Vaccinations with live-attenuated Leishmania major promastigotes and challenge infection with L. major in BALB/c mice.

BACKGROUND Currently there is no vaccine available in use against any form of leishmaniases worldwide. OBJECTIVE To assess potential of a live-attenuated Leishmania major promastigates, for protection against a challenge infection with L. major in BALB/c mice. DESIGN A laboratory based study. SETTING Study was carried out at Centre for Biotechnology Research and Development, Kenya Medical Research Institute, Nairobi. RESULTS The greatest protection against challenge with L. major was seen in mice immunised with live parasites (P < 0.001) compared to vaccinations with heat killed or soluble antigens. In general, immunised mice produced high level of antileishmanial antibodies and T cell stimulation to their respective antigens. CONCLUSIONS Our live-attenuated parasites produced by serial sub-culture of L. major parasites 118 times showed the capacity to induce appropriate cell-mediated immune responses and protection against L. major infection in BALB/c mice. Data also suggests that these parasites do not revert to virulence when injected subcutaneously in mice.