S u m m a r y :This study evaluates the differences in host immune responses to defined plasmodial antigens in four geographically different regions in which malaria is endemic. Sera from 5 2 7 individuals were tested for the presence of antibodies specific for three types of plasmodial antigen : liver-stage antigen (LSA-1), blood-stage antigen (SPF 70) and circumsporozoite (CS) antigen (NANP)4.The individuals taking part in the study comprised : patients with transfusional malaria due to Plasmodium falciparum or P. vivax; non-immune migrants residing in an endemic area in Rondônia;Amazonian Indians from the states of Para (Xingu PA) and Mato Grosso (Xingu MT); people living in a hyperendemic area in Africa (Burkina-Faso); and controls that had never been to a mala ria endemic area. None of the transfusional sera displayed antibo dies against sporozoite or to liver stage antigen, although 80% of the P. falciparum transfusional malaria sera contained IgG antibo dies against the blood-stage peptide. A low percentage of Indians from Xingu PA and of non-immune migrants displayed antibodies against liver-stage (27% and 17%) and sporozoite (11% and 12%) peptides, although a greater frequency of antibodies against blood-stage peptide (50% and 49%) was observed in both cases.Indians from Xingu MT exhibited a greater frequency of antibodies against liver, sporozoite and blood-stage peptides (45%, 50% and 58%). Only hyperimmune African individuals exhibited higher percentages of antibodies against liver-(64%) and blood-stage antigens (87%), contrasting with a low frequency of antibodies against the CS repeat (33%). Taken together, the present data confirm that Rondonian migrants and Indians from Xingu PA consti tute populations with limited exposure and immunity to P. falcipa rum malaria infection and conversely, Xingu MT Indians and Africans have been more exposed to malaria infection. In conclu sion this study indicates that the immune response to these malaria parasite peptides can be used to assess malaria transmission in epidemiological surveys. (0 2 1 )5 9 0 -3 5 4 5 ; P h o n e : (0 2 1 )2 8 0 -1 4 8 6 . Financial support : th e w o rk w as sup ported by th e C om m ission o f th e E u ro p e a n C o m m u n ities and th e B ra z ilia n N ation al R esearch C ouncil. R ésum é : RÉPONSE ANTICORPS À DES PEPTIDES SYNTHÉTIQUES DES STADES SANGUINS HÉPATIQUE ET SPOROZOITE DE P . FALCIPARUM DANS DIFFÉRENTES RÉGIONS ENDÉMIQUES

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