The Plasma Membrane P-Type ATPase CtpA Is Required for Mycobacterium tuberculosis Virulence in Copper-Activated...

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 (MtbH37Rv) or the mutant strain (MtbH37RvΔctpA) showed no difference in Mtb bacterial load. However, the same macrophages under copper activation (50 µM CuSO₄) showed impaired replication of the mutant strain. Furthermore, the mutant MtbΔctpA 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, MtbΔctpA-infected BALB/c mice survived longer with significantly lower lung bacterial loads and tissue damage in their lungs than MtbH37Rv-infected mice. Conclusions: This suggests that CtpA is involved in Mtb virulence and that it may be a target for attenuation.