Submitted to: Immunology Research Workshop
Publication Type: Abstract Only
Publication Acceptance Date: September 16, 2003
Publication Date: N/A
Technical Abstract: Bovine viral diarrhea virus (BVDV), a major viral pathogen of cattle in the US, causes disease characterized by immunosuppression and lymphocytopenia. In addition, infection of a fetus in the first 150 days of pregnancy can give rise to a persistently infected calf that sheds the virus for life. This is a major means of dissemination of the virus to naïve animals and herds. BVDV is lymphotrophic and acute infection results in depletion of lymphoid tissues, even with BVDV strains of low virulence. The limited in vitro studies of host cell response done to date were performed in epithelial cells and compared cytopathic and noncytopathic strains without regard to virulence in vivo. Our research has shown that cytopathology in vitro does not correlate with virulence in vivo. We are taking a functional genomics approach, using serial analysis of gene expression (SAGE), to determine the molecular events that take place in the infected lymphoid cells that contribute to the disease syndromes observed in vivo. SAGE is a powerful technology that allows quantitation of transcripts in cells and direct comparisons between libraries and experiments. For these studies, we used the B-cell lymphosarcoma cell line BL-3 and compared virus strains of differing virulence (virulence was based on previous in vivo studies). To date, we have constructed and sequenced SAGE libraries from mRNA derived from non-infected cells, as well as cells infected with high and low virulence BVDV strains. Data analysis is ongoing. Preliminary results from the non-infected cells showed the normal metabolism of these cells with corresponding gene expression levels. When compared to results from BVDV-infected cells, a remodeling of cellular functions was observed that reflected changes that, overall, benefited the replication of the virus. These effects included changes in protein translation, transport and ER processing, intracellular signaling, and some important housekeeping functions. Also observed was a decline in expression of proteins that are involved in detoxification, particularly reactive oxygen species. Some of these changes have suggested new lines of research that should lead to elucidation of the mechanism(s) behind immunosuppression and viral persistence.