Immune responses in vaccinated dogs with autoclaved Leishmania major promastigotes

A comparative study was undertaken on the immunogen power of autoclaved Lei shmania major promastigotes (ALM) vaccines given simultaneously with either BCG or saponin against canine leishmaniasis. The humoral immune response w as assessed by ELISA and western blotting. The cellular immune response was evaluated by the lymphocyte transformation test. Dogs vaccinated simultane ously 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, t he lymphocyte proliferation of these dogs to the crude L. infantum antigen was not significantly different from the control group. In contrast, in dog s vaccinated simultaneously with ALM and BCG, the antibody titres to crude antigen were low. Their sera reacted with the same proteins recognised by s era from dogs vaccinated simultaneously with ALM and saponin by western blo tting. However, the 85-kDa protein was only identified by sera taken from d ogs vaccinated simultaneously with ALM and BCG. These latter exhibited spec ific lymphocyte proliferation to the L. infantum antigen. This cell prolife ration 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 im mune response, which is implicated in protection of dogs against a Leishman ia infection. (C) Inra/Elsevier, Paris.