RESUMEN
The diversity of influenza A viruses (IAV) is primarily hosted by two highly divergent avian orders: Anseriformes (ducks, swans and geese) and Charadriiformes (gulls, terns and shorebirds). Studies of IAV have historically focused on Anseriformes, specifically dabbling ducks, overlooking the diversity of hosts in nature, including gull and goose species that have successfully adapted to human habitats. This study sought to address this imbalance by characterizing spillover dynamics and global transmission patterns of IAV over 10 years at greater taxonomic resolution than previously considered. Furthermore, the circulation of viral subtypes in birds that are either host-adapted (low pathogenic H13, H16) or host-generalist (highly pathogenic avian influenza-HPAI H5) provided a unique opportunity to test and extend models of viral evolution. Using Bayesian phylodynamic modelling we uncovered a complex transmission network that relied on ecologically divergent bird hosts. The generalist subtype, HPAI H5 was driven largely by wild geese and swans that acted as a source for wild ducks, gulls, land birds, and domestic geese. Gulls were responsible for moving HPAI H5 more rapidly than any other host, a finding that may reflect their long-distance, pelagic movements and their immuno-naïve status against this subtype. Wild ducks, long viewed as primary hosts for spillover, occupied an optimal space for viral transmission, contributing to geographic expansion and rapid dispersal of HPAI H5. Evidence of inter-hemispheric dispersal via both the Pacific and Atlantic Rims was detected, supporting surveillance at high latitudes along continental margins to achieve early detection. Both neutral (geographic expansion) and non-neutral (antigenic selection) evolutionary processes were found to shape subtype evolution which manifested as unique geographic hotspots for each subtype at the global scale. This study reveals how a diversity of avian hosts contribute to viral spread and spillover with the potential to improve surveillance in an era of rapid global change.
Asunto(s)
Charadriiformes , Virus de la Influenza A , Gripe Aviar , Animales , Animales Salvajes , Teorema de Bayes , Aves , Patos , Humanos , Virus de la Influenza A/genéticaRESUMEN
Influenza A viruses (IAV) circulate endemically among many wild aquatic bird populations that seasonally migrate between wintering grounds in southern latitudes to breeding ranges along the perimeter of the circumpolar arctic. Arctic and subarctic zones are hypothesized to serve as ecologic drivers of the intercontinental movement and reassortment of IAVs due to high densities of disparate populations of long distance migratory and native bird species present during breeding seasons. Iceland is a staging ground that connects the East Atlantic and North Atlantic American flyways, providing a unique study system for characterizing viral flow between eastern and western hemispheres. Using Bayesian phylodynamic analyses, we sought to evaluate the viral connectivity of Iceland to proximal regions and how inter-species transmission and reassortment dynamics in this region influence the geographic spread of low and highly pathogenic IAVs. Findings demonstrate that IAV movement in the arctic and subarctic reflects wild bird migration around the perimeter of the circumpolar north, favouring short-distance flights between proximal regions rather than long distance flights over the polar interior. Iceland connects virus movement between mainland Europe and North America, consistent with the westward migration of wild birds from mainland Europe to Northeastern Canada and Greenland. Though virus diffusion rates were similar among avian taxonomic groups in Iceland, gulls play an outsized role as sinks of IAVs from other avian hosts prior to onward migration. These data identify patterns of virus movement in northern latitudes and inform future surveillance strategies related to seasonal and emergent IAVs with potential public health concern.
Asunto(s)
Virus de la Influenza A , Gripe Aviar , Animales , Virus de la Influenza A/genética , Gripe Aviar/epidemiología , Teorema de Bayes , Animales Salvajes , Aves , Migración Animal , FilogeniaRESUMEN
Subtype H10 influenza A viruses (IAVs) have been recovered from domestic poultry and various aquatic bird species, and sporadic transmission of these IAVs from avian species to mammals (i.e., human, seal, and mink) are well documented. In 2015, we isolated four H10N7 viruses from gulls in Iceland. Genomic analyses showed four gene segments in the viruses were genetically associated with H10 IAVs that caused influenza outbreaks and deaths among European seals in 2014. Antigenic characterization suggested minimal antigenic variation among these H10N7 isolates and other archived H10 viruses recovered from human, seal, mink, and various avian species in Asia, Europe, and North America. Glycan binding preference analyses suggested that, similar to other avian-origin H10 IAVs, these gull-origin H10N7 IAVs bound to both avian-like alpha 2,3-linked sialic acids and human-like alpha 2,6-linked sialic acids. However, when the gull-origin viruses were compared with another Eurasian avian-origin H10N8 IAV, which caused human infections, the gull-origin virus showed significantly higher binding affinity to human-like glycan receptors. Results from a ferret experiment demonstrated that a gull-origin H10N7 IAV replicated well in turbinate, trachea, and lung, but replication was most efficient in turbinate and trachea. This gull-origin H10N7 virus can be transmitted between ferrets through the direct contact and aerosol routes, without prior adaptation. Gulls share their habitat with other birds and mammals and have frequent contact with humans; therefore, gull-origin H10N7 IAVs could pose a risk to public health. Surveillance and monitoring of these IAVs at the wild bird-human interface should be continued.IMPORTANCE Subtype H10 avian influenza A viruses (IAVs) have caused sporadic human infections and enzootic outbreaks among seals. In the fall of 2015, H10N7 viruses were recovered from gulls in Iceland, and genomic analyses showed that the viruses were genetically related with IAVs that caused outbreaks among seals in Europe a year earlier. These gull-origin viruses showed high binding affinity to human-like glycan receptors. Transmission studies in ferrets demonstrated that the gull-origin IAV could infect ferrets, and that the virus could be transmitted between ferrets through direct contact and aerosol droplets. This study demonstrated that avian H10 IAV can infect mammals and be transmitted among them without adaptation. Thus, avian H10 IAV is a candidate for influenza pandemic preparedness and should be monitored in wildlife and at the animal-human interface.
Asunto(s)
Hurones/virología , Subtipo H10N7 del Virus de la Influenza A/patogenicidad , Infecciones por Orthomyxoviridae/transmisión , Infecciones por Orthomyxoviridae/virología , Aerosoles , Animales , Animales Salvajes/virología , Aves/virología , Línea Celular , Charadriiformes/virología , Genoma Viral , Humanos , Islandia , Subtipo H10N7 del Virus de la Influenza A/clasificación , Subtipo H10N7 del Virus de la Influenza A/genética , Subtipo H10N7 del Virus de la Influenza A/aislamiento & purificación , Gripe Aviar/virología , Infecciones por Orthomyxoviridae/epidemiología , Infecciones por Orthomyxoviridae/patología , Pandemias , Filogenia , Polisacáridos , Sistema Respiratorio/patología , Sistema Respiratorio/virología , Alineación de SecuenciaRESUMEN
Waterfowl and shorebirds are the primary hosts of influenza A virus (IAV), however, in most surveillance efforts, large populations of birds are not routinely examined; specifically marine ducks and other birds that reside predominately on or near the ocean. We conducted a long-term study sampling sea ducks and gulls in coastal Maine for IAV and found a virus prevalence (1.7%) much lower than is typically found in freshwater duck populations. We found wide year-to-year variation in virus detection in sea ducks and that the ocean water temperature was an important factor affecting IAV prevalence. In particular, the ocean temperature that occurred 11 d prior to collecting virus positive samples was important while water temperature measured concurrently with host sampling had no explanatory power for viral detection. We also experimentally showed that IAV is relatively unstable in sea water at temperatures typically found during our sampling. This represents the first report of virus prevalence and actual environmental data that help explain the variation in marine IAV transmission dynamics.
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Virus de la Influenza A , Gripe Aviar/epidemiología , Animales , Aves , Patos , Maine , Océanos y Mares , Prevalencia , TemperaturaRESUMEN
Wellfleet Bay virus (WFBV), a novel orthomyxovirus in the genus Quaranjavirus, was first isolated in 2006 from carcasses of common eider (Somateria mollissima) during a mortality event in Wellfleet Bay (Barnstable County, Massachusetts, USA) and has since been repeatedly isolated during recurrent mortality events in this location. Hepatic, pancreatic, splenic, and intestinal necrosis was observed in dead eiders. We inoculated 6-week-old common eider ducklings with WFBV in an attempt to recreate the naturally occurring disease. Approximately 25% of inoculated eiders had onset of clinical disease and required euthanasia; an additional 18.75% were adversely affected based on net weight loss during the trial. Control ducklings did not become infected and did not have clinical disease. Infected ducklings with clinical disease had pathologic lesions consistent with those observed during natural mortality events. WFBV was reisolated from 37.5% of the inoculated ducklings. Ducklings surviving to 5 days postinoculation developed serum antibody titers to WFBV.
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Anticuerpos Antivirales/biosíntesis , Enfermedades de las Aves/virología , Patos/virología , Necrosis/veterinaria , Infecciones por Orthomyxoviridae/veterinaria , Orthomyxoviridae/fisiología , Animales , Bahías , Enfermedades de las Aves/inmunología , Enfermedades de las Aves/patología , Modelos Animales de Enfermedad , Patos/inmunología , Intestinos/inmunología , Intestinos/patología , Intestinos/virología , Hígado/inmunología , Hígado/patología , Hígado/virología , Massachusetts , Necrosis/inmunología , Necrosis/patología , Necrosis/virología , Orthomyxoviridae/patogenicidad , Infecciones por Orthomyxoviridae/inmunología , Infecciones por Orthomyxoviridae/patología , Infecciones por Orthomyxoviridae/virología , Páncreas/inmunología , Páncreas/patología , Páncreas/virología , Bazo/inmunología , Bazo/patología , Bazo/virología , Pérdida de PesoRESUMEN
The movement of highly pathogenic avian influenza (H5N8) virus across Eurasia and into North America and the virus' propensity to reassort with co-circulating low pathogenicity viruses raise concerns among poultry producers, wildlife biologists, aviculturists, and public health personnel worldwide. Surveillance, modeling, and experimental research will provide the knowledge required for intelligent policy and management decisions.
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Virus de la Influenza A/genética , Gripe Aviar/epidemiología , Gripe Humana/epidemiología , Animales , Aves , China/epidemiología , Monitoreo Epidemiológico , Europa (Continente)/epidemiología , Humanos , Gripe Aviar/virología , Gripe Humana/virología , América del Norte/epidemiologíaRESUMEN
Wild water birds are the natural reservoir for low-pathogenic avian influenza viruses (AIV). However, our ability to investigate the epizootiology of AIV in these migratory populations is challenging and, despite intensive worldwide surveillance, remains poorly understood. We conducted a cross-sectional, retrospective analysis in Pacific Flyway Lesser Snow Geese, Chen caerulescens, to investigate AIV serology and infection patterns. We collected nearly 3000 sera samples from Snow Geese at two breeding colonies in Russia and Canada during 1993-1996 and swab samples from >4000 birds at wintering and migration areas in the United States during 2006-2011. We found seroprevalence and annual seroconversion varied considerably among years. Seroconversion and infection rates also differed between Snow Goose breeding colonies and wintering areas, suggesting that AIV exposure in this gregarious waterfowl species is likely occurring during several phases (migration, wintering, and potentially breeding areas) of the annual cycle. We estimated AIV antibody persistence was longer (14 months) in female geese compared to males (6 months). This relatively long period of AIV antibody persistence suggests that subtype-specific serology may be an effective tool for detection of exposure to subtypes associated with highly pathogenic AIV. Our study provides further evidence of high seroprevalence in Arctic goose populations, and estimates of annual AIV seroconversion and antibody persistence for North American waterfowl. We suggest future AIV studies include serology to help elucidate the epizootiological dynamics of AIV in wild bird populations.
Asunto(s)
Migración Animal , Gansos , Gripe Aviar/epidemiología , Animales , Femenino , Masculino , Estudios Seroepidemiológicos , Factores de Tiempo , Esparcimiento de VirusRESUMEN
It has been proposed that the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus that spread through human populations as a pandemic originated in Asian bats. There is concern that infected humans could transmit the virus to native North American bats; therefore, the susceptibility of several North American bat species to the pandemic virus has been experimentally assessed. Big brown bats (Eptesicus fuscus) were shown to be resistant to infection by SARS-CoV-2, whereas Mexican free-tailed bats (Tadarida brasiliensis) became infected and orally excreted moderate amounts of virus for up to 18 d postinoculation. Little brown bats (Myotis lucifugus) frequently contact humans, and their populations are threatened over much of their range due to white-nose syndrome, a fungal disease that is continuing to spread across North America. We experimentally challenged little brown bats with SARS-CoV-2 to determine their susceptibility and host potential and whether the virus presents an additional risk to this species. We found that this species was resistant to infection by SARS-CoV-2. These findings provide reassurance to wildlife rehabilitators, biologists, conservation scientists, and the public at large who are concerned with possible transmission of this virus to threatened bat populations.
RESUMEN
BACKGROUND: The role of gulls in the ecology of avian influenza (AI) is different than that of waterfowl. Different constellations of subtypes circulate within the two groups of birds and AI viruses isolated from North American gulls frequently possess reassortant genomes with genetic elements from both North America and Eurasian lineages. A 2008 isolate from a Newfoundland Great Black-backed Gull contained a mix of North American waterfowl, North American gull and Eurasian lineage genes. METHODS: We isolated, sequenced and phylogenetically compared avian influenza viruses from 2009 Canadian wild birds. RESULTS: We analyzed six 2009 virus isolates from Canada and found the same phylogenetic lineage had persisted over a larger geographic area, with an expanded host range that included dabbling and diving ducks as well as gulls. All of the 2009 virus isolates contained an internal protein coding set of genes of the same Eurasian lineage genes except PB1 that was from a North American lineage, and these genes continued to evolve by genetic drift. We show evidence that the 2008 Great Black-backed Gull virus was derived from this lineage with a reassortment of a North American PA gene into the more stable core set of internal protein coding genes that has circulated in avian populations for at least 2 years. From this core, the surface glycoprotein genes have switched several times creating H13N6, H13N2, and H16N3 subtypes. These gene segments were from North American lineages except for the H16 and N3 vRNAs. CONCLUSIONS: This process appears similar to genetic shifts seen with swine influenza where a stable "triple reassortant internal gene" core has circulated in swine populations with genetic shifts occurring with hemaggluttinin and neuraminidase proteins getting periodically switched. Thus gulls may serve as genetic mixing vessels for different lineages of avian influenza, similar to the role of swine with regards to human influenza. These findings illustrate the need for continued surveillance in gull and waterfowl populations, both on the Pacific and especially Atlantic coasts of North America, to document virus intercontinental movement and the role of gull species in the evolution and epidemiology of AI.
Asunto(s)
Aves/virología , Evolución Molecular , Virus de la Influenza A/clasificación , Virus de la Influenza A/genética , Gripe Aviar/virología , Virus Reordenados/clasificación , Virus Reordenados/genética , Animales , Canadá , Análisis por Conglomerados , Flujo Genético , Inestabilidad Genómica , Genotipo , Virus de la Influenza A/aislamiento & purificación , Filogenia , ARN Viral/genética , Virus Reordenados/aislamiento & purificación , Análisis de Secuencia de ADNRESUMEN
Avian influenza viruses can pose serious risks to agricultural production, human health, and wildlife. An understanding of viruses in wild reservoir species across time and space is important to informing surveillance programs, risk models, and potential population impacts for vulnerable species. Although it is recognized that influenza A virus prevalence peaks in reservoir waterfowl in late summer through autumn, temporal and spatial variation across species has not been fully characterized. We combined two large influenza databases for North America and applied spatiotemporal models to explore patterns in prevalence throughout the annual cycle and across the continental United States for 30 waterfowl species. Peaks in prevalence in late summer through autumn were pronounced for dabbling ducks in the genera Anas and Spatula, but not Mareca. Spatially, areas of high prevalence appeared to be related to regional duck density, with highest predicted prevalence found across the upper Midwest during early fall, though further study is needed. We documented elevated prevalence in late winter and early spring, particularly in the Mississippi Alluvial Valley. Our results suggest that spatiotemporal variation in prevalence outside autumn staging areas may also represent a dynamic parameter to be considered in IAV ecology and associated risks.
Asunto(s)
Virus de la Influenza A , Gripe Aviar , Migración Animal , Animales , Animales Salvajes , Patos , Humanos , Gripe Aviar/epidemiología , Prevalencia , Estados Unidos/epidemiologíaRESUMEN
The utility of using Nobuto paper strips for the detection of avian influenza antibodies was examined in mallards (Anas platyrhynchos) experimentally infected with low pathogenic avian influenza viruses. Blood was collected 2 wk after infection and was preserved either as serum or whole blood absorbed onto Nobuto strips. Analysis of samples using a commercially available blocking enzyme-linked immunosorbent assay revealed comparable results (> or = 96% sensitivity for all methods) between sera stored at -30 C and the Nobuto strip preservation method even when the Nobuto strips were stored up to 3 mo at room temperature (RT). Significant differences were detected in the ratio of sample absorbance to negative control absorbance for Nobuto strips stored at RT compared with sera stored at -30 C, although these differences did not affect the ability of the test to reliably detect positive and negative samples. Nobuto strips are a convenient and sensitive alternative to the collection of serum samples when maintaining appropriate storage temperatures is difficult.
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Anseriformes , Anticuerpos Antivirales/sangre , Ensayo de Inmunoadsorción Enzimática/veterinaria , Virus de la Influenza A/inmunología , Gripe Aviar/virología , Papel , Animales , Recolección de Muestras de Sangre/métodos , Recolección de Muestras de Sangre/veterinaria , Técnicas de Laboratorio Clínico , Gripe Aviar/sangre , Gripe Aviar/inmunología , Filtros Microporos , Pruebas Serológicas , Manejo de EspecímenesRESUMEN
BACKGROUND: The 2015 highly pathogenic avian influenza virus (HPAIV) H5N2 clade 2.3.4.4 outbreak in upper midwestern U.S. poultry operations was not detected in wild birds to any great degree during the outbreak, despite wild waterfowl being implicated in the introduction, reassortment, and movement of the virus into North America from Asia. This outbreak led to the demise of over 50 million domestic birds and occurred mainly during the northward spring migration of adult avian populations. OBJECTIVES: There have been no experimental examinations of the pathogenesis, transmission, and population impacts of this virus in adult wild waterfowl with varying exposure histories-the most relevant age class. METHODS: We captured, housed, and challenged adult wild mallards (Anas platyrhynchos) with HPAIV H5N2 clade 2.3.4.4 and measured viral infection, viral excretion, and transmission to other mallards. RESULTS: All inoculated birds became infected and excreted moderate amounts of virus, primarily orally, for up to 14 days. Cohoused, uninoculated birds also all became infected. Serological status had no effect on susceptibility. There were no obvious clinical signs of disease, and all birds survived to the end of the study (14 days). CONCLUSIONS: Based on these results, adult mallards are viable hosts of HPAIV H5N2 regardless of prior exposure history and are capable of transporting the virus over short and long distances. These findings have implications for surveillance efforts. The capture and sampling of wild waterfowl in the spring, when most surveillance programs are not operating, are important to consider in the design of future HPAIV surveillance programs.
Asunto(s)
Subtipo H5N2 del Virus de la Influenza A , Gripe Aviar , Enfermedades de las Aves de Corral , Animales , Brotes de Enfermedades , Patos , Humanos , Subtipo H5N2 del Virus de la Influenza A/genética , Gripe Aviar/epidemiología , Aves de Corral , Enfermedades de las Aves de Corral/epidemiologíaRESUMEN
Since 2014, widespread, annual mortality events involving multiple species of seabirds have occurred in the Gulf of Alaska, Bering Sea, and Chukchi Sea. Among these die-offs, emaciation was a common finding with starvation often identified as the cause of death. However, saxitoxin (STX) was detected in many carcasses, indicating exposure of these seabirds to STX in the marine environment. Few data are available that describe the effects of STX in birds, thus presenting challenges for determining its contributions to specific mortality events. To address these knowledge gaps, we conducted an acute oral toxicity trial in mallards (Anas platyrhynchos), a common laboratory avian model, using an up-and-down method to estimate the median lethal dose (LD50) for STX. Using an enzyme-linked immunosorbent assay (ELISA), we tested select tissues from all birds and feces from those individuals that survived initial dosing. Samples with an ELISA result that exceeded approximately 10 µg 100 g-1 STX and randomly selected ELISA negative samples were further tested by high-performance liquid chromatography (HPLC). Tissues collected from mallards were also examined grossly at necropsy and then later by microscopy to identify lesions attributable to STX. The estimated LD50 was 167 µg kg-1 (95% CI = 69-275 µg kg-1). Saxitoxin was detected in fecal samples of all mallards tested for up to 48 h after dosing and at the end of the sampling period (7 d) in three birds. In those individuals that died or were euthanized <2 h after dosing, STX was readily detected throughout the gastrointestinal tract but only infrequently in heart, kidney, liver, lung, and breast muscle. No gross or microscopic lesions were observed that could be attributable to STX exposure. Given its acute toxicity, limited detectability, and frequent occurrence in the Alaska marine environment, additional research on STX in seabirds is warranted.
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Aves , Saxitoxina , Alaska , Animales , Cromatografía Líquida de Alta Presión , Saxitoxina/análisis , Saxitoxina/toxicidadRESUMEN
The recently emerged novel coronavirus, SARS-CoV-2, is phylogenetically related to bat coronaviruses (CoVs), specifically SARS-related CoVs from the Eurasian bat family Rhinolophidae. As this human pandemic virus has spread across the world, the potential impacts of SARS-CoV-2 on native North American bat populations are unknown, as is the ability of North American bats to serve as reservoirs or intermediate hosts able to transmit the virus to humans or to other animal species. To help determine the impacts of the pandemic virus on North American bat populations, we experimentally challenged big brown bats (Eptesicus fuscus) with SARS-CoV-2 under BSL-3 conditions. We inoculated the bats both oropharyngeally and nasally, and over the ensuing three weeks, we measured infectivity, pathology, virus concentrations in tissues, oral and rectal virus excretion, virus transmission, and clinical signs of disease. We found no evidence of SARS-CoV-2 infection in any examined bat, including no viral excretion, no transmission, no detectable virus in tissues, and no signs of disease or pathology. Based on our findings, it appears that big brown bats are resistant to infection with the SARS-CoV-2. The potential susceptibility of other North American bat species to SARS-CoV-2 remains to be investigated.
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COVID-19 , Quirópteros , Coronaviridae , Animales , COVID-19/veterinaria , Humanos , América del Norte/epidemiología , Filogenia , SARS-CoV-2RESUMEN
Raccoonpox virus (RCN) has been used as a recombinant vector against several mammalian pathogens but has not been tested in birds. The replication of RCN in chick embryo fibroblasts (CEFs) and chickens was studied with the use of highly pathogenic avian influenza virus H5N1 hemagglutinin (HA) as a model antigen and luciferase (luc) as a reporter gene. Although RCN replicated to low levels in CEFs, it efficiently expressed recombinant proteins and, in vivo, elicited anti-HA immunoglobulin yolk (IgY) antibody responses comparable to inactivated influenza virus. Biophotonic in vivo imaging of 1-wk-old chicks with RCN-luc showed strong expression of the luc reporter gene lasting up to 3 days postinfection. These studies demonstrate the potential of RCN as a vaccine vector for avian influenza and other poultry pathogens.
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Pollos , Subtipo H5N1 del Virus de la Influenza A/inmunología , Vacunas contra la Influenza/inmunología , Gripe Aviar/prevención & control , Poxviridae , Animales , Células Cultivadas , Embrión de Pollo , Fibroblastos/virología , Regulación Viral de la Expresión Génica , Vectores Genéticos , Hemaglutininas/metabolismo , Vacunas contra la Influenza/administración & dosificación , Vacunas Virales , Cultivo de VirusRESUMEN
We tested coyote (Canis latrans), fox (Urocyon cinereoargenteus, Vulpes vulpes), and raccoon (Procyon lotor) sera for influenza A virus (IAV) exposure. We found 2/139 samples (1 coyote, 1 raccoon) had IAV antibodies and hemagglutination inhibition assays revealed the antibodies to the 2009/2010 H1N1 human pandemic virus or to the 2007 human seasonal H1N1 virus.
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Coyotes/virología , Zorros/virología , Virus de la Influenza A , Infecciones por Orthomyxoviridae/veterinaria , Mapaches/virología , Animales , Anticuerpos Antivirales/sangre , Coyotes/sangre , Zorros/sangre , Infecciones por Orthomyxoviridae/epidemiología , Infecciones por Orthomyxoviridae/virología , Mapaches/sangre , Estados Unidos/epidemiologíaRESUMEN
Raccoons (Procyon lotor) are common, widely distributed animals that frequently come into contact with wild waterfowl, agricultural operations, and humans. Serosurveys showed that raccoons are exposed to avian influenza virus. We found antibodies to a variety of influenza virus subtypes (H10N7, H4N6, H4N2, H3, and H1) with wide geographic variation in seroprevalence. Experimental infection studies showed that raccoons become infected with avian and human influenza A viruses, shed and transmit virus to virus-free animals, and seroconvert. Analyses of cellular receptors showed that raccoons have avian and human type receptors with a similar distribution as found in human respiratory tracts. The potential exists for co-infection of multiple subtypes of influenza virus with genetic reassortment and creation of novel strains of influenza virus. Experimental and field data indicate that raccoons may play an important role in influenza disease ecology and pose risks to agriculture and human health.
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Animales Salvajes/virología , Anticuerpos Antivirales/sangre , Virus de la Influenza A/clasificación , Virus de la Influenza A/aislamiento & purificación , Gripe Aviar/transmisión , Gripe Humana/transmisión , Infecciones por Orthomyxoviridae/veterinaria , Mapaches/virología , Animales , Aves/virología , Humanos , Subtipo H3N2 del Virus de la Influenza A/patogenicidad , Virus de la Influenza A/inmunología , Virus de la Influenza A/patogenicidad , Gripe Aviar/virología , Gripe Humana/virología , Infecciones por Orthomyxoviridae/epidemiología , Infecciones por Orthomyxoviridae/transmisión , Infecciones por Orthomyxoviridae/virologíaRESUMEN
Swine play an important role in the disease ecology of influenza. Having cellular receptors in common with birds and humans, swine provide opportunities for mixed infections and potential for genetic reassortment between avian, human, and porcine influenza. Feral swine populations are rapidly expanding in both numbers and range and are increasingly coming into contact with waterfowl, humans, and agricultural operations. In this study, over 875 feral swine were sampled from six states across the United States for serologic evidence of exposure to influenza. In Oklahoma, Florida, and Missouri, USA, no seropositive feral swine were detected. Seropositive swine were detected in California, Mississippi, and Texas, USA. Antibody prevalences in these states were 1% in Mississippi, 5% in California, and 14.4% in Texas. All seropositive swine were exposed to H3N2 subtype, the predominant subtype currently circulating in domestic swine. The only exceptions were in San Saba County, Texas, where of the 15 seropositive samples, four were positive for H1N1 and seven for both H1N1 and H3N2. In Texas, there was large geographical and temporal variation in antibody prevalence and no obvious connection to domestic swine operations. No evidence of exposure to avian influenza in feral swine was uncovered. From these results it is apparent that influenza in feral swine poses a risk primarily to swine production operations. However, because feral swine share habitat with waterfowl, prey on and scavenge dead and dying birds, are highly mobile, and are increasingly coming into contact with humans, the potential for these animals to become infected with avian or human influenza in addition to swine influenza is a distinct possibility.
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Anticuerpos Antivirales/sangre , Subtipo H1N1 del Virus de la Influenza A/inmunología , Subtipo H3N2 del Virus de la Influenza A/inmunología , Infecciones por Orthomyxoviridae/veterinaria , Sus scrofa/virología , Enfermedades de los Porcinos/epidemiología , Animales , Animales Salvajes/virología , Reservorios de Enfermedades/veterinaria , Femenino , Humanos , Masculino , Infecciones por Orthomyxoviridae/epidemiología , Infecciones por Orthomyxoviridae/transmisión , Estudios Seroepidemiológicos , Enfermedades de los Porcinos/transmisión , Estados Unidos/epidemiología , ZoonosisRESUMEN
Highly pathogenic avian influenza virus (HPAIV) is a multihost pathogen with lineages that pose health risks for domestic birds, wild birds, and humans. One mechanism of intercontinental HPAIV spread is through wild bird reservoirs, and wild birds were the likely sources of a Eurasian (EA) lineage HPAIV into North America in 2014. The introduction resulted in several reassortment events with North American (NA) lineage low-pathogenic avian influenza viruses and the reassortant EA/NA H5N2 went on to cause one of the largest HPAIV poultry outbreaks in North America. We evaluated three hypotheses about novel HPAIV introduced into wild and domestic bird hosts: (i) transmission of novel HPAIVs in wild birds was restricted by mechanisms associated with highly pathogenic phenotypes; (ii) the HPAIV poultry outbreak was not self-sustaining and required viral input from wild birds; and (iii) reassortment of the EA H5N8 generated reassortant EA/NA AIVs with a fitness advantage over fully Eurasian lineages in North American wild birds. We used a time-rooted phylodynamic model that explicitly incorporated viral population dynamics with evolutionary dynamics to estimate the basic reproductive number (R0) and viral migration among host types in domestic and wild birds, as well as between the EA H5N8 and EA/NA H5N2 in wild birds. We did not find evidence to support hypothesis (i) or (ii) as our estimates of the transmission parameters suggested that the HPAIV outbreak met or exceeded the threshold for persistence in wild birds (R0 > 1) and poultry (R0 ≈ 1) with minimal estimated transmission among host types. There was also no evidence to support hypothesis (iii) because R0 values were similar among EA H5N8 and EA/NA H5N2 in wild birds. Our results suggest that this novel HPAIV and reassortments did not encounter any transmission barriers sufficient to prevent persistence when introduced to wild or domestic birds.
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We diagnosed infectious canine hepatitis in a free-ranging brown bear ( Ursus arctos horribilis) cub from Alaska, US, found dead in October 2015. Intranuclear inclusion bodies were present in hepatocytes, and immunohistochemistry showed reactivity to adenoviral antigens. Sequencing of the hexon protein of adenovirus showed 100% identity to canine adenovirus 1.