The herpes simplex virus type 1 immediate-early protein ICP4 specifically induces increased transcription of the human ubiquitin B gene without affecting the ubiquitin A and C genes.

Lytic infection with herpes simplex virus causes increased ubiquitin gene transcription. This effect is reproduced in cells expressing the viral immediate early protein ICP4 in the absence of other viral proteins but is not seen at the nonpermissive temperature in cells expressing the temperature-sensitive ICP4 protein of HSV-1 tsK. Studies with probes specific to the three human ubiquitin genes indicate that only the Ubi B gene is sensitive to ICP4-mediated induction whereas the Ubi A and C genes are unaffected. The significance of these effects for the mechanism by which ICP4 transcriptionally activates viral and a few cellular genes is discussed.