Immunization of rabbits with zeolite absorbed Trypanosoma gambiense inactive vaccine.

T. Gambiense was treated with natural zeolite, a very powdery mineral material which has strong absorptive capacity from the cationic exchangeable properties, and kept at 4 degrees C for 3 days. Rabbits injected with this inactivated vaccine were completely protected from a challenge inoculation of homologous viable parasites. Collected immune sera by weekly intervals from the immunized animals were tested for their ability to agglutinate trypanosomes. Serum antibodies were shown high titers 3 weeks post-inoculation, i.e., 1:512, and plateau of this titer was persistent up 3-4 weeks. For the experiment of passive protective effects of rabbit immune sera, mice were inoculated with 100 viable T. Gambiense by subcutaneous or intracerebral routes and then immediately performed two injection doses of 0.1 ml antiserum at intervals of 24 hours by subcutaneous. The protective ability was remarkable at the first to second weeks after the last immunization and then slightly decreased although a high level of agglutination titer remained in immune serum.