Identification of Viruses in Molossus Bats from the Brazilian Amazon: A Descriptive Metagenomic Analysis.

Bats are widely distributed in Brazil, including the Amazon region, and their association with viral pathogens is well-known. This work aimed to evaluate the metavirome in samples of Molossus sp. bats captured in the Brazilian Amazon from 2019 to 2021. Lung samples from 58 bats were divided into 13 pools for RNA isolation and sequencing followed by bioinformatic analysis. The Retroviridae family showed the highest abundance of viral reads. Although no complete genome could be recovered, the Paramyxoviridae and Dicistroviridae families showed the formation of contigs with satisfactory identity and size characteristics for further analysis. One contig of the Paramyxoviridae family was characterized as belonging to the genus Morbillivirus, being grouped most closely phylogenetically to Porcine morbillivirus. The contig related to the Dicistroviridae family was identified within the Cripavirus genus, with 94%, 91%, and 42% amino acid identity with Culex dicistrovirus 2, Rhopalosiphum padi, and Aphid lethal paralysis, respectively. The presence of viruses in bats needs constant updating since the study was able to identify viral sequences related to families or genera still poorly described in the literature in association with bats.

Viral Interference between the Insect-Specific Virus Brejeira and the Saint Louis Encephalitis Virus In Vitro.

The Saint Louis encephalitis virus (SLEV) is an encephalitogenic arbovirus (Flaviviridae family) that has a wide geographical distribution in the western hemisphere, especially in the Americas. The negevirus Brejeira (BREV) was isolated for the first time in Brazil in 2005. This study aimed to verify the existence of a possible interfering effect of BREV on the course of SLEV infection and vice versa. We used clone C6/36 cells. Three combinations of MOIs were used (SLEV 0.1 × BREV 1; SLEV 1 × BREV 0.1; SLEV 1 × BREV 1) in the kinetics of up to 7 days and then the techniques of indirect immunofluorescence (IFA), a plaque assay on Vero cells, and RT-PCR were performed. Our results showed that the cytopathic effect (CPE) caused by BREV was more pronounced than the CPE caused by SLEV. Results of IFA, the plaque assay, and RT-PCR showed the suppression of SLEV replication in the co-infection condition in all the MOI combinations used. The SLEV suppression was dose-dependent. Therefore, the ISV Brejeira can suppress SLEV replication in Aedes albopictus cells, but SLEV does not negatively interfere with BREV replication.

Neuroimmunology of rabies: New insights into an ancient disease.

Rabies is an ancient neuroinvasive viral (genus Lyssavirus, family Rhabdoviridae) disease affecting approximately 59,000 people worldwide. The central nervous system (CNS) is targeted, and rabies has a case fatality rate of almost 100% in humans and animals. Rabies is entirely preventable through proper vaccination, and thus, the highest incidence is typically observed in developing countries, mainly in Africa and Asia. However, there are still cases in European countries and the United States. Recently, demographic, increasing income levels, and the coronavirus disease 2019 (COVID-19) pandemic have caused a massive raising in the animal population, enhancing the need for preventive measures (e.g., vaccination, surveillance, and animal control programs), postexposure prophylaxis, and a better understanding of rabies pathophysiology to identify therapeutic targets, since there is no effective treatment after the onset of clinical manifestations. Here, we review the neuroimmune biology and mechanisms of rabies. Its pathogenesis involves a complex and poorly understood modulation of immune and brain functions associated with metabolic, synaptic, and neuronal impairments, resulting in fatal outcomes without significant histopathological lesions in the CNS. In this context, the neuroimmunological and neurochemical aspects of excitatory/inhibitory signaling (e.g., GABA/glutamate crosstalk) are likely related to the clinical manifestations of rabies infection. Uncovering new links between immunopathological mechanisms and neurochemical imbalance will be essential to identify novel potential therapeutic targets to reduce rabies morbidity and mortality.

Phylogenetic analysis of rabies surveillance samples from north and northeast Brazil.

Viruses of the Lyssavirus genus are classified into several genotypes (GT1 to GT7), of which only GT1 (classic rabies virus-RABV) has a cosmopolitan distribution and circulates in Brazil. GT1 is subdivided into several antigenic variants (AgV) maintained in independent cycles with a narrow host range and distinct geographic distributions, namely, AgV1 and AgV2 found in dogs, AgV3 in the vampire bats Desmodus rotundus, and AgV4 and AgV6 in bats non-hematophagous Tadarida brasiliensis and Lasiurus cinereus, a common variant of marmoset (Callithrix jacchus), and crab-eating fox (Cerdocyon thous). In this study, we performed phylogenetic analysis to identify at the antigenic variant level; six RABV genomes derived from the Rabies Surveillance in the north and northeast regions of Brazil. The analysis resulted in the formation of 11 monophyletic clusters, each corresponding to a particular variant, with high bootstrap support values. The samples were positioned inside the AgV3, AgV6, and Callithrix variant clades. This is the first report of the AgV6 variant found in northern Brazil, which provides valuable information for rabies surveillance in the country. The possibility of viral spillover has been much debated, as it deals with the risk of shifting transmission from a primary to a secondary host. However, more genomic surveillance studies should be performed, with a greater number and diversity of samples to better understand the transmission dynamics of each variant to detect changes in its geographic distribution and spillover events.

Emergence of a New Strain of DENV-2 in South America: Introduction of the Cosmopolitan Genotype through the Brazilian-Peruvian Border.

Dengue virus 2 (DENV-2) seriously contributes to dengue-related mortality. It includes five nonsylvatic genotypes, with cosmopolitan being the most widespread with a significant contribution to the total number of DENV-2 cases globally. In South America, the cosmopolitan genotype was first recorded in 2019 in Madre de Dios, Peru, and then in Goiás (Midwest Brazil) in November 2021. In this study, we tested 163 human serum samples from Acre (Northern Brazil) collected during a DENV outbreak between 2020 and 2021 for all DENV genotypes by RT-qPCR. Of the 163 samples, 139 were positive for DENV-2, and 5 were positive for DENV-1. Five DENV-2-positive samples from early 2021 were sequenced, and the sequences clustered with the three other DENV-2 cosmopolitan genotype sequences already recorded on the continent. These results create a geographical link, suggesting the possible route of introduction of the DENV-2 cosmopolitan genotype into Brazil through the border with Peru, from which it may have dispersed to Midwest Brazil.

Novel Rodent Arterivirus Detected in the Brazilian Amazon.

As part of a continuous effort to investigate the viral communities associated with wild mammals at the human-animal interface in an Amazonian metropolitan region, this study describes the detection of a novel rodent-borne arterivirus. A sample containing pooled organs of Oecomys paricola was submitted to RNA sequencing, and four sequences taxonomically assigned as related to the Arteriviridae family were recovered, corresponding to an almost complete genome of nearly 13 kb summed. In the phylogenetic analysis with the standard domains used for taxa demarcation in the family, the tentatively named Oecomys arterivirus 1 (OAV-1) was placed within the clade of rodent- and porcine-associated viruses, corresponding to the Variarterivirinae subfamily. The divergence analysis, based on the same amino acid alignment, corroborated the hypothesis that the virus may represent a new genus within the subfamily. These findings contribute to the expansion of the current knowledge about the diversity, host and geographical range of the viral family. Arterivirids are non-human pathogens and are usually species-specific, but the susceptibility of cell lines derived from different organisms should be conducted to confirm these statements for this proposed new genus in an initial attempt to assess its spillover potential.

Isolation of Flaviviruses and Alphaviruses with Encephalitogenic Potential Diagnosed by Evandro Chagas Institute (Pará, Brazil) in the Period of 1954-2022: Six Decades of Discoveries.

Viruses with encephalitogenic potential can cause neurological conditions of clinical and epidemiological importance, such as Saint Louis encephalitis virus, Venezuelan equine encephalitis virus, Eastern equine encephalitis virus, Western equine encephalitis virus, Dengue virus, Zika virus, Chikungunya virus, Mayaro virus and West Nile virus. The objective of the present study was to determine the number of arboviruses with neuroinvasive potential isolated in Brazil that corresponds to the collection of viral samples belonging to the Department of Arbovirology and Hemorrhagic Fevers, Evandro Chagas Institute (SAARB/IEC) of the Laboratory Network of National Reference for Arbovirus Diagnosis from 1954 to 2022. In the analyzed period, a total of 1,347 arbovirus samples with encephalitogenic potential were isolated from mice; 5,065 human samples were isolated exclusively by cell culture; and 676 viruses were isolated from mosquitoes. The emergence of new arboviruses may be responsible for diseases still unknown to humans, making the Amazon region a hotspot for infectious diseases due to its fauna and flora species characteristics. The detection of circulating arboviruses with the potential to cause neuroinvasive diseases is constant, which justifies the continuation of active epidemiological surveillance work that offers adequate support to the public health system regarding the virological diagnosis of circulating arboviruses in Brazil.

Zika Virus Infection Damages the Testes in Pubertal Common Squirrel Monkeys (Saimiri collinsi).

During the Zika virus (ZIKV) outbreak and after evidence of its sexual transmission was obtained, concerns arose about the impact of the adverse effects of ZIKV infection on human fertility. In this study, we evaluated the clinical-laboratory aspects and testicular histopathological patterns of pubertal squirrel monkeys (Saimiri collinsi) infected with ZIKV, analyzing the effects at different stages of infection. The susceptibility of S. collinsi to ZIKV infection was confirmed by laboratory tests, which detected viremia (mean 1.63 × 106 RNA copies/µL) and IgM antibody induction. Reduced fecal testosterone levels, severe testicular atrophy and prolonged orchitis were observed throughout the experiment by ultrasound. At 21 dpi, testicular damage associated with ZIKV was confirmed by histopathological and immunohistochemical (IHC) analyses. Tubular retraction, the degeneration and necrosis of somatic and germ cells in the seminiferous tubules, the proliferation of interstitial cells and an inflammatory infiltrate were observed. ZIKV antigen was identified in the same cells where tissue injuries were observed. In conclusion, squirrel monkeys were found to be susceptible to the Asian variant of ZIKV, and this model enabled the identification of multifocal lesions in the seminiferous tubules of the infected group evaluated. These findings may suggest an impact of ZIKV infection on male fertility.

Co-infection of Peruvian horse sickness virus and West Nile virus associated with neurological diseases in horses from Brazil.

In 2018, during the surveillance for West Nile virus (WNV) in horses with neurological clinical signs in the state of Espírito Santo (Brazil), 19 animals were investigated, and 52 biological samples were collected for WNV diagnostic. One brain sample was positive for WNV by RT-qPCR and the virus was isolated in C6/36 cell culture and sequenced. We obtained a nearly complete genome of WNV co-infected with Peruvian horse sickness virus (PHSV) in the cell culture. After confirmation of PHSV by next-generation sequencing, a new PHSV RT-qPCR protocol was developed, which was used to detect another horse positive only for PHSV. This assay provides a simple and direct method for easy identification of PHSV from biological samples from horses and may become a useful tool in the epidemiological surveillance of this virus. It is the first case of PHSV in Brazil, and only the third country overall to report, 23 years after the first confirmed notification in Peru. Moreover, it is the first reported co-infection of PHSV and WNV in a horse with neurological signs, confirmed by RT-qPCR.

Arboviruses in Free-Ranging Birds and Hematophagous Arthropods (Diptera, Nematocera) from Forest Remnants and Urbanized Areas of an Environmental Protection Area in the Amazon Biome.

The rapid and disorderly urbanization in the Amazon has resulted in the insertion of forest fragments into cities, causing the circulation of arboviruses, which can involve hematophagous arthropods and free-ranging birds in the transmission cycles in urban environments. This study aimed to evaluate the circulation of arboviruses in free-ranging birds and hematophagous arthropods captured in an Environmental Protection Area in the Belem metropolitan area, Brazil. Birds were captured using mist nets, and hematophagous arthropods were collected using a human protected attraction technique and light traps. The birds' sera were subjected to a hemagglutination inhibition test to detect antibodies against 29 arbovirus antigens. Arthropod macerates were inoculated into C6/36 and VERO cell cultures to attempt viral isolation and were tested using indirect immunofluorescence, subsequent genetic sequencing and submitted for phylogenetic analysis. Four bird sera were positive for arbovirus, and one batch of Psorophora ferox was positive for Flavivirus on viral isolation and indirect immunofluorescence. In addition, the Ilheus virus was detected in the sequencing and phylogenetic analysis. The presence of antibodies in sera from free-ranging birds and the isolation of Ilheus virus in Psorophora ferox indicate the circulation of arboviruses in forest remnants in the urban center of Belem.

First Genomic Evidence of a Henipa-like Virus in Brazil.

The viral genus Henipavirus includes two highly virulent zoonotic viruses of serious public health concern. Hendra henipavirus and Nipah henipavirus outbreaks are restricted to Australia and Southeast Asia, respectively. The Henipavirus genus comprises mostly bat-borne viruses, but exceptions have already been described as novel viruses with rodents and shrews as reservoir animals. In the Americas, scarce evidence supports the circulation of these viruses. In this communication, we report a novel henipa-like virus from opossums (Marmosa demerarae) from a forest fragment area in the Peixe-Boi municipality, Brazil, after which the virus was named the Peixe-Boi virus (PBV). The application of next-generation sequencing and metagenomic approach led us to discover the original evidence of a henipa-like virus genome in Brazil and South America and the original description of a henipa-like virus in marsupial species. These findings emphasize the importance of further studies to characterize PBV and clarify its ecology, impact on public health, and its relationship with didelphid marsupials and henipaviruses.

Absence of Anti-RBD Antibodies in SARS-CoV-2 Infected or Naive Individuals Prior to Vaccination with CoronaVac Leads to Short Protection of Only Four Months Duration.

The COVID-19 pandemic is the biggest public health threat facing the world today. Multiple vaccines have been approved; however, the emergence of viral variants such as the recent Omicron raises the possibility of booster doses to achieve adequate protection. In Brazil, the CoronaVac (Sinovac, Beijing, China) vaccine was used; however, it is important to assess the immune response to this vaccine over time. This study aimed to monitor the anti-SARS-CoV-2 antibody responses in those immunized with CoronaVac and SARS-CoV-2 infected individuals. Samples were collected between August 2020 and August 2021. Within the vaccinated cohort, some individuals had a history of infection by SARS-CoV-2 prior to immunization, while others did not. We analyzed RBD-specific and neutralizing-antibodies. Anti-RBD antibodies were detected in both cohorts, with a peak between 45-90 days post infection or vaccination, followed by a steady decline over time. In those with a previous history of COVID-19, a higher, longer, more persistent response was observed. This trend was mirrored in the neutralization assays, where infection, followed by immunization, resulted in higher, longer lasting responses which were conditioned on the presence of levels of RBD antibodies right before the vaccination. This supports the necessity of booster doses of CoronaVac in due course to prevent serious disease.

West Nile Virus in the State of Ceará, Northeast Brazil.

In June 2019, a horse with neurological disorder was diagnosed with West Nile virus (WNV) in Boa Viagem, a municipality in the state of Ceará, northeast Brazil. A multi-institutional task force coordinated by the Brazilian Ministry of Health was deployed to the area for case investigation. A total of 513 biological samples from 78 humans, 157 domestic animals and 278 free-ranging wild birds, as well as 853 adult mosquitoes of 22 species were tested for WNV by highly specific serological and/or molecular tests. No active circulation of WNV was detected in vertebrates or mosquitoes by molecular methods. Previous exposure to WNV was confirmed by seroconversion in domestic birds and by the detection of specific neutralizing antibodies in 44% (11/25) of equids, 20.9% (14/67) of domestic birds, 4.7% (13/278) of free-ranging wild birds, 2.6% (2/78) of humans, and 1.5% (1/65) of small ruminants. Results indicate that not only equines but also humans and different species of domestic animals and wild birds were locally exposed to WNV. The detection of neutralizing antibodies for WNV in free-ranging individuals of abundant passerine species suggests that birds commonly found in the region may have been involved as amplifying hosts in local transmission cycles of WNV.

Reporter Virus Neutralization Test Evaluation for Dengue and Zika Virus Diagnosis in Flavivirus Endemic Area.

Reporter virus neutralization test (RVNT) has been used as an alternative to the more laborious and time-demanding conventional PRNT assay for both DENV and ZIKV. However, few studies have investigated how these techniques would perform in epidemic areas with the circulation of multiple flavivirus. Here, we evaluate the performance of ZIKV and DENV Rluc RVNT and ZIKV mCh RVNT assays in comparison to the conventional PRNT assay against patient sera collected before and during ZIKV outbreak in Brazil. These samples were categorized into groups based on (1) acute and convalescent samples according to the time of disease, and (2) laboratorial diagnostic results (DENV and ZIKV RT-PCR and IgM-capture ELISA). Our results showed that DENV Rluc assay presented 100% and 78.3% sensitivity and specificity, respectively, with 93.3% accuracy, a similar performance to the traditional PRNT. ZIKV RVNT90, on the other hand, showed much better ZIKV antibody detection performance (around nine-fold higher) when compared to PRNT, with 88% clinical sensitivity. Specificity values were on average 76.8%. Even with these results, however, ZIKV RVNT90 alone was not able to reach a final diagnostic conclusion for secondary infection in human samples due to flavivirus cross reaction. As such, in regions where the flavivirus differential diagnosis represents a challenge, we suggest the establishment of a RVNT panel including other flaviviruses circulating in the region, associated with the other serological techniques such as IgM ELISA and the investigation of seroconversion, in order to help define an accurate diagnostic conclusion using serology.

Challenges of Rabies Surveillance in the Eastern Amazon: The Need of a One Health Approach to Predict Rabies Spillover.

Brazil has been promoting essential improvements in health indicators by implementing free-access health programs, which successfully reduced the prevalence of neglected zoonosis in urban areas, such as rabies. Despite constant efforts from the authorities to monitor and control the disease, sylvatic rabies is a current issue in Amazon's communities. The inequalities among Amazon areas challenge the expansion of high-tech services and limit the implementation of active laboratory surveillance to effectively avoid outbreaks in human and non-human hosts, which also reproduces a panorama of vulnerability in risk communities. Because rabies is a preventable disease, the prevalence in the particular context of the Amazon area highlights the failure of surveillance strategies to predict spillovers and indicates the need to adapt the public policies to a "One Health" approach. Therefore, this work assesses the distribution of free care resources and facilities among Pará's regions in the oriental Amazon; and discusses the challenges of implanting One Health in the particular context of the territory. We indicate a much-needed strengthening of the sylvatic and urban surveillance networks to achieve the "Zero by 30" goal, which is inextricable from multilateral efforts to combat the progressive biome's degradation.

Immunological impact of tetrahydrobiopterin on the central nervous system in a murine model of rabies virus infection.

Currently, the Milwaukee protocol presents healing results in human beings affected by the rabies virus. However, there are many points to clarify on the action of drugs and the immune mechanism involved in the evolution of the disease. One of the drugs used is biopterin, which is an important cofactor for nitric oxide, important for preventing vasospasm. Thus, we describe the effect of biopterin on some inflammatory factors in a rabies virus infection developed in an animal model. The immunological mediators studied in animals infected with rabies virus submitted to doses of sapropterin were Anti-RABV, IL-6, IL-2, IL-17a, INF-gamma and Anti-iNOS. It is suggested that the medication in the context of a RABV infection already installed, had the effect of modulating the inflammatory mechanisms mainly linked to the permeability of the blood-brain barrier and the migration of cytotoxic cells.

Prenatal disorders and congenital Zika syndrome in squirrel monkeys.

During the Zika virus (ZIKV) outbreak in Brazil (2015-2016), the clinical manifestations associated with its infection were complex and included miscarriage and congenital malformations, not previously described. In this study, we evaluated the prenatal conditions of pregnant female squirrel monkeys (Saimiri collinsi) infected during different gestational thirds (GTs) and assessed all clinical aspects, diagnostic imaging, viremia and the immune response. In our study, 75% of the infected animals in the 1st GT group had significant clinical manifestations, such as miscarriage and prolonged viremia associated with a late immune response. Consequently, their neonates showed fetal neuropathology, such as cerebral hemorrhage, lissencephaly or malformations of the brain grooves, ventriculomegaly, and craniofacial malformations. Thus, our study demonstrated the relevance of pregnant squirrel monkeys as a model for the study of ZIKV infection in neonates due to the broad clinical manifestations presented, including the typical congenital Zika syndrome manifestations described in humans.

Serological evidence of Eastern equine encephalitis circulation in equids in Pará state, Brazil.

Serum samples from 89 equids were analyzed (75 horses, 9 donkeys, and 5 mules) from the municipality of Viseu, Pará state, Brazil. Samples were collected in November 2014 and August 2015. The antibody prevalence against the following alphaviruses was estimated: Eastern equine encephalitis virus, Western equine encephalitis virus, Mucambo virus, and Mayaro virus. Seroprevalence was determined by the hemagglutination inhibition (HI) technique. Sera that exhibited HI antibodies with heterotypic reactions for the analyzed viruses were subjected to the 90% plaque reduction neutralization test (PRNT90). The HI prevalence of monotypic reactions to EEEV was 7.9%, and that of WEEV was 1.1%, as confirmed by PRNT90. Viral isolation attempts were negative for all tested blood samples. Our results suggest the circulation of equine encephalitis complex viruses. Future studies should evaluate the possible involvement of arthropod hosts and residents in the viral transmission in the study area.

Foram analisadas amostras de soros de 89 equídeos (75 equinos, 9 asininos e 5 muares) oriundos do município de Viseu, estado do Pará. As amostras foram coletadas no período de novembro de 2014 e agosto de 2015. Foram estimadas as prevalências de anticorpos contra os seguintes Alfavírus: vírus da Encefalite equina leste (EEEV), vírus da Encefalite equina oeste (WEEV), vírus Mucambo (MUCV), and vírus Mayaro (MAYV). A soroprevalência foi determinada por técnicas de Inibição da Hemaglutinação (IH), porém os soros que apresentaram anticorpos IH com reações heterotípicas para os vírus analisados foram submetidos ao PRNT90. A prevalência de reações monotípicas por IH para EEEV foi de 7, 9% e para WEEV foi de 1,1%, confirmadas por PRNT90. A tentativa de isolamento viral foi negativa em todas as amostras de sangue testadas. Nossos resultados sugerem a circulação de vírus do complexo das encefalites equinas. Estudos futuros devem ser realizados para avaliar possível envolvimento de hospedeiros artrópodes e residentes na área de abrangência do estudo.

Evaluation of immunoglobulin M-specific capture enzyme-linked immunosorbent assays and commercial tests for flaviviruses diagnosis by a National Reference Laboratory.

Zika and Dengue viruses present considerable immunological cross-reactivity, resulting in a troublesome serodiagnosis due to occurrence of false positive results. Due to Brazil's wide variety of circulating flaviviruses we aimed to access the use of in house serological tests adapted by National Reference Laboratory for Arboviruses in Brazil and evaluate commercial tests available. We evaluated in house IgM ELISAs for the individual detection of anti-ZIKV, -DENV, and -YFV IgM, against a panel of samples positive for dengue, zika, yellow fever, Rocio, Ilheus, Saint Louis encephalitis, West Nile and chikungunya. We also evaluated two commercial kits for dengue and zika IgM detection recommended by the Brazilian Ministry of Health in 2015. The sensitivity and specificity for the in house ZIKV IgM ELISA was 60.0 % and 88.6 % and for the in house DENV IgM ELISA was 100 % and 82.2 %, respectively. The in house YFV IgM ELISA presented 100 % for both sensitivity and specificity. The Novagnost Zika Virus IgM test presented a sensitivity of 47.3 % and specificity of 85.3 % and the Serion ELISA classic Dengue Virus IgM, 92.8 % and 58.9 %, respectively. Overall, both in house ELISAs for ZIKV and DENV adapted and evaluated here, presented better performances than the commercial kits tested.

Experimental infection of golden hamsters with Guama virus (Peribunyaviridae, Orthobunyavirus).

The Guama virus (GMAV) is a member of Peribunyaviridae family, Orthobunyavirus genus. Several strains of the virus were isolated in South and Central Americas from several hosts, such as humans, wild animals, including nonhuman primates, wild rodents and mosquitoes as well as mice used as sentinels. The virus is able to cause febrile disease in humans. Here we describe for the first time pathologic and biochemical findings in golden hamsters (Mesocricetus auratus) infected with the prototype GMAV. Blood and organs of infected and control animals were collected every 24 h after infection from the 1st to the 7th day post infection (dpi) and at 21 dpi when experiment was ended. The tissues were processed for histopathology and immunohistochemistry. The blood and serum were used to determine viremia and biochemical markers plus to detect anti-GMAV antibodies. The viremia was early detected already on the 1st dpi and it was no longer detected on the 3rd dpi. Total anti-GMAV antibodies were detected from the 6th dpi. Hepatic markers as ALT of infected animals were increased and showed statistically significant difference in comparison with control animals, indicating damage of the liver; indeed the liver was the most affected organ, but other organs presented lesions and positive GMAV immunostaining as brain, lung, liver, spleen, and kidney. Our findings indicate that golden hamsters are a good animal model for experimental infection of the GMAV.