The overall goal of this proposal is to define the role of the cellular stress response in the modulation of viral infection of the central nervous system (CNS) using canine distemper virus (CDV) encephalitis as a model. Preliminary in vitro studies have demonstrated that the stress response increases CDV mRNA expression which, in turn, enhances viral infection parameters. Examination of CNS tissues from infected animals showed that CDV induces the stress response, suggesting a positive feed- back loop between viral infection and stress response induction. The first objective is to define the basis for stress response-induced alterations in CDV RNA metabolism and to confirm the broader applicability of these phenomenon using measles virus (MV). Emphasis is placed upon the family of 70 kDa heat shock proteins (HSP7O) (i.e., 72k and 73k HSP) since: (a) 72k HSP is the predominant stress-responsive HSP; (b)I have provided evidence supporting a role for 72k HSP in CDV transcription; (c) HSP7O proteins are most frequently incriminated in the response to or support of infections by other viruses. The role of 72k HSP as a transcriptional cofactor for CDV will be established in cell-free transcriptional assays. The effect of cellular stress on CDV mRNA half life will also be determined, identifying conditions in which profiles of CDV gene-specific mRNA serve as biochemical markers for specific viral phenotypes and/or cellular stress states. Finally, the relevance of cellular stress to MV mRNA metabolism will be documented using the approach established for CDV. The second objective will establish the in situ role of HSP7O proteins in stress- mediated alterations of virus infection phenotype. Translational inhibition of 72k and 73k HSP will be mediated by phosphorothioate antisense oligonucleotides. The third objective will determine the effect of stress-induced alterations in CDV RNA metabolism on viral phenotype in canine cerebellar explant cultures, a cell system which is physiologically more relevant to CNS infection. Specific stress response inducers (i.e., hyperthermia and inflammatory cytokines) will be used to dissect the paradoxical relationship between the cytoprotective effects of 72k HSP and the promoting effects on virus infection. The specific role of 72k HSP in mediating these stress response-mediated events will be determined by antisense inhibition of 72k HSP expression. Future in vivo studies can determine how immune clearance mechanisms modulate the outcome of virus- stress response interaction. Establishing a protective or detrimental role of the CNS stress response rn viral encephalitis will provide a basis for therapeutic intervention based upon HSP modulation.
