Figure 2.
Innate Immune Control by Macroautophagy
Viruses, bacteria, and parasites get cleared or interfere with their destruction by macroautophagy. Herpesviruses encode inhibitors of autophagosome formation, whereas picornaviruses and coronaviruses inhibit fusion of autophagosmes with lysosomes in order to replicate on autophagosomal membranes. Rickettsia conorii and group A Streptococcus, examples of bacterial pathogens that escape the endosome, are degraded by macroautophagy, but Shigella flexneri has developed an escape strategy that avoids its import into autophagosomes. Brucella abortus and Legionella pneumophila block autophagosome-lysosome fusion and replicate in autophagic vesicles. Pathogens such as Toxoplasma gondii and Mycobacterium tuberculosis condition phagosomes as replication niches, which can be cleared by macroautophagy after immune activation of the host cell.