MECHANISM OF HOST RESTRICTION OF ADENOVIRUS-ASSOCIATED VIRUS-REPLICATION IN AFRICAN-GREEN MONKEY KIDNEY-CELLS

Human adenovirus (Ad) serotypes provide an early factor(s) that is necessary for adenovirus-associated virus (AAV) multiplication in human cell lines. However, little, if any, AAV production occurs in primary African green monkey kidney (AGMK) cells co-infected with AAV and a helper human Ad (non-permissive infection), unless cells are additionally infected with SV-40 (permissive infection). To determine the basis of the host restriction of AAV replication in AGMK cells, AAV DNA, RNA and protein synthesis were analyzed under various conditions of infection. Hybridization reactions revealed no detectable AAV-specific DNA or RNA in infections with AAV alone or in combination with SV-40. In co-infections with AAV and Ad5 or Ad7, the synthesis of both AAV- and Ad-specific DNA and RNA occurred without a significant rise in titer of either virus. During non-permissive infection, AAV DNA synthesis was abnormal in that an expected accumulation of single-stranded progeny molecules was not observed. Although intact 20S AAV transcripts were present in the cytoplasm of AGMK cells during non-permissive infection in amounts ranging from 50-80% of that found during permissive infection, AAV-specific polypeptides were not demonstrable by polyacrylamide gel electrophoresis. Evidently, the host restriction of AAV replication in AGMK cells is exerted at the level of translation of the single AAV mRNA. One or more of the AAV polypeptides specified by this message is required for the production of single-stranded AAV progeny DNA.