PIRS1 AND PTRS1 ARE PRESENT IN HUMAN CYTOMEGALOVIRUS VIRIONS

The virus-coded proteins pIRS1 and pTRSI were found associated with pu rified human cytomegalovirus virions. The proteins were not degraded w hen intact virions, were treated with trypsin, which suggests that the y are localized inside the viral particle. In transfection experiments pIRS1 and pTRSI modestly activated expression from a reporter plasmid containing the viral major immediate-early promoter but did not influ ence the activity of a reporter carrying the irs1/trs1 immediate-early promoter. Both reporters were activated by the combination of pIRS1 o r pTRS1 and pUL69, which is also present in virions.