Lymphostimulatory and delayed-type hypersensitivity responses to a candidate leprosy vaccine strain: Mycobacterium habana.

Lymphostimulatory and delayed-type hypersensitivity (DTH) immune responses to a candidate antileprosy vaccine Mycobacterium habana have been quantified in inbred AKR mice. M. habana vaccine in three physical states, live, heat-killed and gamma-irradiated, was given intradermally to separate groups of mice and after 28 days these mice were given subcutaneous challenge with heat-killed M. leprae and heat-killed M. habana in the left hind footpad. Live BCG vaccine alone and in combination with gamma-irradiated M. habana were also compared similarly. A sufficient degree of DTH response was generated in mice by M. habana vaccine in all physical forms against two challenge antigens (lepromin and habanin). The BCG combination with M. habana did not increase the DTH response indicating internal adjuvanticity endowed in M. habana. The active hypersensitivity of immunized mice was transferable to syngeneic mice by the transfer of sensitized cells from the donor to the recipient mice intravenously. M. leprae-infected Rhesus monkey PBMC have shown comparable stimulatory response with M. habana (sonicate), and M. leprae (sonicate) antigens. The possibility of developing M. habana as a candidate antileprosy vaccine is discussed.