Viral Studies of SV40 Tumorigenesis in Hamsters

Abstract

After subcutaneous inoculation into newborn hamsters, SV40 virus rapidly declined in titer and could not be detected between the 10th postinoculation day and the time of tumor development, 4 months later. Frequency of virus recovery from tumor extracts appeared to be related to tumor size; 4 (31%) of 13 small tumors, 16 (62%) of 26 medium tumors, and 5 (25%) of 20 large tumors yielded virus, with titers highest in the medium-sized tumors. Neutralizing antibody developed proportionally to tumor size, even in several animals which had serial tumor biopsies consistently negative for virus; this antibody was probably largely responsible for lack of virus isolation from large tumors. The failure to recover virus during the latent period may be a manifestation of the highly integrated cell-virus relationship found in SV40 tumor cells.