Efficient expression of the adeno-associated virus type 5 p41 capsid gene promoter in 293 cells does not require Rep

Efficient expression of the adeno-associated virus type 5 (AAV5) P41 capsid gene promoter required adenovirus E1A and/or E1B; however, in contrast to what was observed for expression of the AAV2 capsid gene promoter (P40), neither adenovirus infection nor the large Rep protein was required. Although both the AAV2 and the AAV5 large Rep proteins efficiently bound the (GAGY)(3) Rep-binding element, the AAV5 large Rep protein transactivated transcription of the inducible AAV2 P40 promoter much less well than AAV2 large Rep. Differences in their activation potentials were mapped to the amino-terminal region of the proteins, and the poorly transactivating AAV5 Rep protein could competitively inhibit AAV2 Rep transactivation.