Identification of a repressor of late gene expression within the AcMNPV genome

Viral replication and late gene expression of Autographa californica multiple nucleopolyhedrovirus (AcMNPV) requires a series of late expression factors. We examined the AcMNPV genome for additional factors which affect late gene expression. During these investigations, a segment of the AcMNPV genome located immediately downstream to LEF-7 was found to possess a repressor activity. Elimination of this region resulted in greatly enhanced late gene expression. We were unable to link repressor activity to a single open reading frame, suggesting that a cis-acting element rather than a trans-acting factor is responsible for this phenomenon.