Immunoprotective behaviour of liposome entrapped cell wall subunit of Mycobacterium tuberculosis against experimental tuberculous infection in mice

We wanted to determine the immunoprotective behaviour of cell wall protein peptidoglycan complex (CW-PPC) of Mycobacterium tuberculosis H37Ra, using liposomes as adjuvant, in an experimental animal model. Immunization of mice with CW-PPC entrapped in liposomes induced both humoral response, as measured by enzyme-linked immunosorbent assay (ELISA), and cell-mediated immune responses, as seen by delayed type hypersensitivity (DTH) and leucocyte migration inhibition (LMI) techniques. Ten days after complete immunization, the animals were challenged with median lethal dose (LD50) of M. tuberculosis H37Rv. The animals exhibited significant protection, as evident by 72% survival after 30 days of infection, compared to 38% survival in control animals. Protective effect of immunization with liposome entrapped CW-PPC was further substantiated by significant decrease in the number of viable bacilli in lungs, liver and spleen of immunized animals, as compared to control animals. These results indicate that immunization with liposome-entrapped mycobacterial cell wall protein peptidoglycan complex induces protection against experimental tuberculosis.