Down-regulation of E1a expression by E3 gene products in group C adenoviruses

Abstract

Mutant group C adenoviruses defective in expression of the E3 transcription unit were found to overexpress E1a proteins relative to wild-type adenoviruses. This result suggests that one or more proteins encoded in the E3 region (present in wild-type viruses) down-regulate E1a expression. This interpretation was confirmed by transfection experiments in which a plasmid expressing the E3 region reduced expression of E1a in 293 cells. Experiments to examine the molecular basis of this down-regulation of E1a suggest that E3 protein products interfere with the translation of viral mRNA molecules.