Early and delayed shut-off of host protein synthesis in cells infected with herpes simplex virus.

A mutant of herpes simplex virus type 1 [HSV-1(HFEM)], tsB7, appears to have two temperature-sensitive functions. One is required during the first hour of infecting a cell (suggesting that it is performed by a virion protein) and the other is the non-essential function of "early shut-off" of cellular protein synthesis, which is mediated by a virion protein. The latter function remained temperature-sensitive in a revertant virus (RC2) grown at the non-permissive temperature (39 degrees C). However, under these conditions RC2 did cause inhibition of host synthesis, showing that "delayed shut-off", requiring virus protein synthesis, can occur independently of early shut-off, which is mediated by a virion protein. Early shut-off by u.v.-irradiated tsB7 was reversed when the temperature was raised, whereas delayed shut-off by intact tsB7 was not. Of two wild-type strains of virus examined, HSV-1(F) also exhibited temperature-sensitive early shut-off, but HSV-2(G) did not.