Positive Diversifying Selection on the Plasmodium falciparum surf4.1 Gene in Thailand

Phonepadith Xangsayarath; Morakot Kaewthamasorn; Kazuhide Yahata; Shusuke Nakazawa; Jetsumon Sattabongkot; Rachanee Udomsangpetch; Osamu Kaneko

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Positive Diversifying Selection on the Plasmodium falciparum surf_4.1 Gene in Thailand

Author: Phonepadith Xangsayarath ; Morakot Kaewthamasorn ; Kazuhide Yahata ; Shusuke Nakazawa ; Jetsumon Sattabongkot ; Rachanee Udomsangpetch ; Osamu Kaneko
Publication Type:Journal Article
Keywords: Plasmodium falciparum positive diversifying selection; allele frequency distribution
From:Tropical Medicine and Health 2012;40(3):79-87
CountryJapan
Language:English
Abstract: Plasmodium falciparum SURFIN_4.1 is a type I transmembrane protein thought to locate on the merozoite surface and to be responsible for a reversible adherence to the erythrocyte before invasion. In this study, we evaluated surf_4.1 gene segment encoding extracellular region for polymorphism, the signature of positive selection, the degree of linkage disequilibrium, and temporal change in allele frequency distribution in P. falciparum isolates from Thailand in 1988–89, 2003, and 2005. We found that SURFIN_4.1 is highly polymorphic, particularly at the C-terminal side of the variable region located just before a predicted transmembrane region. A signature of positive diversifying selection on the variable region was detected by multiple tests and, to a lesser extent, on conserved N-terminally located cysteine-rich domain by Tajima’s D test. Linkage disequilibrium between sites over a long distance (> 1.5 kb) was detected, and multiple SURFIN_4.1 haplotype sequences detected in 1988/89 still circulated in 2003. Few of the single amino acid polymorphism allele frequency distributions were significantly different between the 1988/89 and 2003 groups, suggesting that the frequency distribution of SURFIN_4.1 extracellular region remained stable over 14 years.