AFRICAN BUFFALO SERUM CONTAINS NOVEL TRYPANOCIDAL PROTEIN

The high ability of African buffalo, as compared to domestic cattle, t o control infections with Trypanosoma brucei brucei ILTat 1.4 organism s did not correlate with the timing or magnitude of parasite surface c oat-specific antibody responses and may have resulted from the constit utive presence in buffalo blood of a novel trypanocidal factor. Buffal o plasma and serum contained material that killed bloodstream stage T. b. brucei, T. b. rhodesiense, T. b. gambiense, T. evansi, T. congolen se, and T. vivax organisms during four h of incubation at 37 degrees C in vitro. Serum from eland was also trypanocidal whereas serum from o ryx, waterbuck, yellow-back duiker, cattle, horse, sheep, goat, mouse, rat, and rabbit was not trypanocidal. The buffalo serum trypanocidal material was not lipoprotein, or Igc, and had the following properties : 1) a density of >1.24 g/ml determined by flotation ultracentrifugati on; 2) insolubility in 50% saturated ammonium sulphate; 3) non-reactiv ity with anti-bovine IgM, and anti-bovine IgG; 4) non-reactivity with protein G, and protein A; 5) a relative molecular mass of 152 kDa dete rmined by chromatography on Sephacryl S 300, and of 133 kDa determined by chromatography of the 50% SAS cut of IgG-depleted buffalo serum on Superose 12; 6) no associated cholesterol; and 7) inactivation by dig estion with proteinase K that was immobilized on agarose.