Experimental immunity against trypanosomiasis in sheep

Three groups of male sheep were used. Group one was not inoculated; group two was inoculated with T. rhodesiense homogonate and group three with T. rhodesiense "fraction 3". Subsequently they were challenged with 1 x 10(6) T. vivax. Group inoculated with T. rhodesiense fraction 3 had high IgG levels and parasitemia was absent.