Population structure of the genes encoding the polymorphic Plasmodium falciparum apical membrane antigen 1: implications for vaccine design.
Immunization with the highly polymorphic Plasmodium falciparum apical membrane antigen 1 (PfAMA1) induces protection in animals but primarily against parasites that express the same or similar alleles. One strategy to overcome the obstacle of polymorphism is to combine PfAMA1 proteins representing major haplotypes into one vaccine. To determine the minimum number of haplotypes that would confer broad protection, we sequenced the coding region of PfAMA1 from 97 clones from around the world and 61 isolates from Mali, identifying 150 haplotypes for domains 1 to 3 that included previous sequences. A clustering algorithm grouped the 150 haplotypes into six populations that were independent of geographic location. Each of the six populations contained haplotypes predominantly of that population (predominant haplotypes) and haplotypes that were a mixture of haplotypes represented in other populations (admixed haplotypes). To determine the biological relevance of the populations identified through the clustering algorithm, antibodies induced against one predominant haplotype of population 1 (3D7) and one admixed haplotype of population 5 (FVO) were tested for their ability to block parasite invasion of erythrocytes. Parasites expressing PfAMA1s belonging to population 1 were efficiently inhibited by 3D7-specific antibodies, whereas parasites expressing PfAMA1s belonging to other populations were not. For FVO-specific antibodies, we observed growth inhibition against itself as well as isolates belonging to populations 3 and 6. Our data suggests that the inclusion of PfAMA1 sequences from each of the six populations may result in a vaccine that induces protective immunity against a broad range of malaria parasites.
Malaria Vaccine Development Branch, National Institute of Allergy and Infections Diseases, National Institutes of Health, Bethesda, MD 20892-0425, USA.
Junhui
J
Duan
Jianbing
J
Mu
Mahamadou Ali
MA
Thera
Deirdre
D
Joy
Sergei L
SL
Kosakovsky Pond
David
D
Diemert
Carole
C
Long
Hong
H
Zhou
Kazutoyo
K
Miura
Amed
A
Ouattara
Amagana
A
Dolo
Ogobara
O
Doumbo
Xin-Zhuan
XZ
Su
Louis
L
Miller
D000818:Animals; D000953:Antigens, Protozoan / Q000145:classification / Q000235:genetics* / Q000276:immunology*; D015195:Drug Design; D006239:Haplotypes; D017780:Malaria Vaccines / Q000235:genetics* / Q000276:immunology*; D008565:Membrane Proteins / Q000145:classification / Q000235:genetics* / Q000276:immunology*; D010963:Plasmodium falciparum / Q000145:classification / Q000235:genetics* / Q000276:immunology*; D020641:Polymorphism, Single Nucleotide; D011153:Population / Q000235:genetics; D015800:Protozoan Proteins / Q000145:classification / Q000235:genetics* / Q000276:immunology*; D017422:Sequence Analysis, DNA; D020539:Sequence Analysis, Protein
D000953:Antigens, Protozoan; D017780:Malaria Vaccines; D008565:Membrane Proteins; D015800:Protozoan Proteins; C090077:apical membrane antigen I, Plasmodium