INHIBITION OF ADENOVIRUS-TRANSFORMED CELL ONCOGENICITY BY ADENO-ASSOCIATED VIRUS

Adeno-associated virus (AAV) inhibited the oncogenicity and transforming ability of adenovirus (Ad). Using the H14b Ad-transformed hamster cell line, a model system was developed to characterize the molecular events responsible for these inhibitory effects. AAV infection of H14b cells decreases their oncogenicity by .apprx. 3-fold. The tumors that do arise are significantly smaller and have a longer latent period. AAV infection alters the in vitro properties of the H14b cells, reducing efficiency in methyl cellulose by 38-92% and saturation density by 2- to 4-fold. The molecular basis of this inhibition appears to be an inhibition of production of the 58[kilodalton]K tumor antigen as determined by fluorescent antibody and immunoprecipitation studies. The reduction in the levels of tumor antigens are not due to alterations or loss of the Ad genome within H14b cells but may reflect an alteration in transcription or processing of Ad-specific mHNA. AAV infection of H14b cells does not lead to detectable levels of AAV DNA synthesis, but some AAV transcripts are made. This is the 1st instance in which AAV transcription was detected in an Ad-transformed cell line.