Autophagy is an evolutionary conserved mechanism for the sequestration and subsequent lysosomal degradation of discrete intracellular portions of eukaryotic cells, facilitating the removal of materials not degraded through the ubiquitin-proteasome pathway. In addition, autophagy plays important roles in innate and adaptive immune responses to pathogens.
Several viruses are able to activate host autophagy as a cellular survival mechanism. Indeed, viruses can activate programmed cell death during infection that prevent them from spreading to healthy tissue. By activating autophagy, viruses delay or inhibit apoptosis. For example, SV40 ST antigen protects cancer cells under glucose deprivation by triggering autophagy. KSHV Rta is able to enhance the autophagic process in order to facilitate viral lytic replication.