Author ORCID Identifier

https://orcid.org/0000-0002-0403-190X

Semester

Fall

Date of Graduation

2025

Document Type

Dissertation

Degree Type

PhD

College

Davis College of Agriculture, Natural Resources and Design

Department

Wildlife and Fisheries Resources

Committee Chair

Patricia Mazik

Committee Member

Luke Iwanowicz

Committee Member

Amy Welsh

Committee Member

Brent Murry

Abstract

Viruses are among the most abundant biological entities on Earth, yet their diversity and ecological roles in aquatic vertebrates, particularly fishes, remain poorly characterized. This dissertation advances fish virology through integrative approaches that combine historical context, molecular diagnostics, and genomic discovery. A novel hepadnavirus (ApHBV) was identified in asymptomatic Alosa pseudoharengus, emphasizing the prevalence of subclinical infections in migratory forage species. In Catostomus commersonii, transcriptomic profiling revealed sexually dimorphic immune responses to hepatitis B and C-like viruses, highlighting complex host-pathogen dynamics. In Micropterus nigricans, next-generation sequencing uncovered a novel nackednavirus and multiple adomaviruses within hyperpigmented lesions, expanding the known virome of a key sportfish. During pandemic-related fieldwork constraints, a nationwide aquarium-based survey confirmed MnA-1 as the dominant agent in blotchy bass syndrome and validated photographic lesion scoring as a diagnostic proxy. Comparative genomics across five Micropterus species revealed distinct MnA-1 genogroups with recent divergence, suggesting anthropogenic stocking as a driver of viral evolution. Collectively, these findings illuminate hidden viral diversity, refine surveillance methodologies, and provide a framework for understanding disease ecology in freshwater systems.

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