Alpha-tubulin-specific protease that is required for entry into epithelial cells and for subsequent intra- and intercellular spreading. Contributes to bacterial entry into epithelial cells by inducing microtubule (MT) destabilization and the formation of membrane ruffles. The membrane ruffling evoked by VirA results from the activation of host rac1, which is associated with the destruction of MT networks. Creates a tunnel inside the host cell cytoplasm by breaking down the microtubule infrastructure. This facilitates the bacterium's movement through the cytoplasm and also helps other bacteria move faster during the invasion of the eukaryotic cell. Is absolutely required for virulence (By similarity). Monomer. Interacts specifically with alpha tubulin, a major component of microtubule (By similarity). Translocated into the host cell via the type III secretion system (TTSS). Localizes in the cytoplasm of the infected cell (By similarity). Belongs to the protease EspG/VirA family.