CHARACTERIZATION OF THE UL4 GENE-PRODUCT OF HERPES-SIMPLEX VIRUS TYPE-2

We have identified the herpes simplex virus type 2 (HSV-2) UL4 gene pr oduct using a rabbit polyclonal antiserum raised against a recombinant 6xHis-UL4 fusion protein expressed in Escherichia coli. The antiserum reacted specifically with a 27-kDa protein in HSV-2 186-infected cell lysates. The protein was not detectable in the presence of the viral DNA synthesis inhibitor, suggesting that the UL4 gene was expressed as a gamma(2) gene. Indirect immunofluorescence studies localized the UL 4 protein within the nucleus as discrete punctate forms at late times postinfection. However, when expressed in the absence of other viral p roteins, the UL4 protein was limited to the cytoplasm, indicating that an interaction with one or more other virus-induced proteins was resp onsible for the nuclear localization during infection. Subnuclear frac tionation studies showed that the protein was released from the nuclea r structure of infected cells by high salt treatment. Moreover, the UL 4 protein was detected in purified virions and light particles.