Listeria monocytogenesInterferes with Host Cell Mitosis through Its Virulence Factors InlC and ActA

Listeria monocytogenesis among the best-characterized intracellular pathogens. Its virulence factors, and the way they interfere with host cells to hijack host functions and promote the establishment and dissemination of the infection, have been the focus of multiple studies over the last 30 years. During cellular infection,L. monocytogeneswas shown to induce host DNA damage and delay the host cell cycle to its own benefit. However, whether the cell cycle stage would interfere with the capacity ofListeriato infect human cultured cell lines was never assessed. We found here thatL. monocytogenespreferentially infects cultured cells in G2/M phases. Inside G2/M cells, the bacteria lead to an increase in the overall mitosis duration by delaying the mitotic exit. We showed thatL. monocytogenesinfection causes a sustained activation of the spindle assembly checkpoint, which we correlated with the increase in the percentage of misaligned chromosomes detected in infected cells. Moreover, we demonstrated that chromosome misalignment inListeria-infected cells required the function of twoListeriavirulence factors, ActA and InlC. Our findings show the pleiotropic role ofListeriavirulence factors and their cooperative action in successfully establishing the cellular infection.