A Plasmodium vivax vaccine candidate displays limited allele polymorphism, which does not restrict recognition by antibodies.
BACKGROUND
The 19 kDa C-terminal region of the merozoite surface protein 1 (MSP1(19)) has been suggested as candidate for part of a subunit vaccine against malaria. A major concern in vaccine development is the polymorphism observed in different plasmodial strains. The present study examined the extension and immunological relevance of the allelic polymorphism of the MSP1(19) from Plasmodium vivax, a major human malaria parasite.


METHODS
We cloned and sequenced 88 gene fragments representing the MSP1(19) from 28 Brazilian isolates of P. vivax. Subsequently, we evaluated the reactivity of rabbit polyclonal antibodies, a monoclonal antibody, and a panel of 80 human sera to bacterial and yeast recombinant proteins representing the two allelic forms of P. vivax MSP1(19) described thus far.


RESULTS
We observed that DNA sequences encoding MSP1(19) were not as variable as the equivalent region of other species of Plasmodium, being conserved among Brazilian isolates of P. vivax. Also, we found that antibodies are directed mainly to conserved epitopes present in both allelic forms of the protein.


CONCLUSIONS
Our findings suggest that the use of MSP1(19) as part of a subunit vaccine against P. vivax might be greatly facilitated by the limited genetic polymorphism and predominant recognition of conserved epitopes by antibodies.
Soares
I S
IS
Departamento de Microbiologia, Imunologia e Parasitologia, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil.
Barnwell
J W
JW
Ferreira
M U
MU
Gomes Da Cunha
M
M
Laurino
J P
JP
Castilho
B A
BA
Rodrigues
M M
MM
D000483:Alleles; D000818:Animals; D000906:Antibodies / Q000276:immunology; D001426:Bacterial Proteins / Q000235:genetics / Q000276:immunology; D001938:Brazil; D005656:Fungal Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D006801:Humans; D007106:Immune Sera; D016780:Malaria, Vivax / Q000276:immunology*; D020066:Merozoite Surface Protein 1 / Q000235:genetics* / Q000276:immunology*; D010966:Plasmodium vivax / Q000235:genetics / Q000276:immunology*; D011110:Polymorphism, Genetic; D016052:Protozoan Vaccines; D011817:Rabbits; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism
D000906:Antibodies; D001426:Bacterial Proteins; D005656:Fungal Proteins; D007106:Immune Sera; D020066:Merozoite Surface Protein 1; D016052:Protozoan Vaccines; D011993:Recombinant Fusion Proteins