Virus-Host Immune System Interaction in a Ranavirus-Amphibian Model

University Of Mississippi Medical Center, Jackson MS

Investigators

Abstract

The goal of this project is to identify and characterize viral genes that control virulence and/or mediate immune evasion in the African clawed toad (Xenopus laevis) using frog virus 3 as a model. This project uses new technologies that selectively knock down the expression of specific viral genes, and generate mutant viruses in which specific candidate genes have been deleted. Mutant viruses will then be used to infect toads and the role of the candidate genes in disease and immune evasion determined. For example, it is likely that host has developed mechanisms to recognize and eliminate invading viruses, and that, in turn, viruses encode proteins designed to block those defenses. Such arms races are important in the evolution of both the host and the pathogen. If this is correct, then viral mutants where these countermeasures are deleted will fail to cause disease in infected animals. Successfully completed, this project will shed light on viral genes that control pathogenesis and, optimistically, reveal pathways used by the host to contain and eventually eliminate virus infections. In addition, this project may also uncover ways in which defects in amphibian immunity contribute to amphibian declines by making otherwise resistant animals susceptible to infection. Finally, this study may enhance understanding of the evolution of the immune system, and provide insight into ways to protect endangered amphibians from viruses and other pathogens. This project also has broader implications for the overall problem of worldwide decline in amphibian populations due in part to disease. It will provide training opportunities to a new generation of investigators in this field which is needed. Integral to the project is an outreach component to investigators at one of this nation?s Historically Black Colleges to enhance broadening participation in the field.