Immune responses in vaccinated dogs with autoclaved Leishmania major promastigotes.

A comparative study was undertaken on the immunogen power of autoclaved Leishmania major promastigotes (ALM) vaccines given simultaneously with either BCG or saponin against canine leishmaniasis. The humoral immune response was assessed by ELISA and western blotting. The cellular immune response was evaluated by the lymphocyte transformation test. Dogs vaccinated simultaneously with ALM and saponin showed high antibody titres to crude L. infantum antigens after the first vaccine booster and reacted with several antigens, with molecular weights from 26 to 108 kDa by western blotting. However, the lymphocyte proliferation of these dogs to the crude L. infantum antigen was not significantly different from the control group. In contrast, in dogs vaccinated simultaneously with ALM and BCG, the antibody titres to crude antigen were low. Their sera reacted with the same proteins recognised by sera from dogs vaccinated simultaneously with ALM and saponin by western blotting. However, the 85-kDa protein was only identified by sera taken from dogs vaccinated simultaneously with ALM and BCG. These latter exhibited specific lymphocyte proliferation to the L. infantum antigen. This cell proliferation was observed for approximately 9 months after the first dose of the vaccine. This study indicates that a combination of ALM as the vaccine and BCG as the adjuvant, in the dog model, was successful in inducing a cell immune response, which is implicated in protection of dogs against a Leishmania infection.