Antibody Responses to Plasmodium falciparum Merozoite Surface Protein–1 and Efficacy of Amodiaquine in Gabonese Children with P. falciparum Malaria

The relationship between the efficacy of amodiaquine for the treatment of uncomplicated Plasmodium falciparum malaria and preexisting antibodies against merozoite surface protein (MSP)–1, a blood-stage P. falciparum antigen, was investigated. The immunoglobulin G antibody response to different MSP-1 recombinant proteins was evaluated in plasma samples from Gabonese children with uncomplicated malaria who were treated with amodiaquine. The prevalence of anti–MSP-1 antibodies was similar among patients with either parasitological and clinical cure after treatment (n=102) or treatment failure (n=51) by day 28 (83% in both groups). However, associations between antibody responses to K1 and MAD20 allelic families and therapeutic success were found (P