Properties of an adenovirus type 2 mutant, Ad2dl807, having a deletion near the right-hand genome terminus: failure to help AAV replication.

We have analyzed the ability of an adenovirus type 2 mutant, Ad2dl807, to support replication of adeno-associated virus (AAV). This mutant has a deletion extending from early region 3 through the late fiber gene and into early region 4. Since AAV growth does not require Ad early region 3 or the fiber gene, the Ad2dl807 mutant allows analysis of the function of Ad early region 4 in AAV growth. As determined by assay of AAV DNA, RNA, and protein synthesis as well as the number of cells producing AAV and the yield of infectious AAV particles, growth of AAV with the dl807 mutant is decreased 10- to 20-fold. The residual AAV growth is probably due to the presence of a low level of contaminating viable Ad virions in the dl807 preparations. These observations indicate that an Ad early region 4 function is required at a very early stage of AAV DNA replication to allow amplification of duplex replicating (RF) DNA. Thus growth of AAV offers an independent probe for adenovirus early region 4 functions.