Mayaro Virus Research Articles

Vector competence of Aedes aegypti, Aedes albopictus, and Culex quinquefasciatus mosquitoes for Mayaro virus.

Newly emerging or re-emerging arthropod-borne viruses (arboviruses) are important causes of human morbidity and mortality worldwide. Arboviruses such as Dengue (DENV), Zika (ZIKV), Chikungunya (CHIKV), and West Nile virus (WNV) have undergone extensive geographic expansion in the tropical and sub-tropical regions of the world. In the Americas the main vectors of DENV, ZIKV, and CHIKV are mosquito species adapted to urban environments, namely Aedes aegypti and Aedes albopictus, whereas the main vector of WNV is Culex quinquefasciatus. Given the widespread distribution in the Americas and high permissiveness to arbovirus infection, these mosquito species may play a key role in the epidemiology of other arboviruses normally associated with sylvatic vectors. Here, we test this hypothesis by determining the vector competence of Ae. aegypti, Ae. albopictus, and Cx. quinquefasciatus to Mayaro (MAYV) virus, a sylvatic arbovirus transmitted mainly by Haemagogus janthinomys that has been causing an increasing number of outbreaks in South America, namely in Brazil. Using field mosquitoes from Brazil, female mosquitoes were experimentally infected, and their competence for infection and transmission rates of MAYV was evaluated. We found consistent infection rate for MAYV in Ae. aegypti (57.5%) and Ae. albopictus (61.6%), whereas very low rates were obtained for Cx. quinquefasciatus (2.5%). Concordantly, we observed high potential transmission ability in Ae. aegypti and Ae. albopictus (69.5% and 71.1% respectively), in contrast to Cx. quinquefasciatus, which could not transmit the MAYV. Notably, we found that very low quantities of virus present in the saliva (undetectable by RT-qPCR) were sufficiently virulent to guarantee transmission. Although Ae. aegypti and Ae. albopictus mosquitoes are not the main vectors for MAYV, our studies suggest that these mosquitoes could play a significant role in the transmission of this arbovirus, since both species showed significant vector competence for MAYV (Genotype D), under laboratory conditions.

Establishment of wMel Wolbachia in Aedes aegypti mosquitoes and reduction of local dengue transmission in Cairns and surrounding locations in northern Queensland, Australia.

Background: The wMel strain of Wolbachia has been successfully introduced into Aedes aegypti mosquitoes and subsequently shown in laboratory studies to reduce transmission of a range of viruses including dengue, Zika, chikungunya, yellow fever, and Mayaro viruses that cause human disease. Here we report the entomological and epidemiological outcomes of staged deployment of Wolbachia across nearly all significant dengue transmission risk areas in Australia. Methods: The wMel strain of Wolbachiawas backcrossed into the local Aedes aegyptigenotype (Cairns and Townsville backgrounds) and mosquitoes were released in the field by staff or via community assisted methods. Mosquito monitoring was undertaken and mosquitoes were screened for the presence of Wolbachia. Dengue case notifications were used to track dengue incidence in each location before and after releases. Results: Empirical analyses of the Wolbachia mosquito releases, including data on the density, frequency and duration of Wolbachia mosquito releases, indicate that Wolbachia can be readily established in local mosquito populations, using a variety of deployment options and over short release durations (mean release period 11 weeks, range 2-22 weeks). Importantly, Wolbachia frequencies have remained stable in mosquito populations since releases for up to 8 years. Analysis of dengue case notifications data demonstrates near-elimination of local dengue transmission for the past five years in locations where Wolbachia has been established. The regression model estimate of Wolbachia intervention effect from interrupted time series analyses of case notifications data prior to and after releases, indicated a 96% reduction in dengue incidence in Wolbachia treated populations (95% confidence interval: 84 - 99%). Conclusion: Deployment of the wMel strain of Wolbachia into local Ae. aegypti populations across the Australian regional cities of Cairns and most smaller regional communities with a past history of dengue has resulted in the reduction of local dengue transmission across all deployment areas.

In-depth characterization of a novel live-attenuated Mayaro virus vaccine candidate using an immunocompetent mouse model of Mayaro disease

Mayaro virus (MAYV) is endemic in South American countries where it is responsible for sporadic outbreaks of acute febrile illness. The hallmark of MAYV infection is a highly debilitating and chronic arthralgia. Although MAYV emergence is a potential threat, there are no specific therapies or licensed vaccine. In this study, we developed a murine model of MAYV infection that emulates many of the most relevant clinical features of the infection in humans and tested a live-attenuated MAYV vaccine candidate (MAYV/IRES). Intraplantar inoculation of a WT strain of MAYV into immunocompetent mice induced persistent hypernociception, transient viral replication in target organs, systemic production of inflammatory cytokines, chemokines and specific humoral IgM and IgG responses. Inoculation of MAYV/IRES in BALB/c mice induced strong specific cellular and humoral responses. Moreover, MAYV/IRES vaccination of immunocompetent and interferon receptor-defective mice resulted in protection from disease induced by the virulent wt MAYV strain. Thus, this study describes a novel model of MAYV infection in immunocompetent mice and highlights the potential role of a live-attenuated MAYV vaccine candidate in host’s protection from disease induced by a virulent MAYV strain.

Introduction: Evolution of inflammatory arthritis from innate to adaptive immune mechanisms.

Introduction: Evolution of inflammatory arthritis from innate to adaptive immune mechanisms.

Mayaro virus in Latin America and the Caribbean.

ABSTRACTObjectives.To assess the distribution of Mayaro virus (MAYV) in Latin America and the Caribbean and evaluate existing country-level MAYV surveillance mechanisms.Methods.Research was conducted from May 2018 through May 2019 to collect data from academic literature on Mayaro fever in Latin America and the Caribbean. PubMed, ClinicalKey, Scopus, Nature, SciELO, LILACS, and Google Scholar were searched for peer-reviewed journal articles, and data from health authorities, including the Pan American Health Organization (PAHO) and ministries of health, was also sought. MAYV-related publications published from 1954 through 2019 were screened. Publications that added to the overall understanding of MAYV, including its geographical and epidemiological distribution, were included in this report.Results.A total of 901 MAYV cases have been reported in humans in countries in Latin America and the Caribbean. Since its discovery in 1954 in Trinidad and Tobago, MAYV has been isolated from individuals living in Argentina, Bolivia, Brazil, Ecuador, French Guiana, Haiti, Mexico, Panama, Peru, and Venezuela. Of those 901 cases, 42 of them were reported exclusively by health authorities. In contrast, 843 confirmed and presumptive autochthonous cases and an additional 16 imported cases were identified in academic literature. No country-level surveillance mechanisms for MAYV were recorded in academic literature or by health authorities.Conclusions.This report demonstrates that MAYV surveillance efforts are limited in comparison to the virus’s presence in Latin America and the Caribbean, highlighting the importance of enhancing arboviral surveillance systems in the affected countries.

Robustness of Serologic Investigations for Chikungunya and Mayaro Viruses following Coemergence.

Since 2013, the arthropod-borne Chikungunya virus (CHIKV) has cocirculated with the autochthonous Mayaro virus (MAYV) in Latin America. Both belong to the same alphavirus serocomplex, termed the Semliki Forest serocomplex. The extent of antibody cross-reactivity due to the antigenic relatedness of CHIKV and MAYV in commonly used serologic tests remains unclear. By testing 64 CHIKV- and 37 MAYV-specific sera from cohort studies conducted in Peru and Brazil, we demonstrate about 50% false-positive test results using commercially available enzyme-linked immunosorbent assays (ELISAs) based on structural antigens. In contrast, combining ELISAs for CHIKV and MAYV significantly increased positive predictive values (PPV) among all cohorts from 35.3% to 88.2% for IgM and from 61.3% to 96.8% for IgG (P < 0.0001). Testing of longitudinally collected CHIKV-specific patient sera indicated that ELISA specificity is highest for IgM testing at 5 to 9 days post-onset of symptoms (dpo) and for IgG testing at 10 to 14 dpo. IgG cross-reactivity in ELISA was asymmetric, occurring in 57.9% of MAYV-specific sera compared to 29.5% of CHIKV-specific sera. Parallel plaque reduction neutralization testing (PRNT) for CHIKV and MAYV increased the PPV from 80.0% to 100% (P = 0.0053). However, labor-intense procedures and delayed seroconversion limit PRNT for patient diagnostics. In sum, individual testing for CHIKV or MAYV only is prone to misclassifications that dramatically impact patient diagnostics and sero-epidemiologic investigation. Parallel ELISAs for both CHIKV and MAYV provide an easy and efficient solution to differentiate CHIKV from MAYV infections. This approach may provide a template globally for settings in which alphavirus coemergence imposes similar problems.IMPORTANCE Geographically overlapping transmission of Chikungunya virus (CHIKV) and Mayaro virus (MAYV) in Latin America challenges serologic diagnostics and epidemiologic surveillance, as antibodies against the antigenically related viruses can be cross-reactive, potentially causing false-positive test results. We examined whether widely used ELISAs and plaque reduction neutralization testing allow specific antibody detection in the scenario of CHIKV and MAYV coemergence. For this purpose, we used 37 patient-derived MAYV-specific sera from Peru and 64 patient-derived CHIKV-specific sera from Brazil, including longitudinally collected samples. Extensive testing of those samples revealed strong antibody cross-reactivity in ELISAs, particularly for IgM, which is commonly used for patient diagnostics. Cross-neutralization was also observed, albeit at lower frequencies. Parallel testing for both viruses and comparison of ELISA reactivities and neutralizing antibody titers significantly increased diagnostic specificity. Our data provide a convenient and practicable solution to ensure robust differentiation of CHIKV- and MAYV-specific antibodies.

Modeling Chikungunya control strategies and Mayaro potential outbreak in the city of Rio de Janeiro.

Mosquito-borne diseases have become a significant health issue in many regions around the world. For tropical countries, diseases such as Dengue, Zika, and Chikungunya, became epidemic in the last decades. Health surveillance reports during this period were crucial in providing scientific-based information to guide decision making and resources allocation to control outbreaks. In this work, we perform data analysis of the last Chikungunya epidemics in the city of Rio de Janeiro by applying a compartmental mathematical model. Sensitivity analyses were performed in order to describe the contribution of each parameter to the outbreak incidence. We estimate the "basic reproduction number" for those outbreaks and predict the potential epidemic outbreak of the Mayaro virus. We also simulated several scenarios with different public interventions to decrease the number of infected people. Such scenarios should provide insights about possible strategies to control future outbreaks.

An emerging public health threat: Mayaro virus increases its distribution in Peru

BackgroundThe infection caused by Mayaro virus (MAYV), which presents as an acute febrile illness, is considered a neglected tropical disease. The virus is an endemic and emerging pathogen in South America and the Caribbean, responsible for occasional and poorly characterized outbreaks. Currently there is limited information about its expansion and risk areas. MethodsA cross-sectional study was performed in 10 urban primary care health centers in the Cajamarca region of Peru from January to June 2017. A total of 359 patients with suspected febrile illness were assessed. RNA was extracted from serum samples, following which MAYV real-time reverse transcriptase PCR (RT-PCR) for the detection of the nsP1 gene was performed. ResultsMAYV was detected in 11.1% (40/359) of samples after RT-PCR amplification and confirmatory DNA sequencing. Most infections were detected in the adult population aged 18–39 years (40%) and 40–59 years (32.5%). Headache was the most frequent symptom in patients with MAYV infection (77.5%), followed by fever (72.5%), myalgia (55.0%), and arthralgia (50.0%). During the study, most of the MAYV cases were seen in May (47.5%) and April (35.0%), corresponding to the dry season (months without rain). ConclusionsThis study is novel in describing the presence of MAYV in Cajamarca, an Andean region of Peru. Symptoms are non-specific and can be confused with those of other arbovirus or bacterial infections. Molecular biology methods such as RT-PCR allow the timely and accurate detection of MAYV and could thus be considered as a tool for surveillance in endemic areas.

Establishment of wMel Wolbachia in Aedes aegypti mosquitoes and reduction of local dengue transmission in Cairns and surrounding locations in northern Queensland, Australia

Background: The wMel strain of Wolbachia has been successfully introduced into Aedes aegypti mosquitoes and subsequently shown in laboratory studies to reduce transmission of a range of viruses including dengue, Zika, chikungunya, yellow fever, and Mayaro viruses that cause human disease. Here we report the entomological and epidemiological outcomes of staged deployment of Wolbachia across nearly all significant dengue transmission risk areas in Australia. Methods: The wMel strain of Wolbachia was backcrossed into the local Aedes aegypti genotype (Cairns and Townsville backgrounds) and mosquitoes were released in the field by staff or via community assisted methods. Mosquito monitoring was undertaken and mosquitoes were screened for the presence of Wolbachia. Dengue case notifications were used to track dengue incidence in each location before and after releases. Results: Empirical analyses of the Wolbachia mosquito releases, including data on the density, frequency and duration of Wolbachia mosquito releases, indicate that Wolbachia can be readily established in local mosquito populations, using a variety of deployment options and over short release durations (mean release period 11 weeks, range 2-22 weeks). Importantly, Wolbachia frequencies have remained stable in mosquito populations since releases for up to 8 years. Analysis of dengue case notifications data demonstrates near-elimination of local dengue transmission for the past five years in locations where Wolbachia has been established. The regression model estimate of Wolbachia intervention effect from interrupted time series analyses of case notifications data prior to and after releases, indicated a 96% reduction in dengue incidence in Wolbachia treated populations (95% confidence interval: 84 – 99%). Conclusion: Deployment of the wMel strain of Wolbachia into local Ae. aegypti populations across the Australian regional cities of Cairns and most smaller regional communities with a past history of dengue has resulted in the reduction of local dengue transmission across all deployment areas.

Expression and Purification of Recombinant Mayaro Virus Envelope Glycoproteins E1 and E2 to Develop a Mayaro Virus Detection System

Expression and Purification of Recombinant Mayaro Virus Envelope Glycoproteins E1 and E2 to Develop a Mayaro Virus Detection System

Lack of activity of rutin isolated from Tontelea micrantha leaves against Vero and BHK, fungi, bacteria and Mayaro virus and its in silico activity

Objectives: This work aimed to evaluate the antibacterial, antifungal, and anti-Mayaro virus (MAYV) activity of rutin, a flavonoid isolated from the leaves of Tontelea micrantha (Celastraceae). Materials and Methods: The antibacterial and antifungal activities were evaluated by the broth microdilution method through the determination of the minimum inhibitory concentration. The anti-MAYV activity was determined by the rutin concentration required to protect 50% of the cells after viral infection. The indirect 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide colorimetric assay was used to determine the cytotoxic concentration of rutin to 50% of Vero and BHK cells. The antimicrobial activity spectrum of rutin was predicted using the online software prediction of activity spectra for substances (PASS). Results: Although the PASS prediction had shown that a higher probability of rutin acts as an antifungal agent, the in vitro assays showed no antimicrobial activity. Regarding the cytotoxicity assay, rutin was not toxic to Vero and BHK cells. Conclusions: Many biological activities have been described for flavonoids, but the flavone rutin did not show antimicrobial activity in vitro. The results obtained in this work suggest that rutin is not a promising antimicrobial agent.

Mayaro fever: A brief review on the immune profile

Mayaro virus is an emergent alphavirus that infects humans, leading to Mayaro fever. Approximately fifty percent of infected patients develop arthritis symptoms in the recovery phase, a phase that can last up to a year. The literature about Mayaro virus infection and its immune response is scarce, which may hamper the development of treatment strategies. We summarize changes in cytokines and chemokines in the acute and recovery phase in Mayaro virus infected patients, and relate this molecular characterization with the immune response. VEGF and IL-12/p70 show pronounced changes in patients in the acute phase, suggesting the development of cellular immunity and Th1 response. IL-6, IL-7, CXCL8/IL-8, IL-13, IL-17, and IFN-γ are elevated in patients with arthritis symptoms in the long-term recovery phase, which may be related to the continuous inflammatory process, a possible Th2 inhibiting and promoting Th17 process. Although few studies discuss the issue, with a small number of patients and different backgrounds, inflammatory and immune response and manifestations seem to be closely linked. This information may help to develop the appropriate treatment strategies in Mayaro virus infection. Therefore, we analyzed and summarized data available in literature.

Serological evidence of arboviruses and coccidia infecting horses in the Amazonian region of Brazil.

BackgroundArboviruses and protozoans can cause neurologic disorders in horses. In Brazilian Amazon, several horses presenting signs compatible with disorders caused by these infectious agents have been observed.ObjectiveTo contribute to the knowledge of this epidemiological picture, we sought to construct a serological diagnostic panel for neurotrophic infectious agents in local horses.Material and methodsA total of 213 blood samples from horses were collected from 29 farms in three municipalities. Samples were evaluated and considered positive when they met the following criteria: titers ≥ 1:80 with the indirect fluorescent antibody test (IFAT) for apicomplexan protozoans; positive recombinant enzyme-linked immunosorbent assay (ELISA) with subsequent titers ≥ 1:10 by the PRNt for viruses; and detection under direct microscopic examination for Trypanosoma evansi.ResultsNo horses were found to be infected by T. evansi, and only two were infected Toxoplasma gondii and/or Neospora spp. The highest protozoan infection rate was observed for Sarcocystis neurona (40.3%; n = 86/213). Among the positive ELISA samples tested by the plaque reduction neutralization test (PRNT90), 92% (n = 76/83) were positive for St Louis Encephalitis virus, 43% (n = 6/14) were positive for West Nile virus and 33% (n = 16/48) were positive for Mayaro virus. Eighteen percent (n = 39/213) of horses were co-infected by S. neurona and at least one arbovirus, particularly SLEV and/or MAYV.ConclusionSamples positive for SLEV associated with S. neurona, including samples from horses that had recovered from neurological signs were frequent, and must be considered when investigating the possible causes of neurological diseases in South Roraima horses.

Effects of Chikungunya virus immunity on Mayaro virus disease and epidemic potential

Mayaro virus (MAYV) causes an acute febrile illness similar to that produced by chikungunya virus (CHIKV), an evolutionary relative in the Semliki Forest virus complex of alphaviruses. MAYV emergence is typically sporadic, but recent isolations and outbreaks indicate that the virus remains a public health concern. Given the close phylogenetic and antigenic relationship between CHIKV and MAYV, and widespread distribution of CHIKV, we hypothesized that prior CHIKV immunity may affect MAYV pathogenesis and/or influence its emergence potential. We pre-exposed immunocompetent C57BL/6 and immunocompromised A129 or IFNAR mice to wild-type CHIKV, two CHIKV vaccines, or a live-attenuated MAYV vaccine, and challenged with MAYV. We observed strong cross-protection against MAYV for mice pre-exposed to wild-type CHIKV, and moderately but significantly reduced cross-protection from CHIKV-vaccinated animals. Immunity to other alphavirus or flavivirus controls provided no protection against MAYV disease or viremia. Mechanistic studies suggested that neutralizing antibodies alone can mediate this protection, with T-cells having no significant effect on diminishing disease. Finally, human sera obtained from naturally acquired CHIKV infection cross-neutralized MAYV at high titers in vitro. Altogether, our data suggest that CHIKV infection can confer cross-protective effects against MAYV, and the resultant reduction in viremia may limit the emergence potential of MAYV.

Host nutritional status affects alphavirus virulence, transmission, and evolution.

Malnourishment, specifically overweight/obesity and undernourishment, affects more than 2.5 billion people worldwide, with the number affected ever-increasing. Concurrently, emerging viral diseases, particularly those that are mosquito-borne, have spread dramatically in the past several decades, culminating in outbreaks of several viruses worldwide. Both forms of malnourishment are known to lead to an aberrant immune response, which can worsen disease outcomes and reduce vaccination efficacy for viral pathogens such as influenza and measles. Given the increasing rates of malnutrition and spread of arthropod-borne viruses (arboviruses), there is an urgent need to understand the role of host nutrition on the infection, virulence, and transmission of these viruses. To address this gap in knowledge, we infected lean, obese, and undernourished mice with arthritogenic arboviruses from the genus Alphavirus and assessed morbidity, virus replication, transmission, and evolution. Obesity and undernourishment did not consistently influence virus replication in the blood of infected animals except for reductions in virus in obese mice late in infection. However, morbidity was increased in obese mice under all conditions. Using Mayaro virus (MAYV) as a model arthritogenic alphavirus, we determined that both obese and undernourished mice transmit virus less efficiently to mosquitoes than control (lean) mice. In addition, viral genetic diversity and replicative fitness were reduced in virus isolated from obese compared to lean controls. Taken together, nutrition appears to alter the course of alphavirus infection and should be considered as a critical environmental factor during outbreaks.

Fatty acid synthase and stearoyl-CoA desaturase-1 are conserved druggable cofactors of Old World Alphavirus genome replication

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.

Mayaro Virus Induction of Oxidative Stress is Associated With Liver Pathology in a Non-Lethal Mouse Model

Mayaro virus (MAYV) causes Mayaro fever in humans, a self-limiting acute disease, with persistent arthralgia and arthritis. Although MAYV has a remerging potential, its pathogenic mechanisms remain unclear. Here, we characterized a model of MAYV infection in 3–4-week BALB/c mice. We investigated whether the liver acts as a site of viral replication and if the infection could cause histopathological alterations and an imbalance in redox homeostasis, culminating with oxidative stress. MAYV-infected mice revealed lower weight gain; however, the disease was self-resolving. High virus titre, neutralizing antibodies, and increased levels of aspartate and alanine aminotransferases were detected in the serum. Infectious viral particles were recovered in the liver of infected animals and the histological examination of liver tissues revealed significant increase in the inflammatory infiltrate. MAYV induced significant oxidative stress in the liver of infected animals, as well as a deregulation of enzymatic antioxidant components. Collectively, this is the first study to report that oxidative stress occurs in MAYV infection in vivo, and that it may be crucial in virus pathogenesis. Future studies are warranted to address the alternative therapeutic strategies for Mayaro fever, such as those based on antioxidant compounds.

Viral Zoonoses

Human infection by zoonotic viruses—pathogens that normally infect animals—may result in no obvious illness, a nonspecific viral syndrome, or more severe illness typically characterized by hemorrhagic fever, encephalitis, or rash arthralgia. Transmission usually occurs by direct contact with or a bite from an infected animal or arthropod. Viral families discussed include Flaviviridae, Bunyaviridae, Arenaviridae, Filoviridae, Togaviridae, Rhabdoviridae, Paramyxoviridae, and Reoviridae, with consideration given to the epidemiology, diagnosis, treatment, and prevention of specific viruses. Hemorrhagic fevers addressed include dengue fever, dengue hemorrhagic fever, yellow fever, Crimean-Congo hemorrhagic fever, and Rift Valley fever; hantavirus infections; and the Marburg and Ebola viruses. Encephalitic fever–causing viruses discussed include La Crosse; Japanese; Murray Valley; St. Louis; tick-borne; West Nile; Powassan; eastern, western, and Venezuelan equine; rabies; Nipah; Barmah Forest; and Colorado tick fever. Rash arthralgia may be caused by the Barmah Forest, Chikungunya, Mayaro, O’nyong-nyong, Ross River, and dengue viruses. Other viral zoonoses considered include monkey B virus, ruminant and primate poxvirus, Newcastle, and foot-and-mouth diseases, as well as vesicular stomatitis virus infection. A diagram depicts the generalized arbovirus maintenance cycle. Tables list the important viral zoonoses that cause human disease, the principal hantaviruses that cause human disease, the arenaviruses that cause significant human illness, and the viral zoonoses endemic in the United States. This review contains 1 figure, 32 tables, and 80 references. Key words: dengue, diagnosis, encephalitis, epidemic, epidemiology, infection, rabies, virus, vaccine

Viral Zoonoses

Human infection by zoonotic viruses—pathogens that normally infect animals—may result in no obvious illness, a nonspecific viral syndrome, or more severe illness typically characterized by hemorrhagic fever, encephalitis, or rash arthralgia. Transmission usually occurs by direct contact with or a bite from an infected animal or arthropod. Viral families discussed include Flaviviridae, Bunyaviridae, Arenaviridae, Filoviridae, Togaviridae, Rhabdoviridae, Paramyxoviridae, and Reoviridae, with consideration given to the epidemiology, diagnosis, treatment, and prevention of specific viruses. Hemorrhagic fevers addressed include dengue fever, dengue hemorrhagic fever, yellow fever, Crimean-Congo hemorrhagic fever, and Rift Valley fever; hantavirus infections; and the Marburg and Ebola viruses. Encephalitic fever–causing viruses discussed include La Crosse; Japanese; Murray Valley; St. Louis; tick-borne; West Nile; Powassan; eastern, western, and Venezuelan equine; rabies; Nipah; Barmah Forest; and Colorado tick fever. Rash arthralgia may be caused by the Barmah Forest, Chikungunya, Mayaro, O’nyong-nyong, Ross River, and dengue viruses. Other viral zoonoses considered include monkey B virus, ruminant and primate poxvirus, Newcastle, and foot-and-mouth diseases, as well as vesicular stomatitis virus infection. A diagram depicts the generalized arbovirus maintenance cycle. Tables list the important viral zoonoses that cause human disease, the principal hantaviruses that cause human disease, the arenaviruses that cause significant human illness, and the viral zoonoses endemic in the United States. This review contains 1 figure, 32 tables, and 80 references. Key words: dengue, diagnosis, encephalitis, epidemic, epidemiology, infection, rabies, virus, vaccine

Differential Susceptibility and Innate Immune Response of Aedes aegypti and Aedes albopictus to the Haitian Strain of the Mayaro Virus.

Mayaro (MAYV) is an emerging arthropod-borne virus belonging to the Alphavirus genus of the Togaviridae family. Although forest-dwelling Haemagogus mosquitoes have been considered as its main vector, the virus has also been detected in circulating Aedes ssp mosquitoes. Here we assess the susceptibility of Aedes aegypti and Aedes albopictus to infection with MAYV and their innate immune response at an early stage of infection. Aedes albopictus was more susceptible to infection with MAYV than Ae. aegypti. Analysis of transcript levels of twenty immunity-related genes by real-time PCR in the midgut of both mosquitoes infected with MAYV revealed increased expression of several immune genes, including CLIP-domain serine proteases, the anti-microbial peptides defensin A, E, cecropin E, and the virus inducible gene. The regulation of certain genes appeared to be Aedes species-dependent. Infection of Ae. aegypti with MAYV resulted in increased levels of myeloid differentiation2-related lipid recognition protein (ML26A) transcripts, as compared to Ae. albopictus. Increased expression levels of thio-ester-containing protein 22 (TEP22) and Niemann–Pick type C1 (NPC1) gene transcripts were observed in infected Ae. albopictus, but not Ae. aegypti. The differences in these gene expression levels during MAYV infection could explain the variation in susceptibility observed in both mosquito species.