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Open Access Research

Polymorphism and epitope sharing between the alleles of merozoite surface protein-1 of Plasmodium falciparum among Indian isolates

Anitha Mamillapalli13, Sujatha Sunil2, Suraksha S Diwan2, Surya K Sharma1, Prajesh K Tyagi1, Tridibes Adak1, Hema Joshi1 and Pawan Malhotra2*

Author Affiliations

1 Department of Parasitolgy, National Institute for Malaria Research, New Delhi, India

2 Malaria Group, Internationl Centre for Genetic Engineering and Biotechnology, New Delhi, India

3 presently working at Centre for Cellular and Molecular Biology, Hyderabad, India

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Malaria Journal 2007, 6:95  doi:10.1186/1475-2875-6-95

Published: 20 July 2007

Abstract

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.

Conclusion

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.