The transcription strategy of bovine adeno-associated virus (B-AAV) combines features of both adeno-associated virus type 2 (AAV2) and type 5 (AAV5)

The parvoviruses bovine adeno-associated virus (B-AAV) and adeno-associated vir-us type 5 (AAV5) have similar transcription maps. However, while the AAV5 capsid gene promoter P41 possesses a high basal level in 293 cells, and is further activated only poorly by Rep during adenovirus type 5 (Ad5) infection, the B-AAV P41 promoter has a low basal activity within RepCap constructs in these cells and can be strongly activated by its Rep protein in the presence of Ad5 when a Rep-binding element (RBE) is included in cis at either end of the molecule. These differences are not due to A differences in the intrinsic activating capability of the individual Rep proteins. Both viral promoters contain AP1 and CRE elements that contribute to their basal activity; however, the nature of the B-AAV P41 promoter itself and the surrounding sequences contribute to its relatively lower basal activity. In addition, the B-AAV upstream transcription units themselves also are activated in the presence of Ad5 and Rep. Thus, although the transcription map of B-AAV is much more closely related to AAV5, activation of its promoters is functionally more like the prototype AAV2. (c) 2007 Elsevier Inc. All rights reserved.