Conditional lethal mutants of adenovirus type 2-simian virus 40 hybrids. II. Ad2+ND1 host-range mutants that synthesize fragments of the Ad2+ND1 30K protein

Abstract

Adenovirus type 2 (Ad2) grows 1000 times less well in monkey cells than in human cells. This defect can be overcome upon co-infection of cells with SV40 and also when the relevant part of the SV40 genome is integrated into the adenovirus genome to form an adenovirus-SV40 hybrid virus. The nondefective Ad2-SV40 hybrid virus Ad2+ND1, which contains an insertion of 17% of the SV40 genome, was used to isolate host-range mutants which are defective in growth on [African green] monkey [kidney CV-1] cells although they grow normally on human [HeLa] cells. Like Ad2, these mutants are defective in the synthesis of late proteins in monkey cells. A 30,000-MW protein (30K), unique to Ad2+ND1-infected cells, can be synthesized in vitro, using Ad2+ND1 mRNA that contains SV40 sequences. 30K is not seen in cells infected with those host-range mutants that are most defective in growth on monkey cells, and translation in vitro of SV40-specific mRNA from these cells produces new unique polypeptides instead of 30K. Genetic and biochemical analyses indicate that these mutants carry point mutations rather than deletions.