A STUDY OF ANTIBODY AND T-CELL RECOGNITION OF RHOPTRY-ASSOCIATED PROTEIN-1 (RAP-1) AND RAP-2 RECOMBINANT PROTEINS AND PEPTIDES OF PLASMODIUM-FALCIPARUM IN MIGRANTS AND RESIDENTS OF THE STATE OF RONDONIA, BRAZIL

Humoral and cellular responses were examined among natives and migrant s in an area of the Amazon region of Brazil. Rhoptry-associated protei n-1 (RAP-1) and RAP-2 expressed in Escherichia coli expression systems , a peptide corresponding to the epitope bound by inhibitory anti-RAP- 1 antibodies, and four other RAP-1 and RAP-2 synthetic peptides were u sed in these studies. Plasma from the native population had greater Ig G reactivity to the N-terminal third of RAP-1 than the migrant populat ion; both populations had low levels of IgM to this region of RAP-1. T he IgG reactivity to RAP-2 and to the C-terminal third of RAP-1, as we ll as for all the peptides, including the peptide from the inhibitory domain, were low or absent in both populations. In contrast, there wer e a high number of subjects with an IgM response to the peptides. Cell ular responses were measured by proliferation of peripheral blood mono nuclear cells (PBMC) and, in some subjects, by reverse transcription-p olymerase chain reaction for interleukin-2 (IL-2), interferon-gamma (I FN-gamma), IL-4, and IL-10. Proliferation of PBMC was low when stimula ted by recombinant proteins, peptides, or parasite lysate. Both RAP-1 and RAP-2 stimulated cytokine production by donor T cells; IL-2, IL-4, and IFN-gamma RNA transcripts were observed in response to recombinan t proteins and parasite lysate, but with no uniform trends. From the o bserved antibody responses, RAP-1 appears to be more immunogenic than RAP-2.