Host-Microbe Interactions: Understanding the Mechanism of Autophagy in Viral Replication and Immune Evasion.

Autophagy is a highly conserved catabolic process in eukaryotic cells that maintains cellular homeostasis by degrading damaged or superfluous intracellular components. Autophagy plays a dual, paradoxical role during viral infection. However, for most viruses, the induction of autophagy provides a favorable intracellular environment for the full completion of their life cycles. Most viruses that benefit from autophagy adopt a "regulate but not destroy" strategy, i.e., they initiate the autophagic process while suppressing their immune system through mechanisms such as blocking autophagosome-lysosome fusion. This allows them to avoid self-elimination while redirecting other functions of the autophagic machinery-for instance, utilizing autophagy-derived structures such as autophagosomes and double-membrane vesicles (DMVs) as specialized sites for viral genome replication, particle assembly, and maturation. The maintenance of cellular homeostasis by autophagy is crucial for the establishment of viral infection, as it provides a viable cellular microenvironment for viral replication; after infection occurs, inhibiting the degradative function of autophagy becomes a key strategy for viruses. Although canonical degradative autophagy exerts a negative effect on most viruses, redirected nondegradative autophagic structures and repurposed autophagic mechanisms are essential for the efficient replication of various viruses. In-depth analysis of this dynamic virus-autophagy interplay will provide important insights for elucidating virus-host interactions and developing autophagy-targeted antiviral strategies.