Natural antibody response to Plasmodium falciparum merozoite antigens MSP5, MSP9 and EBA175 is associated to clinical protection in the Brazilian Amazon

摘要: Antibodies have an essential role in the acquired immune response against blood stage P. falciparum infection. Although several antigens been identified as important antibody targets, it is still elusive which to be recognized for clinical protection. Herein, we analyzed antibodies from plasmas symptomatic or asymptomatic individuals living same geographic area Western Amazon, measuring their recognition of multiple merozoite antigens. Specific fragments genes encoding proteins AMA1 and members MSP EBL families circulating field isolates present patients were amplified by PCR. After cloning expression different versions recombinant GST-fusion peptides, tested reactivity patients’ ELISA presence IgG subclasses most reactive plasmas. 11 out 24 either infections. MSP9 (X2 DF=1 = 9.26/p = 0.0047) MSP5 (X2 DF=1 = 8.29/p = 0.0069) more prevalent whereas opposite was observed MSP1 block 2-MAD20 (X2 DF=1 = 6.41/p = 0.0206, Fisher’s exact test). Plasmas reacted intensely MSP4 (U = 210.5, p < 0.03), (U = 212, p < 0.004), (U = 189.5, p < 0.002) EBA175 (U = 197, p < 0.014, Mann-Whitney’s U IgG1 IgG3 predominant all antigens, but some also presented with IgG2 IgG4. The (OR = 0.112, IC95% = 0.021-0.585) (OR = 0.125, IC95% = 0.030-0.529, cross tab analysis) predicted 8.9 8 times less chances, respectively, symptoms. Higher levels associated odds ratios 9.4 (IC95% = 1.29-69.25) 5.7 (IC95% = 1.12-29.62, logistic regression), status. Merozoite targets cytophilic MSP5, independently decreased