Coronaviruses, Lysosomes, and Secondary Bacterial Infections: Coronaviruses Outsmart the Host.

Lysosomes are key organelles that contribute to homeostatic functions such as autophagy-mediated recycling of cellular components and innate immune response through phagocytosis-mediated pathogen killing during infections. Viruses such as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of coronavirus disease 2019 (COVID-19), has developed unique adaptation to not only avoid lysosome-mediated destruction but also actively utilize lysosomal machinery to both enter and exit cells. To survive the highly hostile lysosomal environment, coronaviruses deacidify the lysosomes, potentially by manipulating H+ ion exchange across the lysosomal lumen, ensuring coronavirus survival. At the same time, this deacidification not only impairs cellular homeostatic functions such as autophagy but also renders the host susceptible to secondary bacterial infections. Furthermore, lysosomal enzymes promote extensive cell death and tissue damage during secondary bacterial infections. Thus, targeting lysosomal pathways provide a great opportunity to limit both viral replication and subsequent negative impact on host immunity against secondary bacterial infections.