Molecular aspects of viral replication, pathogenesis, and evolution. The major focus of the laboratory is the retrovirus, equine infectious anemia virus. EIAV studies include evolution of virulence during rapid virus passage, modification of cell signaling pathways mediated by viral glycoproteins, effects of proinflammatory cytokines on virus replication and disease, and detailed mapping of EIAV virulence determinants. We also study the recently discovered avian bornavirus, etiological agent of proventricular dilatation disease of parrots, in conjunction with colleagues from the Schubot center.