Polymorphism and epitope sharing between the alleles of merozoite surface protein-1 of Plasmodium falciparum among Indian isolates.
BACKGROUND
The C-terminal region of merozoite surface protein-1 (MSP-1) is one of the leading candidates for vaccination against the erythrocytic stages of malaria. However, a major concern in the development of MSP-1 based malaria vaccine is the polymorphism observed in different geographical Plasmodium falciparum isolates. To explore whether the sequence heterogeneity of PfMSP-1 leads to variation in naturally acquired anti-MSP-119 antibodies, the present study was undertaken to study PfMSP-119 sequence polymorphism in malaria-endemic villages in eastern India and also carried out a competition enzyme-linked immunosorbent assay using three PfMSP-119 variant forms.


METHODS
The sequence variations in the C-terminal region of PfMSP-119 were determined in a malaria endemic region. Three PfMSP-119 variants were produced in Escherichia coli (PfMSP119QKNG-L, PfMSP119EKNG-L and PfMSP119ETSR-F) and an immunodepletion assay was carried out using the corresponding patients' sera.


RESULTS
Results revealed predominance of PfMAD20 allele among Indian field isolates. Seven PfMSP-119 variant forms were isolated in a singe geographical location. Three of PfMSP-119 variant forms when expressed in E. coli showed presence of cross-reaction as well as variant specific antibodies in malaria infected patient sera.


CONCLUSIONS
The present study demonstrates the existence of allele specific antibodies in P. falciparum-infected patient sera, however their role in protection requires further investigation. These results thereby, suggest the importance of a multi-allelic PfMSP-119 based vaccine for an effective malaria control.
Mamillapalli
Anitha
A
Department of Parasitolgy, National Institute for Malaria Research, New Delhi, India. anitha52@hotmail.com <anitha52@hotmail.com>
Sunil
Sujatha
S
Diwan
Suraksha S
SS
Sharma
Surya K
SK
Tyagi
Prajesh K
PK
Adak
Tridibes
T
Joshi
Hema
H
Malhotra
Pawan
P
D000293:Adolescent; D000483:Alleles; D000595:Amino Acid Sequence; D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood / Q000276:immunology; D000953:Antigens, Protozoan / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D002648:Child; D002675:Child, Preschool; D004797:Enzyme-Linked Immunosorbent Assay; D000939:Epitopes / Q000235:genetics*; D018740:Genetic Heterogeneity; D006801:Humans; D015151:Immunoblotting; D007194:India; D007223:Infant; D016778:Malaria, Falciparum / Q000097:blood / Q000469:parasitology; D020066:Merozoite Surface Protein 1 / Q000235:genetics* / Q000276:immunology / Q000378:metabolism; D008969:Molecular Sequence Data; D010963:Plasmodium falciparum / Q000235:genetics* / Q000276:immunology; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D015800:Protozoan Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid
D000913:Antibodies, Protozoan; D000953:Antigens, Protozoan; D000939:Epitopes; D020066:Merozoite Surface Protein 1; D015800:Protozoan Proteins