Viral escape from immune recognition: multiple strategies of adenoviruses.

Human adenoviruses can cause persistent infections in man. The strategies of C type adenoviruses (types Ad2 and Ad5) to evade immune recognition are many, but all involve single early genetic regions (E3). Gene(s) within E3 have been shown to allow the adenovirus to avert cytokine-mediated apoptosis. Furthermore, the E3 region controls the cytotoxic T cell epitope (a major histocompatibility complex [MHC] class I molecule with an adenovirus-derived peptide) on the cell surface of infected cells. On the one hand the E3 gene product 19 kDa can bind to nascent class I MHC in the endoplasmic reticulum and thus prevent its transport to the cell surface, and on the other hand the E3 region down-regulates the E1a gene product, the immunodominant cytotoxic T cell determinant.