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Geology topics

S. LaPatra

Publications and source records attributed to S. LaPatra.

5 recordsLinked to original sources
USGS2006

Ichthyophonus-induced cardiac damage: a mechanism for reduced swimming stamina in salmonids

Swimming stamina, measured as time-to-fatigue, was reduced by approximately two-thirds in rainbow trout experimentally infected with Ichthyophonus. Intensity of Ichthyophonus infection was most severe in cardiac muscle but multiple organs were infected to a lesser extent. The mean heart weight of infected fish was 40% greater than that of uninfected fish, the result of parasite biomass, infiltration of immune cells and fibrotic (granuloma) tissue surrounding the parasite. Diminished swimming stamina is hypothesized to be due to cardiac failure resulting from the combination of parasite-damaged heart muscle and low myocardial oxygen supply during sustained aerobic exercise. Loss of stamina in Ichthyophonus-infected salmonids could explain the poor performance previously reported for wild Chinook and sockeye salmon stocks during their spawning migration. ?? 2006 Blackwell Publishing Ltd.

Journal of Fish Diseases↗
USGS2001

Understanding aquatic animal virus survival and trafficking and its role in risk assessment

The stability of infectious agents in different media and under different physical and chemical environments has been extensively studied for some viruses and virtually ignored for others. Gaps in our knowledge are due in part to difficulties in reproducing virus «life cycles» and determination if the agent is in fact inactive. Additionally, isolation of the agent under certain conditions can present significant challenges. Studies on the susceptibility of viruses to different physical or chemical parameters have often been conducted under artificial conditions and quantitative data on the rate of inactivation are lacking for many agents. Using infectious hematopoietic necrosis virus (IHNV) as an example, survival was assessed under different environmental conditions. Three IHNV isolates that exhibited antigenic and genetic differences were diluted either in freshwater collected from a spring, after it passed through a fish farm, or the river that received water from the fish farm. Each treatment was incubated at 15o C in a water bath and samples were removed daily. Virus concentrations were determined by plaque assay on EPC cells. Virus suspended in spring water survived longer than virus incubated in water obtained from a fish farm or the river. Virus suspended in river water exhibited a 99.99% reduction in virus concentrations in less than 24 h. Survival of IHNV was also evaluated at different temperatures. A 1982 isolate appeared to be less temperature sensitive than isolates collected in 1990. A preliminary study was also conducted to determine the genetic similarity of IHNV isolates present downstream in a river system from the state of Idaho. Isolates were analyzed using the RNase protection assay (RPA) and by nucleotide sequencing of RT-PCR products of specific isolates. Genetic typing of IHNV allows monitoring of virus traffic and may provide insight into the epizootiology and mechanisms of virus spread. These results illustrate the complexity in evaluating virus survival and trafficing and using this sort of information in risk assessment.

Conference Paper↗
USGS1997

Immunogenicity of synthetic peptides representing neutralizing epitopes on the glycoprotein of infectious hematopoietic necrosis virus

Three peptides, P76, P226, and P268 representing 3 putative antigen~c determinants on the glycoprotein of infectious hematopoietic necrosis virus (IHNV), were synthesized and injected into rainbow trout Oncorhynchus mykiss to assess their immunogen~city. Antisera extracted from the immunized trout were analyzed uslng an enzyme linked imrnunosorbent assay (ELISA) for the presence of antibodies that could bind to the peptides or to intact virions of IHNV. The antisera were also tested for neutralizing activity against IHNV by a complement-mediated neutralization assay. In general, recognition of the peptides and IHNV was low and only a few antibody binding patterns were demonstrated. Antisera from fish injected with P76 constructs recognized the homologous peptide more than the heterologous peptides, whereas antisera from fish inoculated with either P226 or P268 constructs recognized P76 equally, or better, than the homologous peptide; however, there was a high degree of individual variation within each treatment group. Neutralization actlvlty was demonstrated by serum from a single flsh lnlected with one of the pept~des (P268) and from 7 of 10 positive control f~sh Infected with an attenuated strain of IHNV Possible explanations for the dichotomous immune responses are discussed. These results indicate we need to improve our overall understanding of the

Diseases of Aquatic Organisms↗