THE USE OF HETEROLOGOUS PROMOTERS FOR ADENOASSOCIATED VIRUS (AAV) PROTEIN EXPRESSION IN AAV VECTOR PRODUCTION

Although adeno-associated virus (AAV) vectors are potentially useful g ene transfer vehicles for gene therapy, the vector production system i s currently at the developmental stage. We constructed AAV helper plas mids (Rep and Cap expression plasmids) by replacing a native AAV promo ter, p5, with various heterologous promoters to examine whether the ef ficiency of AAV vector production was influenced by modulating the AAV protein expression pattern. The helper plasmids containing heterologo us promoters (EF, CMV, SV40, B19p6, and CAG promoters, respectively) e xpressed Rep78/68 more efficiently than a conventional helper plasmid (pIM45), but the expression of Rep52/40 and Cap decreased, resulting i n a significant reduction in AAV vector production. Furthermore, the e fficiency of vector production never fully recovered even if the Cap p roteins were supplied by an additional expression plasmid. A large amo unt of Rep78/68 and/or a reduced level of Rep52/40 may have deleteriou s effects on AAV vector production. The present findings will aid in t he development of a more efficient AAV vector production system.