A longitudinal study of human antibody responses to Plasmodium falciparum rhoptry-associated protein 1 in a region of seasonal and unstable malaria transmission.
Rhoptry-associated protein 1 (RAP1) of Plasmodium falciparum is a nonpolymorphic merozoite antigen that is considered a potential candidate for a malaria vaccine against asexual blood stages. In this longitudinal study, recombinant RAP1 (rRAP1) proteins with antigenicity similar to that of P. falciparum-derived RAP1 were used to analyze antibody responses to RAP1 over a period of 4 years (1991 to 1995) of 53 individuals naturally exposed to P. falciparum malaria. In any 1 year during the study, between 23 and 39% of individuals who had malaria developed immunoglobulin G (IgG) antibodies detectable with at least one rRAP1 protein. However, the anti-RAP1 antibody responses were detected only during or shortly after clinical malarial infections. RAP1 antibody levels declined rapidly (within 1 to 2 months) following drug treatment of the infections. No anti-RAP1 antibodies were usually detected a few months after the end of malaria transmission, during the dry season, or by the start of the next malaria season. Thus, RAP1 IgG responses were very short-lived. The short duration of RAP1 antibody response may explain the apparent lack of response in a surprisingly high proportion of individuals after clinical malarial infections. For some individuals who experienced more than one malarial infection, a higher anti-RAP1 antibody response to subsequent infections than to earlier infections was observed. This suggested secondary responses to RAP1 and thus the development of immunological memory for RAP1.
Fonjungo
P N
PN
Institute of Cell, Animal and Population Biology, University of Edinburgh, Edinburgh EH9 3JT, Scotland.
Elhassan
I M
IM
Cavanagh
D R
DR
Theander
T G
TG
Hviid
L
L
Roper
C
C
Arnot
D E
DE
McBride
J S
JS
D000328:Adult; D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood / Q000276:immunology*; D000953:Antigens, Protozoan / Q000276:immunology*; D015331:Cohort Studies; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood / Q000276:immunology; D007075:Immunoglobulin M / Q000097:blood / Q000276:immunology; D008137:Longitudinal Studies; D016778:Malaria, Falciparum / Q000097:blood / Q000276:immunology* / Q000635:transmission; D010963:Plasmodium falciparum / Q000276:immunology; D015800:Protozoan Proteins / Q000276:immunology*; D011993:Recombinant Fusion Proteins / Q000276:immunology; D012621:Seasons; D013997:Time Factors
D000913:Antibodies, Protozoan; D000953:Antigens, Protozoan; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D015800:Protozoan Proteins; D011993:Recombinant Fusion Proteins; C065352:rhoptry associated protein, Plasmodium