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.