Immunogenicity and Protective Efficacy of “Mycobacterium w” against Mycobacterium tuberculosisin Mice Immunized with Live versus Heat-Killed M. wby the Aerosol or Parenteral Route

ABSTRACTAs the disease caused by Mycobacterium tuberculosiscontinues to be a burden, there is a concerted effort to find new vaccines to combat this problem. One of the important vaccine strategies is whole bacterial vaccines. This approach relies on multiple antigens and built-in adjuvanticity. Other mycobacterial strains which share cross-reactive antigens with M. tuberculosishave been considered as alternatives to M. bovisfor vaccine use. One such strain, “Mycobacterium w”, had been evaluated for its immunomodulatory properties in leprosy. A vaccine against leprosy based on killed M. wis approved for human use, where it has resulted in clinical improvement, accelerated bacterial clearance, and increased immune responses to Mycobacterium lepraeantigens. M. wshares antigens not only with M. lepraebut also with M. tuberculosis, and initial studies have shown that vaccination with killed M. winduces protection against tuberculosis in Mycobacterium bovisBCG responder, as well as BCG nonresponder, strains of mice. Hence, we further studied the protective potential of M. wand the underlying immune responses in the mouse model of tuberculosis. We analyzed the protective efficacy of M. wimmunization in both live and killed forms through the parenteral route and by aerosol immunization, compared with that of BCG. Our findings provide evidence that M. whas potential protective efficacy against M. tuberculosis. M. wactivates macrophage activity, as well as lymphocytes. M. wimmunization by both the parenteral route and aerosol adminstration gives higher protection than BCG given by the parenteral route in the mouse model of tuberculosis.