Theses and Dissertations

ORCID

0009-0005-8752-2833

Advisor

Allen, Peter

Committee Member

Hanson, Larry

Committee Member

Griffin, Matthew

Committee Member

Stilwell, Justin

Committee Member

Tekedar, Hasan

Date of Degree

8-12-2026

Original embargo terms

Visible MSU Only 2 Years

Document Type

Dissertation - Campus Access Only

Major

Forest Resources (Wildlife, Fisheries & Aquaculture)

Degree Name

Doctor of Philosophy (Ph.D.)

College

College of Forest Resources

Department

Department of Wildlife, Fisheries and Aquaculture

Abstract

Ictavirus ictaluridallo1 (Ictalurid herpesvirus 1; IcHV1), the etiological agent of channel catfish virus disease (CCVD), is a highly pathogenic alloherpesvirus that poses a significant threat to catfish aquaculture in the United States. Although IcHV1 has long served as an important model for alloherpesvirus research, the mechanisms governing viral infection, pathogenesis, and host-responses remain incompletely understood. This dissertation investigated host-virus interactions through integrated in vivo and in vitro approaches. Characterization of viral dissemination and tissue tropism through a novel in situ technique revealed rapid systemic spread within 24-hr post-infection, preceding lesion development. The heart tissue was identified as an important target tissue for viral detection in addition to the kidney, and evidence of viral neurotropism was observed. The progressive loss of viral detection at later stages of infection suggested viral clearance or persistence at levels below the detection limits. Evaluation of pathophysiology demonstrated that IcHV1 infection causes severe anemia and significant hepatic dysfunction, with the spleen, kidney, and liver serving as major organs involved in disease progression thereby contributing to clinical signs and mortality. To facilitate systematic studies, a novel continuous channel catfish fin cell line, CCF-HV1, was established and characterized. The authenticated, mycoplasma-free cell line exhibited long-term stability in culture and after cryopreservation, and was susceptible to IcHV1 and other catfish viruses. These characteristics support its utility as a model system for fish health research, diagnostics, and alloherpesvirus-host interaction studies. Transcriptomic analyses of IcHV1-infected catfish cell cultures representing multiple cell types revealed conserved expression of viral replication and assembly genes across cell types, accompanied by distinct host responses. Fibroblasts were primary targets of viral manipulation and structural remodeling, macrophages mounted strong innate immune responses that may restrict early infection, and B cells predominantly exhibited metabolic and oxidative stress responses. Collectively, these findings demonstrate that IcHV1 infection is characterized by rapid systemic dissemination, tissue tropism, multi-organ dysfunction, and cell-type-dependent host responses. The development of the CCF-HV1 cell line provides a robust platform for future studies of alloherpesvirus biology, viral adaptation, and host-virus interactions.

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