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Mayaro virus (MAYV) is the causative agent of Mayaro fever, which is characterized mainly by acute fever and long-term severe arthralgia, common manifestations of other arbovirus infections, making the correct diagnosis a challenge. Besides, MAYV infections have been reported in South America, especially in Brazil. However, the lack of vaccines or specific antiviral drugs to control these infections makes the search for new antivirals an urgent need. Herein, we evaluated the antiviral potential of synthetic β-enaminoesters derivatives against MAYV replication and their pharmacokinetic and toxicological (ADMET) properties using in vitro and in silico strategies. For this purpose, Vero cells were infected with MAYV at an MOI of 0.1, treated with compounds (50 µM) for 24 h, and virus titers were quantified by plaque reduction assays. Compounds 2b (83.33%) and 2d (77.53%) exhibited the highest activity with inhibition rates of 83.33% and 77.53%, respectively. The most active compounds 2b (EC 50  = 18.92 µM; SI > 52.85), and 2d (EC 50  = 14.52 µM; SI > 68.87) exhibited higher potency and selectivity than the control drug suramin (EC 50  = 38.97 µM; SI > 25.66). Then, we investigated the mechanism of action of the most active compounds. None of the compounds showed virucidal activity, neither inhibited virus adsorption, but compound 2b inhibited virus entry (62.64%). Also, compounds 2b and 2d inhibited some processes involved with the release of new virus particles. Finally, in silico results indicated good ADMET parameters of the most active compounds and reinforced their promising profile as drug candidates against MAYV., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

The Alphavirus genus includes viruses that cause encephalitis due to neuroinvasion and viruses that cause arthritis due to acute and chronic inflammation. There is no approved therapeutic for alphavirus infections, but significant efforts are ongoing, more so in recent years, to develop vaccines and therapeutics for alphavirus infections. This review article highlights some of the major advances made so far to identify small molecules that can selectively target the structural and the nonstructural proteins in alphaviruses with the expectation that persistent investigation of an increasingly expanding chemical space through a variety of structure-based design and high-throughput screening strategies will yield candidate drugs for clinical studies. While most of the works discussed are still in the early discovery to lead optimization stages, promising avenues remain for drug development against this family of viruses.

Various low-density lipoprotein receptors (LPRs) have been identified as entry factors for alphaviruses, and structures of the corresponding virion-receptor complexes have been determined. Here, we analyze the similarities and differences in the receptor binding modes of multiple alphaviruses to understand their ability to infect a wide range of hosts. We further discuss the challenges associated with the development of broad-spectrum treatment strategies against a diverse range of alphaviruses., (© 2024. The Author(s).)

Introduction: Mayaro fever is an emerging viral disease that manifests as an acute febrile illness. The disease is self-limiting, however joint pain can persist for months leading to chronic arthralgia. There is no specific treatment available, which ultimately leads to socioeconomic losses in populations at risk as well as strains to the public health systems., Areas Covered: We reviewed the candidate treatments proposed for Mayaro virus (MAYV) infection and disease, including antiviral compounds targeting viral or host mechanisms, and pathways involved in disease development and pathogenicity. We assessed compound screening technologies and experimental infection models used in these studies and indicated the advantages and limitations of available technologies and intended therapeutic strategies., Expert Opinion: Although several compounds have been suggested as candidate treatments against MAYV infection, notably those with antiviral activity, most compounds were assessed only in vitro . Compounds rarely progress to in vivo or preclinical studies, and such difficulty may be associated with limited experimental models. MAYV biology is largely inferred from related alphaviruses and reflected by few studies focusing on target proteins or mechanisms of action for MAYV. Therapeutic strategies targeting pathogenic inflammatory responses have shown potential against MAYV-induced disease in vivo , which might reduce long-term sequelae.

Arthritis and periodontitis are inflammatory diseases that share several immunopathogenic features. The expansion in the study of virus-induced arthritis has shed light on how this condition could impact other parts of the human body, including the mouth. Viral arthritis is an inflammatory joint disease caused by several viruses, most notably the alphaviruses Chikungunya virus (CHIKV), Sindbis virus (SINV), Ross River virus (RRV), Mayaro virus (MAYV), and O'nyong'nyong virus (ONNV). These viruses can induce an upsurge of matrix metalloproteinases and immune-inflammatory mediators such as Interleukin-6 (IL6), IL-1β, tumor necrosis factor, chemokine ligand 2, and receptor activator of nuclear factor kappa-B ligand in the joint and serum of infected individuals. This can lead to the influx of inflammatory cells to the joints and associated muscles as well as osteoclast activation and differentiation, culminating in clinical signs of swelling, pain, and bone resorption. Moreover, several data indicate that these viral infections can affect other sites of the body, including the mouth. The human oral cavity is a rich and diverse microbial ecosystem, and viral infection can disrupt the balance of microbial species, causing local dysbiosis. Such events can result in oral mucosal damage and gingival bleeding, which are indicative of periodontitis. Additionally, infection by RRV, CHIKV, SINV, MAYV, or ONNV can trigger the formation of osteoclasts and upregulate pro-osteoclastogenic inflammatory mediators, interfering with osteoclast activation. As a result, these viruses may be linked to systemic conditions, including oral manifestations. Therefore, this review focuses on the involvement of alphavirus infections in joint and oral health, acting as potential agents associated with oral mucosal inflammation and alveolar bone loss. The findings of this review demonstrate how alphavirus infections could be linked to the comorbidity between arthritis and periodontitis and may provide a better understanding of potential therapeutic management for both conditions., (© The Author(s) 2024. Published by Oxford University Press on behalf of Applied Microbiology International.)

Mayaro virus is an emerging arbovirus that causes nonspecific febrile illness or arthralgia syndromes similar to the Chikungunya virus, a virus closely related from the Togaviridae family. MAYV outbreaks occur more frequently in the northern and central-western states of Brazil; however, in recent years, virus circulation has been spreading to other regions. Due to the undifferentiated initial clinical symptoms between MAYV and other endemic pathogenic arboviruses with geographic overlapping, identification of patients infected by MAYV might be underreported. Additionally, the lack of specific prophylactic approaches or antiviral drugs limits the pharmacological management of patients to treat symptoms like pain and inflammation, as is the case with most pathogenic alphaviruses. In this context, this review aims to present the state-of-the-art regarding the screening and development of compounds/molecules which may present anti-MAYV activity and infection inhibition.

The discovery and the development of safe and efficient therapeutics against arthritogenic alphaviruses (e.g., chikungunya virus) remain a continuous challenge. Alkaloids are structurally diverse and naturally occurring compounds in plants, with a wide range of biological activities including beneficial effects against prominent pathogenic viruses and inflammation. In this short review, we discuss the effects of some alkaloids of three biologically relevant structural classes (isoquinolines, indoles and quinolizidines). Based on various experimental models (viral infections and chronic diseases), we highlight the immunomodulatory effects of these alkaloids. The data established the capacity of these alkaloids to interfere in host antiviral and inflammatory responses through key components (antiviral interferon response, ROS production, inflammatory signaling pathways and pro- and anti-inflammatory cytokines production) also involved in alphavirus infection and resulting inflammation. Thus, these data may provide a convincing perspective of research for the use of alkaloids as immunomodulators against arthritogenic alphavirus infection and induced inflammation.

Enteric pathogens overcome barrier immunity within the intestinal environment that includes the endogenous flora. The microbiota produces diverse ligands, and the full spectrum of microbial products that are sensed by the epithelium and prime protective immunity is unknown. Using Drosophila, we find that the gut presents a high barrier to infection, which is partially due to signals from the microbiota, as loss of the microbiota enhances oral viral infection. We report cyclic dinucleotide (CDN) feeding is sufficient to protect microbiota-deficient flies from enhanced oral infection, suggesting that bacterial-derived CDNs induce immunity. Mechanistically, we find CDN protection is dSTING- and dTBK1-dependent, leading to NF-kB-dependent gene expression. Furthermore, we identify the apical nucleoside transporter, CNT2, as required for oral CDN protection. Altogether, our studies define a role for bacterial products in priming immune defenses in the gut., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2021 The Author(s). Published by Elsevier Inc. All rights reserved.)

Mayaro virus (MAYV) is an emergent alphavirus that causes MAYV fever. It is often associated with debilitating symptoms, particularly arthralgia and myalgia. MAYV infection is becoming a considerable health issue that, unfortunately, lacks a specific antiviral treatment. Favipiravir, a broad-spectrum antiviral drug, has recently been shown to exert anti-MAYV activity in vitro. In the present study, the potential of Favipiravir to inhibit MAYV replication in an in vivo model was evaluated. Immunocompetent mice were orally administrated 300 mg/kg/dose of Favipiravir at pre-, concurrent-, or post-MAYV infection. The results showed a significant reduction in infectious viral particles and viral RNA transcripts in the tissues and blood of the pre- and concurrently treated infected mice. A significant reduction in the presence of both viral RNA transcript and infectious viral particles in the tissue and blood of pre- and concurrently treated infected mice was observed. By contrast, Favipiravir treatment post-MAYV infection did not result in a reduction in viral replication. Interestingly, Favipiravir strongly decreased the blood levels of the liver disease markers aspartate- and alanine aminotransferase in the pre- and concurrently treated MAYV-infected mice. Taken together, these results suggest that Favipiravir is a potent antiviral drug when administered in a timely manner.

Mayaro virus (MAYV) is a neglected arthropod-borne virus found in the Americas. MAYV infection results in Mayaro fever, a non-lethal debilitating disease characterized by a strong inflammatory response affecting the joints and muscles. MAYV was once considered endemic to forested areas in Brazil but has managed to adapt and spread to urban regions using new vectors, such as Aedes aegypti , and has the potential to cause serious epidemics in the future. Currently, there are no vaccines or specific treatments against MAYV. In this study, the antiviral activity of a series of synthetic cyclic ketones were evaluated for the first time against MAYV. Twenty-four compounds were screened in a cell viability assay, and eight were selected for further evaluation. Effective concentration (EC 50 ) and selectivity index (SI) were calculated and compound 9-(5-(4-chlorophenyl]furan-2-yl)-3,6-dimethyl-3,4,5,6,7,9-hexahydro-1H-xanthene-1,8(2))-dione (9) (EC 50 = 21.5 µmol·L -1 , SI = 15.8) was selected for mechanism of action assays. The substance was able to reduce viral activity by approximately 70% in both pre-treatment and post-treatment assays.

Infection caused by Mayaro virus (MAYV) is responsible for causing acute nonspecific fever, in which the majority of patients develop incapacitating and persistent arthritis/arthralgia. Mayaro fever is a neglected and underreported disease without treatment or vaccine, which has gained attention in recent years after the competence of Aedes aegypti to transmit MAYV was observed in the laboratory, coupled with the fact that cases are being increasingly reported outside of endemic forest areas, calling attention to the potential of an urban cycle arising in the near future. Thus, to mitigate the lack of information about the pathological aspects of MAYV, we previously described the involvement of oxidative stress in MAYV infection in cultured cells and in a non-lethal mouse model. Additionally, we showed that silymarin, a natural compound, attenuated MAYV-induced oxidative stress and inhibited MAYV replication in cells. The antioxidant and anti-MAYV effects prompted us to determine whether silymarin could also reduce oxidative stress and MAYV replication after infection in an immunocompetent animal model. We show that infected mice exhibited reduced weight gain, hepatomegaly, splenomegaly, anaemia, thrombocytopenia, leukopenia, increased liver transaminases, increased pro-inflammatory cytokines and liver inflammation, increased oxidative damage biomarkers, and reduced antioxidant enzyme activity. However, in animals infected and treated with silymarin, all these parameters were reversed or significantly improved, and the detection of viral load in the liver, spleen, brain, thigh muscle, and footpad was significantly reduced. This work reinforces the potent hepatoprotective, antioxidant, anti-inflammatory, and antiviral effects of silymarin against MAYV infection, demonstrating its potential against Mayaro fever disease., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Alphaviruses are a group of arboviruses that generate chronic inflammatory rheumatisms in humans. Currently, no approved vaccines or antiviral therapies are available to prevent or treat alphavirus-induced diseases. The aim of this study was to evaluate the repositioning of the anti-cancer molecule irinotecan as a potential modulator of the antiviral and inflammatory responses of primary human synovial fibroblasts (HSF), the main stromal cells of the joint synovium. HSF were exposed to O'nyong-nyong virus (ONNV) and polyinosinic-polycytidylic acid (PIC) to mimic, respectively, acute and chronic infectious settings. The cytokine IL-1β was used as a major pro-inflammatory cytokine to stimulate HSF. Quantitative RT-PCR analysis revealed that irinotecan at 15 µM was able to amplify the antiviral response (i.e., interferon-stimulated gene expression) of HSF exposed to PIC and reduce the expression of pro-inflammatory genes (CXCL8, IL-6 and COX-2) upon IL-1β treatment. These results were associated with the regulation of the expression of several genes, including those encoding for STAT1, STAT2, p53 and NF-κB. Irinotecan did not modulate these responses in both untreated cells and cells stimulated with ONNV. This suggests that this drug could be therapeutically useful for the treatment of chronic and severe (rather than acute) arthritis due to viruses.

The antiviral innate immune response mainly involves type I interferon (IFN) in mammalian cells. The contribution of the RNA silencing machinery remains to be established, but several recent studies indicate that the ribonuclease DICER can generate viral siRNAs in specific conditions. It has also been proposed that type I IFN and RNA silencing could be mutually exclusive antiviral responses. In order to decipher the implication of DICER during infection of human cells with alphaviruses such as the Sindbis virus and Semliki forest virus, we determined its interactome by proteomics analysis. We show that DICER specifically interacts with several double-stranded RNA binding proteins and RNA helicases during viral infection. In particular, proteins such as DHX9, ADAR-1 and the protein kinase RNA-activated (PKR) are enriched with DICER in virus-infected cells. We demonstrate that the helicase domain of DICER is essential for this interaction and that its deletion confers antiviral properties to this protein in an RNAi-independent, PKR-dependent, manner., Competing Interests: The authors have declared that no competing interests exist.

O'nyong-nyong virus is an alphavirus closely related to chikungunya virus, causing arthralgia, rash and fever. Alphaviruses mainly target synovial fibroblasts and persists in the joints of patients, possibly leading to chronic arthritis. To date, no specific antiviral treatment is available for ONNV infection and induced-inflammation. Primary human synovial fibroblasts cells were used to assess infection by ONNV and the resulting cytokine responses. Phenolics (gallic acid, caffeic acid and chlorogenic acid, curcumin and quercetin) and a curcuminoids-rich extract from turmeric were tested for their antiviral and anti-inflammatory capacities. We showed that infection occurred in HSF cells and increased gene expression and protein secretion of two major proinflammatory CCL-2 and IL-1β markers. In ONNV-infected HSF cells (MOI 1), we found that non-cytotoxic concentrations of phenolics (10 µM) reduced the level of viral RNA (E1, E2, nsP1, nsP2) and downregulated CCL-2 and IL-1β expression and secretion. These results highlighted the high value of the flavonol quercetin to reduce viral RNA levels and inflammatory status induced by ONNV in HSF cells.

Alphaviruses are (mainly) arthropod-borne viruses that belong to the family of the Togaviridae. Based on the disease they cause, alphaviruses are divided into an arthritogenic and an encephalitic group. Arthritogenic alphaviruses such as the chikungunya virus (CHIKV), the Ross River virus (RRV) and the Mayaro virus (MAYV) have become a serious public health concern in recent years. Epidemics are associated with high morbidity and the infections cause in many patients debilitating joint pain that can persist for months to years. The recent (2013-2014) introduction of CHIKV in the Americas resulted in millions of infected persons. Massive outbreaks of CHIKV and other arthritogenic alphaviruses are likely to occur in the future. Despite the worldwide (re-)emergence of these viruses, there are no antivirals or vaccines available for the treatment or prevention of infections with alphaviruses. It is therefore of utmost importance to develop antiviral strategies against these viruses. We here review the possible molecular targets in the replication cycle of these viruses for the development of antivirals. In addition, we provide an overview of the currently available in vitro systems and mouse infection models that can be used to assess the potential antiviral effect against these viruses., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Tropical infectious diseases cause millions of deaths every year in developing countries, with about half of the world population living at risk. Mayaro virus (MAYV) is an emerging arbovirus that causes Mayaro fever, which is characterized by fever, headache, diarrhea, arthralgia, and rash. These symptoms can be clinically indistinguishable from other arboviruses, such as Dengue, Zika, and Chikungunya, which makes the diagnosis and treatment of the disease more difficult. Though, the Mayaro virus is a potential candidate to cause large-scale epidemics on the scale of ZIKV and CHIKV. Despite this, there is no licensed vaccine or antiviral for the treatment of Mayaro fever and most arboviruses, so the design and development of candidates for antiviral drugs are urgently needed. In this context, this mini-review aims to provide an overview of studies of anti-MAYV derivatives and highlight the importance of the discovery and development of promising drug candidates for Mayaro fever., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Arboviruses are a diverse group of viruses that are among the major causes of emerging infectious diseases. Arboviruses from the genera flavivirus and alphavirus are the most important human arboviruses from a public health perspective. During recent decades, these viruses have been responsible for millions of infections and deaths around the world. Over the past few years, several investigations have been carried out to identify antiviral agents to treat these arbovirus infections. The use of synthetic antiviral compounds is often unsatisfactory since they may raise the risk of viral mutation; they are costly and possess either side effects or toxicity. One attractive strategy is the use of plants as promising sources of novel antiviral compounds that present significant inhibitory effects on these viruses. In this review, we describe advances in the exploitation of compounds and extracts from natural sources that target the vital proteins and enzymes involved in arbovirus replication., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Chikungunya virus (CHIKV) is a rapidly emerging mosquito-borne RNA virus that causes epidemics of debilitating disease in tropical and sub-tropical regions with autochtonous transmission in regions with temperate climate. Currently, there is no licensed vaccine or specific antiviral drug available against CHIKV infection. In this study, we examine the role, in the CHIKV viral cycle, of fatty acid synthase (FASN) and stearoyl-CoA desaturase (SCD1), two key lipogenic enzymes required for fatty acid production and early desaturation. We show that both enzymes and their upstream regulator PI3K are required for optimal CHIKV infection. We demonstrate that pharmacologic manipulation of FASN or SCD1 enzymatic activity by non-toxic concentrations of cerulenin or CAY10566 decreases CHIKV genome replication. Interestingly, a similar inhibitory effect was also obtained with Orlistat, an FDA-approved anti-obesity drug that targets FASN activity. These drugs were also effective against Mayaro virus (MAYV), an under-studied arthritogenic Old world Alphavirus endemic in South American countries with potential risk of emergence, urbanization and dispersion to other regions. Altogether, our results identify FASN and SCD1 as conserved druggable cofactors of Alphavirus genome replication and support the broad-spectrum activity of drugs targeting the host fatty acids metabolism., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Recently the anti-viral effects of prophylactic treatment with the low-molecular-weight heparan sulfate mimetic PG545 in Ross River virus (RRV) infected mice were reported. We further investigated the related, transient pathophysiology of PG545 drug treatment in RRV-infected and mock-infected PG545-treated mice. PG545 treatment resulted in mild lethargy and piloerection, on days after the drug administration. Mice were treated with two or three doses of PG545 within a ten-day period and were subsequently culled at peak disease or at disease resolution. The treatment responses of the spleen and liver were assessed through histology, flow cytometry, gene arrays and serum biochemistry. Microscopy showed an expanded red pulp in the spleen following either two or three treatments with PG545. The red pulp expansion was further demonstrated by the proliferation of megakaryocytes and erythrocyte precursors within the spleen. In addition, flow cytometry and gene array analyses revealed a reduction of lymphocytes within the spleens of PG545-treated mice. Previously unreported, RRV-induced elevations of aspartate aminotransferase (AST) and alanine transaminase (ALT) enzymes and creatinine were also noted in the RRV-infected mice. However, PG545 only reduced AST and ALT levels but not the creatinine levels in infected mice during treatment. Mice treated with three doses of PG545 also showed hepatosplenomegaly and anaemia, which were reversed upon discontinuation of the treatment. In summary, this study demonstrates that dose and frequency related haemopoietic pathophysiology such as hepatosplenomegaly and anaemia, occurred in C57BL/6 mice treated with PG545. However, this effect was reversible once drug administration is terminated., Competing Interests: The authors have declared that no competing interests exist.

Alphaviruses are arthropod-transmitted RNA viruses that can cause arthralgia, myalgia, and encephalitis in humans. Since the role of cellular kinases in alphavirus replication is unknown, we profiled kinetic changes in host kinase abundance and phosphorylation following chikungunya virus (CHIKV) infection of fibroblasts. Based upon the results of this study, we treated CHIKV-infected cells with kinase inhibitors targeting the Src family kinase (SFK)-phosphatidylinositol 3-kinase (PI3K)-AKT-mTORC signaling pathways. Treatment of cells with SFK inhibitors blocked the replication of CHIKV as well as multiple other alphaviruses, including Mayaro virus, O'nyong-nyong virus, Ross River virus, and Venezuelan equine encephalitis virus. Dissecting the effect of SFK inhibition on alphavirus replication, we found that viral structural protein levels were significantly reduced, but synthesis of viral genomic and subgenomic RNAs was unaffected. By measuring the association of viral RNA with polyribosomes, we found that the SFK inhibitor dasatinib blocks alphavirus subgenomic RNA translation. Our results demonstrate a role for SFK signaling in alphavirus subgenomic RNA translation and replication. Targeting host factors involved in alphavirus replication represents an innovative, perhaps paradigm-shifting, strategy for exploring the replication of CHIKV and other alphaviruses while promoting antiviral therapeutic development., (Copyright © 2019 Broeckel et al.)

Arthritogenic alphaviruses are a group of medically important arboviruses that cause inflammatory musculoskeletal disease in humans with debilitating symptoms, such as arthralgia, arthritis, and myalgia. The arthritogenic, or Old World, alphaviruses are capable of causing explosive outbreaks, with some viruses of major global concern. At present, there are no specific therapeutics or commercially available vaccines available to prevent alphaviral disease. Infected patients are typically treated with analgesics and non-steroidal anti-inflammatory drugs to provide often inadequate symptomatic relief. Studies to determine the mechanisms of arthritogenic alphaviral disease have highlighted the role of the host immune system in disease pathogenesis. This review discusses the current knowledge of the innate immune response to acute alphavirus infection and alphavirus-induced immunopathology. Therapeutic strategies to treat arthritogenic alphavirus disease by targeting the host immune response are also examined.

Tetherin is an interferon-inducible, antiviral host factor that broadly restricts enveloped virus release by tethering budded viral particles to the plasma membrane. In response, many viruses have evolved tetherin antagonists. The human tetherin gene can express two isoforms, long and short, due to alternative translation initiation sites in the N-terminal cytoplasmic tail. The long isoform (L-tetherin) contains 12 extra amino acids in its N terminus, including a dual tyrosine motif (YDYCRV) that is an internalization signal for clathrin-mediated endocytosis and a determinant of NF-κB activation. Tetherin restricts alphaviruses, which are highly organized enveloped RNA viruses that bud from the plasma membrane. L-tetherin is more efficient than S-tetherin in inhibiting alphavirus release in 293 cells. Here, we demonstrated that alphaviruses do not encode an antagonist for either of the tetherin isoforms. Instead, the isoform specificity reflected a requirement for tetherin endocytosis. The YXY motif in L-tetherin was necessary for alphavirus restriction in 293 cells but was not required for rhabdovirus restriction. L-tetherin's inhibition of alphavirus release correlated with its internalization but did not involve NF-κB activation. In contrast, in U-2 OS cells, the YXY motif and the L-tetherin N-terminal domain were not required for either robust tetherin internalization or alphavirus inhibition. Tetherin forms that were negative for restriction accumulated at the surface of infected cells, while the levels of tetherin forms that restrict were decreased. Together, our results suggest that tetherin-mediated virus internalization plays an important role in the restriction of alphavirus release and that cell-type-specific cofactors may promote tetherin endocytosis. IMPORTANCE The mechanisms of tetherin's antiviral activities and viral tetherin antagonism have been studied in detail for a number of different viruses. Although viral countermeasures against tetherin can differ significantly, overall, tetherin's antiviral activity correlates with physical tethering of virus particles to prevent their release. While tetherin can mediate virus endocytic uptake and clearance, this has not been observed to be required for restriction. Here we show that efficient tetherin inhibition of alphavirus release requires efficient tetherin endocytosis. Our data suggest that this endocytic uptake can be mediated by tetherin itself or by a tetherin cofactor that promotes uptake of an endocytosis-deficient variant of tetherin., (Copyright © 2019 American Society for Microbiology.)

The New World alphaviruses, Venezuelan, eastern and western equine encephalitis viruses (VEEV, EEEV, and WEEV), are important human pathogens due to their ability to cause varying levels of morbidity and mortality in humans. There is also concern about VEEV and EEEV being used as bioweapons. Currently, a FDA-approved antiviral is lacking for New World alphaviruses. In this review, the function of each viral protein is discussed with an emphasis on how these functions can be targeted by therapeutics. Both direct acting antivirals as well as inhibitors that impact host protein interactions with viral proteins are described. Non-structural protein 3 (nsP3), capsid, and E2 proteins have garnered attention in recent years, whereas little is known regarding host protein interactions of the other viral proteins and is an important avenue for future study., (Copyright © 2019 Elsevier B.V. All rights reserved.)

The chikungunya virus (CHIKV) is a mosquito-borne virus that belongs to the genus Alphavirus, family Togaviridae. It is the cause of chikungunya fever in humans, which presents a serious global threat due to its high rate of contagion. The clinical symptoms of CHIKV include fever and persistent, severe arthritis. Micafungin has broad-spectrum fungicidal activity against Candida spp. is a promising echinocandin that was recently approved by the U.S. Food and Drug Administration (FDA) and has demonstrated activity against Candida and Aspergillus. Recent studies have demonstrated the antiviral activity of micafungin; however, the inhibitory effects against CHIKV have yet to be investigated. Our objectives in this study were to explore the antiviral effects of micafungin on CHIKV infection and to elucidate the potential molecular mechanisms of inhibition. We determined that micafungin has the ability to counter CHIKV-induced cytopathic effects. We further discovered that micafungin limits virus replication, release, cell-to-cell transmission, and also slightly affected virus stability during high doses treatment. The efficacy of micafungin was further confirmed against two clinical isolates of CHIKV and two alphaviruses: Sindbis virus (SINV) and Semliki Forest virus (SFV). Our findings suggest that micafungin has considerable potential as a novel inhibitor against the viral replication, and intracellular and extracellular transmission of CHIKV, and has a little effect on virus stability. Our findings also suggest that micafungin could have curative effects on other alphavirus infections., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Mayaro virus (MAYV) is a neglected arbovirus belonging to the family Togaviridae. Its infection leads to Mayaro fever, with clinical manifestations such as fever, myalgia, headache, rash, arthralgia, vomiting, and diarrhea. The most prominent complaint from infected person is the long-lasting arthritis/arthralgia. The treatment for Mayaro fever is mainly symptom-based and there are no vaccines or antiviral drugs currently available, thus, natural products with anti-MAYV activity may provide a potential alternative. Recent evidences suggest that oxidative stress plays an important role in MAYV infection and compounds capable of modulating oxidative stress could represent a novel therapeutic approach in modulating MAYV-associated oxidative cellular damage. Silymarin is a complex extracted of Silybum marianum, or milk thistle, and its major active compound is silybin, which has a remarkable biological effect. Its antioxidant and antiviral effects, including its antiviral activity against the Chikungunya virus (CHIKV), prompted us to think whether silymarin could also reduce the replication of the MAYV and restore the pro-oxidant/antioxidant balance in the context of MAYV infection, leading to reduced cellular oxidative stress. We assessed the antiviral activity and protective effect of silymarin against oxidative stress in MAYV-infected HepG2 cells. Cytopathic effect inhibition, viral replication, and plaque reduction assays were used to determine the anti-MAYV activity of silymarin. Additionally, we determined whether silymarin could reduce MAYV-induced oxidative cell damage. Briefly, silymarin exhibited potent antiviral activity against MAYV and reduced MAYV-induced ROS formation and levels of malondialdehyde (MDA) and carbonyl protein, which are biomarkers of oxidative stress. In conclusion, the ability of silymarin to inhibit MAYV replication and attenuate MAYV-induce oxidative stress warrants further investigation of this compound as a novel therapeutic approach to Mayaro fever disease., (Copyright © 2018. Published by Elsevier B.V.)

Alphaviruses are enveloped, positive single-stranded RNA viruses, typically transmitted by arthropods. They often cause arthralgia or encephalitic diseases in infected humans and there is currently no targeted antiviral treatment available. The re-emergence of alphaviruses in Asia, Europe, and the Americas over the last decade, including chikungunya and o'nyong'nyong viruses, have intensified the search for selective inhibitors. In this review, we highlight key molecular determinants within the alphavirus replication complex that have been identified as viral targets, focusing on their structure and functionality in viral dissemination. We also summarize recent structural data of these viral targets and discuss how these could serve as templates to facilitate structure-based drug design and development of small molecule inhibitors., Competing Interests: The authors declare no conflict of interest.

Infection of weanling C57BL/6 mice with the TE strain of Sindbis virus (SINV) causes nonfatal encephalomyelitis associated with hippocampal-based memory impairment that is partially prevented by treatment with 6-diazo-5-oxo-l-norleucine (DON), a glutamine antagonist (Potter et al., J Neurovirol 21:159, 2015). To determine the mechanism(s) of protection, lymph node and central nervous system (CNS) tissues from SINV-infected mice treated daily for 1 week with low (0.3mg/kg) or high (0.6mg/kg) dose DON were examined. DON treatment suppressed lymphocyte proliferation in cervical lymph nodes resulting in reduced CNS immune cell infiltration, inflammation, and cell death compared to untreated SINV-infected mice. Production of SINV-specific antibody and interferon-gamma were also impaired by DON treatment with a delay in virus clearance. Cessation of treatment allowed activation of the antiviral immune response and viral clearance, but revived CNS pathology, demonstrating the ability of the immune response to mediate both CNS damage and virus clearance., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Unlabelled: Inflammation is a necessary part of the response to infection but can also cause neuronal injury in both infectious and autoimmune diseases of the central nervous system (CNS). A neurovirulent strain of Sindbis virus (NSV) causes fatal paralysis in adult C57BL/6 mice during clearance of infectious virus from the CNS, and the virus-specific immune response is implicated as a mediator of neuronal damage. Previous studies have shown that survival is improved in T-cell-deficient mice and in mice with pharmacological inhibition of the inflammatory response and glutamate excitotoxicity. Because glutamine metabolism is important in the CNS for the generation of glutamate and in the immune system for lymphocyte proliferation, we tested the effect of the glutamine antagonist DON (6-diazo-5-oxo-l-norleucine) on the outcome of NSV infection in mice. DON treatment for 7 days from the time of infection delayed the onset of paralysis and death. Protection was associated with reduced lymphocyte proliferation in the draining cervical lymph nodes, decreased leukocyte infiltration into the CNS, lower levels of inflammatory cytokines, and delayed viral clearance. In vitro studies showed that DON inhibited stimulus-induced proliferation of lymphocytes. When in vivo treatment with DON was stopped, paralytic disease developed along with the inflammatory response and viral clearance. These studies show that fatal NSV-induced encephalomyelitis is immune mediated and that antagonists of glutamine metabolism can modulate the immune response and protect against virus-induced neuroinflammatory disease., Importance: Encephalomyelitis due to infection with mosquito-borne alphaviruses is an important cause of death and of long-term neurological disability in those who survive infection. This study demonstrates the role of the virus-induced immune response in the generation of neurological disease. DON, a glutamine antagonist, inhibited the proliferation of lymphocytes in response to infection, prevented the development of brain inflammation, and protected mice from paralysis and death during treatment. However, because DON inhibited the immune response to infection, clearance of the virus from the brain was also prevented. When treatment was stopped, the immune response was generated, brain inflammation occurred, virus was cleared, and mice developed paralysis and died. Therefore, more definitive treatment for alphaviral encephalomyelitis should inhibit virus replication as well as neuroinflammatory damage., (Copyright © 2016, American Society for Microbiology. All Rights Reserved.)

Mosquito-borne viruses are important causes of death and long-term neurologic disability due to encephalomyelitis. Studies of mice infected with the alphavirus Sindbis virus have shown that outcome is dependent on the age and genetic background of the mouse and virulence of the infecting virus. Age-dependent susceptibility reflects the acquisition by neurons of resistance to virus replication and virus-induced cell death with maturation. In mature mice, the populations of neurons most susceptible to infection are in the hippocampus and anterior horn of the spinal cord. Hippocampal infection leads to long-term memory deficits in mice that survive, while motor neuron infection can lead to paralysis and death. Neuronal death is immune-mediated, rather than a direct consequence of virus infection, and associated with entry and differentiation of pathogenic T helper 17 cells in the nervous system. To modulate glutamate excitotoxicity, mice were treated with an N-methyl-D-aspartate receptor antagonist, α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptor antagonists or a glutamine antagonist. The N-methyl-D-aspartate receptor antagonist MK-801 protected hippocampal neurons but not motor neurons, and mice still became paralyzed and died. α-Amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptor antagonists GYKI-52466 and talampanel protected both hippocampal and motor neurons and prevented paralysis and death. Glutamine antagonist 6-diazo-5-l-norleucine protected hippocampal neurons and improved memory generation in mice surviving infection with an avirulent virus. Surprisingly, in all cases protection was associated with inhibition of the antiviral immune response, reduced entry of inflammatory cells into the central nervous system, and delayed virus clearance, emphasizing the importance of treatment approaches that include prevention of immunopathologic damage.

Accumulating evidence indicates that type I interferon (IFN) mediates the host protective response to RNA viruses. However, the anti-viral effector molecules involved in this response have not been fully identified. Here, we show that zinc-finger anti-viral protein (ZAP), an IFN-inducible gene, plays a critical role in the elimination of Sindbis virus (SINV) in vitro and in vivo. The loss of ZAP greatly enhances the replication of SINV but does not inhibit type I IFN production in primary mouse embryonic fibroblasts (MEFs). ZAP binds and destabilizes SINV RNA, thereby suppressing the replication of SINV. Type I IFN fails to suppress SINV replication in ZAP-deficient MEFs, whereas the ectopic expression of ZAP is sufficient to suppress the replication of SINV in MEFs lacking the expression of type I IFN and the IFN-inducible genes. ZAP-deficient mice are highly susceptible to SINV infection, although they produce sufficient amounts of type I IFN. Therefore, ZAP is an RNA-sensing anti-viral effector molecule that mediates the type-I-IFN-dependent host defense against SINV., (© The Japanese Society for Immunology. 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Background: Interferons (IFN) are cytokines secreted by vertebrate cells involved in activation of signaling pathways that direct the synthesis of antiviral genes. To gain a global understanding of antiviral genes induced by type I IFNs in salmonids, we used RNA-seq to characterize the transcriptomic changes induced by type I IFN treatment and salmon alphavirus subtype 3 (SAV-3) infection in TO-cells, a macrophage/dendritic like cell-line derived from Atlantic salmon (Salmo salar L) head kidney leukocytes., Results: More than 23 million reads generated by RNA-seq were de novo assembled into 58098 unigenes used to generate a total of 3149 and 23289 differentially expressed genes (DEGs) from TO-cells exposed to type I IFN treatment and SAV-3 infection, respectively. Although the DEGs were classified into genes associated with biological processes, cellular components and molecular function based on gene ontology classification, transcriptomic changes reported here show upregulation of genes belonging to the canonical type I IFN signaling pathways together with a broad spectrum of antiviral genes that block virus replication in host cells. In addition, the transcriptome shows a profile of genes associated with apoptosis as well as genes that activate adaptive immunity. Further, our findings show that the profile of genes expressed by TO-cells is comparable to orthologous genes expressed by mammalian macrophages and dendritic cells in response to type I IFNs. Twenty DEGs randomly selected for qRT-PCR confirmed the validity of the transcriptomic changes detected by RNA-seq by showing that the genes upregulated by RNA-seq were also upregulated by qRT-PCR and that genes downregulated by RNA-seq were also downregulated by qRT-PCR., Conclusions: The de novo assembled transcriptome presented here provides a global description of genes induced by type I IFNs in TO-cells that could serve as a repository for future studies in fish cells. Transcriptome analysis shows that a large proportion of IFN genes expressed in this study are comparable to IFNs genes expressed in mammalia. In addition, the study shows that SAV-3 is a potent inducer of type I IFNs and that the responses it induces in TO-cells could serve as a model for studying IFN responses in salmonids.

Bioassay-guided purification of an EtOAc extract of the whole plant of Euphorbia amygdaloides ssp. semiperfoliata using a chikungunya virus-cell-based assay led to the isolation of six new (1-4, 9, and 10) and six known (5-7, 8, 11, and 12) jatrophane esters. Their planar structures and relative configurations were determined by extensive spectroscopic analysis, and their absolute configurations by X-ray analysis. These compounds were investigated for selective antiviral activity against chikungunya virus (CHIKV), Semliki Forest virus, Sindbis virus, and HIV-1 and HIV-2 viruses. Compound 3 was found to be the most potent and selective inhibitor of the replication of CHIKV and of HIV-1 and HIV-2 (EC50 = 0.76, IC50 = 0.34 and 0.043 μM, respectively). A preliminary structure-activity relationship study demonstrated that potency and selectivity are very sensitive to the substitution pattern on the jatrophane skeleton. Although replication strategies of CHIK and HIV viruses are quite different, the mechanism of action by which these compounds act may involve a similar target for both viruses. The present results provide additional support for a previous hypothesis that the anti-CHIKV activity could involve a PKC-dependent mechanism.

We present two facile approaches for introducing multivalent displays of tyrosine sulfate mimetic ligands on the surface of cellulose nanocrystals (CNCs) for application as viral inhibitors. We tested the efficacy of cellulose nanocrystals, prepared either from cotton fibers or Whatman filter paper, to inhibit alphavirus infectivity in Vero (B) cells. Cellulose nanocrystals were produced by sulfuric acid hydrolysis leading to nanocrystal surfaces decorated with anionic sulfate groups. When the fluorescent marker expressing Semliki Forest virus vector, VA7-EGFP, was incubated with CNCs, strong inhibition of virus infectivity was achieved, up to 100 and 88% for cotton and Whatman CNCs, respectively. When surface sulfate groups of CNCs were exchanged for tyrosine sulfate mimetic groups (i.e. phenyl sulfonates), improved viral inhibition was attained. Our observations suggest that the conjugation of target-specific functionalities to CNC surfaces provides a means to control their antiviral activity. Multivalent CNCs did not cause observable in vitro cytotoxicity to Vero (B) cells or human corneal epithelial (HCE-T) cells, even within the 100% virus-inhibitory concentrations. Based on the similar chemistry of known polyanionic inhibitors, our results suggest the potential application of CNCs as inhibitors of other viruses, such as human immunodeficiency virus (HIV) and herpes simplex viruses.

The global emergence of Chikungunya virus (CHIKV) infection is alarming and currently there is no licensed vaccine or antiviral treatment available to mitigate this disease. CHIKV infection typically results in high viral load with an outcome of high fever, skin rashes, muscle pain, and sequelae of prolonged arthritis, which occurs in >90% of the infected cases. In this study, using biochemical pull-downs, mass-spectrometry, and microscopic imaging techniques, we have identified novel interactions between CHIKV nsP3 or nsP4 proteins with the host stress-pathway chaperone HSP-90 protein. Indeed, silencing of HSP-90 transcripts using siRNA disrupts CHIKV replication in cultured cells. Furthermore, drugs targeting HSP-90, such as commercially available geldanamycin, as well as other specific HSP-90 inhibitor drugs that had been obtained from a purinome mining approach (HS-10 and SNX-2112) showed dramatic reduction in viral titers and reduced inflammation in a CHIKV mouse model of severe infection and musculopathy. The detailed study of the underlying molecular mechanism of these viral and host protein interactions may provide a platform to develop novel therapeutics against CHIKV infection., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Chikungunya virus is an emerging arbovirus that is widespread in tropical regions and is spreading quickly to temperate climates with recent epidemics in Africa and Asia and documented outbreaks in Europe and the Americas. It is having an increasingly major impact on humankind, with potentially life-threatening and debilitating arthritis. There is no treatment available, and only in the past 24 months have lead compounds for development as potential therapeutics been reported. This Perspective discusses the chikungunya virus as a significant, new emerging topic for medicinal chemistry, highlighting the key viral target proteins and their molecular functions that can be used in drug design, as well as the most important ongoing developments for anti-chikungunya virus research. It represents a complete picture of the current medicinal chemistry of chikungunya, supporting the development of chemotherapeutics through drug discovery and design targeting this virus.

Chikungunya virus (CHIKV) has received global attention due to the series of large-scale outbreaks in different parts of the world including Africa, Indian Ocean Islands, India and South-East Asia. The appearance of many unusual severe manifestations including neurological disorders was reported in post resurgence epidemics with implication of novel East Central South African (ECSA) genotype with E1:A226V mutation. The molecular mechanism of CHIKV neuropathogenesis is not yet understood and very little is known about the host-pathogen interactions. In the present study replication kinetics and innate immune response of ECSA genotype of CHIKV with and without A226V mutation were determined in mouse neuroblastoma cell line (N2a). The 226V mutant strain was more replication competent in N2a cells with a peak titer of 10(8)PFU/ml compared to 10(6)PFU/ml for A226 virus. Besides, the 226V mutant virus showed relatively less induction of antiviral genes i.e. IFN-β, OAS-3, MX-2, ISG-15 and Toll like receptors 3 and 7 as compared to non mutant strain (A226). Further pretreatment of N2a cells either with Poly I: C, IFN-β or TNF-α resulted in inhibition of CHIKV replication hence confirming the role of TLR mediated innate immune response in CHIKV pathogenesis. Differential regulation of TLRs and associated down stream antiviral genes might have attributed for increased pathogenesis of the 226V mutant novel ECSA genotype of CHIKV during the recent epidemics., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Chikungunya virus (CHIKV) is a reemerging mosquito-borne pathogen that causes incapacitating disease in humans characterized by intense joint pain that can persist for weeks, months, or even years. Although there is some evidence of persistent CHIKV infection in humans suffering from chronic rheumatologic disease symptoms, little is known about chronic disease pathogenesis, and no specific therapies exist for acute or chronic CHIKV disease. To investigate mechanisms of chronic CHIKV-induced disease, we utilized a mouse model and defined the duration of CHIKV infection in tissues and the associated histopathological changes. Although CHIKV RNA was readily detectable in a variety of tissues very early after infection, CHIKV RNA persisted specifically in joint-associated tissues for at least 16 weeks. Inoculation of Rag1(-/-) mice, which lack T and B cells, resulted in higher viral levels in a variety of tissues, suggesting that adaptive immunity controls the tissue specificity and persistence of CHIKV infection. The presence of CHIKV RNA in tissues of wild-type and Rag1(-/-) mice was associated with histopathological evidence of synovitis, arthritis, and tendonitis; thus, CHIKV-induced persistent arthritis is not mediated primarily by adaptive immune responses. Finally, we show that prophylactic administration of CHIKV-specific monoclonal antibodies prevented the establishment of CHIKV persistence, whereas therapeutic administration had tissue-specific efficacy. These findings suggest that chronic musculoskeletal tissue pathology is caused by persistent CHIKV infection and controlled by adaptive immune responses. Our results have significant implications for the development of strategies to mitigate the disease burden associated with CHIKV infection in humans.

Chikungunya virus, a re-emerging mosquito-borne alphavirus, causes fever, rash and persistent arthralgia/arthritis in humans. Severe outbreaks have occurred resulting in infections of millions of people in Southeast Asia and Africa. Currently there are no antiviral drugs or vaccines for prevention and treatment of chikungunya infections. Herein we report the current status of research on antiviral drugs and vaccines for chikungunya virus infections.

Chikungunya virus (CHIKV) is a mosquito-borne arthrogenic alphavirus that causes acute febrile illness in humans accompanied by joint pains and in many cases, persistent arthralgia lasting weeks to years. The re-emergence of CHIKV has resulted in numerous outbreaks in the eastern hemisphere, and threatens to expand in the foreseeable future. Unfortunately, no effective treatment is currently available. The present study reports the use of resazurin in a cell-based high-throughput assay, and an image-based high-content assay to identify and characterize inhibitors of CHIKV-infection in vitro. CHIKV is a highly cytopathic virus that rapidly kills infected cells. Thus, cell viability of HuH-7 cells infected with CHIKV in the presence of compounds was determined by measuring metabolic reduction of resazurin to identify inhibitors of CHIKV-associated cell death. A kinase inhibitor library of 4,000 compounds was screened against CHIKV infection of HuH-7 cells using the resazurin reduction assay, and the cell toxicity was also measured in non-infected cells. Seventy-two compounds showing ≥50% inhibition property against CHIKV at 10 µM were selected as primary hits. Four compounds having a benzofuran core scaffold (CND0335, CND0364, CND0366 and CND0415), one pyrrolopyridine (CND0545) and one thiazol-carboxamide (CND3514) inhibited CHIKV-associated cell death in a dose-dependent manner, with EC50 values between 2.2 µM and 7.1 µM. Based on image analysis, these 6 hit compounds did not inhibit CHIKV replication in the host cell. However, CHIKV-infected cells manifested less prominent apoptotic blebs typical of CHIKV cytopathic effect compared with the control infection. Moreover, treatment with these compounds reduced viral titers in the medium of CHIKV-infected cells by up to 100-fold. In conclusion, this cell-based high-throughput screening assay using resazurin, combined with the image-based high content assay approach identified compounds against CHIKV having a novel antiviral activity--inhibition of virus-induced CPE--likely by targeting kinases involved in apoptosis.

Chikungunya virus (CHIKV) has re-emerged as a significant public health threat since the 2005 chikungunya fever epidemic in La Réunion. Driven by the medical importance of this virus, as well as the lack of approved antivirals, research into the field of CHIKV antivirals has recently intensified. Potential therapeutics that have been reported to show anti-CHIKV activity in vitro range from known broad-spectrum antivirals like chloroquine to novel strategies involving RNA silencing technology. Although most of the earlier efforts focused on compounds that target host components, some recent studies have reported viral targets such as nonstructural proteins. This article examines the reported in vitro and in vivo efficacies, as well as the therapeutic potential of these antiviral compounds., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Chikungunya virus (CHIKV) is the aetiological agent of the mosquito-borne disease chikungunya fever, a debilitating arthritic disease that, during the past 7years, has caused immeasurable morbidity and some mortality in humans, including newborn babies, following its emergence and dispersal out of Africa to the Indian Ocean islands and Asia. Since the first reports of its existence in Africa in the 1950s, more than 1500 scientific publications on the different aspects of the disease and its causative agent have been produced. Analysis of these publications shows that, following a number of studies in the 1960s and 1970s, and in the absence of autochthonous cases in developed countries, the interest of the scientific community remained low. However, in 2005 chikungunya fever unexpectedly re-emerged in the form of devastating epidemics in and around the Indian Ocean. These outbreaks were associated with mutations in the viral genome that facilitated the replication of the virus in Aedes albopictus mosquitoes. Since then, nearly 1000 publications on chikungunya fever have been referenced in the PubMed database. This article provides a comprehensive review of chikungunya fever and CHIKV, including clinical data, epidemiological reports, therapeutic aspects and data relating to animal models for in vivo laboratory studies. It includes Supplementary Tables of all WHO outbreak bulletins, ProMED Mail alerts, viral sequences available on GenBank, and PubMed reports of clinical cases and seroprevalence studies., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Part of the Togaviridae family, alphaviruses, including chikungunya virus (CHIKV), Sindbis virus (SINV) and Ross River virus (RRV), are able to cause significant inflammatory pathologies ranging from arthritis to encephalitis. Following symptomatic infection with arthritis-associated alphaviruses, patients often experience severe joint pain, affecting distal and small joints, which can last six months or longer. Recently, methotrexate (MTX), a disease modifying anti-rheumatic drug (DMARD), was used to treat patients experiencing chronic rheumatic symptoms following infection with CHIKV. Here, the effect of MTX on Ross River virus disease (RRVD) in mice was examined to better understand its therapeutic potential for alphaviral-induced musculoskeletal disease and to further our knowledge of the development of alphaviral pathologies. Using a mouse model, we analyzed the effect of MTX on RRVD. RRV disease pathogenesis in response to MTX treatment was determined by measuring levels of proinflammatory factors, cellular infiltrates, viral titer and histological analysis of infected tissues. RRV-infected mice receiving MTX treatment rapidly developed musculoskeletal disease, which correlated with a significant influx of inflammatory cell infiltrates into the skeletal muscle tissue. Although no difference was observed in the level of proinflammatory cytokines and chemokines, the viral load increased at early time points post infection in the serum and quadriceps of MTX treated mice, possibly contributing to disease pathogenesis. Results suggest that MTX treatment of acute RRVD in mice provides no therapeutic benefit and underline the importance of inflammatory monocytes in alphaviral induced arthritides.

Objectives: To observe the effect of homeopathic therapy in Chikungunya Fever (CF) and in Post-Chikungunya Chronic Arthritis (PCCA) in a primary health care setting., Methods: A prospective observational study was conducted at Delhi Government Homeopathic Dispensary, Aali Village, New Delhi, India, for a period of 6 months, from 1st October 2010 to 31st March 2011. 126 patients (75 CF, 51 PCCA) were enrolled based on predefined inclusion criteria. A single homeopathic medicine was prescribed for each patient after case taking with the help of Materia Medica and/or Repertory. Results were evaluated on the basis of visual analogue scale and symptom scores., Results: Complete recovery was seen in 84.5% CF cases in a mean time of 6.8 days. 90% cases of PCCA recovered completely in a mean time of 32.5 days., Conclusion: Homeopathic therapy may be effective in CF and PCCA. A randomized controlled trial should be considered., (Copyright © 2013 The Faculty of Homeopathy. Published by Elsevier Ltd. All rights reserved.)

Chikungunya virus (CHIKV) is an Arbovirus that is transmitted to humans primarily by the mosquito species Aedes aegypti. Infection with this pathogen is often associated with fever, rash and arthralgia. Neither a vaccine nor an antiviral drug is available for the prevention or treatment of this disease. Albeit considered a tropical pathogen, adaptation of the virus to the mosquito species Aedes albopictus, which is also very common in temperate zones, has resulted in recent outbreaks in Europe and the US. In the present study, we report on the discovery of a novel series of compounds that inhibit CHIKV replication in the low μM range. In particular, we initially performed a virtual screening simulation of ∼5 million compounds on the CHIKV nsP2, the viral protease, after which we investigated and explored the Structure-Activity Relationships of the hit identified in silico. Overall, a series of 26 compounds, including the original hit, was evaluated in a virus-cell-based CPE reduction assay. The study of such selective inhibitors will contribute to a better understanding of the CHIKV replication cycle and may represents a first step towards the development of a clinical candidate drug for the treatment of this disease., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Searching for stimulators of the innate antiviral response is an appealing approach to develop novel therapeutics against viral infections. Here, we established a cell-based reporter assay to identify compounds stimulating expression of interferon-inducible antiviral genes. DD264 was selected out of 41,353 compounds for both its immuno-stimulatory and antiviral properties. While searching for its mode of action, we identified DD264 as an inhibitor of pyrimidine biosynthesis pathway. This metabolic pathway was recently identified as a prime target of broad-spectrum antiviral molecules, but our data unraveled a yet unsuspected link with innate immunity. Indeed, we showed that DD264 or brequinar, a well-known inhibitor of pyrimidine biosynthesis pathway, both enhanced the expression of antiviral genes in human cells. Furthermore, antiviral activity of DD264 or brequinar was found strictly dependent on cellular gene transcription, nuclear export machinery, and required IRF1 transcription factor. In conclusion, the antiviral property of pyrimidine biosynthesis inhibitors is not a direct consequence of pyrimidine deprivation on the virus machinery, but rather involves the induction of cellular immune response.

Chikungunya virus (CHIKV) infection generally causes a debilitating arthritis in infected patients. Infection with CHIKV is generally not life-threatening and is associated with a mortality rate <0.1%. However, close to 100% of those infected will develop symptoms of disease, primarily involving swelling and pain of the joints, which can last for months or even years. A model that mimics these symptoms is needed for thedevelopment of therapies to ameliorate disease and control viral infection. In this chapter, we describe the establishment of a model of CHIKV infection in mice that is nonlethal and utilizes footpad swelling and virus titer of various tissues as key disease parameters. This model was developed primarily for use in evaluating the in vivo efficacy of candidate antiviral agents, although important questions regarding basic biology and pathogenesis of the disease may also be elucidated using this system.

Hand pain is a relatively common complaint, and careful anamnesis and clinical examination may reveal its aetiology. Multiple joint involvement suggests either osteoarthritis or inflammatory arthritis. In the returning traveller, a more exotic explanation might be the case. A 31 year old woman was referred to our outpatient clinic for evaluation due to peripheral joint arthralgia. The symptoms started six months earlier, on the same day she returned from a three-week holiday in India. There were no signs of inflammatory arthritis or osteoarthritis. Blood tests were normal. Chikungunya virus serology was positive. The patient received symptomatic treatment with nonsteroid anti-inflammatory drugs and improved over a period of months. We describe the first case of Chikungunya fever diagnosed in our hospital.

Purpose of Review: Dengue virus (DENV) and chikungunya virus (CHIKV) cause significant morbidity in many world regions and their epidemiology, pathogenesis, vector issues, and control and prevention continue to fascinate researchers. This review focuses on the progress in these areas in the past 2 years., Recent Findings: Recent studies have highlighted the features of the epidemiology of DENV and CHIKV in Africa, some places of transmission being detected through travelers as sentinels. Autochthonous transmission of both viruses has been documented in France, raising concern regarding the potential for outbreaks where a competent vector, Aedes albopictus, is present. Some aspects of immune response following DENV and CHIKV infections have been elucidated. New diagnostic techniques for DENV have been explored as well as treatment for CHIKV. Research on Wolbachia as a means of biologic control of mosquito-borne infections including DENV and CHIKV has made significant progress., Summary: These studies further our understanding of the evolving DENV and CHIKV epidemiology and potential transmission in nonendemic regions, and can contribute to the assessment of travelers. The new information on immunological responses to these viruses influences the vaccine development. Risk factors for severe disease and new therapeutic options could improve current treatment. Finally, research on Wolbachia holds promise in these two important vector-borne viral infections.

Unique disorders appear episodically in human populations and cause life-threatening systemic or neurological disease. Historical examples of such disorders include von Economo encephalitis, a disorder of presumed viral etiology; acquired immune deficiency syndrome, caused by the human immunodeficiency virus; and severe acute respiratory syndrome, caused by a member of the coronavirus family. This article describes the factors that contribute to the emergence of infectious diseases and focuses on selected recent examples of emerging viral infections that can affect the nervous system of infants, children, and adolescents., (Copyright © 2012 Elsevier Inc. All rights reserved.)

Venezuelan, western, and eastern equine encephalitis viruses are New World alphaviruses that are recognized as potential agents of biowarfare and bioterrorism owing to their morbidity and mortality in humans, ease of production, considerable stability, and high infectivity in aerosols. As a result, these encephalitic alphaviruses are defined as category B select agents. Studies involving infection of nonhuman primates have been instrumental in gaining an understanding of the in vivo pathogenesis of these viruses and have provided relevant models to evaluate the efficacy of candidate human vaccines. Recent advances have led to refinement and further characterization of these models toward the goal of utility in the licensure of next-generation alphavirus vaccines and therapeutics for use in humans by the Animal Rule., (Copyright © 2012 Elsevier B.V. All rights reserved.)