Isolation and characterization of a large molecular-weight polypeptide of herpes simplex virus type 1

Infection of human embryonic lung cells at the nonpermissive temperature (39°) with tsB2, a DNA-negative mutant of herpes simplex virus type 1 (HSV-1) resulted in the accumulation of a large molecular-weight (175,000) virus-induced polypeptide detectable by SDS-polyacrylamide gel electrophoresis. This polypeptide (VP175) was detectable only in small amounts and was found mainly in the nuclear fraction of cells infected with tsB2 at the permissive temperature (34°) or with wild-type HSV-1 at both 34° and 39°. However at 39° VP175 accumulated to become the major component in both the cytoplasmic and nuclear fractions of tsB2-infected cells. Identical results were obtained with a second mutant (tsB21) in the same complementation group. Temperature-shift studies suggest that the events responsible for the accumulation of VP175 at 39° occur early in the replicative cycle. With the use of a combination of SDS-preparative and analytical disc gel electrophoresis, VP175 was isolated and rabbit antisera to this polypeptide were prepared. By immunofluorescence assay, anti-VP175 sera reacted only with the nucleus of wild-type HSV-1-infected cells, whereas tsB2-infected cells cultured at 39° showed both cytoplasmic and nuclear immunofluorescence. In addition, the anti-VP175 serum reacted preferentially with HSV-1 as compared with HSV-2-infected cells, suggesting a possible type specificity for the reagent.