To determine whether the intact, infected endothelial cells were undergoing active viral replication, we analyzed infected cells for the expression of early and late lytic replication-associated M3 and gB. As predicted, 3T3 fibroblasts, which support lytic replication, expressed both M3 and gB (Fig. 3B ). In contrast, S11 B cells, which contain latent cHV68, did not express either M3 or gB. Intact, infected MB114 endothelial cells not only expressed M3 and gB early (36 hours), but also at six and 12 days post-infection. A faster migrating gB-specific band was also detected at six days post-infection, and may indicate differential glycosylation or degradation. Additionally, infected MB114 endothelial cells were positive for surface protein expression of gp150 at both 12 and 24 days post-infection (Fig. 3C ). Our analysis of lytic protein expression indicated that endothelial cells which remained intact after cHV68 infection expressed early and late lytic proteins, indicating that not only did cHV68 infected endothelial cells still contain virus, these cells also expressed viral proteins indicative of active viral replication, and not latency.