Viral tropism and pathology associated with viral hemorrhagic septicemia in larval and juvenile Pacific herring

Lovy, Jan; Lewis, Nir; Hershberger, Paul K.; Bennett, William E.; Meyers, Theodore R.; Garver, Kyle A.

doi:10.1016/j.vetmic.2012.07.020

Cited by 29 publications

(18 citation statements)

References 32 publications

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“…A partial explanation of this apparent paradox was provided by studies demonstrating that chronic and persistent VHSV infections can occur in Pacific Herring (Hershberger et al 2010b). Although these VHSV survivors become refractory to the disease, they remain capable of replicating VHSV upon subsequent reexposure (Hershberger et al 2010b;Lovy et al 2012). Therefore, chronic and persistent infections with VHSV are thought to occur among a small percentage of individuals in a population, and these chronic infections can ignite population-level epizootic cascades when host and environmental conditions shift in favor of the disease (e.g., host resistance declines due to colder water temperatures, infection pressure increases due to limited water exchange or elevated fish densities, and/or herd immunity decreases due to the removal of refractory individuals or the influx of susceptible cohorts to the population).…”

Section: Viral Hemorrhagic Septicemiamentioning

confidence: 99%

Infectious Diseases of Fishes in the Salish Sea

et al. 2013

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Enfermedades infecciosas en los peces del mar de SalishRESUMEN: Tal como sucede en las regiones marinas de otras partes del mundo, los peces del mar de Salish hospedan cantidad de patógenos, incluyendo nematodos, tremátodos, protozoarios, protistas, bacterias, virus y crustáceos. En este trabajo se hace una revisión de algunas de las enfermedades infecciosas mejor documentadas que muy posiblemente contribuyen a la pérdida significativa de peces en el mar de Salish y se discuten los factores ambientales y ecológicos que pueden influenciar los impactos de la enfermedad a nivel poblacional. La demostración de estas enfermedades y sus consecuencias en recursos críti-cos y amenazados, justifica expandir la vigilancia sobre patógenos e incorporar un pronóstico de enfermedades y herramientas de mitigación en los esfuerzos de restauración de ecosistemas.ABSTRACT: As in marine regions throughout other areas of the world, fishes in the Salish Sea serve as hosts for many pathogens, including nematodes, trematodes, protozoans, protists, bacteria, viruses, and crustaceans. Here, we review some of the better-documented infectious diseases that likely contribute to significant losses among free-ranging fishes in the Salish Sea and discuss the environmental and ecological factors that may affect the population-level impacts of disease. Demonstration of these diseases and their impacts to critical and endangered resources provides justification to expand pathogen surveillance efforts and to incorporate disease forecasting and mitigation tools into ecosystem restoration efforts.

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Section: Viral Hemorrhagic Septicemiamentioning

confidence: 99%

Infectious Diseases of Fishes in the Salish Sea

et al. 2013

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“…The mortality of infected goldfish was relatively low compared to other freshwater fish species (Groocock et al 2012, Cornwell et al 2013b, but high numbers of goldfish that survived infection were carriers of the virus in the brain at the end of Expt 1. Other investigators have reported chronic VHSV infections persistent in nervous tissue (Neukirch & Glass 1984, Neukirch 1986, Hershberger et al 2010, Lovy et al 2012. Brude seth et al (2002) found VHSV in brain specimens as early as Day 5 post infection and virus present in the neurons and neuroglia cells; all sections of the brain were infected, without any pattern of cell specificity.…”

Section: Discussionmentioning

confidence: 94%

Goldfish Carassius auratus susceptibility to viral hemorrhagic septicemia virus genotype IVb depends on exposure route

Getchell¹,

Erkinharju²,

Johnson³

et al. 2015

Dis. Aquat. Org.

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We assessed the susceptibility of goldfish Carassius auratus to infection by genotype IVb of the viral hemorrhagic septicemia virus. Goldfish were infected by intraperitoneal injections of 106 plaque-forming units (pfu) fish-1, single bath exposure of 105 pfu ml-1 for 24 h, or consumption of 0.4 g of commercial fish feed soaked in 107 pfu per 8 fish. The mortality rate of intraperitoneal-infected goldfish was 10 to 32%, although the virus was detected by quantitative RT-PCR in 77% (65/84) of the survivors at the end of the 42 d trial, suggesting a carrier state. Severe gross lesions were observed in many of the moribund and dead goldfish such as hemorrhaging in the skin, fin, liver, kidney, brain, intestine, and eye as well as abdominal distension, bilateral exophthalmia, and splenomegaly. There was minimal morbidity or mortality in the immersion, feeding, or control groups.

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“…This observation indicated that VHSV is maintained covertly in populations of wild Pacific herring at an extremely low prevalence that is often undetectable even by the highly sensitive cell culture and quantitative PCR techniques (Garver et al 2011) on >60 fish samples; however, the virus can quickly express in the same population in response to stressful physical conditions including capture, handling, transport, and (or) confinement of these individuals. The mechanism(s) of viral persistence in these populations likely involves some combination of chronic infections among neurotropic carriers (Lovy et al 2012), active infections with viral shedding by a very small percentage of individuals (Hershberger et al 2010a), and low-level replication of the virus in partially immune individuals (Hershberger et al 2010b). …”

Section: Principle #3: Pacific Herring Serve As Reservoirs Of Vhsvmentioning

confidence: 99%

“…Protection against future outbreaks of the disease is most likely conferred by the production of specific antibodies (Hershberger et al 2011b;Wilson et al 2014) that remain protective at very low circulating titers. Although VHSV is eventually cleared from the systemic tissues of recovered and refractory individuals, it can persist covertly for extended periods in the immunologically privileged cells of the central nervous system, including the brain and peripheral nerves (Lovy et al 2012). Further research is necessary to determine whether the disease can reactivate in these neurotropic carriers and whether these carriers serve as a source of exogenous virus for infecting other herring.…”

Section: Refractory Stagementioning

confidence: 99%

Principles underlying the epizootiology of viral hemorrhagic septicemia in Pacific herring and other fishes throughout the North Pacific Ocean

Hershberger

Garver

Winton

2016

Can. J. Fish. Aquat. Sci.

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Although viral hemorrhagic septicemia virus (VHSV) typically occurs at low prevalence and intensity in natural populations of Pacific herring (Clupea pallasii) and other marine fishes in the Northeast Pacific Ocean, epizootics of the resulting disease (VHS) periodically occur, often in association with observed fish kills. Here we identify a list of principles, based on a combination of field studies, controlled laboratory experiments, and previously unpublished observations, that govern the epizootiology of VHS in Pacific herring. A thorough understanding of these principles provides the basis for identifying risk factors that predispose certain marine fish populations to VHS epizootics, including the lack of population resistance, presence of chronic viral carriers in a population, copious viral shedding by infected individuals, cool water temperatures, limited water circulation patterns, and gregarious host behavioral patterns. Further, these principles are used to define the epizootiological stages of the disease in Pacific herring, including the susceptible (where susceptible individuals predominate a school or subpopulation), enzootic (where infection prevalence and intensity are often below the limits of reasonable laboratory detection), disease amplification (where infection prevalence and intensity increase rapidly), outbreak (often accompanied by host mortalities with high virus loads and active shedding), recovery (in which the mortality rate and virus load decline owing to an active host immune response), and refractory stages (characterized by little or no susceptibility and where viral clearance occurs in most VHS survivors). In addition to providing a foundation for quantitatively assessing the potential risks of future VHS epizootics in Pacific herring, these principles provide insights into the epizootiology of VHS in other fish communities where susceptible species exist.Résumé : Si le virus de la septicémie hémorragique virale (VSHV) est typiquement présent à faible prévalence et intensité dans les populations naturelles de hareng du Pacifique (Clupea pallasii) et d'autres poissons marins dans le nord-est de l'océan Pacifique, des épizooties de la maladie en découlant (SHV) se produisent périodiquement, souvent associées à des mortalités de poissons observées. Nous présentons une liste de principes, reposant sur une combinaison d'études de terrain, d'essais contrôlés en laboratoire et d'observations non publiées, qui régissent l'épizootiologie de la SHV chez le hareng du Pacifique. Une compréhen-sion exhaustive de ces principes fournit les bases qui permettent de cerner les facteurs de risque prédisposant certaines populations de poissons marins aux épizooties de SHV, dont l'absence de résistance de la population, la présence de porteurs viraux chroniques dans une population, l'élimination copieuse du virus par des individus infectés, de faibles températures de l'eau, une circulation de l'eau limitée et des comportements grégaires des hôtes. Ces principes sont en outre utilisés pour ...

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Viral tropism and pathology associated with viral hemorrhagic septicemia in larval and juvenile Pacific herring

Cited by 29 publications

References 32 publications

Infectious Diseases of Fishes in the Salish Sea

Infectious Diseases of Fishes in the Salish Sea

Goldfish Carassius auratus susceptibility to viral hemorrhagic septicemia virus genotype IVb depends on exposure route

Principles underlying the epizootiology of viral hemorrhagic septicemia in Pacific herring and other fishes throughout the North Pacific Ocean

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