FIG. 4.

(A) Parasitemia development (left axis) and occurrence of trypanosomosis-associated anemia (RBC; right axis) in splenectomized B6129SF2 mice. The parasitemia values presented are mean parasite counts (# Par.)/ml of blood ± standard deviations. (B) Survival was followed for five individual mice, and five other mice were sacrificed for serum collection on days 7, 14, 28, 36, and 40, respectively. (C and D) Infection-induced specific anti-VSG IgM (C) and IgG2a and -2b (D) isotype serum endpoint titers were determined in a VSG solid-phase ELISA system (0.2 μg/well), using sera collected on days 7, 14, and 28 and just prior to the lethal end of the infection. (E and F) The same sera were used to determine specific IgM (E) and IgG2a and -2b (F) isotype serum endpoint titers in an ELISA system that used total soluble trypanosome extracts as a solid-phase coating (0.5 μg/well).