GENETIC STUDIES WITH TUMORIGENIC ADENOVIRUSES .2. HETEROGENEITY OF CYT MUTANTS OF ADENOVIRUS TYPE-12

The cytocidal, large-plaque-forming, and low tumorigenic cyt mutants of two strains (Huie and 1131) of adenovirus type 12 (Ad. 12) are heterogeneous. Some isolates (kb) produce maximal cyt cytopathic effect (CPE), but fail to propagate in a line of KB cells (KB-1, nonpermissive), while other isolates (kb+) as well as parental viruses multiply in these cells. Both cyt kb+ and cyt kb propagate readily in another line of KB cells (KB-2, permissive). Hexon antigen is not produced in cyt kb infections of KB-1 cells, whereas T antigen is produced apparently normally. Parental viruses complement the growth of cyt kb in KB-1 cells. The cyt kb mutants are heterogeneous with respect to spontaneous revertibility. Some revert to cyt+kb+, while others do not. The revertants are recovered after two passages in KB-1 cells and are as tumorigenic as parental viruses. It may be hypothesized that cyt kb mutations are nonsense mutations. © 1969.