PEA15 and disease arising from reactivation of latent virus: Furthermore, given that it has been shown that the UL138 gene product up-regulates TNFR1 expression during lytic [59,60] and latent infection [61], potentially sensitising latently infected cells to TNFR1 mediated apoptosis, the concomitant up-regulation of PEA-15 would be a sensible pro-survival strategy.