Immunogenicity of MSP-1 in rabbits, Aotus monkeys, and humans semi-immune to malaria. Antibodies specific for p83, p30, p38, and p42 were quantified in the various sera via an enzyme-linked immunosorbent assay yielding the fragment-specific titers shown. (A) Rabbits (n = 2) immunized with full-size MSP-1D assembled from p83/30 plus p38/42. The animals were primed with 100 μg of MSP-1D in CFA followed by two 100-μg boosts in Freund's incomplete adjuvant. (B) Aotus lemurinus griseimembra monkeys (n = 10) were immunized with 50 μg of MSP-1F isolated from parasites in CFA followed by two boosts of 50 μg of MSP-1F in Freund's incomplete adjuvant. (C) Human sera were obtained from 11 blood donors of the District Hospital of Nouna, Burkina Faso.