| Through the study of the viral pathogenesis, the mechanisms of disease can be elucidated providing specific targets for therapeutic intervention intended to prevent the development of disease. We conducted four studies to gain a better understanding of SARS-CoV disease pathogenesis and therapeutic design. We conducted two studies to investigate SARS-CoV evolution and adaptation to the human host. We have also investigated the importance of the innate immunity in protection from SARS-CoV disease. Lastly, we evaluated the protective efficacy of vaccination in senescent populations.;The prototypic civet SZ16 spike (S) gene was engineered into our epidemic strain infectious clone (icSARS) to create the recombinant icSZ16-S virus. A mutant of icSZ16-S (icSZ16-S K479N) was passaged on human airway epithelial cells (HAE) and resultant "evolved" viruses contained mutations in S that enhanced interactions with the receptor (hACE2) though adaptive mutations differed from those seen during the epidemic. icSARS grew equally well in cells expressing the civet or human receptor while icSZ16-S only grew within civet expressing cells. Dual species tropism is retained by the epidemic strain suggesting it evolved through repeated passage between human and civet hosts.;Mice deficient in MyD88 (MyD88-/-), an adapter protein that mediates Toll-like receptor (TLR), IL-1R, and IL-18R signaling, are far more susceptible to mouse adapted SARS-CoV (rMA15) infection. Despite increased viral loads, the expression of multiple proinflammatory cytokines and chemokines within lung tissue was significantly reduced in MyD88-/- mice compared to wild-type mice suggesting that MyD88-mediated innate immune signaling and inflammatory cell recruitment to the lung are required for protection from lethal rMA15 infection.;We have developed a senescent BABL/c mouse model of SARS-CoV pathogenesis where infection with the mouse adapted SARS-CoV bearing a GD03 S glycoprotein (rMA15 GD03-S) mortality in senescent mice. We vaccinated senescent mice with Venezuelan equine encephalitis virus replicon particles (VRP) expressing Urbani-S, GD03-S, SZ16-S, a pool of all three S expressing VRPs or control VRPs in a prime/boost regimen. After rMA15 GD03-S infection, all mice in the VRP HA and SZ16-S groups died while Urbani-S, GD03-S and Pool-S groups demonstrated 11, 29, 33% survival rates, respectively. |
