Mutants of Simian Virus 40 Differing in Plaque Size, Oncogenicity, and Heat Sensitivity

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Abstract
Takemoto , K. K. (National Institute of Allergy and Infectious Diseases, Bethesda, Md.), R. L. Kirschstein, and K. Habel . Mutants of simian virus 40 differing in plaque size, oncogenicity, and heat sensitivity. J. Bacteriol. 92: 990–994. 1966.—Three mutants of simian virus 40 were isolated on the basis of the type of plaques produced in primary cultures of African green monkey kidney cells and designated as L (large), S (small), and M (minute) strains. Significant differences in oncogenicity for hamsters were observed, with the 50% oncogenic dose being 10 4.5 for the L, 10 5.2 for the S, and 10 5.8 for the M strains. All three strains were capable of transforming human diploid cells (W138 strain). At temperatures up to 41 C, the S and M mutants were capable of multiplying to titers almost equivalent to those obtained at 37 C. In contrast, infectious virus was not produced when cells were infected with the L mutant and were incubated at temperatures above 39 C, although complement-fixing viral and tumor antigens were formed. The temperature-sensitive phase of replication of the L strain was shown to be a late stage in viral maturation or assembly.