PARTIAL SUBSTITUTION OF THE FUNCTIONS OF THE HERPES-SIMPLEX VIRUS-1 U(L)13 GENE BY THE HUMAN CYTOMEGALOVIRUS U(L)97 GENE

The predicted amino acid sequence of the human cytomegalovirus U(L)97 protein bears partial homology to the herpes simplex virus 1 U(L)13 pr otein, especially in regions that are homologous to conserved domains characteristic of protein kinases. Earlier studies showed that U(L)13 mediated the posttranslational processing of several herpes simplex vi rus 1 proteins including ICP22. Whereas no kinase activity has been sp ecifically attributed to U(L)13, it has been shown that U(L)97 can pho sphorylate ganciclovir. To examine whether U(L)97 can substitute for U (L)13, we constructed a herpes simplex virus 1 recombinant virus, R497 0, in which U(L)13 was replaced by U(L)97 and in addition, the thymidi ne kinase gene was deleted. Characterization of this recombinant virus showed the following: (1) The recombinant virus grew as well as the w ild-type virus in BHKTK+ cells, which restricted the growth of the U(L )13(-) virus. (2) U(L)97 could partially mediate the posttranslational modification of HSV-1 ICP22. This modification correlated with the re storation of the amounts of ICP0 and U(s)11 proteins, which were down regulated in the U(L)13(-) virus-infected cells. (3) The recombinant v irus was sensitive to ganciclovir in Vero- and KHOS-infected cells but not in the 143 thymidine kinase minus cells derived from KHOS cells. Vero cells infected with this recombinant virus phosphorylated gancicl ovir. We conclude that U(L)97 partially compensates for U(L)13 functio ns. (C) 1996 Academic Press, Inc.