Human IgG subclass antibodies to the 19 kilodalton carboxy terminal fragment of Plasmodium falciparum merozoite surface protein 1 (MSP1(19)) and predominance of the MAD20 allelic type of MSP1 in Uganda.
OBJECTIVE
To determine the natural human humoral immune responses to the 19 kilodalton carboxy terminal fragment of Plasmodium falciparum merozoite surface protein 1 (MSP1(19)), a malaria candidate vaccine antigen and to determine the prevalence of MAD20 and K1 alleles of P. falciparum MSP1.


METHODS
Community based cross-sectional study.


METHODS
Atopi Parish, Apac District, Uganda, 1995.


METHODS
Three hundred and seventy four Ugandans between <1 and 70 years old provided serum samples.


METHODS
IgG subclass antibodies by ELISA; MAD20 and K1 allelic types of MSP1 by PCR.


RESULTS
Both the prevalence and the mean concentration of serum IgG1, and to a lesser extent IgG3, antibodies increased with age. IgG2 or IgG4 antibodies were virtually nonexistent. The cross-reactivity between the 4 sequence variants (E-KNG, E-TSR, Q-KNG and Q-TSR) of MSP1(19) was confirmed; however, a minority of sera preferentially recognised the KNG but not the TSR variants. All 33 P. falciparum isolates from different parts of Uganda carried the E-TSR (Mad20) allelic type and 3 isolates were mixed infections with E-TSR (MAD20) and Q-KNG (K1) allelic types, confirming the rarity of the K1 allele in Uganda.


CONCLUSIONS
There is a robust IgG1 antibody response to the malaria vaccine candidate antigen MSP1(19) which begins at an early age. Future cohort studies are necessary to estblish the impact of these antibodies on clinical immunity to malaria. The MAD20 allelic type of MSP1 id predominant in Ugandan P. falciparum isolates.
Apio
B
B
Med Biotech Laboratories, Kampala, Uganda.
Nalunkuma
A
A
Okello
D
D
Riley
E
E
Egwang
T G
TG
D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood*; D000953:Antigens, Protozoan / Q000235:genetics / Q000276:immunology; D003429:Cross Reactions; D004797:Enzyme-Linked Immunosorbent Assay; D005787:Gene Frequency; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood*; D016778:Malaria, Falciparum / Q000453:epidemiology / Q000276:immunology; D020066:Merozoite Surface Protein 1 / Q000235:genetics / Q000276:immunology*; D008970:Molecular Weight; D010446:Peptide Fragments / Q000235:genetics / Q000276:immunology; D010963:Plasmodium falciparum / Q000235:genetics / Q000276:immunology*; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D016036:Seroepidemiologic Studies; D014454:Uganda / Q000453:epidemiology
D000913:Antibodies, Protozoan; D000953:Antigens, Protozoan; D007074:Immunoglobulin G; D020066:Merozoite Surface Protein 1; D010446:Peptide Fragments