Second, we analyzed the percent of cells that remained viable after cHV68 infection at a low MOI. Immediately following removal of the viral inoculum (t = 0), mouse embryonic fibroblasts (MEFs) and primary lung endothelial cells did not differ significantly in viability (p.0.05) (Fig. 8B) . However, at 48 hours post-infection with wildtype cHV68, primary lung endothelial cells were significantly more viable than MEFs (p,0.001), and remained significantly more viable at 96 (p,0.05) and 120 hours post-infection (p,0.001). Notably, endothelial cells infected with the v-cyclin deficient cHV68 had reduced viability at 48, 96, and 120 hours post-infection. Given that cells were infected at a very low MOI, it was not surprising that a proportion of MEFs (28.5%611.1 SEM) were viable at 96 hours post-infection. However, unlike endothelial cells, MEFs were mostly lysed by 120 hours post-infection with wildtype virus. These data demonstrate that primary endothelial cells surpass MEFs in viability following cHV68 infection, and that this outcome is promoted by the v-cyclin.