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At least 649 records · Page 36Linked to original sources
USGS2023

DNA virome composition of two sympatric wild felids, bobcat (Lynx rufus) and puma (Puma concolor) in Sonora, Mexico

With viruses often having devastating effects on wildlife population fitness and wild mammals serving as pathogen reservoirs for potentially zoonotic diseases, determining the viral diversity present in wild mammals is both a conservation and One Health priority. Additionally, transmission from more abundant hosts could increase the extinction risk of threatened sympatric species. We leveraged an existing circular DNA enriched metagenomic dataset generated from bobcat ( Lynx rufus , n = 9) and puma ( Puma concolor , n = 13) scat samples non-invasively collected from Sonora, Mexico, to characterize fecal DNA viromes of each species and determine the extent that viruses are shared between them. Using the metaWRAP pipeline to co-assemble viral genomes for comparative metagenomic analysis, we observed diverse circular DNA viruses in both species, including circoviruses, genomoviruses, and anelloviruses. We found that differences in DNA virome composition were partly attributed to host species, although there was overlap between viruses in bobcats and pumas. Pumas exhibited greater levels of alpha diversity, possibly due to bioaccumulation of pathogens in apex predators. Shared viral taxa may reflect dietary overlap, shared environmental resources, or transmission through host interactions, although we cannot rule out species-specific host-virus coevolution for the taxa detected through co-assembly. However, our detection of integrated feline foamy virus (FFV) suggests Sonoran pumas may interact with domestic cats. Our results contribute to the growing baseline knowledge of wild felid viral diversity. Future research including samples from additional sources (e.g., prey items, tissues) may help to clarify host associations and determine the pathogenicity of detected viruses.

Sonora↗
USGS2021

Viral-like particles are associated with endosymbiont pathology in Florida corals affected by stony coral tissue loss disease

Stony coral tissue loss disease (SCTLD) was first documented in 2014 near the Port of Miami, Florida, and has since spread north and south along Florida’s Coral Reef, killing large numbers of more than 20 species of coral and leading to the functional extinction of at least one species, Dendrogyra cylindrus . SCTLD is assumed to be caused by bacteria based on presence of different molecular assemblages of bacteria in lesioned compared to apparently healthy tissues, its apparent spread among colonies, and cessation of spread of lesions in individual colonies treated with antibiotics. However, light microscopic examination of tissues of corals affected with SCTLD has not shown bacteria associated with tissue death. Rather, microscopy shows dead and dying coral cells and symbiotic dinoflagellates (endosymbionts) indicating a breakdown of host cell and endosymbiont symbiosis. It is unclear whether host cells die first leading to death of endosymbionts or vice versa. Based on microscopy, hypotheses as to possible causes of SCTLD include infectious agents not visible at the light microscopy level or toxicosis, perhaps originating from endosymbionts. To clarify this, we examined corals affected with SCTLD and apparently healthy corals using transmission electron microscopy. Endosymbionts in SCTLD-affected and apparently healthy corals consistently had varying degrees of pathology associated with elongated particles compatible in morphology with filamentous positive single-stranded RNA viruses of plants termed anisometric viral-like particles (AVLP). There was apparent progression from early to late replication of AVLP in the cytoplasm of endosymbionts adjacent to or at times within chloroplasts, with morphologic changes in chloroplasts consistent with those seen in plant cells infected by viruses. Coral host cell pathology appeared limited to massive proliferation and lysis of mucus cells. Based on these findings, we hypothesize that SCTLD is a viral disease of endosymbionts leading to coral host death. Efforts to confirm the presence of a virus associated with SCTLD through other means would be appropriate. These include showing the presence of a virus through molecular assays such as deep sequencing, attempts to grow this virus in the laboratory through culture of endosymbionts, localization of virus in tissue sections using immunohistochemistry or in situ hybridization, and experimental infection of known-virus-negative corals to replicate disease at the gross and microscopic level.

Florida↗
USGS2024

Freshwater mussel viromes increase rapidly in diversity and abundance when hosts are released from captivity into the wild

Freshwater mussels create habitat, filter water, and enhance food webs, but they are also among the world’s most imperiled taxa. Conservation efforts largely rely on captive propagation in which mussels are grown in protected aquaculture environments (hatcheries) for later release. Recent evidence has highlighted the importance of pathogens in population losses of freshwater mussels. In response to ongoing mass mortality events of freshwater mussels in the Upper Tennessee River Basin in Virginia and Tennessee, USA, we conducted a multi-year study to document viruses across multiple restoration sites and compare them to viruses in mussels from the hatchery. Viral communities changed greatly after mussels were released. Of the 681 viruses of the 27 families we documented, only 20 viruses were found exclusively in hatchery mussels, compared to 451 viruses found only in mussels stocked to the wild. After release, mussels rapidly acquired new viruses, and the number of viruses increased steadily over time. These findings have implications for how mussel introduction programs might be managed for greater success, for example, by incorporating acclimatization periods prior to full release.

Tennessee, Virgnia↗
USGS2021

Temperature variation and host immunity regulate viral persistence in a salmonid host

Environmental variation has important effects on host–pathogen interactions, affecting large-scale ecological processes such as the severity and frequency of epidemics. However, less is known about how the environment interacts with host immunity to modulate virus fitness within hosts. Here, we studied the interaction between host immune responses and water temperature on the long-term persistence of a model vertebrate virus, infectious hematopoietic necrosis virus (IHNV) in steelhead trout ( Oncorhynchus mykiss ). We first used cell culture methods to factor out strong host immune responses, allowing us to test the effect of temperature on viral replication. We found that 15 ∘ "> ∘ C water temperature accelerated IHNV replication compared to the colder 10 and 8 ∘ "> ∘ C temperatures. We then conducted in vivo experiments to quantify the effect of 6, 10, and 15 ∘ "> ∘ C water temperatures on IHNV persistence over 8 months. Fish held at 15 and 10 ∘ "> ∘ C were found to have higher prevalence of neutralizing antibodies compared to fish held at 6 ∘ "> ∘ C. We found that IHNV persisted for a shorter time at warmer temperatures and resulted in an overall lower fish mortality compared to colder temperatures. These results support the hypothesis that temperature and host immune responses interact to modulate virus persistence within hosts. When immune responses were minimized (i.e., in vitro) virus replication was higher at warmer temperatures. However, with a full potential for host immune responses (i.e., in vivo experiments) longer virus persistence and higher long-term virulence was favored in colder temperatures. We also found that the viral RNA that persisted at later time points (179 and 270 days post-exposure) was mostly localized in the kidney and spleen tissues. These tissues are composed of hematopoietic cells that are favored targets of the virus. By partitioning the effect of temperature on host and pathogen responses, our results help to better understand environmental drivers of host–pathogen interactions within hosts, providing insights into potential host–pathogen responses to climate change.

Pathogens↗
USGS2000

Characterization of poxviruses from forest birds in Hawaii

Two strains of avian pox viruses were isolated from cutaneous lesions in Hawaiian crows ( Corvus hawaiiensis ) examined in 1994 and a third from a biopsy obtained in 1992 from an infected bird of the Apapane species ( Himatione sanguinea ) by inoculation of the chorioallantoic membranes (CAM) of developing chicken embryos. The resulting proliferative CAM lesions contained eosinophilic cytoplasmic inclusion bodies characteristic of pox virus infection. The pathogenicity of these three viruses in domestic chickens was mild as evidenced by the development of relatively minor lesions of short duration at the sites of inoculation. Their virulence in this host was similar to that of a fowlpox virus (FPV) vaccine strain and contrasted greatly with the ability of two field strains of FPV to produce extensive proliferative lesions. One of the Hawaiian crow pox virus isolates as well as the one originating from the Apapane species could be propagated in two secondary avian cell lines, QT-35 and LMH. A comparison of the restriction fragment length polymorphisms (RFLP) of the genomes of the two cell line-adapted viruses, generated by Eco RI digestion, revealed a limited degree of similarity. Moreover, neither profile was comparable to those of the two field isolates of FPV, which were almost indistinguishable from each other. Thus, based on the genetic distinctness of the two Hawaiian bird viruses, they appear to represent different strains of avipoxvirus.

Hawaii↗
USGS2017

A serosurvey of Greater Sage-grouse ( Centrocercus urophasianus ) in Nevada, USA

To better understand the potential avian diseases in Greater Sage-grouse ( Centrocercus urophasianus ) in the Great Basin in Nevada, we collected 31 blood samples March–April 2014 and tested for antibodies to eight viruses and two bacteria. Specifically, sera were tested for antibodies to avian leukosis virus type A, B, and J (ALV-A, ALV-B, and ALV-J, respectively), infectious bursal disease virus, infectious bronchitis virus, reticuloendothelial virus, avian influenza virus (AIV), West Nile virus, Pasteurella multocida (PM), and Salmonella enterica serovar Pullorum. Serum antibodies against ALV-A and -B (1/31, 3%), ALV-J (5/31, 16%), PM (1/31, 3%), and AIV (2/31, 6%) were detected by enzyme-linked immunosorbent assay (ELISA). While ELISA tests used have only been validated in domestic poultry, the serologic data should be used as a potential indicator of the range of bacterial and viral infectious agents that can infect the Greater Sage-grouse.

Nevada↗
USGS2014

Molecular epidemiology and evolution of fish Novirhabdoviruses

The genus Novirhabdoviridae contains several of the important rhabdoviruses that infect fish hosts. There are four established virus species: Infectious hematopoietic necrosis virus (IHNV), Viral hemorrhagic septicemia virus (VHSV), Hirame rhabdovirus (HIRRV), and Snakehead rhabdovirus (SHRV). Viruses of these species vary in host and geographic range, and they have all been studied at the molecular and genomic level. As globally significant pathogens of cultured fish, IHNV and VHSV have been particularly well studied in terms of molecular epidemiology and evolution. Phylogenic analyses of hundreds of field isolates have defined five major genogroups of IHNV and four major genotypes of VHSV worldwide. These phylogenies are informed by the known histories of IHNV and VHSV, each involving a series of viral emergence events that are sometimes associated with host switches, most often into cultured rainbow trout. In general, IHNV has relatively low genetic diversity and a narrow host range, and has been spread from its endemic source in North American to Europe and Asia due to aquaculture activities. In contrast, VHSV has broad host range and high genetic diversity, and the source of emergence events is virus in widespread marine fish reservoirs in the northern Atlantic and Pacific Oceans. Common mechanisms of emergence and host switch events include use of raw feed, proximity to wild fish reservoirs of virus, and geographic translocations of virus or naive fish hosts associated with aquaculture.

Book chapter↗
USGS1989

Comparison of infectious hematopoietic necrosis in natural and experimental infections of spawning salmonids by infectivity and immunohistochemistry

Infectious hematopoietic necrosis (IHN) continues to be a serious virus disease of salmonids with epizootics recorded in both wild and hatchery populations (Williams and Amend 1976; Carlisle et al 1979; Groberg and Fryer 1983; Saft and Pratt 1986; Traxler 1987; Follett et al 1987; Meyers et al 1988). While originally enzootic in western North America, the virus appears to be spreading further (Sano et al 1977; de Kinkelin et al 1987; Bovo et al 1987). In hatchery outbreaks occurring in regions where the virus is not enzootic, it is often possible to trace the virus to the importation of infected fingerlings or contaminated eggs. In regions where the virus is widespread among stocks of fish, the source of virus infection is more difficult to establish particularly in watersheds where there are anadromous salmonids. Although salmonid fish surviving infection as fry and returning from the ocean to spawn are considered to be parental carriers of IHNV, there is very little data to support this hypothesis. Amend (1975) in the study of rainbow trout reported that in a population surviving infection and assayed a few years later found that a few trout were carrying virus. This is the study often cited as evidence for the carrier status of returning salmonids. LaPatra et al (1987) presented data that indicated IHNV has been transmitted horizontally through water from adult chinook salmon (Oncorhynchus tshawytscha) to adult coho salmon (O. kisutch) at a hatchery in northern California. They suggested that horizontal transmission may be an important means for perpetuating IHN. However, the actual mechanisms for persistence and transmission of IHN among fish in a watershed is likely to be complex and involve multiple species and age groups as well as intermediate vectors and/or reservoirs.

Book chapter↗
USGS1999

Controlled field and laboratory studies on VHS and Ichtyophonus in Pacific herring: Section II in Investigations of disease factors affecting declines of Pacific herring populations in Prince William Sound

From 1995 through 1998 the controlled disease studies covered a wide range of topics including virus survival in seawater, development of natural immunity, effects of oil exposure on immunity, effect of synthetic immunosuppressants, epizootiology of VHSV in net pens, antibody production and the natural history of VHS in Pacific herring. Both VHSV and I. hoferi were was observed in fish that reached two-years-old while in captivity. Prior to 2 years old, fish that shown to be. serious pathogens of juvenile hening. A natural age-related resistance to VHS virus plaque assay and resistance to reinfection with the known minimum lethal dose of virus. survived an initial infection by VHSV developed an acquired immunity detectable by in vitro Three years of consecutive monthly sampling of wild 0-year herring in Puget Sound revealed a VHSV carrier rate below 1%, but that this level of virus shedding was adequate to initiate an epizootic under confined conditions, and probably resulted in infection of free-ranging fish also. Over 50% of the virus was recoverable from seawater after 2 hours, was still detectable after six hours, and survived up to 100 h when ovarian fluid was present in the water. Studies in PWS demonstrated that closed pounds play a role in transmission of VHSV to impounded fish steadily increased with confinement time and viral tissue titers were at very high susceptible fish, resulting in the rapid spread of virus within the pens. Prevalence of VHSV from levels in fish being released after 8 days in captivity. Viable virus was also recovered from the water inside and outside the net pens at levels adequate to initiate an epizootic in susceptible fish. of herring and that vitro culture was the most sensitive method for detecting it. Studies on Ichthyophonus hoferi demonstrated that the organism is a potential serious pathogen No evidence for increased susceptibility, mortality or loss of disease resistance was observed in wild or laboratory-reared herring exposed to oil or synthetic corticosteroids, either prior to or following exposure to VHSV.

Report↗
USGS2022

Divergent Serpentoviruses in free-ranging invasive pythons and native colubrids in southern Florida, United States

Burmese python ( Python bivittatus ) is an invasive snake that has significantly affected ecosystems in southern Florida, United States. Aside from direct predation and competition, invasive species can also introduce nonnative pathogens that can adversely affect native species. The subfamily Serpentovirinae (order Nidovirales ) is composed of positive-sense RNA viruses primarily found in reptiles. Some serpentoviruses, such as shingleback nidovirus, are associated with mortalities in wild populations, while others, including ball python nidovirus and green tree python nidovirus can be a major cause of disease and mortality in captive animals. To determine if serpentoviruses were present in invasive Burmese pythons in southern Florida, oral swabs were collected from both free-ranging and long-term captive snakes. Swabs were screened for the presence of serpentovirus by reverse transcription PCR and sequenced. A total serpentovirus prevalence of 27.8% was detected in 318 python samples. Of the initial swabs from 172 free-ranging pythons, 42 (24.4%) were positive for multiple divergent viral sequences comprising four clades across the sampling range. Both sex and snout-vent length were statistically significant factors in virus prevalence, with larger male snakes having the highest prevalence. Sampling location was statistically significant in circulating virus sequence. Mild clinical signs and lesions consistent with serpentovirus infection were observed in a subset of sampled pythons. Testing of native snakes (n = 219, 18 species) in part of the python range found no evidence of python virus spillover; however, five individual native snakes (2.3%) representing three species were PCR positive for unique, divergent serpentoviruses. Calculated pairwise uncorrected distance analysis indicated the newly discovered virus sequences likely represent three novel genera in the subfamily Serpentovirinae. This study is the first to characterize serpentovirus in wild free-ranging pythons or in any free-ranging North America reptile. Though the risk these viruses pose to the invasive and native species is unknown, the potential for spillover to native herpetofauna warrants further investigation.

Florida↗
USGS2024

Heterologous exchanges of glycoprotein and non-virion protein in novirhabdoviruses: Assessment of virlence in yellow perch (Perca flavescens) and rainbow trout (Oncorhynchus mykiss)

Infectious hematopoietic necrosis virus (IHNV) and viral hemorrhagic septicemia virus (VHSV) are rhabdoviruses in two different species belonging to the Novirhabdovirus genus. IHNV has a narrow host range restricted to trout and salmon species, and viruses in the M genogroup of IHNV have high virulence in rainbow trout ( Oncorhynchus mykiss ). In contrast, the VHSV genotype IVb that invaded the Great Lakes in the United States has a broad host range, with high virulence in yellow perch ( Perca flavescens ), but not in rainbow trout. By using reverse-genetic systems of IHNV-M and VHSV-IVb strains, we generated six IHNV:VHSV chimeric viruses in which the glycoprotein (G), non-virion-protein (NV), or both G and NV genes of IHNV-M were replaced with the analogous genes from VHSV-IVb, and vice versa. These chimeric viruses were used to challenge groups of rainbow trout and yellow perch. The parental recombinants rIHNV-M and rVHSV-IVb were highly virulent in rainbow trout and yellow perch, respectively. Parental rIHNV-M was avirulent in yellow perch, and chimeric rIHNV carrying G, NV, or G and NV genes from VHSV-IVb remained low in virulence in yellow perch. Similarly, the parental rVHSV-IVb exhibited low virulence in rainbow trout, and chimeric rVHSV with substituted G, NV, or G and NV genes from IHNV-M remained avirulent in rainbow trout. Thus, the G and NV genes of either virus were not sufficient to confer high host-specific virulence when exchanged into a heterologous species genome. Some exchanges of G and/or NV genes caused a loss of host-specific virulence, providing insights into possible roles in viral virulence or fitness, and interactions between viral proteins.

Viruses↗
USGS2025

Hiding in plain sight: Genomic characterization of a novel nackednavirus and evidence of diverse adomaviruses in a hyperpigmented lesion of a largemouth bass (Micropterus salmoides)

Largemouth bass (LMB; Micropterus nigricans ) are popular both as a sportfish and an aquaculture species. At present, six described viruses are associated with LMB, of which two are typically considered in cases of LMB mortality events. Advances in discovery and diagnostic capabilities using next-generation sequencing have augmented surveillance efforts and subsequently led to the discovery of novel cryptogenic viruses. Here, we present evidence of three novel viruses from a single skin sample collected from a hyperpigmented melanistic lesion of an LMB with blotchy bass syndrome associated with MnA-1 co-infection. These viruses represent recently described groups of viruses (adomaviruses and nackednaviruses) that infect fish. Both are markedly understudied and of unknown significance to fish health. This work highlights the diversity of viruses associated with LMB and further advances our understanding of the LMB virome. Application of de novo sequencing approaches presents an opportunity to explore a new frontier of host–pathogen relationships and microbes associated with changing environments.

Virginia↗
USGS2016

Hepeviruses of fish

Originally reported from California, the cutthroat trout virus (CTV) has now been isolated from eight species of salmonids in North America. Early work focused on the replication and physical characteristics of the small, round virus, but not until 20 years later was it determined to be most closely related to viruses causing hepatitis E in humans or infecting avian and mammalian hosts. The genome of CTV consists of 7269 nucleotides of positive-sense, single-stranded RNA with a genome organization similar to other members of the family Hepeviridae , although the amino acid sequence identity appears low enough to support creation of a novel genus. While CTV has not been associated with acute disease in fish, the virus was able to form persistently infected cell cultures that may aid research in treatment of hepatitis E-like viruses affecting humans or other animals. Interestingly, trout exposed to CTV were protected for about a month against subsequent exposure to Infectious hematopoietic necrosis virus . Replicating agents suspected to be CTV can be confirmed by polymerase chain reaction (PCR) and sequencing.

Book chapter↗
USGS2012

Comparative effectiveness of membrane bioreactors, conventional secondary treatment, and chlorine and UV disinfection to remove microorganisms from municipal wastewaters

Log removals of bacterial indicators, coliphage, and enteric viruses were studied in three membrane bioreactor (MBR) activated-sludge and two conventional secondary activated-sludge municipal wastewater treatment plants during three recreational seasons (May-Oct.) when disinfection of effluents is required. In total, 73 regular samples were collected from key locations throughout treatment processes: post-preliminary, post-MBR, post-secondary, post-tertiary, and post-disinfection (UV or chlorine). Out of 19 post-preliminary samples, adenovirus by quantitative polymerase chain reaction (qPCR) was detected in all 19, enterovirus by quantitative reverse transcription polymerase chain reaction (qRT-PCR) was detected in 15, and norovirus GI by qRT-PCR was detected in 11. Norovirus GII and Hepatitis A virus were not detected in any samples, and rotavirus was detected in one sample but could not be quantified. Although culturable viruses were found in 12 out of 19 post-preliminary samples, they were not detected in any post-secondary, post-MBR, post-ultraviolet, or post-chlorine samples. Median log removals for all organisms were higher for MBR secondary treatment (3.02 to >6.73) than for conventional secondary (1.53-4.19) treatment. Ultraviolet disinfection after MBR treatment provided little additional log removal of any organism except for somatic coliphage (>2.18), whereas ultraviolet or chlorine disinfection after conventional secondary treatment provided significant log removals (above the analytical variability) of all bacterial indicators (1.18-3.89) and somatic and F-specific coliphage (0.71 and >2.98). Median log removals of adenovirus across disinfection were low in both MBR and conventional secondary plants (no removal detected and 0.24), and few removals of individual samples were near or above the analytical variability of 1.2 log genomic copies per liter. Based on qualitative examinations of plots showing reductions of organisms throughout treatment processes, somatic coliphage may best represent the removal of viruses across secondary treatment in both MBR and conventional secondary plants. F-specific coliphage and Escherichia coli may best represent the removal of viruses across the disinfection process in MBR facilities, but none of the indicators represented the removal of viruses across disinfection in conventional secondary plants.

Water Research↗
USGS2004

Isolation and characterization of a rhabdovirus from starry flounder (Platichthys stellatus) collected from the northern portion of Puget Sound, Washington, USA

The initial characterization of a rhabdovirus isolated from a single, asymptomatic starry flounder (Platichthys stellatus) collected during a viral survey of marine fishes from the northern portion of Puget Sound, Washington, USA, is reported. Virions were bullet-shaped and approximately 100 nm long and 50 nm wide, contained a lipid envelope, remained stable for at least 14 days at temperatures ranging from -80 to 5 degrees C and grew optimally at 15 degrees C in cultures of epithelioma papulosum cyprini (EPC) cells. The cytopathic effect on EPC cell monolayers was characterized by raised foci containing rounded masses of cells. Pyknotic and dark-staining nuclei that also showed signs of karyorrhexis were observed following haematoxylin and eosin, May-Grunwald Giemsa and acridine orange staining. PAGE of the structural proteins and PCR assays using primers specific for other known fish rhabdoviruses, including Infectious hematopoietic necrosis virus, Viral hemorrhagic septicemia virus, Spring viremia of carp virus, and Hirame rhabdovirus, indicated that the new virus, tentatively termed starry flounder rhabdovirus (SFRV), was previously undescribed in marine fishes from this region. In addition, sequence analysis of 2678 nt of the amino portion of the viral polymerase gene indicated that SFRV was genetically distinct from other members of the family Rhabdoviridae for which sequence data are available. Detection of this virus during a limited viral survey of wild fishes emphasizes the void of knowledge regarding the diversity of viruses that naturally infect marine fish species in the North Pacific Ocean.

Journal of General Virology↗
USGS2012

Migration strategy affects avian influenza dynamics in mallards ( Anas platyrhynchos ).

Studies of pathogen transmission typically overlook that wildlife hosts can include both migrant and resident populations when attempting to model circulation. Through the application of stable isotopes in flight feathers, we estimated the migration strategy of mallards ( Anas platyrhynchos ) occurring on California wintering grounds. Our study demonstrates that mallards- a principal host of avian influenza virus (AIV) in nature, contribute differently to virus gene flow depending on migration strategy. No difference in AIV prevalence was detected between resident (9.6%), intermediate-distance (9.6%) and long-distance migrants (7.4%). Viral diversity among the three groups was also comparable, possibly owing to viral pool mixing when birds converge at wetlands during winter. However, migrants and residents contributed differently to the virus gene pool at wintering wetlands. Migrants introduced virus from northern breeding grounds (Alaska and the NW Pacific Rim) into the wintering population, facilitating gene flow at continental scales, but circulation of imported virus appeared to be limited. In contrast, resident mallards acted as AIV reservoirs facilitating year-round circulation of limited subtypes (i.e. H5N2) at lower latitudes. This study supports a model of virus exchange in temperate regions driven by the convergence of wild birds with separate geographic origins and exposure histories.

Molecular Ecology↗
USGS1976

Comparative membrane microviscosity of fish and mammalian rhabdoviruses studied by fluorescence depolarization

The microviscosity of the hydrophobic region of the membrane of infectious hematopoietic necrosis virus was determined using fluorescence depolarization analysis of the probe 1,6-diphenyl-1,3,5-hexatriene and was found to be much lower at 37 C than that of another rhabdovirus, vesicular stomatitis virus. However, the microviscosity of this fish virus at 18 C, the temperature at which it was grown, corresponded to the microviscosity of vesicular stomatitis virus at 37 C. Data obtained with the fish virus host cell (chinook salmon embryo cells) grown at 18 C suggest that its membranes have a lower microviscosity than either L-929 or BHK-21 cells (the vesicular stomatitis virus host cells) grown at 37 C.

Journal of Virology↗
USGS2011

Wild bird migration across the Qinghai-Tibetan Plateau: A transmission route for highly pathogenic H5N1

Background Qinghai Lake in central China has been at the center of debate on whether wild birds play a role in circulation of highly pathogenic avian influenza virus H5N1. In 2005, an unprecedented epizootic at Qinghai Lake killed more than 6000 migratory birds including over 3000 bar-headed geese ( Anser indicus ). H5N1 subsequently spread to Europe and Africa, and in following years has re-emerged in wild birds along the Central Asia flyway several times. Methodology/Principal Findings To better understand the potential involvement of wild birds in the spread of H5N1, we studied the movements of bar-headed geese marked with GPS satellite transmitters at Qinghai Lake in relation to virus outbreaks and disease risk factors. We discovered a previously undocumented migratory pathway between Qinghai Lake and the Lhasa Valley of Tibet where 93% of the 29 marked geese overwintered. From 2003–2009, sixteen outbreaks in poultry or wild birds were confirmed on the Qinghai-Tibet Plateau, and the majority were located within the migratory pathway of the geese. Spatial and temporal concordance between goose movements and three potential H5N1 virus sources (poultry farms, a captive bar-headed goose facility, and H5N1 outbreak locations) indicated ample opportunities existed for virus spillover and infection of migratory geese on the wintering grounds. Their potential as a vector of H5N1 was supported by rapid migration movements of some geese and genetic relatedness of H5N1 virus isolated from geese in Tibet and Qinghai Lake. Conclusions/Significance This is the first study to compare phylogenetics of the virus with spatial ecology of its host, and the combined results suggest that wild birds play a role in the spread of H5N1 in this region. However, the strength of the evidence would be improved with additional sequences from both poultry and wild birds on the Qinghai-Tibet Plateau where H5N1 has a clear stronghold.

Qinghai Lake↗