Tyrosine phosphorylation of bovine herpesvirus 1 tegument protein VP22 correlates with the incorporation of VP22 into virions

Tyrosine phosphorylation has been shown to play a role in the replication o f several herpesviruses. In this report, we demonstrate that bovine herpesv irus 1 infection triggered tyrosine phosphorylation of proteins with molecu lar masses similar to those of phosphorylated viral structural proteins. On e of the tyro sine-phosphorylated viral structural proteins was the tegumen t protein VP22. A tyrosine 38-to-phenylalanine mutation totally abolished t he phosphorylation of VP22 in transfected cells. However, construction of a VP22 tyrosine 38-to-phenylalanine mutant virus demonstrated that VP22 was still phosphorylated but that the phosphorylation site may change to the C terminus rather than be in the N terminus as in wild-type VP22. In addition , the loss of VP22 tyrosine phosphorylation correlated with reduced incorpo ration of VP22 compared to that of envelope glycoprotein D in the mutant vi ruses but not with the amount of VP22 produced during virus infection. Our data suggest that tyrosine phosphorylation of VP22 plays a role in virion a ssembly.