HERPES-SIMPLEX VIRUS-DNA CLEAVAGE AND PACKAGING - ASSOCIATION OF MULTIPLE FORMS OF U(L)15-ENCODED PROTEINS WITH B-CAPSID REQUIRES AT LEAST THE U(L)6, U(L)17, AND U(L)28 GENES

The U(L)15 gene of herpes simpler virus (HSV) is one of several genes required for the packaging of viral DNA into intranuclear B capsids to produce C capsids that become enveloped at the inner nuclear membrane . A rabbit antiserum directed against ULS-encoded protein recognized t hree proteins with apparent M(r)s of 79,000, 80,000, and 83,000 in hig hly purified B capsids. The 83,000-M-r protein aas detected in type C capsids and comigrated with the product of a U(L)15 cDNA transcribed a nd translated in vitro. The 83,000- and 80,000-M-r proteins were readi ly detected in purified virions. Inasmuch as (i) none of these protein s were detectable in capsids purified from cells infected with HSV-1(D elta U(L)15), a virus lacking an intact U(L)15 gene, and (ii) correspo nding proteins in capsids purified from cells infected with a recombin ant virus [HSV-1(R7244), containing a 20-codon tag at the 3' end of U( L)15] were decreased in electrophoretic mobility relative to the wild- type proteins, we conclude that the proteins with apparent M(r)s of 83 ,000, 80,000, and 79,000 are products of U(L)15 with identical C termi ni. The 79,000-, 80,000-, and 83,000-M-r proteins remained associated with B capsids in the presence of 0.5 M guanidine HCl and remained det ectable in capsids treated with 2.0 M guanidine HCl and lacking protei ns associated with the capsid core. These data, therefore, indicate th at U(L)15-encoded proteins are integral components of B capsids. Only the 83,000-M-r protein was detected in B capsids purified from cells i nfected with viruses lacking the U(L)6, U(L)17, or U(L)28 genes, which are required for DNA cleavage and packaging, suggesting that capsid a ssociation of the 80,000- and 79,000-M-r proteins requires intact clea vage and packaging machinery. These data, therefore, indicate that cap sid association of the 80,000- and 79,000-M-r U(L)15-encoded proteins reflects a previously unrecognized step in the DNA cleavage and packag ing reaction.