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BACKGROUND: As a primary vector of bluetongue virus (BTV) in the US, seasonal abundance and diel flight activity of Culicoides sonorensis has been documented, but few studies have examined how time of host-seeking activity is impacted by environmental factors. This knowledge is essential for interpreting surveillance data and modeling pathogen transmission risk. METHODS: The diel host-seeking activity of C. sonorensis was studied on a California dairy over 3 years using a time-segregated trap baited with CO2. The relationship between environmental variables and diel host-seeking activity (start, peak, and duration of activity) of C. sonorensis was evaluated using multiple linear regression. Fishers exact test and paired-sample z-test were used to evaluate the seasonal difference and parity difference on diel host-seeking activity. RESULTS: Host-seeking by C. sonorensis began and reached an activity peak before sunset at a higher frequency during colder months relative to warmer months. The time that host-seeking activity occurred was associated low and high daily temperature as well as wind speed at sunset. Colder temperatures and a greater diurnal temperature range were associated with an earlier peak in host-seeking. Higher wind speeds at sunset were associated with a delayed peak in host-seeking and a shortened duration of host-seeking. Parous midges reached peak host-seeking activity slightly later than nulliparous midges, possibly because of the need for oviposition by gravid females before returning to host-seeking. CONCLUSIONS: This study demonstrates that during colder months C. sonorensis initiates host-seeking and reaches peak host-seeking activity earlier relative to sunset, often even before sunset, compared to warmer months. Therefore, the commonly used UV light-baited traps are ineffective for midge surveillance before sunset. Based on this study, surveillance methods that do not rely on light trapping would provide a more accurate estimate of host-biting risk across seasons. The association of environmental factors to host-seeking shown in this study can be used to improve modeling or prediction of host-seeking activity. This study identified diurnal temperature range as associated with host-seeking activity, suggesting that Culicoides may respond to a rapidly decreasing temperature by shifting to an earlier host-seeking time, though this association needs further study.

BACKGROUND: There is only limited information on the clinical presentation, medical management, and outcomes of hospitalized sheep diagnosed with bluetongue virus (BTV) disease. OBJECTIVES: To describe the signalment, history, clinical signs, clinicopathological findings, medical management, and clinical outcomes of sheep diagnosed with BTV disease. ANIMALS: Thirty-five hospitalized sheep with BTV disease. METHODS: Retrospective case series. Medical records from 1989 to 2021 were evaluated. History, signalment, clinical signs, laboratory test results, treatments, and outcomes were recorded. RESULTS: BTV disease was diagnosed from July to December, with a peak proportion (43%; 15/35) of diagnoses recorded in October. Pyrexia and anorexia, respiratory disease, vasculitis, coronitis and lameness, and ulcerative mucosal lesions were present in 71%, 71%, 66%, 49%, and 22% of sheep, respectively. BTV serotypes 10, 11, 13, and 17 were identified, with serotype 17 (75%) being the most frequent. Management of cases included administration of antimicrobials (89%), anti-inflammatories (77%), IV fluids (60%), vitamins (20%), proton-pump inhibitors (14%), diuretics (9%), and antioxidants (9%). Six ewes were pregnant on presentation, but none aborted. Six (17%) sheep died or were euthanized because of clinical deterioration, whereas 83% were discharged. CONCLUSIONS AND CLINICAL IMPORTANCE: The proportion of sheep that survived BTV disease after treatment was relatively high. Serotyping of BTV is recommended because of the mismatch between frequently identified serotypes and the serotype present in the vaccine.

Culicoides biting midge species (Diptera: Ceratopogonidae) of the Obsoletus Group and the Pulicaris Complex are considered the major vectors of bluetongue and Schmallenberg viruses in Europe. Overwintering strategies of these arboviruses are controversially discussed, with the ongoing activity of vector species and a non‐disrupted transmission cycle during winter being a plausible explanation. Although data on Culicoides winter activity are relatively scant, a seasonal vector‐free period (SVFP), during which adult Culicoides are not or hardly active, is questionable. To determine winter activity and define SVFPs according to the EU Commission Regulation No 1266/2007, adult Culicoides were trapped weekly with UV‐light traps from October to April 2019/2020 and 2020/2021 inside and outside stables on 16 farms throughout Germany. Temperature measurements were taken regularly at each trapping site since the temperature is a known driver of biting midge activity. In 960 indoor and outdoor catches, 32,377 Culicoides were trapped, with 90.9% of them belonging to the Obsoletus Group, 6.1% to the Pulicaris Complex and 3.0% to 'other Culicoides' according to morphological identification. The majority (61.3%) of Culicoides were trapped indoors, with substantial numbers of specimens collected from October to December, in March and in April, and only a few or no specimens in January and February. Obsoletus Group biting midges were active indoors for almost the entire winter. Outdoors, Culicoides numbers decreased from October to December, few or no specimens were caught from January to March, and high numbers were captured in April. Of the collected Culicoides, 2028 were blood‐fed, of which 94.6% were trapped in the stables. The indoor SVFP, although calculated for blood‐fed instead of parous females, lasted for almost 4 months (late November until mid‐March) in winter 2019/2020 and 2 months (January and February) in winter 2020/2021. The outdoor SVFPs covered almost the entire study period in both winters, with slight differences between the onsets and the ends. The Culicoides activity significantly depended on temperature. Specimens of the Obsoletus Group were caught at an average temperature of 7.4°C (minimum 0.3°C) and of the Pulicaris Complex at an average temperature of 10.3°C (minimum 1.2°C). These temperatures were reached inside the stables over more extended periods than outside. The average indoor temperatures were 1.2 K higher than the average outdoor temperatures, although absolute temperature differences of up to 9.0 K were recorded. Based on Culicoides activity, the results of the present study indicate an almost continuous potential for virus transmission in winter within livestock houses. [ABSTRACT FROM AUTHOR]

Investigations of host feeding behaviour in haematophagous insects are critical to assess transmission routes of vector‐borne diseases. Understanding if a certain species has ornithophilic or mammalophilic feeding behaviour can facilitate future studies focused on pathogens transmission to and from certain host species. Culicoides Latreille (Diptera: Ceratopogonidae) are vectors of several pathogens, which include arboviruses, bacteria and parasites to a considerable diversity of vertebrate hosts. However, most of the studies focused on feeding habits target Culicoides species that could transmit the Bluetongue virus, consequently with a mammalophilic feeding behaviour, leaving aside the Culicoides species that are involved in the transmission of vector‐borne parasites to birds, such as Haemoproteus Kruse (Haemosporida: Haemoproteidae). This study aimed to investigate the source of blood meals of wild‐caught Culicoides using molecular‐based methods and to correlate our findings with the reports of Haemoproteus parasites in Culicoides species. Engorged Culicoides females were collected using ultraviolet (UV)‐light traps at seven different localities in Lithuania in 2021–2023. Biting midges were dissected, and the abdomens of engorged females were used for molecular investigation of the blood meal source. A polymerase chain reaction (PCR) protocol that amplifies a fragment of the Cytochrome B gene of vertebrates was used. Obtained sequences were compared to available information in GenBank database to confirm the source of the blood meal. In total, 258 engorged Culicoides females, representing nine different species, were analysed. The source of blood meal was identified in 29.1% of them with most of the insects having fed on birds (74.7%) and the remaining on mammals (25.3%). Culicoides segnis Campbell, Pelham‐Clinton was the only species to feed exclusively on birds; Culicoides from the Obsoletus group, C. pallidicornis Kieffer and C. punctatus Latreille were found to feed exclusively on mammals; C. festivipennis Kieffer, C. kibunensis Tokunaga and C. pictipennis Staeger had an opportunistic feeding behaviour, with the first two preferably feeding on birds. Due to their feeding behaviour and the presence of Haemoproteus parasites reported in the literature, C. festivipennis, C. kibunensis, C. pictipennis, and C. segnis play an important role in the transmission of those avian vector‐borne parasite in the wild. These Culicoides species were already confirmed as being able to support the development of several Haemoproteus species and lineages. Future studies focused on understanding the epidemiology of avian pathogens transmitted by Culicoides should target these species. [ABSTRACT FROM AUTHOR]

Biting midges of the genus Culicoides (Diptera: Ceratopogonidae) are of huge veterinary importance, mainly as vectors of pathogens, such as Bluetongue virus. Currently, there are no effective methods to protect animals against biting midges, as insecticides have limited or short‐lived efficacy. Biting midges are attracted to hosts by carbon dioxide and by their body odours, which are mainly produced by skin bacteria. In humans, it has been shown that differences between individuals in attractiveness to mosquitoes is mediated by these skin bacterial volatiles. This opens the possibility to protect individuals from biting insects by supplementing their skin microbiome with probiotics. In this study, we investigated this approach by culturing sheep skin bacteria on various media and assessing their effects against field‐caught Culicoides (overwhelmingly Obsoletus group species) as well as laboratory‐reared Culicoides nubeculosus (Meigen). Aerococcus urinaeequi, Bacillus safensis, Bacillus subtilis, Jeotgalicoccus psychrophilus, Micrococcus sp. and Staphylococcus equorum were selected to be tested in a dual‐choice Y‐tube olfactometer, assessing their behavioural effects on biting midges. We revealed an avoidance effect on laboratory‐reared C. nubeculosus when testing B. safensis and B. subtilis. Bacillus safensis and Micrococcus sp. yielded significant repellent potential towards field‐caught Culicoides. These two candidates were subsequently tested in a membrane blood‐feeding assay. When the bacterial species B. safensis was applied to the membrane, a feeding reduction of 83% was observed with field‐caught Culicoides. [ABSTRACT FROM AUTHOR]

The bluetongue virus (BTV), transmitted by biting midges, poses a significant threat to livestock globally. This orbivirus induces bluetongue disease, leading to substantial economic losses in the agricultural sector. The current control measures have limitations, necessitating the development of novel, efficient vaccines. In this study, an immunoinformatics approach is employed to design a multi-epitope subunit vaccine for Ovis aries targeting six BTV serotypes. Focusing on the VP2 capsid protein, the vaccine incorporates B-cell, helper-T lymphocytes (HTL), and cytotoxic T-cell lymphocytes (CTL) epitopes. Molecular docking reveals stable interactions with TLR2 and TLR4 receptors, suggesting the stability of the complex, indicating the potential viability of the multi-epitope vaccine. The computational approach offers a rapid and tailored strategy for vaccine development, highlighting potential efficacy and safety against BTV outbreaks. This work contributes to understanding BTV and presents a promising avenue for effective control. [ABSTRACT FROM AUTHOR]

Bluetongue virus (BTV) is a prevalent midge-borne pathogen that infects ruminant species worldwide. BTV infections range from asymptomatic to lethal, with mechanisms that determine the severity of infection remaining largely undefined. Although it is relatively poorly understood, the immune response to BTV infection is thought to be critical for both the propagation of disease as well as the resolution of infection. To bridge this gap in knowledge, we infected cohorts of sheep and muntjac deer with two serotypes of BTV (BTV10 and BTV17) for longitudinal analysis (30 days). Interestingly, species-specific differences were observed. Circulating virus was detected early and remained detectable for the duration of the sheep study, while infections in muntjac showed faltering detection of BTV10 at 3 weeks post infection. The magnitude of the immune response was subdued in the muntjac when compared to the sheep cohorts, though similar responses were observed. We also assessed midge viral uptake and the ability to replicate BTV. Midges successfully fed on both species, yet those that fed on sheep resulted in more efficient BTV transmission. Our findings demonstrate that differences in BTV infections, immune responses, and vector competence across host species and serotypes will impact global BTV emergence and strategies for mitigation. [ABSTRACT FROM AUTHOR]

Bluetongue virus (BTV) is an agriculturally and economically significant insect-borne virus that causes serious illness and death in sheep and other domestic and wild ruminants in large areas of the world. Numerous BTV serotypes exist, and distant serotypes exhibit unique neutralizing antibody profiles, which target the outermost capsid protein VP2. The predominant serotype-specific nature of the antibody response to VP2 is a barrier to the development of broad-spectrum prophylactic BTV vaccine candidates. Although VP2 is the main serotype determinant of BTV, the structural basis of serotype specificity has not been investigated. In this study, we utilized the recently available atomic structure of VP2 with a modeled tip domain to carry out in silico structural comparisons between distant serotypes BTV1 and BTV8. These analyses identified structural differences in the tip domain, positioned at the apex of VP2, and informed the design of mutant VP2 constructs. Dissection of tip domain antigenicity demonstrated that the region of structural difference between BTV1 and highly virulent BTV8 was a target of BTV neutralizing antibodies and that mutation of this region resulted in a loss of neutralizing antibody recognition. This study has for the first time provided insights into the structural differences, which underpin the serotype-specific neutralizing antibody response to BTV. [ABSTRACT FROM AUTHOR]

Clinical infection and death caused by bluetongue virus infection has been reported in the Eurasian lynx. Bluetongue virus surveillance in the Iberian lynx revealed widespread and repeated exposure to serotypes 1 and 4 in wild and captive populations of this species. This exposure is possibly from a spillover event from sympatric ruminants. [ABSTRACT FROM AUTHOR]

Clinical infection and death caused by bluetongue virus infection has been reported in the Eurasian lynx. Bluetongue virus surveillance in the Iberian lynx revealed widespread and repeated exposure to serotypes 1 and 4 in wild and captive populations of this species. This exposure is possibly from a spillover event from sympatric ruminants.

Abstract Schmallenberg virus (SBV) and bluetongue virus (BTV) are both transmitted by Culicoides biting midges and infect predominantly ruminants. To investigate the extent of virus spread in the 2022 and 2023 vector seasons, we serologically tested wild ruminants from western Germany. While antibodies against BTV were not detected in any animal, regardless of age or sampling time, numerous wild ruminants tested positive for antibodies to SBV. In 2022, a low seroprevalence of 4.92% was measured. In sharp contrast, 40.15% of the animals tested positive in 2023. Of the young animals, about 31.82% were seropositive, clearly indicating large-scale SBV circulation in summer and autumn 2023.

Abstract Bluetongue virus (BTV) infection induces profound and intricate changes in the transcriptional profile of the host to facilitate its survival and replication. However, there have been no whole-transcriptome studies on ovine lung microvascular endothelial cells (OLMECs) infected with BTV. In this study, we comprehensively analysed the whole-transcriptome sequences of BTV-1 serotype-infected and mock-infected OLMECs and subsequently performed bioinformatics differential analysis. Our analysis revealed 1215 differentially expressed mRNA transcripts, 82 differentially expressed long noncoding RNAs (lncRNAs) transcripts, 63 differentially expressed microRNAs (miRNAs) transcripts, and 42 differentially expressed circular RNAs (circRNAs) transcripts. Annotation from Gene Ontology, enrichment from the Kyoto Encyclopedia of Genes and Genomes, and construction of endogenous competing RNA network analysis revealed that the differentially expressed RNAs primarily participated in viral sensing and signal transduction pathways, antiviral and immune responses, inflammation, and extracellular matrix (ECM)-related pathways. Furthermore, protein‒protein interaction network analysis revealed that BTV may regulate the conformation of ECM receptor proteins and change their biological activity through a series of complex mechanisms. Finally, on the basis of real-time fluorescence quantitative polymerase chain reaction results, the expression trends of the differentially expressed RNA were consistent with the whole-transcriptome sequencing data, such as downregulation of the expression of COL4A1, ITGA8, ITGB5, and TNC and upregulation of the expression of CXCL10, RNASEL, IRF3, IRF7, and IFIHI. This study provides a novel perspective for further investigations of the mechanism of the ECM in the BTV-host interactome and the pathogenesis of lung microvascular endothelial cells.

Bluetongue (BT) is an economically important contagious viral disease transmitted by insect vectors of Culicoides species affecting both domestic and wild ruminants caused by Genus Orbivirus of Reoviridae family. Present in vivo study for the first time conducted to understand the role of oxidative stress and acute phase proteins in the pathogenesis of endothelial injury in target blood vessels of BTV-4 infected sheep. Twelve sheep of either sex were divided into two groups of six animals each and infected intradermally at multiple sites in the neck region with 6×105.9 TCID50/ml of BTV-4 and animals of control group were inoculated with uninfected tissue culture fluid. Animals were sacrificed at 3, 7, 15, 28, 60, and 90 days post infection (dpi) and postmortem examination was conducted. Oxidative stress parameters like LPO, SOD, GPO and catalase in the blood vessels, hemolysate and serum were estimated. Oxidative stress parameter like LPO was upregulated and anti-oxidant parameters like SOD and GPO were downregulated in blood vessels homogenates, hemolysate and serum of BTV-4 infected animals than uninfected control. This shows the role of oxidative stress in causing endothelial cell damage during BTV infection. Acute phase proteins like CRP and fibrinogen in serum and plasma were estimated and found upregulated in BTV-4 infected animals, which shows that inflammatory changes during the disease causes vascular damage. Prothrombin time was estimated in plasma of BTV-4 infected animals and was prolonged in BTV infected animals indicating coagulation disorder. Increased oxidative stress and fibrinogen, and prolonged prothrombin time indicated the coagulation disorders induced by BTV infection by causing endothelial cell damage and severe vascular disease results in congestion, haemorrhages and edema in the blood vessels and other target organs in sheep.

Background and Aim: Bluetongue is a vector-borne, emerging disease that poses a severe threat to most domesticated animals. A cross-sectional study was conducted to estimate the prevalence of bluetongue virus (BTV) disease in apparently healthy sheep and goats in Kalat, Balochistan. Materials and Methods: A total of 270 serum samples (sheep: 150 and goat: 120) were collected and screened for the detection of anti-BTV antibodies using a competitive enzyme-linked immunosorbent assay. The data regarding different contributory risk factors were also collected using a predesigned questionnaire. Results: It revealed that overall, 27.4% (74/270, 95% confidence interval, χ2 = 1.71, p = 0.12) prevalence in both sheep and goat populations. The highest prevalence of 47% (32/68) was recorded in Surab city with the lowest prevalence of 15.49% (11/71) in the Manguchar area. In contrast, in Kalat 28.1% (9/32), Daan area 24% (12/50), and Marap area 22.44% (11/49), seropositivity was recorded. Upon sex bases, antibodies were almost equally found in both male 28.57% (8/28) and female 27.27% (66/242) animal populations. Moreover, all four breeds (Balochi, Khurasani, Lehri, and Rakhshani) were equally and potentially seropositive. The Khurasani breed was the most susceptible to 34.69% (17/49), followed by the Balochi breed, 45/145 (31%) seropositivity. The prevalence of BTV was 16.66% (1/6) in Rakhshani breed and 15.71% (11/70) in Lehri breed., Ticks were found in almost 21% of animals, while 93% of animals were reared on open grazing in rangelands. Conclusion: This study clearly indicates widespread BTV infection in small ruminants in the study area that may pose serious threats to livestock farming. Further extensive studies are recommended to study the prevalence of disease in different agroecological zones of the province. This also warns the high-ups to manage concrete efforts to eradicate and control the disease in the area.

Since 1998, notifiable bluetongue virus (BTV) serotypes 1–4, 6, 8, 9, 11, and 16 have been reported in Europe. In August 2006, a bluetongue (BT) outbreak caused by BTV serotype 8 began in northwestern Europe. The Netherlands was declared BT-free in February 2012, and annual monitoring continued. On September 3, 2023, typical BT clinical manifestations in sheep were notified to the Netherlands Food and Product Safety Consumer Authority. On September 6, we confirmed BTV infection through laboratory diagnosis; notifications of clinical signs in cattle were also reported. We determined the virus was serotype 3 by whole-genome sequencing. Retrospective analysis did not reveal BTV circulation earlier than September. The virus source and introduction route into the Netherlands remains unknown. Continuous monitoring and molecular diagnostic testing of livestock will be needed to determine virus spread, and new prevention strategies will be required to prevent BTV circulation within the Netherlands and Europe.

In October 2023, bluetongue virus serotype 3 (BTV-3) emerged in Germany, where Schmallenberg virus is enzootic. We detected BTV-3 in 1 pool of Culicoides biting midges collected at the time ruminant infections were reported. Schmallenberg virus was found in many vector pools. Vector trapping and analysis could elucidate viral spread.

Bluetongue virus (BTV) infection induces profound and intricate changes in the transcriptional profile of the host to facilitate its survival and replication. However, there have been no whole-transcriptome studies on ovine lung microvascular endothelial cells (OLMECs) infected with BTV. In this study, we comprehensively analysed the whole-transcriptome sequences of BTV-1 serotype-infected and mock-infected OLMECs and subsequently performed bioinformatics differential analysis. Our analysis revealed 1215 differentially expressed mRNA transcripts, 82 differentially expressed long noncoding RNAs (lncRNAs) transcripts, 63 differentially expressed microRNAs (miRNAs) transcripts, and 42 differentially expressed circular RNAs (circRNAs) transcripts. Annotation from Gene Ontology, enrichment from the Kyoto Encyclopedia of Genes and Genomes, and construction of endogenous competing RNA network analysis revealed that the differentially expressed RNAs primarily participated in viral sensing and signal transduction pathways, antiviral and immune responses, inflammation, and extracellular matrix (ECM)-related pathways. Furthermore, protein‒protein interaction network analysis revealed that BTV may regulate the conformation of ECM receptor proteins and change their biological activity through a series of complex mechanisms. Finally, on the basis of real-time fluorescence quantitative polymerase chain reaction results, the expression trends of the differentially expressed RNA were consistent with the whole-transcriptome sequencing data, such as downregulation of the expression of COL4A1, ITGA8, ITGB5, and TNC and upregulation of the expression of CXCL10, RNASEL, IRF3, IRF7, and IFIHI. This study provides a novel perspective for further investigations of the mechanism of the ECM in the BTV-host interactome and the pathogenesis of lung microvascular endothelial cells. [ABSTRACT FROM AUTHOR]

Bluetongue (BT) is an arthropod‐borne viral disease that primarily affects ruminants in tropical and temperate regions. In the present study, a cross‐sectional survey was conducted to define the seroprevalence of Bluetongue virus and to identify the possible risk factors correlated with BTV seropositivity among cattle, sheep, and goats during the period 2015‐2016 in Gadarif State. A total of 420 cattle, 877 sheep, and 641 goat serum samples were collected randomly from 12 localities. Information about age, sex, breed, area ecology, and location was obtained for each sample. Bluetongue seroprevalence was estimated using competitive enzyme‐linked immunosorbent assay (cELISA). The overall seroprevalence of BTV was 92.9% (390/420), 76.4% (670/877), and 85.3% (547/641) among cattle, sheep, and goats, respectively. Multivariate analysis followed univariate analysis showed that there was a significant difference (p < 0.05) between location, area ecology and age groups of cattle, sheep, and goats, and seropositivity to BTV. In addition, a significant association (p < 0.05) was observed between sex and seropositivity to BTV in sheep. In conclusion, BTV antibodies are highly prevalent in Gadarif State and susceptible livestock are at risk of exposition with BTV. Consequently, these animals have protection against specific BTV serotypes. [ABSTRACT FROM AUTHOR]

Background and Aim: Bluetongue is a vector-borne, emerging disease that poses a severe threat to most domesticated animals. A cross-sectional study was conducted to estimate the prevalence of bluetongue virus (BTV) disease in apparently healthy sheep and goats in Kalat, Balochistan. Materials and Methods: A total of 270 serum samples (sheep: 150 and goat: 120) were collected and screened for the detection of anti-BTV antibodies using a competitive enzyme-linked immunosorbent assay. The data regarding different contributory risk factors were also collected using a predesigned questionnaire. Results: It revealed that overall, 27.4% (74/270, 95% confidence interval, χ² = 1.71, p = 0.12) prevalence in both sheep and goat populations. The highest prevalence of 47% (32/68) was recorded in Surab city with the lowest prevalence of 15.49% (11/71) in the Manguchar area. In contrast, in Kalat 28.1% (9/32), Daan area 24% (12/50), and Marap area 22.44% (11/49), seropositivity was recorded. Upon sex bases, antibodies were almost equally found in both male 28.57% (8/28) and female 27.27% (66/242) animal populations. Moreover, all four breeds (Balochi, Khurasani, Lehri, and Rakhshani) were equally and potentially seropositive. The Khurasani breed was the most susceptible to 34.69% (17/49), followed by the Balochi breed, 45/145 (31%) seropositivity. The prevalence of BTV was 16.66% (1/6) in Rakhshani breed and 15.71% (11/70) in Lehri breed., Ticks were found in almost 21% of animals, while 93% of animals were reared on open grazing in rangelands. Conclusion: This study clearly indicates widespread BTV infection in small ruminants in the study area that may pose serious threats to livestock farming. Further extensive studies are recommended to study the prevalence of disease in different agroecological zones of the province. This also warns the high-ups to manage concrete efforts to eradicate and control the disease in the area. [ABSTRACT FROM AUTHOR]

Bluetongue (BT) is a Culicoides midge-borne hemorrhagic disease affecting cervids and ruminant livestock species, resulting in significant economic losses from animal production and trade restrictions. Experimental animal infections using the α/β interferon receptor knockout IFNAR mouse model and susceptible target species are critical for understanding viral pathogenesis, virulence, and evaluating vaccines. However, conducting experimental vector-borne transmission studies with the vector itself are logistically difficult and experimentally problematic. Therefore, experimental infections are induced by hypodermic injection with virus typically derived from baby hamster kidney (BHK) cells. Unfortunately, for many U.S. BTV serotypes, it is difficult to replicate the severity of the disease seen in natural, midge-transmitted infections by injecting BHK-derived virus into target host animals. Using the IFNAR BTV murine model, we compared the virulence of traditional BHK cell-derived BTV-17 with C. sonorensis midge (W8) cell-derived BTV-17 to determine whether using cells of the transmission vector would provide an in vitro virulence aspect of vector-transmitted virus. At both low and high doses, mice inoculated with W8-BTV-17 had an earlier onset of viremia, earlier onset and peak of clinical signs, and significantly higher mortality compared to mice inoculated with BHK-BTV-17. Our results suggest using a Culicoides W8 cell-derived inoculum may provide an in vitro vector-enhanced infection to more closely represent disease levels seen in natural midge-transmitted infections while avoiding the logistical and experimental complexity of working with live midges. [ABSTRACT FROM AUTHOR]

Bluetongue (BT) is an economically important contagious viral disease transmitted by insect vectors of Culicoides species affecting both domestic and wild ruminants caused by Genus Orbivirus of Reoviridae family. Present in vivo study for the first time conducted to understand the role of oxidative stress and acute phase proteins in the pathogenesis of endothelial injury in target blood vessels of BTV-4 infected sheep. Twelve sheep of either sex were divided into two groups of six animals each and infected intradermally at multiple sites in the neck region with 6×105.9 TCID50/ml of BTV-4 and animals of control group were inoculated with uninfected tissue culture fluid. Animals were sacrificed at 3, 7, 15, 28, 60, and 90 days post infection (dpi) and postmortem examination was conducted. Oxidative stress parameters like LPO, SOD, GPO and catalase in the blood vessels, hemolysate and serum were estimated. Oxidative stress parameter like LPO was upregulated and anti-oxidant parameters like SOD and GPO were downregulated in blood vessels homogenates, hemolysate and serum of BTV-4 infected animals than uninfected control. This shows the role of oxidative stress in causing endothelial cell damage during BTV infection. Acute phase proteins like CRP and fibrinogen in serum and plasma were estimated and found upregulated in BTV-4 infected animals, which shows that inflammatory changes during the disease causes vascular damage. Prothrombin time was estimated in plasma of BTV-4 infected animals and was prolonged in BTV infected animals indicating coagulation disorder. Increased oxidative stress and fibrinogen, and prolonged prothrombin time indicated the coagulation disorders induced by BTV infection by causing endothelial cell damage and severe vascular disease results in congestion, haemorrhages and edema in the blood vessels and other target organs in sheep. [ABSTRACT FROM AUTHOR]

Culicoides are responsible for a number of diseases transmitted to the animals causing severe health conditions and great economic losses. The outbreak of bluetongue virus in Albania in 2014 and lumpy skin disease in 2016 strongly indicated the establishment of a sentinel herd surveillance in the country ruminant farms. Considering all evidence for Albania, investigation of species composition and abundance of Culicoides on livestock farms was performed in 10 sentinel sites. Ultraviolet-light traps (OVI-traps) were placed in selected sites for collection of Culicoides starting from April 15 to July 30, 2021. A total of 37,111 Culicoides midges from 18 different species were collected during the investigation. The most abundant species identified were C. newsteadi and C. obsoletus. Moreover, three species were described for the first time in Albania (C. collessi, C. chiopterus and C. immaculatus). Presence and abundance of the collected Culicoides spp. are associated with potential outbreak of diseases (i.e. bluetongue, ephemeral fever) linked with their transmission from Culicoides. [ABSTRACT FROM AUTHOR]

Simple Summary: Abortions in ruminants lead to economic losses to livestock-owning communities. The major causes of these abortions are infectious agents. Surveillance of the infectious agents that cause abortions is important to the overall improvement of livestock productivity. Most LMICs have scarce or inadequate surveillance platforms for these pathogens. In this review article, we have summarized the current status of the available surveillance platforms in place for the infectious agents that lead to abortions in ruminants, as well as the sero-epidemiology of these pathogens. Ruminant abortion events cause economic losses. Despite the importance of livestock production for food security and the livelihoods of millions of people in the world's poorest communities, very little is known about the scale, magnitude, or causes of these abortions in Africa and Asia. The aim of this review was to determine the current status of surveillance measures adopted for ruminant abortigenic pathogens in Africa and Asia and to explore feasible surveillance technologies. A systematic literature search was conducted using PRISMA guidelines for studies published between 1 January 1990 and 1 May 2024 that reported epidemiological surveys of abortigenic pathogens Africa and Asia. A meta-analysis was used to estimate the species-specific sero-prevalence of the abortigenic agents and the regions where they were detected. In the systematic literature search, 39 full-text manuscripts were included. The most prevalent abortigenic pathogens with sero-prevalence greater than 10% were BHV-1, Brucella, Chlamydia abortus, Neospora caninum, RVFV, and Waddlia chondrophila in cattle, BVDV in sheep, and RVFV and Toxoplasma gondii in goats in Africa. In Asia, Anaplasma, BHV-1, Bluetongue virus, Brucella, and BVDV were prevalent in cattle, whereas Mycoplasma was important in goats and sheep. [ABSTRACT FROM AUTHOR]

Since 1998, notifiable bluetongue virus (BTV) serotypes 1-4, 6, 8, 9, 11, and 16 have been reported in Europe. In August 2006, a bluetongue (BT) outbreak caused by BTV serotype 8 began in northwestern Europe. The Netherlands was declared BT-free in February 2012, and annual monitoring continued. On September 3, 2023, typical BT clinical manifestations in sheep were notified to the Netherlands Food and Product Safety Consumer Authority. On September 6, we confirmed BTV infection through laboratory diagnosis; notifications of clinical signs in cattle were also reported. We determined the virus was serotype 3 by whole-genome sequencing. Retrospective analysis did not reveal BTV circulation earlier than September. The virus source and introduction route into the Netherlands remains unknown. Continuous monitoring and molecular diagnostic testing of livestock will be needed to determine virus spread, and new prevention strategies will be required to prevent BTV circulation within the Netherlands and Europe. [ABSTRACT FROM AUTHOR]

Rift Valley fever virus (RVFV) causes disease outbreaks in livestock and humans; however, its inter-epidemic circulation is poorly understood, similar to other arboviruses affecting cattle such as bluetongue virus (BTV) and epizootic hemorrhagic disease virus (EHDV). Serum samples were collected in Baringo County, Kenya from 400 cattle, accompanied by a risk factor questionnaire. Serological tests were then conducted to determine the exposure of cattle to RVFV, BTV, and EHDV. RVFV, BTV, and EHDV IgG seroprevalence rates were 15.5%, 91.5%, and 91%, respectively. Seropositivity for RVFV, BTV, and EHDV was significantly higher in adult cattle, as well as in females for RVFV. Cattle with herd owners aged between 30–39 years were less likely to be seropositive for RVFV compared to those with owners over the age of 60 years. High seroprevalence of BTV and EHDV in cattle indicates significant exposure and the subclinical circulation of these viruses, presenting a risk of outbreaks to sheep and naïve cattle. Moreover, the detection of RVFV-seropositive young cattle born after the last reported outbreak suggests inter-epidemic circulation of the virus. Overall, monitoring these arboviruses in cattle is crucial in understanding their distribution and seroprevalence during inter-epidemic periods. [ABSTRACT FROM AUTHOR]

In 2021, a pregnant Rottweiler dog living on a sheep farm was diagnosed with clinical bluetongue (BT) infection. This study reports on the investigation of this farm where bluetongue virus (BTV) infection was diagnosed in this atypical host species. Samples were collected during farm visits 14, 28, 60, and 89 days after the onset of clinical signs in the pregnant Rottweiler. Blood was collected from all farm dogs (n = 6) and tested for BTV genome using a reverse‐transcriptase quantitative PCR (RT‐qPCR) assay and BTV antibodies with the competitive ELISA (cELISA) and dogs positive by RT‐qPCR were further tested using virus neutralization (VN) serological testing. Blood was also collected from 16 sick sheep and tested using RT‐qPCR. Midges were trapped on the study farm using an Onderstepoort UV light trap placed above a sheep pen for 36 hr at the first farm (14 days) visit. Parous/gravid midges were tested by BTV RT‐qPCR in batches of up to 200 midges per species. Blood‐fed midges (n = 308) were tested using a PCR species probe (KAPA Multiplex Master Mix) to identify the host species on which the midge had fed. Three dogs (n = 3/6) had detectable BTV RNA with RT‐qPCR and high VN antibody titers to BTV. All RT‐qPCR‐positive dogs and one additional dog tested cELISA seropositive (n = 4/6). Bluetongue virus RNA was detected in 5/16 sheep tested. The most abundant midge species was Culicoides imicola (99.3%) and BTV was only detected in this species (n = 3/4 batches of 200 parous midges). Dog blood was not detected in any blood‐fed midges tested. The occurrence of natural BT viraemia in exposed dogs creates a potential risk of BTV entry into BT‐free countries through dog importation. It remains unclear whether BT viremia in dogs is capable of onward transmission. [ABSTRACT FROM AUTHOR]

Introduction: Bluetongue (BT), caused by bluetongue virus (BTV), is an important arthropod-borne livestock disease listed by the World Organization for Animal Health. Live-attenuated and inactivated vaccines have permitted to control BT but they do not simultaneously protect against the myriad of BTV serotypes. Recently, we identified the highly conserved BTV nonstructural protein NS1 and the N-terminal region of NS2 as antigens capable of conferring multiserotype protection against BTV. Methods: Here, we designed Modified Vaccinia Ankara (MVA) viral vectors that expressed BTV-4 proteins VP2 or VP7 along with NS1 and NS2-Nt as well as MVAs that expressed proteins VP2, VP7 or NS1 and NS2-Nt. Results: Immunization of IFNAR(-/-) mice with two doses of MVA-NS1-2A-NS2- Nt protected mice from BTV-4M infection by the induction of an antigenspecific T cell immune response. Despite rMVA expressing VP7 alone were not protective in the IFNAR(-/-) mouse model, inclusion of VP7 in the vaccine formulation amplified the cell-mediated response induced by NS1 and NS2-Nt. Expression of VP2 elicited protective non-cross-reactive neutralizing antibodies (nAbs) in immunized animals and improved the protection observed in the MVANS1-2A-NS2-Nt immunized mice when these three BTV antigens were coexpressed. Moreover, vaccines candidates co-expressing VP2 or VP7 along with NS1 and NS2-Nt provided multiserotype protection. We assessed protective efficacy of both vaccine candidates in sheep against virulent challenge with BTV-4M. Discussion: Immunization with MVA-VP7-NS1-2A-NS2-Nt partially dumped viral replication and clinical disease whereas administration of MVA-VP2-NS1-2ANS2-Nt promoted a complete protection, preventing viraemia and the pathology produced by BTV infection. [ABSTRACT FROM AUTHOR]

Introduction: Bluetongue (BT) poses a significant threat to the livestock industry, affecting various animal species and resulting in substantial economic losses. The existence of numerous BT virus (BTV) serotypes has hindered control efforts, highlighting the need for broad-spectrum vaccines. Methodology: In this study, we evaluated the conserved amino acid sequences within key non-structural (NS) proteins of BTV and identified numerous highly conserved murine- and bovine-specific MHC class I-restricted (MHC-I) CD8+ and MHC-II-restricted CD4+ epitopes. We then screened these conserved epitopes for antigenicity, allergenicity, toxicity, and solubility. Using these epitopes, we developed in silico-based broad-spectrum multiepitope vaccines with Toll-like receptor (TLR-4) agonists. The predicted proinflammatory cytokine response was assessed in silico using the C-IMMSIM server. Structural modeling and refinement were achieved using Robetta and GalaxyWEB servers. Finally, we assessed the stability of the docking complexes through extensive 100-nanosecond molecular dynamics simulations before considering the vaccines for codon optimization and in silico cloning. Results: We found many epitopes that meet these criteria within NS1 and NS2 proteins and developed in silico broad-spectrum vaccines. The immune simulation studies revealed that these vaccines induce high levels of IFN-γ and IL-2 in the vaccinated groups. Protein-protein docking analysis demonstrated promising epitopes with strong binding affinities to TLR-4. The docked complexes were stable, with minimal Root Mean Square Deviation and Root Mean Square Fluctuation values. Finally, the in silico-cloned plasmids have high % of GC content with > 0.8 codon adaptation index, suggesting they are suitable for expressing the protein vaccines in prokaryotic system. Discussion: These next-generation vaccine designs are promising and warrant further investigation in wet lab experiments to assess their immunogenicity, safety, and efficacy for practical application in livestock. Our findings offer a robust framework for developing a comprehensive, broad-spectrum vaccine, potentially revolutionizing BT control and prevention strategies in the livestock industry. [ABSTRACT FROM AUTHOR]

The study aimed to investigate molecularly the presence of flea-borne viruses in infested small ruminants with fleas. It was carried out in Egypt's Northern West Coast (NWC) and South Sinai Governorate (SSG). Three specific primers were used targeting genes, ORF103 (for Capripoxvirus and Lumpy skin disease virus), NS3 (for Bluetongue virus), and Rdrp (for Coronavirus), followed by gene sequencing and phylogenetic analyses. The results revealed that 78.94% of sheep and 65.63% of goats were infested in the NWC area, whereas 49.76% of sheep and 77.8% of goats were infested in the SSG region. Sheep were preferable hosts for flea infestations (58.9%) to goats (41.1%) in the two studied areas. Sex and age of the animals had no effects on the infestation rate (p > 0.05). The season and site of infestation on animals were significantly different between the two areas (p < 0.05). Ctenocephalides felis predominated in NWC and Ctenocephalides canis in SSG, and males of both flea species were more prevalent than females. Molecular analysis of flea DNA revealed the presence of Capripoxvirus in all tested samples, while other viral infections were absent. Gene sequencing identified three isolates as sheeppox viruses, and one as goatpox virus. The findings suggest that Capripoxvirus is adapted to fleas and may be transmitted to animals through infestation. This underscores the need for ongoing surveillance of other pathogens in different regions of Egypt. [ABSTRACT FROM AUTHOR]

The article focuses on the spread and impact of bluetongue virus (BTV), specifically BTV serotype 3 (BTV-3), in European ruminants, highlighting its emergence in the Netherlands and subsequent spread to Belgium, the United Kingdom, and Germany by 2023, necessitating regulatory responses under EU guidelines to manage outbreaks.

Hemorrhagic disease (HD) of deer is caused by epizootic hemorrhagic disease virus (EHDV) or bluetongue virus (BTV) and is considered one of the most important viral diseases of white-tailed deer (Odocoileus virginianus). Despite evidence of changing patterns of HD in the northeastern and upper midwestern US, the historical and current patterns of HD in the Great Plains remain poorly described. We used results from an annual survey documenting HD mortality to characterize historic and current patterns of HD in the northern and central Great Plains (North Dakota, South Dakota, Nebraska, Kansas, and Oklahoma), US, between 1982 and 2020. Further, we assessed temporal change using linear regression to determine change in annual reporting intensity (percentage of counties in a state with reported HD) and change in reporting frequency (the number of years a county or state reported HD) during each decade between 1982 and 2020. Across the 38-yr study period, HD reports expanded northeast across latitude and longitude. Intensity of HD reports significantly increased during this period for three (North Dakota, South Dakota, Kansas) of five states examined. Frequency of reports also increased for all five states. Such changes in northern latitudes might lead to increased deer mortality in regions where HD epizootics have been historically less frequent. Understanding how patterns of HD are changing on the landscape is important when considering future deer management in the face of other mortality factors. [ABSTRACT FROM AUTHOR]

Bluetongue virus (BTV, Sedoreoviridae: Orbivirus) causes an economically important disease, namely, bluetongue (BT), in domestic and wild ruminants worldwide. BTV is endemic to South India and has occurred with varying severity every year since the virus was first reported in 1963. BT can cause high morbidity and mortality to sheep flocks in this region, resulting in serious economic losses to subsistence farmers, with impacts on food security. The epidemiology of BTV in South India is complex, characterized by an unusually wide diversity of susceptible ruminant hosts, multiple vector species biting midges (Culicoides spp., Diptera: Ceratopogonidae), which have been implicated in the transmission of BTV and numerous co-circulating virus serotypes and strains. BT presence data (1997–2011) for South India were obtained from multiple sources to develop a presence/absence model for the disease. A non-linear discriminant analysis (NLDA) was carried out using temporal Fourier transformed variables that were remotely sensed as potential predictors of BT distribution. Predictive performance was then characterized using a range of different accuracy statistics (sensitivity, specificity, and Kappa). The top ten variables selected to explain BT distribution were primarily thermal metrics (land surface temperature, i.e., LST, and middle infrared, i.e., MIR) and a measure of plant photosynthetic activity (the Normalized Difference Vegetation Index, i.e., NDVI). A model that used pseudo-absence points, with three presence and absence clusters each, outperformed the model that used only the recorded absence points and showed high correspondence with past BTV outbreaks. The resulting risk maps may be suitable for informing disease managers concerned with vaccination, prevention, and control of BT in high-risk areas and for planning future state-wide vector and virus surveillance activities. [ABSTRACT FROM AUTHOR]

Bluetongue is a non-zoonotic arboviral disease transmitted by biting midges of the genus Culicoides. Among 1,347 Culicoides species, 30 are known to be vectors of the disease. Bluetongue affects domestic and wild ruminants across all continents, except the Antarctica, causing growing economic losses in livestock production and international trade. In this work, we focused on potential mechanisms underlying the bluetongue virus emergence and spread. Of these mechanisms, the emergence of novel serotypes makes vaccination controversial despite its effectiveness, along with the vector’s ability to acquire the virus and successfully transmit it, spatio-temporal adaptation, and identification of new transmission routes. We also discussed the predisposition of the vertebrate and invertebrate hosts to contract the virus, as well as factors hijacking vector population activity and abundance. Indeed, the ecological dynamics of biting midges strongly influence the ability of the virus to be transmitted and to cause epizootic into parts of the world never before affected, helped by interactions between the pathogen and its host in addition to multiple routes deployed to escape defense barriers in the target infected cells. The points raised in this review can help inform aspects of interest for future studies that may elucidate factors to consider in monitoring and controlling the expansion of Culicoides-transmitted arboviruses.

Bluetongue (BT) and Epizootic Hemorrhagic Disease (EHD) are two notifiable animal diseases transmitted to ruminants by small hematophagous midges belonging to the Culicoides genus. The etiological agents, Bluetongue virus (BTV) and Epizootic hemorrhagic disease virus (EHDV), are both members of the Sedoreoviridae family and Orbivirus genus, which include double-stranded (ds) RNA segmented genomes (10 segments). By the end of the summer 2023, first's outbreaks of EHD were reported from the south west of France, concurrently with unexpectedly severe BT cases in Central France and Corsica. Within a few weeks, numerous BT and EHD outbreaks were recorded with significant sanitary and economic impact on cattle and sheep farms (no sanitary impact of EHD for sheep). Using a customized SISPA approach and the nanopore sequencing technology we successfully recovered genomic sequences from viral isolates and blood samples from infected animals from EHD and BT outbreaks. Three different viruses were responsible for these outbreaks: EHDV-8, BTV-8 and BTV-4. The EHDV-8 strain detected in France corresponded to the strain circulating in Tunisia, Sardinia and Spain since 2021 and 2022. A new BTV-8 strain of unknown origin, clearly different from the enzootic strain circulating in France since 2015, was responsible of the BT outbreaks in domestic ruminants in 2023 on both mainland France and Corsica. A second BTV, BTV-4, also involved in BT outbreaks in Corsica, corresponded to a BTV-4 strain occasionally detected on Corsica island since 2016, suggesting either a new introduction of this strain or a silent circulation on the field. The exceptional nature of orbivirus epizootics in France in 2023, including new introduction, emergence or incursions, raises numerous questions regarding BTV and EHDV dynamics and epidemiology and stresses out the need to identify factors involved in these emergences.

Schmallenberg virus (SBV) and bluetongue virus (BTV) are both transmitted by Culicoides biting midges and infect predominantly ruminants. To investigate the extent of virus spread in the 2022 and 2023 vector seasons, we serologically tested wild ruminants from western Germany. While antibodies against BTV were not detected in any animal, regardless of age or sampling time, numerous wild ruminants tested positive for antibodies to SBV. In 2022, a low seroprevalence of 4.92% was measured. In sharp contrast, 40.15% of the animals tested positive in 2023. Of the young animals, about 31.82% were seropositive, clearly indicating large-scale SBV circulation in summer and autumn 2023. [ABSTRACT FROM AUTHOR]

Infectious pancreatic necrosis virus (IPNV) causes economic losses with a highly variable mortality rate worldwide, especially in rainbow trout. The virus has a double-stranded bi-partite RNA genome designated segment A and B. New complete genome sequences of nine rainbow trout isolates from Turkey were determined and subjected to phylogenetic analysis, identifying all as genotype 5 (serotype Sp). A time-dependent change in the extended pathogenicity motif of VP2 from P217T221A247 (PTA) to PTE P217T221E247 over a period of 10 years was identified. A wider analysis of 99 IPNV sequences from Turkey and Iran revealed the emergence of the motif PTE from 2007 to 2017, inducing significant morbidity in fry by 2013. In fact, displacement of the PTA motif, by the PTE motif in IPNV isolates appeared to be connected to a production peak of rainbow trout in 2013. An additional CAI analysis provided more evidence, indicating that rainbow trout culture in Turkey has an influence on the evolution of IPNV. [ABSTRACT FROM AUTHOR]

The serological surveillance of bluetongue in bulk tank milk is an efficient and cost-effective method for the early detection of bluetongue virus incursions in unvaccinated free areas of the disease. In addition, the availability of standardized and reliable reagents and refined diagnostic procedures with high sensitivity and specificity are essential for surveillance purposes. However, no available reference materials for bluetongue virus serological surveillance in bulk tank milk exist. This study shows the production and characterization of reference material for the implementation of a commercially available bluetongue milk ELISA test in official laboratories, as well as the evaluation of a procedure to increase the sensitivity in samples with low levels of antibodies. This procedure, based on milk protein concentration, allowed us to notably increase the ELISA test's analytical sensitivity, which is useful for milk samples from farms with low within-herd prevalence or pools of bulk tank milk samples. The standardized milk reference material produced here, together with the evaluated procedure to improve analytical sensitivity, could be applied as tools to ensure an accurate diagnosis by official laboratories in bluetongue unvaccinated free areas. [ABSTRACT FROM AUTHOR]

Retrospective serological and case diagnostic data of endemic bluetongue virus (BTV) and epizootic hemorrhagic disease virus (EHDV) provide evidence of viral transmission among livestock and wildlife from 2016 in Kansas and Nebraska. Serological testing of mature cattle in nine distinct regional zones of Kansas revealed 76% to 100% had detectable antibodies to BTV and/or EHDV. Specimens tested in the Kansas Veterinary Diagnostic Laboratory (55 submissions) were 51% test positive for antibodies to BTV and/or EHDV. Specimens tested in the Nebraska Veterinary Diagnostic Center (283 submissions) were 25% test positive for antibodies to BTV and/or EHDV. Low disease incidence in white-tailed deer and other susceptible wild ungulates was observed during 2016. However, there were no confirmed reports of disease in livestock in either state. The reasons for emergence of significant clinical disease in livestock and wildlife populations remain undefined. [ABSTRACT FROM AUTHOR]

This study investigated the sero-epidemiology of bluetongue in ruminants in North-Western Pakistan. A total of 3,173 serum samples were collected from small (n = 1,651) and large (n = 1,522) ruminants being reared by farmers in 14 districts. Antibodies to bluetongue virus (BTV) were detected using competitive ELISA. The overall prevalence of BTV antibodies was 65%. A significant association (P < 0.05) between the prevalence of BTV antibodies and the risk factors including sex, species, age, area, husbandry practices and breed was shown by univariate analysis. In multivariate analysis, the seroprevalence was 6.5 (95% CL = 3.7–11.4), 5.9 (95% CL = 3.8–9.4) and 2.4 (95% CL = 1.5–3.7) times higher in buffaloes, cattle and goats than sheep, respectively. The seroprevalence was 1.4 (95% CL = 1.1–1.7) times higher in local breeds than in cross/exotic breeds. The seroprevalence was 1.6 (95% CL = 1.1 to 2.3) times higher in sedentary animals than in nomadic animals. The seroprevalence was significantly associated with age. Further work is required to determine the BTV serotypes prevalent in the study area for effective control of the disease. [ABSTRACT FROM AUTHOR]

Rabbit haemorrhagic disease viruses (RHDV) belong to the family Caliciviridae, genus Lagovirus europaeus, genogroup GI, comprising four genotypes GI.1–GI.4, of which the genotypes GI.1 and GI.2 are pathogenic RHD viruses, while the genotypes GI.3 and GI.4 are non-pathogenic RCV (Rabbit calicivirus) viruses. Among the pathogenic genotypes GI.1 and GI.2 of RHD viruses, an antigenic variant of RHDV, named RHDVa—now GI.1a–RHDVa, was distinguished in 1996; and in 2010, a variant of RHDV—named RHDVb, later RHDV2 and now GI.2–RHDV2/b—was described; and recombinants of these viruses were registered. Pathogenic viruses of the genotype GI.1 were the cause of a disease described in 1984 in China in domestic (Oryctolagus (O.) cuniculus domesticus) and wild (O. cuniculus) rabbits, characterised by a very rapid course and a mortality rate of 90–100%, which spread in countries all over the world and which has been defined since 1989 as rabbit haemorrhagic disease. It is now accepted that GI.1–RHDV, including GI.1a–RHDVa, cause the predetermined primary haemorrhagic disease in domestic and wild rabbits, while GI.2–RHDV2/b cause it not only in rabbits, including domestic rabbits' young up to 4 weeks and rabbits immunised with rabbit haemorrhagic disease vaccine, but also in five various species of wild rabbits and seven different species of hares, as well as wild ruminants: mountain muskoxen and European badger. Among these viruses, haemagglutination-positive, doubtful and harmful viruses have been recorded and described and have been shown to form phylogenogroups, immunotypes, haematotypes and pathotypes, which, together with traits that alter and expand their infectious spectrum (rabbit, hare, wild ruminant, badger and various rabbit and hare species), are the determinants of their pathogenicity (infectivity) and immunogenicity and thus shape their virulence. These relationships are the aim of our consideration in this article. [ABSTRACT FROM AUTHOR]

The clinical consequences of toxoplasmosis are greatly dependent on the Toxoplasma gondii strain causing the infection. To better understand its epidemiology and design appropriate control strategies, it is important to determine the strain present in infected animals. Serotyping methods are based on the detection of antibodies that react against segments of antigenic proteins presenting strain-specific polymorphic variations, offering a costeffective, sensitive, and non-invasive alternative to genotyping techniques. Herein, we evaluated the applicability of a panel of peptides previously characterized in mice and humans to serotype sheep and pigs. To this end, we used 51 serum samples from experimentally infected ewes (32 type II and 19 type III), 20 sheep samples from naturally infected sheep where the causative strain was genotyped (18 type II and 2 type III), and 40 serum samples from experimentally infected pigs (22 type II and 18 type III). Our ELISA test results showed that a combination of GRA peptide homologous pairs can discriminate infections caused by type II and III strains of T. gondii in sheep and pigs. Namely, the GRA3-I/III-43 vs. GRA3-II-43, GRA6-I/III-213 vs. GRA6-II-214 and GRA6-III- 44 vs. GRA6-II-44 ratios showed a statistically significant predominance of the respective strain-type peptide in sheep, while in pigs, in addition to these three peptide pairs, GRA7-II-224 vs. GRA7-III-224 also showed promising results. Notably, the GRA6-44 pair, which was previously deemed inefficient in mice and humans, showed a high prediction capacity, especially in sheep. By contrast, GRA5-38 peptides failed to correctly predict the strain type in most sheep and pig samples, underpinning the notion that individual standardization is needed for each animal species. Finally, we recommend analyzing for each animal at least 2 samples taken at different time points to confirm the obtained results. [ABSTRACT FROM AUTHOR]

Salmonellosis is one of the important bacterial infectious diseases affecting the health of pigeons. Heretofore, the epidemiological characteristics of Salmonella in pigeon populations in China remain largely unclear. The present study investigated the antimicrobial resistance and genomic characteristics of Salmonella isolates in pigeons in different regions of China from 2022 to 2023. Thirty-two Salmonella isolates were collected and subjected to 24 different antimicrobial agents, representing nine categories. The results showed that these isolates were highly resistant to cefazolin (100%), gentamicin (100%), tobramycin (100%), and amikacin (100%). Three or more types of antimicrobial resistance were present in 90.62% of the isolates, indicating multidrug resistance. Furthermore, using whole genome sequencing technology, we analyzed the profiles of serotypes, multilocus sequence typing, virulence genes, antimicrobial resistance genes, and plasmid replicons and constructed phylogenetic genomics to determine the epidemiological correlation among these isolates. All strains belonged to Salmonella Typhimurium var. Copenhagen and exhibited five antimicrobial resistance genes and more than 150 Salmonella virulence genes. Moreover, each isolate contained both the IncFIB(S) and IncFII(S) plasmids. In addition, phylogenetic analysis showed that all isolates were very close to each other, and isolates from the same region clustered in the same branch. Overall, our findings provide the first evidence for the epidemiological characteristics of Salmonella in pigeons of China, highlighting the importance of preventing salmonellosis in pigeons. [ABSTRACT FROM AUTHOR]

Introduction: Detailed assessment of the population structure of group B Streptococcus (GBS) among adults is still lacking in Saudi Arabia. Here we characterized a representative collection of isolates from colonized and infected adults. Methods: GBS isolates (n=89) were sequenced by Illumina and screened for virulence and antimicrobial resistance determinants. Genetic diversity was assessed by single nucleotide polymorphisms and core-genome MLST analyses. Results: Genome sequences revealed 28 sequence types (STs) and nine distinct serotypes, including uncommon serotypes VII and VIII. Majority of these STs (n=76) belonged to the human-associated clonal complexes (CCs) CC1 (33.71%), CC19 (25.84%), CC17 (11.24%), CC10/CC12 (7.87%), and CC452 (6.74%). Major CCs exhibited intra-lineage serotype diversity, except for the hypervirulent CC17, which exclusively expressed serotype III. Virulence profiling revealed that nearly all isolates (94.38%) carried at least one of the four alpha family protein genes (i.e., alphaC, alp1, alp2/3, and rib), and 92.13% expressed one of the two serine-rich repeat surface proteins Srr1 or Srr2. In addition, most isolates harbored the pilus island (PI)-2a alone (15.73%) or in combination with PI-1 (62.92%), and those carrying PI-2b alone (10.11%) belonged to CC17. Phylogenetic analysis grouped the sequenced isolates according to CCs and further subdivided them along with their serotypes. Overall, isolates across all CC1 phylogenetic clusters expressed Srr1 and carried the PI-1 and PI-2a loci, but differed in genes encoding the alphalike proteins. CC19 clusters were dominated by the III/rib/srr1/PI-1+PI-2a (43.48%, 10/23) and V/alp1/srr1/PI-1+PI-2a (34.78%, 8/23) lineages, whereas most CC17 isolates (90%, 9/10) had the same III/rib/srr2/P1-2b genetic background. Interestingly, genes encoding the CC17-specific adhesins HvgA and Srr2 were detected in phylogenetically distant isolates belonging to ST1212, suggesting that other highly virulent strains might be circulating within the species. Resistance to macrolides and/or lincosamides across all major CCs (n=48) was associated with the acquisition of erm(B) (62.5%, 30/48), erm(A) (27.1%, 13/48), lsa(C) (8.3%, 4/48), and mef(A) (2.1%, 1/48) genes, whereas resistance to tetracycline was mainly mediated by presence of tet(M) (64.18%, 43/67) and tet(O) (20.9%, 14/67) alone or in combination (13.43%, 9/67). Discussion: These findings underscore the necessity for more rigorous characterization of GBS isolates causing infections. [ABSTRACT FROM AUTHOR]

(1) Background: Epizootic hemorrhagic disease virus (EHDV) and bluetongue virus (BTV) are orbiviruses that cause hemorrhagic disease (HD) with significant economic and population health impacts on domestic livestock and wildlife. In the United States, white-tailed deer (Odocoileus virginianus) are particularly susceptible to these viruses and are a frequent blood meal host for various species of Culicoides biting midges (Diptera: Ceratopogonidae) that transmit orbiviruses. The species of Culicoides that transmit EHDV and BTV vary between regions, and larval habitats can differ widely between vector species. Understanding how midges are distributed across landscapes can inform HD virus transmission risk on a local scale, allowing for improved animal management plans to avoid suspected high-risk areas or target these areas for insecticide control. (2) Methods: We used occupancy modeling to estimate the abundance of gravid (egg-laden) and parous (most likely to transmit the virus) females of two putative vector species, C. stellifer and C. venustus, and one species, C. haematopotus, that was not considered a putative vector. We developed a universal model to determine habitat preferences, then mapped a predicted weekly midge abundance during the HD transmission seasons in 2015 (July–October) and 2016 (May–October) in Florida. (3) Results: We found differences in habitat preferences and spatial distribution between the parous and gravid states for C. haematopotus and C. stellifer. Gravid midges preferred areas close to water on the border of well and poorly drained soil. They also preferred mixed bottomland hardwood habitats, whereas parous midges appeared less selective of habitat. (4) Conclusions: If C. stellifer is confirmed as an EHDV vector in this region, the distinct spatial and abundance patterns between species and physiological states suggest that the HD risk is non-random across the study area. [ABSTRACT FROM AUTHOR]

Background: Bluetongue virus (BTV) serotype‐3 (BTV‐3) has been circulating in the Netherlands since September 2023 and was first reported in Kent in the UK in November 2023, picked up via the annual bluetongue surveillance programme. It is a highly pathogenic strain in sheep with limited preventive measures once virus is circulating in the biting midge population. At the time of publication there is no BTV‐3 vaccine available and no cross‐protection from other BTV vaccine strains. There are no specific antiviral medicines available, and therapy focuses on nursing care and anti‐inflammatory medicines to reduce clinical signs, although early euthanasia decisions need to be considered on the grounds of animal welfare. Aim of the article: This article takes the experiences of vets from the Netherlands and describes what practitioners might be able to do to treat clinical cases of BTV‐3, with thanks to Schapendokter (2023) for sharing their practice protocols. [ABSTRACT FROM AUTHOR]

Streptococcus suis (S. suis) is a zoonotic pathogen capable of causing severe diseases in humans and pigs, including meningitis, sepsis, polyserositis, arthritis, and endocarditis. This study aimed to investigate the biological characteristics of 19 strains of S. suis isolated from diseased pigs in Hubei Province between 2021 and 2023. Through bioinformatics analysis, we investigated the serotype, MLST, pan-genome characteristics, SNP, AMR, and ICE of the 19 S. suis isolates. Among the 19 S. suis strains, ten serotypes were identified, and serotype 9 was the most prevalent (21.05%). Ten new alleles and nine new sequence types (STs) were discovered, with ST28 and ST243 emerging as the predominant STs. The results of the pan-genomic analysis of S. suis indicate that there are 943 core genes, 2259 shell genes, and 5663 cloud genes. Through SNP evolutionary analysis, we identified a strong genetic similarity between SS31 and the reference genome P1/7. The analysis of antibiotic resistance genes revealed widespread presence of erm(B) and tet(O) genes among 19 strains of S. suis. This association may be linked to the high resistance of S. suis to lincosamides, macrolides, and tetracyclines. Integrative and conjugative elements (ICEs) and integrative and mobilizable elements (IMEs) were identified in 16 strains, with a carriage rate of 84.21%, and resistance genes were identified within the ICE/IME elements of 8 strains. Antimicrobial susceptibility testing revealed that all strains showed sensitivity to vancomycin and lincomycin but resistance to tilmicosin, tiamulin, amoxicillin, and doxycycline. This study contributes to our understanding of the genomic diversity of S. suis in Hubei Province of China, providing essential data for the comprehensive prevention and control of S. suis infections in China. [ABSTRACT FROM AUTHOR]

Many protein expression systems are primarily utilised to produce a single, specific recombinant protein. In contrast, most biological processes such as virus assembly rely upon a complex of several interacting proteins rather than the activity of a sole protein. The high complexity of the baculovirus genome, coupled with a multiphase replication cycle incorporating distinct transcriptional steps, made it the ideal system to manipulate for high-level expression of a single, or co-expression of multiple, foreign proteins within a single cell. We have developed and utilised a series of recombinant baculovirus systems to unravel the sequential assembly process of a complex non-enveloped model virus, bluetongue virus (BTV). The high protein yields expressed by the baculovirus system not only facilitated structure–function analysis of each viral protein but were also advantageous to crystallography studies and supported the first atomic-level resolution of a recombinant viral protein, the major BTV capsid protein. Further, the formation of recombinant double-shelled virus-like particles (VLPs) provided insights into the structure–function relationships among the four major structural proteins of the BTV whilst also representing a potential candidate for a viral vaccine. The baculovirus multi-gene expression system facilitated the study of structurally complex viruses (both non-enveloped and enveloped viruses) and heralded a new generation of viral vaccines. [ABSTRACT FROM AUTHOR]

The bluetongue virus (BTV), transmitted by biting midges, poses a significant threat to livestock globally. This orbivirus induces bluetongue disease, leading to substantial economic losses in the agricultural sector. The current control measures have limitations, necessitating the development of novel, efficient vaccines. In this study, an immunoinformatics approach is employed to design a multi-epitope subunit vaccine for Ovis aries targeting six BTV serotypes. Focusing on the VP2 capsid protein, the vaccine incorporates B-cell, helper-T lymphocytes (HTL), and cytotoxic T-cell lymphocytes (CTL) epitopes. Molecular docking reveals stable interactions with TLR2 and TLR4 receptors, suggesting the stability of the complex, indicating the potential viability of the multi-epitope vaccine. The computational approach offers a rapid and tailored strategy for vaccine development, highlighting potential efficacy and safety against BTV outbreaks. This work contributes to understanding BTV and presents a promising avenue for effective control.

Bluetongue virus (BTV) is a prevalent midge-borne pathogen that infects ruminant species worldwide. BTV infections range from asymptomatic to lethal, with mechanisms that determine the severity of infection remaining largely undefined. Although it is relatively poorly understood, the immune response to BTV infection is thought to be critical for both the propagation of disease as well as the resolution of infection. To bridge this gap in knowledge, we infected cohorts of sheep and muntjac deer with two serotypes of BTV (BTV10 and BTV17) for longitudinal analysis (30 days). Interestingly, species-specific differences were observed. Circulating virus was detected early and remained detectable for the duration of the sheep study, while infections in muntjac showed faltering detection of BTV10 at 3 weeks post infection. The magnitude of the immune response was subdued in the muntjac when compared to the sheep cohorts, though similar responses were observed. We also assessed midge viral uptake and the ability to replicate BTV. Midges successfully fed on both species, yet those that fed on sheep resulted in more efficient BTV transmission. Our findings demonstrate that differences in BTV infections, immune responses, and vector competence across host species and serotypes will impact global BTV emergence and strategies for mitigation.