Fig 8.

A model for the role of microtubules in the cytoplasmic trafficking and endosomal acidification for AAV2 escape. After binding and endocytosis on the cell surface, AAV2 virions may take two possible trafficking routes toward the nucleus. Route I, for these internalized at sites distal from the nucleus, virions migrate on MT tracks in endosomes to traverse the dense cytoplasm toward the perinuclear regions of host cells. Route II, for these internalized at sites close to the nucleus, virions in endocytic vesicles can reach the nucleus by slower MT-independent migration through the cytoplasm between the cytoplasmic membrane and nuclear envelope. For both routes, acidification of the AAV2-containing endosomal compartment happens at the perinuclear region and allows the escape of viral particles from vesicles, a prerequisite step for nuclear entry.