Beclin-1 targeting for viral immune escape.

Macroautophagy is a catabolic pathway in eukaryotic cells that has recently been shown to facilitate pathogen detection, pathogen restriction and pathogen-derived antigen presentation to CD4(+) T cells. Due to these protective functions during immune responses, several pathogens, including RNA and DNA viruses, have developed strategies to inhibit autophagosome generation or maturation. Interestingly, most of the respective viral proteins exert these functions via binding to Beclin-1, an essential macroautophagy protein that constitutes part of the phosphatidylinositol-3 kinase complexes that mark membranes for autophagosome generation and facilitate autophagosome fusion with lyososomes. The viruses that inhibit macroautophagy by this pathway include herpesviruses, HIV and influenza A virus. Inhibition either before or after autophagosome formation seems to benefit their viral replication by different mechanisms, which are discussed here.