Variation in properties of plaque progeny of PARA (defective simian papovavirus 40)-adenovirus 7.

One hundred and twelve progeny from double plaque-purified clones were derived from the original PARA (defective simian papovavirus 40)-adenovirus 7 population. These progeny were found to differ in their oncogenic potential in newborn hamsters with progeny from 20 clones not inducing any tumors during 1 year of observation. The varying tumorigenicity of the individual clonal progeny was not related to the titer of PARA (particle aiding replication of adenovirus) in the inoculum. There was a perfect correlation between the tumor antigen content of the tumor cells and the antibody response of the tumor-bearing host. The tumors containing both adenovirus and simian papovavirus 40 (SV40) tumor antigens appeared earlier than those carrying only SV40 tumor antigen. Progeny from clones which induced mixed tumors also produced tumors which contained only SV40 tumor antigen. Three variants of PARA were isolated which induced the synthesis of SV40 tumor antigen in the cytoplasm of infected simian cells; all other clones yielded progeny which induced synthesis of SV40 tumor antigen in the nucleus.