Acidic pH of Early Endosomes Governs SARS-CoV-2 Transport in Host Cells.

Endocytosis is a prominent mechanism for SARS-CoV-2 entry into host cells. Upon internalization into early endosomes (EEs), the virus is transported to late endosomes (LEs), where acidic conditions facilitate spike protein processing and viral genome release. Dynein and kinesin motors drive EE transport along microtubules; dynein moves EEs to the perinuclear region, while kinesins direct them towards the plasma membrane, creating a tug-of-war over the direction of transport.

Acidification of the phagosome orchestrates the motor forces directing its transport.

Phagosomes are dynamic organelles formed by macrophages to capture and destroy microbial pathogens. Phagosome transport from the cell periphery to the perinuclear region, is essential for fusion with lysosomes and the elimination of pathogens. Molecular motors, kinesin and dynein, generate opposing forces, transporting the phagosome away from and towards the lysosome, respectively.