Temperature-sensitive mutants of bovine herpesvirus type 1: mutants which make unaltered levels of 'early' glycoproteins but fail to synthesize a 'late' glycoprotein.

The major glycoproteins of bovine herpesvirus type 1 showed distinct temporal patterns of expression. The glycoproteins GVP 11 and GVP 6 as well as its cleavage products, GVP 11a and GVP 16, were expressed early in the infectious process, whereas GVP 9 was expressed late. Temperature-sensitive mutants were developed and characterized. Mutants belonging to two complementation groups were unable to synthesize DNA at 40 degrees C, the non-permissive temperature. In cells infected with these mutants the late glycoprotein GVP 9 was not synthesized at 40 degrees C, whereas the synthesis of the early glycoproteins GVP 11 and GVP 6 continued at wild-type levels. These studies suggest that the transition from early to late glycoprotein synthesis is linked to viral DNA synthesis.