of which lymphocytes constituted 80%. MRI revealed abnormal signal foci in the bilateral temporal lobes and the right frontal lobe, consistent with findings associated with herpes encephalitis. Despite initial treatment with anti-inflammatory agents, acyclovir antiviral, and antiepileptic medications, the patient did not show improvement, prompting the addition of double filtration plasmapheresis. However, the patient experienced hemorrhagic transformation and succumbed to the illness. Conclusions: This case highlights the challenge of managing VZV encephalitis in the context of significant inflammation and protein elevation in the CSF, and underscores the need for further research into more effective therapeutic strategies for this rare but potentially devastating condition. [ABSTRACT FROM AUTHOR]

Epstein-Barr virus meningoencephalitis is a rare central nervous system infection that lacks standardized treatment. Immunocompetent and immunosuppressed individuals with this condition frequently have poor prognostic outcomes, making the need to identify therapeutic interventions high. Here, we report 2 pediatric cases of severe Epstein-Barr virus meningoencephalitis, both unresponsive to immunoglobulin and corticosteroid therapy, who demonstrated rapid clinical recovery following rituximab administration. Prognostic outcomes revealed marked improvements in symptoms, neurologic function, and quality of life. Rituximab may offer therapeutic potential in severe and refractory Epstein-Barr virus meningoencephalitis through the medication's target of Epstein-Barr virus harboring B cells. This report emphasizes the need for timely evaluation and consideration of rituximab therapy in immunocompetent pediatric patients with Epstein-Barr virus meningoencephalitis. [ABSTRACT FROM AUTHOR]

The European subtype of tick-borne encephalitis virus (TBEV-Eur; species Orthoflavivirus encephalitidis, family Flaviviridae) was the only tick-borne flavivirus present in central Europe known to cause neurologic disease in humans and several animal species. Here, we report a tick-borne flavivirus isolated from Alpine chamois (Rupicapra rupicapra rupicapra) with encephalitis and attached ticks, present over a wide area in the Alps. Cases were detected in 2017 in Salzburg, Austria, and 2023 in Lombardy and Piedmont, Italy. The virus strains exhibit 94.8–97.3% nucleotide identities to each other and are more closely related to Louping ill viruses (LIV; Orthoflavivirus loupingi; 90–92% identities) than to TBEV-Eur (less than 88%). The chamois-derived virus strains, tentatively termed "Alpine chamois encephalitis virus", form a well-supported independent genetic clade with Spanish goat encephalitis virus, clearly separated from other LIV. This supports its designation as a new virus subtype with the proposed shared taxonomic name "Spanish goat and Alpine chamois encephalitis virus subtype" within the species Orthoflavivirus loupingi. The zoonotic potential of this newly identified virus subtype as well as its host range in other animal species including farm animals needs to be further investigated. [ABSTRACT FROM AUTHOR]

Neurotropic alphaviruses such as Venezuelan equine encephalitis virus (VEEV) are critical human pathogens that continually expand to naïve populations and for which there are no licensed vaccines or therapeutics. VEEV is highly infectious via the aerosol route and is a recognized weaponizable biothreat that causes neurological disease in humans. The neuropathology of VEEV has been attributed to an inflammatory immune response in the brain yet the underlying mechanisms and specific immune cell populations involved are not fully elucidated. This study uses single-cell RNA sequencing to produce a comprehensive transcriptional profile of immune cells isolated from the brain over a time course of infection in a mouse model of VEEV. Analyses reveal differentially activated subpopulations of microglia, including a distinct type I interferon-expressing subpopulation. This is followed by the sequential infiltration of myeloid cells and cytotoxic lymphocytes, also comprising subpopulations with unique transcriptional signatures. We identify a subpopulation of myeloid cells that form a distinct localization pattern in the hippocampal region whereas lymphocytes are widely distributed, indicating differential modes of recruitment, including that to specific regions of the brain. Altogether, this study provides a high-resolution analysis of the immune response to VEEV in the brain and highlights potential avenues of investigation for therapeutics that target neuroinflammation in the brain. [ABSTRACT FROM AUTHOR]

Encephalitic alphaviruses (EEVs), Traumatic Brain Injuries (TBI), and organophosphorus nerve agents (NAs) are three diverse biological, physical, and chemical injuries that can lead to long-term neurological deficits in humans. EEVs include Venezuelan, eastern, and western equine encephalitis viruses. This review describes the current understanding of neurological pathology during these three conditions, provides a comparative review of case studies vs. animal models, and summarizes current therapeutics. While epidemiological data on clinical and pathological manifestations of these conditions are known in humans, much of our current mechanistic understanding relies upon animal models. Here we review the animal models findings for EEVs, TBIs, and NAs and compare these with what is known from human case studies. Additionally, research on NAs and EEVs is limited due to their classification as high-risk pathogens (BSL-3) and/or select agents; therefore, we leverage commonalities with TBI to develop a further understanding of the mechanisms of neurological damage. Furthermore, we discuss overlapping neurological damage mechanisms between TBI, NAs, and EEVs that highlight novel medical countermeasure opportunities. We describe current treatment methods for reducing neurological damage induced by individual conditions and general neuroprotective treatment options. Finally, we discuss perspectives on the future of neuroprotective drug development against long-term neurological sequelae of EEVs, TBIs, and NAs. [ABSTRACT FROM AUTHOR]

The genus Alphavirus harbors arboviruses of great concern, such as the Chikungunya virus and the equine encephalitis viruses. Transmission of pathogenic alphaviruses by mosquitoes could be influenced by insect-specific alphaviruses such as Eilat virus (EILV). However, insect-specific alphaviruses are rarely found in wild mosquitoes and only a few have been described in the literature. Here, we report the detection of EILV in a Culex univittatus mosquito from the north-eastern Namibian Zambezi region. Full genome analysis of MP458-NA-2018 showed 94.5% nucleotide identity to an EILV isolate from Israel. MP458-NA-2018 grouped with EILV in phylogenetic analysis and was placed within the clade of insect-specific alphaviruses. The virus was isolated in mosquito cells and shown to be restricted to insects as hosts by the inability to infect different vertebrate cell lines and a complete block of virus replication at 34°C. We further showed that infection of cells with EILV MP458-NA-2018 reduced production of infectious particles of Sindbis virus by 2000-fold over the entire course of infection, whereas reduction rates of Bagaza and Middleburg virus were approximately 3-10-fold and dependent on time after infection. While production of infectious particles of cells superinfected with the Chikungunya virus were approximately 30-fold reduced and more pronounced at a lower multiplicity of infection of 0.01, EILV seemed to enhance production of West Nile virus infectious particles by >5-fold when superinfected at a multiplicitiy of infection of 0.1. In summary, EILV from the Namibian Zambezi region influences in vitro replication of endemic flavi- and alphaviruses. [ABSTRACT FROM AUTHOR]

Eastern equine encephalitis virus (EEEV) is a mosquito-transmitted alphavirus that, among humans, can cause a severe and often fatal illness. The zoonotic EEEV enzootic cycle involves a cycle of transmission between Culiseta melanura and avian hosts, frequently resulting in spillover to dead-end vertebrate hosts such as humans and horses. Interestingly, it has been described that the W132G mutation of the very low-density lipoprotein receptor (VLDLR), the receptor of EEEV, significantly enhanced the VLDLR-mediated cell attachment of EEEV. The patient's metabolism plays a pivotal role in shaping the complex landscape of viral zoonosis. EEEV represents a significant public health concern due to its severe clinical outcomes, challenging epidemiological characteristics, and certain risk factors that heighten susceptibility among specific populations or age groups. Age is one of several predictors that can impact the outcome of EEEV infection; juvenile animals appear to be particularly vulnerable to severe disease. This has also been observed in natural infections, as children are often the most severely impacted humans. The aim of this piece is to shed light on the intricate relationship between human metabolism and the Eastern equine encephalitis virus. [ABSTRACT FROM AUTHOR]

Background: Culex tritaeniorhynchus has long been considered the primary vector of Japanese encephalitis virus (JEV), but until recently, it was considered exotic to Australia. When the species was detected in the country's Northern Territory (NT) for the first time, the Western Australia (WA) Department of Health was cognisant of the risk it posed to the State because of the shared border and continuous mosquito habitat adjoining the two jurisdictions. The aim of this study was to undertake intensive mosquito surveillance in the Kimberley region to ascertain whether Cx. tritaeniorhynchus was present in WA, define the extent of its distribution and undertake phylogenetic analysis of select specimens to support hypothesized routes of entry into the state. Methods: Carbon dioxide (CO2)-baited encephalitis virus surveillance (EVS) mosquito traps were deployed at various sites throughout the Kimberley region by surveillance officers within the Medical Entomology unit of the Western Australia (WA) Department of Health. Mosquitoes were then morphologically identified, and a subset of four specimens were confirmed as Cx. tritaeniorhynchus by molecular identification using Cytochrome Oxidase I (COI) DNA data and phylogenetic analysis. Results: From 31 March 2021 to 30 May 2024, a total of 211 female Cx. tritaeniorhynchus specimens were collected from 21 unique trap sites in the Kimberley's Shire of Wyndham-East Kimberley (SWEK). Four COI DNA barcode regions were amplified and successfully sequenced for analysis. These sequences fell within a clade recognised as Cx. tritaeniorhynchus and specifically all sequences were in a clade with other specimens from the NT and Timor-Leste. Conclusions: This study represents the first detection of Cx. tritaeniorhynchus in WA. Given the widespread nature of trap sites that yielded the species and consecutive seasons over which it was observed, the authors surmise that Cx. tritaeniorhynchus is now established within the northeast Kimberley region. The findings are significant given the detection of the species coincides with the first significant outbreak of JEV activity on mainland Australia involving an estimated 45 human cases of Japanese encephalitis, 80 impacted commercial piggeries and widespread feral pig activity. Although the role that Cx. tritaeniorhynchus may play in JEV transmission into the future is not yet understood, it presents a potential risk to public health in the region. [ABSTRACT FROM AUTHOR]

Tick-borne encephalitis virus (TBEV) is a significant public health concern, particularly in rural regions, like the Caucasus, where tick-borne diseases are prevalent. The review contains comprehensive data on TBEV circulation in the Caucasus region, demonstrating TBE cases in the North Caucasus and Georgia, as well as the identification of new endemic foci in Armenia and Azerbaijan, highlighting the need for further epidemiological studies and surveillance in the region. This review provides an updated overview of TBEV, encompassing its status, subtypes, life cycle and circulation in nature, epidemiology, new approaches to TBE treatment and diagnostics, and recent insights into molecular aspects. Understanding the complexities of TBEV transmission, clinical manifestations, and advancements in diagnostic techniques is crucial for effective management and control strategies. Furthermore, exploring the molecular mechanisms underlying TBEV pathogenesis and host interactions can offer valuable insights for developing novel therapeutics and preventive measures. This comprehensive review aims to consolidate recent research findings and enhance our understanding of TBEV, ultimately contributing to improved public health interventions and patient outcomes. [ABSTRACT FROM AUTHOR]

Alphaviruses are arthropod-borne viruses (i.e. arboviruses) transmitted by mosquitos that are classically divided into two groups that infect humans: encephalitic and arthralgia-associated. While the encephalitic alphaviruses are primarily endemic in North and South America, alphaviruses associated with arthralgia are distributed globally. Given the overlapping clinical manifestations of alphaviruses with other arboviruses, diagnosis is dependent on both exposure history and laboratory testing. In the United States, diagnostic approaches largely rely on detection of host antibodies against these viruses via enzyme-linked immunosorbent assays (ELISAs) or indirect immunofluorescence assays (IFAs) in serum and/or cerebrospinal fluid. Positive results can be confirmed by plaque reduction neutralization testing (PRNT), which remains the reference standard method for anti-alphavirus antibody detection. Increasingly, select public health and reference laboratories are also offering molecular testing for certain alphaviruses, including chikungunya virus and Eastern equine encephalitis virus. Molecular testing, however, is most useful in acutely ill, viremic patients who present within the first week of symptom onset. There are no targeted antivirals for treatment, and prevention relies on protection from mosquito bites. [ABSTRACT FROM AUTHOR]

ABSTRACT: Background: Herpes simplex encephalitis (HSE), caused by herpes simplex virus (HSV) is the most common cause of sporadic encephalitis that often presents as an emergency case of acute or sub-acute nature associated with poor prognosis. Early suspicion and prompt diagnostic testing with adequate antiviral therapy can only reduce morbidity and mortality associated with the disease. This study aims to evaluate the role of serological and molecular diagnosis of encephalitis caused by HSV 1 and 2 for timely detection of the disease. Methods: This cross-sectional study was conducted at the Department of Microbiology, Rajendra Institute of Medical Science, Ranchi, from April 2021 to September 2022. Cerebrospinal fluid (CSF) samples were collected and processed for the detection of HSV DNA by polymerase chain reaction (PCR) as well as serum samples were collected from those patients and were processed for the detection of IgM by ELISA. Results: A total of 188 CSF samples were collected, out of which 4 HSV-1 and 1 HSV-2 samples were found to be positive by conventional PCR. 36 samples were positive for HSV-1 and 2 IgM ELISA. 26.06% of cases belonged to patients between 0 and 10 years of age followed by 17.06% in 51-60 years age groups. Conclusion: PCR is the optimal diagnostic test, but the sample must be collected in the early stages of the disease. Diagnosis by PCR assay of CSF samples targeting HSV DNA is the best confirmatory test at hand for early detection and also helps in estimating the incidence of herpes simplex virus encephalitis. [ABSTRACT FROM AUTHOR]

Bilateral hemorrhagic thalamic lesions in dengue encephalitis resemble lesions seen in acute necrotizing encephalopathy (ANE). We investigate whether dengue-associated ANE (DANE) should be considered an ANE variant or a mimic. Systematic review of dengue encephalitis literature from PubMed and SCOPUS (inception to December 31, 2022). Diagnostic criteria for ANE, acute encephalitis (AE), acute disseminated encephalomyelitis (ADEM), and infection-triggered encephalopathy syndromes were applied. Data on 162 patients (median age 20 [0.4 to 79] years; 69 [42.3%] female; 72 [44.4%] aged ≤18 years) from 103 articles were analyzed. DANE (62, 38.3%) was the commonest, followed by AE (56, 34.6%) and ADEM (27, 16.7%). The main clinical features were fever (100%), thrombocytopenia (79.0%), headache (57.8%), and seizures (43.7%). Patients with DANE had earlier neurological deterioration (3.5 [1 to 8] vs 5 [1 to 14] days in other encephalitis syndromes, P = 0.0127), seizures (54.2% vs 37.4%, P = 0.0471), higher cerebrospinal fluid (CSF) protein (0.92 [0.18 to 4.8] vs 0.73 [1 to 16] g/L, P = 0.0469), thalamic (100% vs 8.0%) and hemorrhagic brain lesions (73.3% vs 7.5%, P < 0.0001). CSF pleocytosis and positive CSF dengue IgM/viral polymerase chain reaction were reported in 66.7% and 78.6% with DANE. Mortality was 16.1% in DANE, and 40.6% of survivors had disability. High-risk ANE severity scores predicted poor outcomes (positive predictive value 64.3% [95% confidence interval 38.8% to 83.7%]). DANE differs from other dengue encephalitis syndromes and is clinicoradiologically indistinguishable from sporadic ANE with sufficient evidence to be considered an ANE variant. [ABSTRACT FROM AUTHOR]

Background and Aims: Tick‐borne encephalitis (TBE) is a serious and acute central nervous system infection caused by the tick‐borne encephalitis virus (TBEV). In recent years, TBE has emerged as a growing public health threat, with cases reported across Europe, the Russian Far East, Japan and China. This study aims to assess the prevalence of TBEV infection and examine behaviours associated with an increased risk of infection among individuals who visited the Heilongjiang Red Cross Sengong General Hospital due to tick bites from 2020 to 2023. Methods and Results: We collected blood samples and administered survey questionnaires from tick‐bitten people. A total of 457 samples were screened using Nested PCR, and the detected TBEV prevalence rate was 29.54% (135/457). The symptoms of redness and swelling at the site of tick bite (42.57%), fever (28.71%) and headache (10.89%) were identified in the TBEV‐positive individuals when they visited the hospital by the physician. Phylogenetic analysis of the partial E gene of TBEV revealed that the predominant strains in the region are highly virulent Far Eastern subtype. However, they do not cluster with the three established evolutionary clades of the Far Eastern type. Questionnaires data analysis identified age and first tick bite as important factors associated with TBEV infection. Conclusions: This study provides basic information on the epidemiology of TBEV in Heilongjiang Province in recent years and identifies that the most related risk factor of infecting TBEV is tick exposure. Further research is needed to develop effective prevention and control measures. [ABSTRACT FROM AUTHOR]

Aims: Zoonotic arboviruses (arthropod‐borne) of the Orthoflavivirus genus, such as West Nile virus (WNV), Usutu virus (USUV) and Tick‐borne encephalitis virus (TBEV), are emerging in Northwestern Europe and pose a threat to both human and animal health. In the Netherlands, passive symptomatic surveillance (notification of clinical cases) in horses is one of the main pillars for the early detection of WNV. For such passive surveillance to work properly, horse owners and veterinarians need to recognize symptoms and report suspected cases to the authorities. Currently, little is known about the seroprevalence of orthoflaviviruses in domestic animals in the Netherlands. Therefore, this study aims at identifying the seroprevalence of WNV and USUV in horses and dogs in the Netherlands. Additionally, this study seeks to evaluate the knowledge and perceptions of Dutch horse owners towards mosquito‐borne viruses. Methods and Results: A cross‐sectional serosurvey in horses and dogs was conducted between May 2021 and May 2022. Serum samples were screened using an ELISA and doubtful and positive samples were confirmed by Virus Neutralization Tests for WNV, USUV and TBEV. A validated questionnaire, the MosquitoWise survey, was used to assess the knowledge and perceptions of Dutch horse owners towards mosquito‐borne viruses between July and October 2022. The serosurvey revealed a low seroprevalence for WNV in horses and no WNV‐positive dogs were found. Similarly, a low USUV seroprevalence was found in dogs. The MosquitoWise survey revealed a high knowledge level for horse owners and high awareness of WNV vaccination but a more limited intent to vaccinate. Conclusions: The low seroprevalences of WNV and USUV indicate many dogs and horses remain susceptible, offering opportunities for trend analysis and surveillance. However, despite multiple recent detections of WNV, USUV, and TBEV in humans, the role of dogs and horses in early detection of human cases is debatable. High awareness among horse owners and the absence of detected equine WNV cases highlight this uncertainty. Continued surveillance is crucial for detecting increased virus circulation and protecting both animal and human health. [ABSTRACT FROM AUTHOR]

Recommendations released by the CDC in 2023 address the need to demonstrate that the RNA genome of positive-strand RNA viruses is inactivated in addition to viral particles. This recommendation is in response to the similarities between host mRNA and the viral genome that allow the viral RNA to be used as a template by host replication mechanisms to produce infectious viruses; therefore, there is concern that through artificial introduction into host cells, active positive-strand RNA genomes can be utilized to produce infectious viruses out of a containment facility. Utilizing 10% formalin for 7 days or 2.5% glutaraldehyde/2% paraformaldehyde in 0.1 M cacodylate buffer (glut/PFA) for 2 days to fix eastern equine encephalitis virus (EEEV)-infected non-human primate (NHP) brain tissue was found to effectively inactivate EEEV particles and genomic RNA. The methods assessed in this paper outline an effective means to validate both genomic RNA and viral particle inactivation. [ABSTRACT FROM AUTHOR]

'Frozen' virus genome sequences are sampled from outbreaks and have unusually low sequence divergence when compared to genome sequences from historical strains. A growing number of 'frozen' virus genome sequences are being reported as virus genome sequencing becomes more common. Examples of 'frozen' sequences include the 1977 H1N1 'Russian' flu; Venezuelan Equine Encephalitis Virus from Venezuela and Colombia in 1995; E71 sequences from a Hand, Foot and Mouth outbreak in 2007–2009 in China; and a polio strain isolated in 2014 from Anhui, China. The origin of these 'frozen' sequences has been attributed to escapes from research facilities and often appears to be associated with vaccine work. Consequently, a new paradigm for pathogen emergence appears in operation, that involves laboratory research or vaccine production which utilizes 'live' virus isolates of historical strains. The accidental release and re-emergence of such strains are straightforward to detect from their genome sequences and should spur the routine sequencing and publication of all known pathogenic viral strains undergoing experimentation, or being used for vaccine manufacture, in order to facilitate tracing. However, it is noted that novel pathogenic viruses accidentally released into the population from research facilities are harder to detect if their sequence has first not been made public, which should prompt the routine sequencing and reporting of all novel pathogenic viruses before experimentation. [ABSTRACT FROM AUTHOR]

Reported tick‐borne‐encephalitis (TBE) cases have been increasing in Western Austria, but no data are available on vaccination‐ and infection‐specific seroprevalence. This study aimed to estimate current TBEV‐seroprevalence in the region and inform prevention programs by comparing anti‐NS1‐based‐incidence rates with reported case numbers and vaccination coverage. Between December 2023 and February 2024, serum samples from 4619 blood donors in Western Austria were collected and analyzed using TBEV‐ and WNV‐IgG‐ELISA assays. Seropositive samples were tested with a TBEV‐anti‐NS1‐IgG‐ELISA to distinguish infections from vaccinations. Borderline samples were retested with serum neutralization and triple‐NS1‐assays. The overall anti‐TBEV‐IgG‐seroprevalence was 80.1% (95%CI 78.9–81.3); 2.7% (95%CI 2.3–3.2) of donors tested positive for anti‐TBEV‐NS1 IgG antibodies, indicating previous infection. The notified incidence rate in Western Austria was 2.7/100 000/year, compared to 136.2/100 000/year based on anti‐TBEV‐NS1‐seropositive donors, denoting a substantial number of unreported cases (mean manifestation index 1.9%). The number of donors with TBEV‐infections varied considerably by district, highlighting potential hotspots for TBEV‐infections. The high anti‐NS1‐based, estimated annual TBE incidence rates show significant differences between districts, highlighting the need for targeted prevention programs. The high rate of undiagnosed TBE cases further suggests that estimated anti‐NS1‐based incidence rates should be considered when defining high‐risk areas. [ABSTRACT FROM AUTHOR]

Background: Approximately twenty-one years of historical mosquito abundance and species surveillance data, collected by the University of Notre Dame and the St. Joseph County (IN) Health Department, from 1976 to 1997 are made available following a data rescue effort. St. Joseph County is a county in Indiana, located on the Michigan-Indiana border, 35 miles from Lake Michigan. New information: The collected data will allow for trends in species to be followed over a wide time range and facilitate further research regarding mosquito-borne diseases, species distribution, phenology and ecological changes over time. [ABSTRACT FROM AUTHOR]

The emergence of Japanese encephalitis virus (JEV) in eastern Australia in 2022 caused extensive reproductive disease in pigs and is a threat to public health. Groups of weaned piglets were experimentally infected with the Australian outbreak strain of JEV (genotype 4). All pigs challenged at 5 weeks of age were infected after an intradermal injection of 1 × 105.5 (n = 4) or 1 × 104.5 TCID50/pig (n = 5). Intranasal instillation was less effective at this age, infecting 3/4 pigs with the same higher dose and 1/5 with the lower dose. Intradermal injection using 1 × 105.0 TCID50/pig also infected 9/9 pigs at 11 weeks of age. Infection in all cases was confirmed by qRT-PCR of blood samples, which identified a viremia peak at 3–4 days and detected JEV-specific antibodies as early as 5 days after the challenge. The detection of JEV in oral and nasal swabs and in saliva from chew ropes was less consistent. JEV was detected in the tonsils of 21/22 infected pigs and was isolated from the tonsils of 9/9 pigs sampled 19 days after the challenge at 11 weeks of age. The infected pigs showed no clinical signs other than pyrexia on Days 4–6. Histopathology consistent with JEV infection was evident in the nervous tissues of all but two pigs sampled 28 days after the challenge and was characterized by meningitis, encephalitis and gliosis throughout the brain. Serological studies showed extensive cross-reactivity between JEV and Murray Valley encephalitis virus using blocking ELISAs. However, the determination of limiting-dilution titres allowed for the identification of the infecting virus. This in vivo infection model will be useful in evaluating JEV vaccines and for comparative pathogenesis studies with other JEV genotypes. [ABSTRACT FROM AUTHOR]

Tick‐borne encephalitis virus (TBEV) can cause life‐threatening central nervous system infection. Changes in cerebrospinal fluid (CSF) metabolites may reflect critical aspects of host responses and end‐organ damage in neuro infection and neuroinflammation. In this study, we applied an untargeted metabolomics screen of CSF samples to investigate the metabolites profile and explore biomarkers for TBEV infection. By analyzing CSF samples from 77 patients with TBEV infection and 23 without TBEV infection, tryptophan metabolism and Citrate cycle were found to be the top important metabolic pathways in differentiating the control and case groups; acetoacetate, 5′‐deoxy‐5′‐(methylthio)‐adenosine, 3‐methyl‐2‐oxobutanoic acid, and so forth. were identified to be metabolic biomarkers (|log2 ${\mathrm{log}}_{2}$FC|> 1, VIP > 1, FDR < 0.05) in CSF and clearly separated the TBEV infection from the noninfected samples. Moreover, four metabolites were identified to be associated with fatal outcome, including kynurenic acid, 5‐hydroxyindole‐3‐acetic acid, DL‐tryptophan, indole‐3‐acrylic acid, demonstrating the potential predictive biomarkers for severe TBEV infection. This study explored the metabolic profile of TBEV infection in CSF samples and identified candidate biomarkers for TBEV infection, which might be useful in target screening for differential diagnosis and therapeutic inter‐vention. [ABSTRACT FROM AUTHOR]

Background: Hemophagocytic lymphohistiocytosis (HLH) is characterized by immune dysregulation that results in an uncontrolled hyperinflammatory state. HLH is classified into two main categories: primary (familial) HLH and secondary (acquired) HLH. Secondary HLH can result from various underlying, including infection-associated hemophagocytic syndrome (IAHS) and macrophage activation syndrome (MAS) associated with rheumatologic disorders, among others. Epstein–Barr virus (EBV) often causes IAHS, but central nervous system (CNS) involvement is rare among systemic lupus erythematosus (SLE) patients. We report a case of EBV encephalitis associated with HLH in a patient with childhood-onset SLE. Case presentation: A 12-year-old girl had received a diagnosis of SLE 2 months before presentation. After a period of inactive disease on treatment, fever and seizures, with altered mental status and hallucinations, developed over several weeks. A complete blood cell count (CBC) revealed pancytopenia, accompanied by elevated levels of inflammatory markers: 86 mm/hr erythrocyte sedimentation rate, 8.9 mg/dl c-reactive protein, and 3,966 ng/mL of ferritin. The differential diagnosis included active neuropsychiatric SLE, CNS infection and neurological manifestations in secondary HLH, which could have represented either IAHS or MAS. Meropenem and acyclovir were initially administered for clinical acute encephalitis, followed by pulse methylprednisolone; however, the fever persisted, and another CBC revealed progressive cytopenia. A bone marrow study showed hypocellularity and active hemophagocytic activity, and intravenous immunoglobulin was additionally given due to the diagnosis of HLH. Cerebrospinal fluid (CSF) analysis showed 60/mm3 white blood cells (N 55%, L 45%), 141 mg/dL glucose (0.7 blood-CSF glucose ratio), < 4 mg/dL protein; results of Gram stain and bacterial culture were negative. The viral encephalitis panel from the CSF confirmed EBV infection. Bone marrow immunohistochemistry examination revealed increasing levels of CD8 + T-cell and equivocal positive results for EBV-encoded RNA in situ hybridization; therefore, HLH potentially associated with EBV was diagnosed. After treatment with IVIg, cyclosporin A, and prednisolone, the patient's symptoms gradually improved and she was eventually able to return to school. Conclusions: Our case highlights the importance of a thorough differential diagnosis, including EBV encephalitis associated with HLH, in patients with childhood SLE, particularly in cases of clinical deterioration occurs after initial treatment. [ABSTRACT FROM AUTHOR]

Nipah virus (NiV) is a highly pathogenic Paramyxovirus associated with outbreaks in Malaysia, Bangladesh, and India with high mortality rates. NiV infection causes fatal respiratory and neurological disease. The majority of survivors suffer from long-term neurological sequelae or late onset and relapsed encephalitis. The pathogenesis of neurological disease is complex and has not been able to be studied in current animal models as they are skewed towards the development of lethal respiratory disease rather than neurological disease. Although NiV neurological disease can be observed in animal models, there is currently no model where the majority of animals consistently develop neurological disease. Here, we developed a new Syrian hamster (Mesocricetus auratus) model to mimic neurological disease in humans. Hamsters were inoculated intracranially in the cerebellomedullary cistern with different doses of NiV, strain Malaysia. Intracranial NiV inoculation in the cerebellomedullary cistern resulted in a rapid progression towards severe neurological disease requiring euthanasia. High Nipah viral loads were detected in the brains, and NiV spread from the CNS to the lungs. Histopathologic examination of the brain showed ischemic necrosis, often accompanied by marked edema and hemorrhage. NiV antigen was detected primarily in meninges and cerebellum, but rarely observed in brain parenchyma. These histological lesions were different from the typical lesions observed in NiV-infected humans. Thus, despite the consistent development of neurological disease, intracranial inoculation does not result in a model representative of NiV neurological disease. Author summary: Nipah virus causes outbreaks of severe respiratory and neurological disease in Bangladesh and India. The majority of Nipah virus-infected patients succumb to the disease; survivors often suffer from lasting neurological consequences of infection. Although Nipah virus infection of the brain is thus an important component of Nipah virus disease, most studies to date have focused on the severe respiratory disease also caused by Nipah virus. In an attempt to develop a robust model to study Nipah virus neurological disease, we infected Syrian hamsters with Nipah virus by injecting the virus directly into the cerebellomedullary cistern in the brain. Animals quickly developed severe neurological disease requiring euthanasia and the virus could be detected at high levels in the brain, and lower levels in the lungs. Interestingly, the changes observed in the brains of infected animals were not the same as those observed in Syrian hamsters infected via other routes, nor those observed in human cases of Nipah virus infection in Malaysia, indicating that the inoculation route determines the course of disease in the brain. [ABSTRACT FROM AUTHOR]

Background: Tuberculous meningitis (TBM) with adults Epstein-Barr (EB) virus encephalitis is a very rare infectious disease, with a high mortality and disability. Metagenomic next-generation sequencing (mNGS) of cerebrospinal fluid (CSF) is highly diagnostic. We report on a case of severe meningoencephalitis caused by coinfection with mycobacterium tuberculosis and EB virus. Brain MRI indicated a parenchyma lesion in the brain. mNGS of CSF indicated Mycobacterium tuberculosis and EB virus amplification, positive serum EB virus IgG antibodies, and improved symptoms after anti-tuberculosis and antiviral treatment. A reexamination of the brainMRI revealed that the significantly absorption of the lesions. Case report: A 49-year-old male patient presented with a chief complaint of headache and fever with consciousness disturbance. The brain magnetic resonance imaging showed a lesions in the right parenchymal brain with uneven enhancement, accompanied by significantly increased intracranial pressure, elevated CSF cell count and protein levels, as well as notably decreased glucose and chloride levels. mNGS of CSF showed the coexistence of Mycobacterium tuberculosis and EBV. The patient was diagnosed as TBM with EBV encephalitis. The patient's symptoms gradually improved with the active administration of anti-tuberculosis combined with antiviral agents, the use of hormones to reduce inflammatory reaction, dehydration to lower intracranial pressure, and intrathecal injection. Subsequent follow-up brain magnetic resonance imaging indicated significant absorption of the lesions, along with a marked decrease in CSF count and protein levels, as well as obvious increase in glucose and chloride levels. Conclusion: TBM associated with adult EBV encephalitis is extremely rare. The disease's early stages are severe and have a high fatality rate. A prompt and accurate diagnosis is particularly important. NGS of CSF is of great value for early diagnosis. [ABSTRACT FROM AUTHOR]

Torque teno virus (TTV) is a ssDNA orphan virus belonging to the Anelloviridae family, but some recent studies suggested its possible involvement in central nervous system (CNS) pathology. We analyzed serum and cerebrospinal fluid samples (CSF) from 109 patients with encephalitis for TTV infection using serological and molecular testing, virus quantitative measurement, and next-generation sequencing-based (NGS) phylogenetic analysis. TTV noncoding region (UTR) and/or open reading frame 1 (ORF-1) sequences were detected in serum of 86 (79%) patients and in nine (8%) patients in CSF. Five of the latter patients were coinfected with various entero- and herpesviruses. Anti-TTV-IgG were detected in 80 (73.4%) sera and in two (1.8%) CSF samples, while anti-TTV-IgM were present in three (2.8%) sera and in none of the CSFs. Phylogenic analysis of CSF-derived TTV ORF-1 sequences revealed the presence of three unique variants in one patient. TTV was quantified in five CSF-serum pairs: in two patients viral loads were similar, and in three serum TTV loads were approximately one log higher. Our results suggest at least an occasional replication of TTV in CNS. However, whether TTV could be the cause of encephalitis requires further studies. [ABSTRACT FROM AUTHOR]

Background Borna disease virus 1 (BoDV-1) causes rare but severe zoonotic infections in humans, presenting as encephalitis. The case-fatality risk is very high and no effective countermeasures have been established so far. An immunopathology is presumed, while data on immune responses in humans are limited. Evidence of a role of the complement system in various neurological disorders and in viral infections of the central nervous system is increasing and specific inhibitors are available as therapeutic options. Methods In this study, we investigated factors of the complement system in the cerebrospinal fluid (CSF) of patients with BoDV-1 infections (n = 17) in comparison to noninflammatory control CSF samples (n = 11), using a bead-based multiplex assay. In addition, immunohistochemistry was performed using postmortem brain tissue samples. Results We found an intrathecal elevation of complement factors of all complement pathways and an active cascade during human BoDV-1 infections. The increase of certain complement factors such as C1q was persistent, and C3 complement deposits were detected in postmortem brain sections. Intrathecal complement levels were negatively correlated with survival. Conclusions Further investigations are warranted to clarify whether targeting the complement cascade by specific inhibitors might be beneficial for patients suffering from severe BoDV-1 encephalitis. [ABSTRACT FROM AUTHOR]

Background: Madariaga virus (MADV), a member of the eastern equine encephalitis virus (EEEV) complex, circulates in Latin America and exhibits distinct evolutionary and ecological features compared to the North American EEEV. While published data have shed light on MADV ecology, several key aspects remain unknown. Methods: In this study, we compiled data on virus isolation, vector competence, and animal serology collected over six decades in Latin America to identify critical knowledge gaps on MADV transmission and ecology. Results: Specific vertebrate animals serving as amplifying hosts and the mosquito species acting as enzootic and epizootic vectors have not yet been identified. Other aspects that remain unclear are the virus current geographic distribution, the role of equines as hosts in epizootic cycles, and the full impact of MADV on human health in endemic regions. Conclusions: The numerous knowledge gaps surrounding MADV, its widespread distribution in Latin America, and its potential to cause severe disease in animals and humans emphasize the urgent need for increased research efforts, heightened awareness, and intensified surveillance towards this potential emerging threat. [ABSTRACT FROM AUTHOR]

West Nile virus (WNV) and St. Louis encephalitis virus (SLEV) are closely related flaviviruses that can cause encephalitis in humans and related diseases in animals. In nature, both are transmitted by Culex, with wild birds, including jays, sparrows, and robins, serving as vertebrate hosts. WNV and SLEV circulate in the same environments and have recently caused concurrent disease outbreaks in humans. The extent that coinfection of mosquitoes or birds may alter transmission dynamics, however, is not well characterized. We therefore sought to determine if coinfection alters infection kinetics and virus levels in birds and infection rates in mosquitoes. Accordingly, American robins (Turdus migratorius), two species of mosquitoes, and vertebrate and invertebrate cells were infected with WNV and/or SLEV to assess how simultaneous exposure may alter infection outcomes. There was variable impact of coinfection in vertebrate cells, with some evidence that SLEV can suppress WNV replication. However, robins had comparable viremia and antibody responses regardless of coinfection. Conversely, in Culex cells and mosquitoes, we saw a minimal impact of simultaneous exposure to both viruses on replication, with comparable infection, dissemination, and transmission rates in singly infected and coinfected mosquitoes. Importantly, while WNV and SLEV levels in coinfected mosquito midguts were positively correlated, we saw no correlation between them in salivary glands and saliva. These results reveal that while coinfection can occur in both avian and mosquito hosts, the viruses minimally impact one another. The potential for coinfection to alter virus population structure or the likelihood of rare genotypes emerging remains unknown. [ABSTRACT FROM AUTHOR]

Western equine encephalitis virus (WEEV) is a mosquito-borne arbovirus (genus Alphavirus, family Togaviridae) that has re-emerged in South America in late 2023, causing severe disease in both horses and humans after a nearly 40-year intermission period. We here describe the virological, serological, pathological, and molecular features of WEEV infection in horses during the 2023–2024 outbreak in Argentina. WEEV-infected horses developed neurological signs with mild to severe encephalitis associated with minimal to abundant WEEV-infected cells, as demonstrated by WEEV-specific in situ hybridization. The distribution of viral RNA was multifocal, with predominance within neuronal bodies, neuronal processes, and glial cells in the medulla oblongata and thalamic regions. Phylogenetic analysis of partial nsP4 sequences from three viral isolates obtained from three different provinces of Argentina support grouping with other temporally current WEEV strains from Uruguay and Brazil under a recently proposed novel lineage. [ABSTRACT FROM AUTHOR]

Background: Herpes simplex virus encephalitis (HSE) frequently triggers secondary anti-N-methyl-d-aspartate receptor encephalitis (NMDARE), but markers predicting the occurrence of this entity (HSE-NMDARE) are lacking. Methods: We conducted a retrospective description of patients with HSE-NMDARE diagnosed between July 2014 and August 2022 and compared them to both patients with regular forms of HSE and NMDARE. Results: Among the 375 patients with NMDARE, 13 HSE-NMDARE were included. The median age was 19 years (0.5–73), 4/13 (31%) were children < 4 years old, and 7/13 (54%) were male. The median time between HSE and NMDARE onset was 30 days (21–46). During NMDARE, symptoms differed from HSE, including increased behavioral changes (92% vs 23%, p = 0.008), movements disorders (62% vs 0%, p = 0.013), and dysautonomia (54% vs 0%, p = 0.041). Compared to 21 patients with regular HSE, patients with HSE-NMDARE more often achieved severity-associated criteria on initial MRIs, with extensive lesions (11/11, 100% vs 10/21, 48%, p = 0.005) and bilateral diffusion-weighted imaging sequence abnormalities (9/10, 90% vs 6/21, 29%, p = 0.002). Compared to 198 patients with regular NMDARE, patients with HSE-NMDARE were more frequently males (7/13, 54% vs 43/198, 22%; p = 0.015) and children < 4 (4/13, 31% vs 14/198, 7%; p = 0.016), with a worse 12-month mRS (2[1–6] vs 1[0–6], p = 0.023). Conclusions: Herein, patients with HSE-NMDARE have a poorer long-term prognosis than patients with regular NMDARE. We report a greater rate of severity-associated criteria on initial MRIs for HSE-NMDARE compared to regular HSE, which may help identify patients with higher risk of HSE-NMDARE. [ABSTRACT FROM AUTHOR]

The list of standard abbreviations for JDS is available at adsa.org/jds-abbreviations-24. Nonstandard abbreviations are available in the Notes. In French dairy goat systems, kids are generally separated from their mother does shortly after birth. The main drivers of this practice are related to health—especially the prevention of the caprine arthritis encephalitis virus (CAEV) transmission—and economics. However, the separation of young ruminants from their does is being increasingly questioned by society and has raised concerns about the satisfaction of their behavioral needs. Some farmers choose to leave their female kids with their does. The aims of this study were to understand their motivations for leaving kids with their does, to describe how kids are reared in this case and how farmers perceive different aspects of the effects of this practice. Individual semi-structured interviews were carried out with 40 farmers who had implemented the kids-with-does practice for at least 1 yr. Compared with the national database describing the French population of dairy goat farmers, the characteristics of the interviewed farmers differed from those of the general population. They were younger and had done longer studies. Their farms were smaller, mainly with rare breeds, and milk was mainly processed on-farm under an organic certification system. They chose to implement this practice for different reasons: ethical considerations, improving integration of kids within the herd, saving time, and increasing comfort at work or improving the kids' growth, welfare, and health. The doe-kid rearing contact practices varied greatly between farms, with some kids staying with their does from a period of 45 d to never being separated; furthermore, some kids remained with their does all day, whereas others remained together part of the day or for a limited time, and daily contact evolved over time. Overall, farmers were satisfied as the benefits quoted were coherent with their motivations to implement this rearing practice. Most have decided to continue the practice, though usually with changes. However, as 40% of them had only 3 yr or less of experience of doe-kid rearing, some had not sufficient hindsight into long-term issues such as the transmission of CAEV. It is crucial to tackle challenges associated with this practice (i.e., potentially wild kids, health issues, and economic consequences stemming from a reduction in marketable milk). [ABSTRACT FROM AUTHOR]

This study focused on analyzing vector-borne diseases (VBDs) in horses, an emerging and re-emerging global issue that affects both equine health and the industry due to economic losses caused by treatments and restrictions on trade. The main diseases of this type include equine piroplasmosis, equine anaplasmosis, and equine encephalitis, caused by pathogens such as Theileria equi, Babesia caballi, Anaplasma phagocytophilum, and viruses transmitted by vectors like ticks, mosquitoes, and flies. The methodology involved a review of studies on pathogens and their vectors, specifically arthropods, and the clinical signs of each disease. Diagnosis is carried out using microscopic examinations, PCR, and serological tests, while treatments range from imidocarb and oxytetracycline to supportive care for encephalitis viruses. The results showed that equine health faces numerous challenges due to the variety of pathogens and vectors, complicating the diagnosis and control of these diseases. It is concluded that implementing epidemiological surveillance strategies, vector control, and early treatment are essential to mitigating the economic and health impacts of these infections. Prevention and management require a multidisciplinary approach, with early warning systems to anticipate outbreaks and initiate immediate interventions to protect equine health and the industry. [ABSTRACT FROM AUTHOR]

Rift Valley fever (RVF) is a mosquito-borne viral zoonosis that causes high fetal and neonatal mortality rates in ruminants and sometimes severe to fatal complications like encephalitis and hemorrhagic fever in humans. There is no licensed RVF vaccine for human use while approved livestock vaccines have suboptimal safety or efficacy. We designed self-amplifying RNA (saRNA) RVF vaccines and assessed their humoral immunogenicity in mice. Plasmid DNA encoding the Rift Valley fever virus (RVFV) medium (M) segment consensus sequence (WT consensus) and its derivatives mutated to enhance cell membrane expression of the viral surface glycoproteins n (Gn) and c (Gc) were assessed for in vitro expression. The WT consensus and best-expressing derivative (furin-T2A) were cloned into a Venezuelan equine encephalitis virus (VEEV) plasmid DNA replicon and in vitro transcribed into saRNA. The saRNA was formulated in lipid nanoparticles and its humoral immunogenicity in BALB/c mice was assessed. High quantities of dose-dependent RVFV Gn IgG antibodies were detected in the serum of all mice immunized with either WT consensus or furin-T2A saRNA RVF vaccines. Significant RVFV pseudovirus-neutralizing activity was induced in mice immunized with 1 µg or 10 µg of the WT consensus saRNA vaccine. The WT consensus saRNA RVF vaccine warrants further development. [ABSTRACT FROM AUTHOR]

Venezuelan equine encephalitis virus (VEEV) is a mosquito-borne +ssRNA virus belonging to the Togaviridae. VEEV is found throughout Central and South America and is responsible for periodic epidemic/epizootic outbreaks of febrile and encephalitic disease in equines and humans. Endemic/enzootic VEEV is transmitted between Culex mosquitoes and sylvatic rodents, whereas epidemic/epizootic VEEV is transmitted between mosquitoes and equids, which serve as amplification hosts during outbreaks. Epizootic VEEV emergence has been shown to arise from mutation of enzootic VEEV strains. Specifically, epizootic VEEV has been shown to acquire amino acid mutations in the E2 viral glycoprotein that facilitate viral entry and equine amplification. However, the abundance of synonymous mutations which accumulate across the epizootic VEEV genome suggests that other viral determinants such as RNA secondary structure may also play a role in VEEV emergence. In this study we identify novel RNA structures in the E1 gene which specifically alter replication fitness of epizootic VEEV in macrophages but not other cell types. We show that SNPs are conserved within epizootic lineages and that RNA structures are conserved across different lineages. We also identified several novel RNA-binding proteins that are necessary for altered macrophage replication. These results suggest that emergence of VEEV in nature requires multiple mutations across the viral genome, some of which alter cell-type specific replication fitness in an RNA structure-dependent manner. Author summary: Understanding how viral pathogens emerge is critical for ongoing surveillance and outbreak preparedness. However, our understanding of the molecular mechanisms that drive viral emergence are still not completely understood. Emergence of the mosquito-borne virus Venezuelan equine encephalitis virus (VEEV) is known to require mutations in the viral attachment protein (E2), which drive viremia and transmission. We have observed that emergent strains (epizootic VEEV) also accumulate many silent mutations, suggesting that other determinants independent of protein sequence also contributes to emergence. In this study we identify novel RNA secondary structures associated with epizootic VEEV that alters viral replication in a cell-type dependent manner. We show that these RNA structures are conserved across epizootic viruses and identify host proteins that specifically bind these RNAs. These findings imply that viral emergence requires multiple mutations, a number of which likely alter viral structure in a manner that benefits viral replication and transmission. [ABSTRACT FROM AUTHOR]

More than 75 arboviruses are indigenous to Australia, of which at least 13 are known to cause disease in humans. Alphaviruses are the most common arboviruses, notably including Ross River and Barmah Forest viruses, which contribute a significant public health and economic burden in Australia. Both can cause febrile illness with arthritic symptoms. Each circulates nationally across diverse climates and environments, and has multi-host, multi-vector dynamics. Several medically important flaviviruses also circulate in Australia. Infection with Murray Valley encephalitis or Kunjin viruses is less common but is associated with brain inflammation. Key research priorities for Australian arboviruses aim to understand clinical manifestations, develop timely diagnostics, and identify transmission cycles that permit the maintenance of arboviruses. While these can now be answered for a handful of notifiable alpha- and flaviviruses there are others for which non-human vertebrate hosts and competent arthropod invertebrate vectors are still to be identified and/or whose role in transmission is not well understood. One or more of these 'neglected' arboviruses may be the causative agent of a proportion of the many thousands of fever-related illnesses reported annually in Australia that at present remain undiagnosed. Here, what is known about enzootic cycling of viruses between arthropod vectors and mammalian and avian reservoir hosts is summarised. How and to what extent these interactions influence the epidemiology of arbovirus transmission and infection is discussed. [ABSTRACT FROM AUTHOR]

Western equine encephalitis virus (WEEV) is a mosquitoborne virus that reemerged in December 2023 in Argentina and Uruguay, causing a major outbreak. We investigated the outbreak using epidemiologic, entomological, and genomic analyses, focusing on WEEV circulation near the Argentina‒Uruguay border in Rio Grande do Sul state, Brazil. During November 2023‒April 2024, the outbreak in Argentina and Uruguay resulted in 217 human cases, 12 of which were fatal, and 2,548 equine cases. We determined cases on the basis of laboratory and clinical epidemiologic criteria. We characterized 3 fatal equine cases caused by a novel WEEV lineage identified through a nearly complete coding sequence analysis, which we propose as lineage C. Our findings highlight the importance of continued surveillance and equine vaccination to control future WEEV outbreaks in South America. [ABSTRACT FROM AUTHOR]

Background: Climate change is likely to increase the risk of human transmission of arboviruses endemic to Canada, including West Nile virus (WNV), Eastern equine encephalitis virus (EEEV) and California serogroup virus (CSV), calling for enhanced surveillance, including entomological surveillance targeting mosquito vectors. A scoping review was carried out to document the public health contributions of entomological surveillance of arboviruses of importance in Canada. Methods: The Ovid® and EBSCO platforms and the grey literature were searched to identify documents published between 2009 and 2023, in English or French, dealing with entomological surveillance of arboviruses of interest, conducted annually for human health purposes under the aegis of a government authority, with specified public health objectives and actions. Results: The 42 selected publications mainly reported two public health objectives of adult mosquito surveillance: early warning of viral circulation and assessment of the level of risk of human transmission. Recommended actions included clinical preparedness, risk communication, promotion of personal protection measures and vector control. The main objectives of immature mosquito surveillance were to identify sites with high larval densities, in order to reduce/eliminate them and target the application of larvicides. Conclusion: In a context of climate change favouring the spread of arboviruses, this study highlights the potential public health contributions of regular entomological surveillance of endemic arboviruses of importance in Canada. It helps support concrete actions to protect the health of the population from the risks of arboviral transmission. [ABSTRACT FROM AUTHOR]

It is well known that N-methyl-D-aspartate receptor encephalitis (NMDARE) can be triggered by infectious encephalitis such as herpes simplex virus 1 encephalitis (HSE). However, the incidence of post-HSE NMDARE in Denmark is unknown. We reviewed literature cases and compared these to retrospectively identified cases of post-HSE NMDARE in Denmark, using a national cohort database of autoimmune encephalitis (AE) and two regional databases of infectious encephalitis patients. We identified 80 post-HSE NMDARE cases in the literature, 66% being children, who more often presented movement disorders, decreased consciousness, and sleep disturbances compared to adults. Eight patients with post-HSE NMDARE were identified from the national cohort database of AE, none being children. Forty-four HSE patients were identified from the regional infectious encephalitis databases. Of these, 16 (36%) fulfilled the Graus criteria for probable/definite NMDARE, and eight (18%) presented a prolonged/relapsing disease course. Ten (23%) were tested for AE during hospitalization. Six (14%) had leftover cerebrospinal fluid available for retrospective autoantibody testing. One out of these six patients (17%) harbored NMDARE antibodies. Thus, in total, nine post-HSE NMDARE patients have been identified in Denmark from 2009 to 2021. Comparing the adult Danish patients to the literature, Danish patients were older, but the clinical phenotype and paraclinical findings were similar. Overall, the incidence of adult post-HSE NMDARE in the Region of Southern Denmark was 0.17 per million people per year and only 7% of adult HSE patients in the region were diagnosed with post-HSE NMDARE. Our findings suggest that adult patients are still underdiagnosed and the absence of pediatric cases diagnosed with post-HSE NMDARE in Denmark is highly concerning. [ABSTRACT FROM AUTHOR]

This article discusses a case of Powassan virus encephalitis in a 9-year-old boy in Canada. Powassan virus is a tick-borne flavivirus that can cause encephalitis and has a high mortality rate. The boy presented with fever, neck stiffness, and headache after attending a summer camping trip. He experienced neurological symptoms and was eventually diagnosed with Powassan virus encephalitis. The article emphasizes the importance of considering arthropod-borne infections in patients with encephalitis, increasing awareness among clinicians, and reporting cases to public health authorities. [Extracted from the article]

Maedi-visna virus (MVV) and caprine arthritis encephalitis virus (CAEV) are members of a group of genetically highly homologous lentiviruses collectively referred to as small ruminant lentiviruses (SRLVs). SRLVs can infect sheep, goats and other small ruminants, causing multisystemic disease with progressive and persistent inflammatory changes, severely reducing animal productivity and impeding animal trade. The capsid protein of SRLVs, p28, is highly conserved among strains and is a commonly used marker for the detection of SRLVs. In this study, two monoclonal antibodies (mAbs), designated G8F7 and A10C12, against p28 were generated using a recombinant p28 protein expressed in Escherichia coli as an immunogen. Functional analysis showed that these two monoclonal antibodies could be used in iELISA, immunofluorescence assays (IFA) and western blot assays to detect p28 or Gag precursor proteins of SRLVs. Two linear epitopes, 61GNRAQKELIQGKLNEEA77 (E61-77) and 187CQKQMDRVLGTRVQQATVEEKMQACR212 (E187-212), which are recognized by G8F7 and A10C12, respectively, were identified through truncation of the GST-fused p28. Amino acid sequence alignment showed that the epitope E61-77 is conserved among SRLVs, with a dominant mutation site (K72R) that does not disrupt recognition by G8F7. E187-212 was found to exhibit variability among SRLVs, but the majority of mutant epitopes are recognized by A10C12, with the exception of a mutant epitope from an isolate with undefined subtypes from Ovis aries, which was not recognized. These findings may facilitate future study of SRLVs and promote the development of methods for the detection of these viruses. [ABSTRACT FROM AUTHOR]

Tick‐borne pathogens (TBPs) are an emerging concern to humans and animals in the Republic of Korea, especially within the military zones of Gangwon Province, a mountainous region abundant with wild fauna and ticks. This study aimed to detect six TBPs in military working dogs (MWDs) and ticks in this region using Nested polymerase chain reaction (nested PCR) and sequencing. The targeted pathogens included Anaplasma phagocytophilum, Bartonella henselae, Borrelia spp., Orientia tsutsugamushi, Severe fever with thrombocytopenia syndrome virus (SFTSV) and tick‐borne encephalitis virus (TBEV). A total of 164 serum samples from MWDs were collected at the Korean Army Military working dog training center and 1418 ticks were collected at various training sites between June 2021 and August 2022. Haemaphysalis longicornis was identified as the predominant species (98.3%, n = 1394), followed by Haemaphysalis flava (1.6%, n = 22) and Ixodes nipponensis (0.1%, n = 2). This study detected A. phagocytophilum and Borrelia theileri in 1.4% (1/72) of the tick pools and detected SFTSV in 0.6% (1/164) of MWD serum samples. The MWD found to be infected with SFTS was a German Shepherd, but showed no significant clinical signs, with a normal complete blood count (CBC). In the phylogenetic analysis, three sequences were acquired. One sequence (OR865211) exhibited 100% homology with 16S rRNA of A. phagocytophilum identified from animals and human patients in the Republic of Korea. Another sequence (OR865152) displayed 99.34%–100% sequence similarity with 16S rRNA of B. theileri fragments. The third sequence (OR865115), which belongs to the SFTS B‐1 genotype, showed 94.7% sequence similarity to a strain identified in the Republic of Korea (KY789441). [ABSTRACT FROM AUTHOR]

Mosquitoes are of great concern in many countries. Culex pipiens L. (Diptera:Culicidae) is the vector of the West Nile virus and Usutu Viruses. Intense use of insecticidal agents has resulted in increased mosquitocidal resistance, and thereby search for new effective mosquitocidal agents. In this context, we have explored the larvicidal potential of Phoenician juniper [Juniperus phoenicea L. (Fam. Cupressaceae)] against Cx. pipiens and studied the chemical composition of the leaf extract. Fresh leaves of J. phoenicea were macerated in 70% methanol. The LC50 at 24, 48 and 72 h post-treatment with methanol extract were 7.14, 3.97 and 3.17 µg/mL, respectively, against Cx. pipiens larvae. In treated larvae, the cells lost integrity, nucleus and cell membrane damage, basal lamina detached, and lost nuclear and cytoplasmic materials. From GC--MS analysis, 19 compounds were detected. Some of the phytochemicals detected in J. phoenicea extract were 9,12-octadecadienoic acid (Z,Z)-(50.2.%), podocarpa-8,11,13-trien-3-one, 14-isopropyl-13-methoxy-(13.2%), -Amino-7,10-dimethyldibenzo [b,f][1,4]oxazepin-11(10H)-one (8.4%), and n-hexadecanoic acid (5.6%). J. phoenicea offered promising larvicidal activity against Cx. pipiens. [ABSTRACT FROM AUTHOR]

Introduction: Identifying coronavirus disease 2019 (COVID-19)-related encephalitis without clear etiological evidence is clinically challenging. The distinctions between this condition and other prevalent encephalitis types remain unknown. Therefore, we aimed to explore the similarities and differences in the clinical characteristics of COVID-19-related encephalitis and other encephalitis types. Methods: Adult patients with encephalitis admitted to the neurology department at Xuanwu Hospital were enrolled and categorized into the following six groups based on the results of metagenomic next-generation sequencing and autoimmune antibody detection in cerebrospinal fluid (CSF): COVID-19-related encephalitis (n = 36), herpes simplex virus type 1 encephalitis (HSV-1 encephalitis; n = 28), human herpesvirus 3 encephalitis (HHV-3 encephalitis; n = 10), NMDAR-antibody encephalitis (n = 18), LGI1-antibody encephalitis (n = 12), and GABAB-antibody encephalitis (n = 8). Results: The predominant characteristics of COVID-19-related encephalitis include a low incidence of seizures (38.9%), cognitive defects (30.6%), and meningeal irritation signs (8.3%). Compared with HSV-1 and HHV-3 encephalitis, COVID-19-related encephalitis exhibited lower white blood cell count (2.5 count/mm3), protein (32.2 mg/dL), and immunoglobulin M, G, and A levels (0.09, 3.2, and 0.46 mg/dL, respectively) in the CSF tests. Abnormal imaging findings were present in only 36.1% of COVID-19-related encephalitis cases, mostly showing diffuse inflammation scattered in various parts, which differed from HSV-1 encephalitis. Additionally, COVID-19-related encephalitis exhibited significant differences in clinical symptoms and CSF white blood cell counts compared with NMDAR-antibody encephalitis; however, it showed limited differences compared with LGI1-antibody and GABAB-antibody encephalitis. Discussion: COVID-19-related encephalitis and herpes virus or autoimmune encephalitis differ clinically. Symptoms and auxiliary examinations can be used as distinguishing tools. [ABSTRACT FROM AUTHOR]

Many aspects of the life cycle and genetics of (+)RNA viruses are directed by their genome replication organelles (ROs), which form as spherular membrane invaginations (this review's primary focus) or double-membrane vesicles. Recent cryo-electron microscopy (cryo-EM) studies have transformed understanding of RO structure and assembly. RO membrane vesicles containing dsRNA replication intermediates are gated to the cytosol by ringed 'crown' complexes of viral RNA replication proteins that direct synthesis, 5′ capping, and release of new mRNA-sense genomic and subgenomic RNAs. Although nodaviruses and alphaviruses are only distantly related, their RO crowns conserve 12-fold symmetry, key enzymatic and structural motifs, and multistage assembly. Continuing studies should enable new antiviral controls and reveal how crown assembly steps are coupled to viral (−)RNA and (+)RNA synthesis, RO vesicle formation, and progeny RNA transfer to translation, new RO formation, and encapsidation. Positive-strand RNA [(+)RNA] viruses include pandemic SARS-CoV-2, tumor-inducing hepatitis C virus, debilitating chikungunya virus (CHIKV), lethal encephalitis viruses, and many other major pathogens. (+)RNA viruses replicate their RNA genomes in virus-induced replication organelles (ROs) that also evolve new viral species and variants by recombination and mutation and are crucial virus control targets. Recent cryo-electron microscopy (cryo-EM) reveals that viral RNA replication proteins form striking ringed 'crowns' at RO vesicle junctions with the cytosol. These crowns direct RO vesicle formation, viral (−)RNA and (+)RNA synthesis and capping, innate immune escape, and transfer of progeny (+)RNA genomes into translation and encapsidation. Ongoing studies are illuminating crown assembly, sequential functions, host factor interactions, etc., with significant implications for control and beneficial uses of viruses. [ABSTRACT FROM AUTHOR]

Tick‐borne encephalitis (TBE) virus is considered the medically most important arthropod‐borne virus in Europe. Although TBE is endemic throughout central Europe, ticks and rodents determine its maintenance in small, difficult‐to‐assess, natural foci. We investigated the interrelation between the population genetics of the main TBE virus (TBEV) vector tick (Ixodes ricinus), the most important reservoir host (Myodes glareolus, syn. Clethrionomys glareolus), and TBEV. Rodents and ticks were sampled on 15 sites within an exploratory study area, which has been screened regularly for TBEV occurrence in ticks for more than 10 years. On all 15 sites, ticks and bank voles were sampled, screened for TBEV presence via serology and RT‐PCR, and genetically examined. Moreover, TBEV isolates derived from these analyses were sequenced. In long‐term TBEV foci bank vole populations show extraordinary genetic constitutions, leading to a particular population structure, whereas ticks revealed a panmictic genetic structure overall sampling sites. Landscape genetics and habitat connectivity modeling (analysis of isolation by resistance) showed no landscape‐related barriers explaining the genetic structure of the bank vole populations. The results suggest that bank voles do not simply serve as TBEV reservoirs, but their genetic composition appears to have a significant influence on establishing and maintaining long‐term natural TBEV foci, whereas the genetic structure of TBEV's main vector I. ricinus does not play an important role in the sustainability of long‐term TBEV foci. A thorough investigation of how and to which extent TBEV and M. glareolus genetics are associated is needed to further unravel the underlying mechanisms. [ABSTRACT FROM AUTHOR]