CONICET | Buscador de Institutos y Recursos Humanos

Q fever is a disease caused by the intracellular pathogen C. burnetii. This bacterium generates a large replicative compartment in the host cell, called parasitophorous vacuole (PV). We show that actin not only is recruited to the PV membrane but is also involved in its biogenesis since treatment of infected cells with actin-depolymerizing agents inhibited PV development in a reversible manner. It is known that actin dynamic is regulated by the Rho family of GTPases. To test if these GTPases play a role in PV biogenesis, after infection with C. burnetii, cells were transfected with pEGFP: Cdc42, RhoA or Rac1 wild types, constitutively active or inactive mutants. The PV was decorated by Cdc42WT and its active mutant V14. Interestingly, in cells overexpressing the V14 mutant a significant PV population of bigger size was observed. Neither co-localization nor change in size distribution of PV was observed in cell expressing the inactive mutant N17 of Cdc42. RhoA WT and its active mutant V14 were also recruited on the PV but not the inactive one. However, in this case a significant smaller size PV population was observed in cell expressing the negative mutant N17. In contrast, Rac1 WT and its mutants did not show any association with the PV. These results suggest that actin, likely modulated by Cdc42 and RhoA, is involved in PV biogenesis.