Protective effect of zeolite absorbed Trypanosoma gambiense inactive vaccines on mice

Inactive T. gambiense vaccines treated with strong absorbent natural zeolite and kept at 4 degrees C for 3 days were injected into mice. After 2 weeks, 75% of the white mice which had received single injection survived, 85% of double injections survived challenge with 100 parasites separated from T. gambiense-infected mouse blood. However, the survival rats of the inoculated mice challenged after 3 weeks were 55% (one injection) and 80% (two injections) respectively. The mice were challenged 2 weeks after they were inoculated with vaccines made in the same way as mentioned above except that the prepared time was lengthened to 6 days. The total survival rates were 67.4% (one injection) and 85% (two injections) and these challenged 3 weeks after inoculation were 50% (one injection) and 80% (two injections). Mice not surviving in the experimental groups lived longer by 3--4 days than those in the controlled ones which had no survivors at all. Inactive vaccines prepared with artificial zeolite showed little protective effect on mice.