The Plasma Membrane P-Type ATPase CtpA Is Required for <i>Mycobacterium tuberculosis</i> Virulence in Copper-Activated Macrophages in a Mouse Model of Progressive Tuberculosis

Background/Objective : Finding new targets to attenuate Mycobacterium tuberculosis ( Mtb ) is key in the development of new TB vaccines. In this context, plasma membrane P-type ATPases are relevant for mycobacterial homeostasis and virulence. In this work, we investigate the role of the copper-transporting P-type ATPase CtpA in Mtb virulence. Methods : The impact of CtpA deletion on Mtb 's capacity to overcome redox stress and proliferate in mouse alveolar macrophages (MH-S) was evaluated, as well as its effect on Mtb immunogenicity. Moreover, the influence of CtpA on the pathogenicity of Mtb in a mouse (BALB/c) model of progressive TB was examined. Results : We found that MH-S cells infected with wild-type ( Mtb H37Rv) or the mutant strain ( Mtb H37RvΔ ctpA ) showed no difference in Mtb bacterial load. However, the same macrophages under copper activation (50 µM CuSO 4 ) showed impaired replication of the mutant strain. Furthermore, the mutant Mtb Δ ctpA strain showed an inability to control reactive oxygen species (ROS) induced by PMA addition during MH-S infection. These results, together with the high expression of the Nox2 mRNA observed in MH-S cells infected with the Mtb ∆ ctpA strain at 3 and 6 days post-infection, suggest a potential role for CtpA in overcoming redox stress under infection conditions. In addition, Mtb Δ ctpA -infected BALB/c mice survived longer with significantly lower lung bacterial loads and tissue damage in their lungs than Mtb H37Rv-infected mice. Conclusions : This suggests that CtpA is involved in Mtb virulence and that it may be a target for attenuation.