Immunoprophylactic studies on cell wall associated proteins ofMycobacterium tuberculosis H37Ra

The cell wall protein peptidoglycan complex (CW-PPC) of Mycobacterium tuberculosis H₃₇Ra was isolated through sequential extraction of lipids, carbohydrates and soluble proteins. CW-PPC emulsified in FIA was found to induce significant protection in mice against challenge with LD₅₀ dose ofM. tuberculosis H₃₇Rv. To identify the immunoprotective components of CW-PPC, the proteins in avid association with peptidogican were dissociated by chemical treatment with trifluoromethanesulthonic acid (CF₃CO₃H): anisole (2:1). Immunoreactivity of total (CW-Pr) as well as its component proteins i.e., 71, 60 and 45 kDa proteins of cell wall was studied in animals immunized with CW-Pr-FIA. The 71 kDa protein was found to be most immunoreactive giving higher T-cell sensitization and humoral responses. Further, immunization of mice with 71 kDa-FIA demonstrated enhanced T- and B- cell responses. Mice immunized with 71 kDa-FIA gave significantly higher protection (P ≤ 0.05) against intravenous challenge with LD₅₀ dose ofM. tuberculosis H₃₇Rv, than BCG immunized animals. The results indicate the potential of 71 kDa cell wall protein as a suitable candidate for Cthe subunit vaccine.