title: Stable Allele Frequency Distribution of the Plasmodium falciparum clag Genes Encoding Components of the High Molecular Weight Rhoptry Protein Complex.
abstract: Plasmodium falciparum Clag protein is a candidate component of the plasmodial surface anion channel located on the parasite-infected erythrocyte. This protein is encoded by 5 separated clag genes and forms a RhopH complex with the other components. Previously, a signature of positive diversifying selection was detected on the hypervariable region of clag2 and clag8 by population-based analyses using P. falciparum originating from Thailand in 1988-1989. In this study, we obtained the sequence of this region of 3 clag genes (clag2, clag8, and clag9) in 2005 and evaluated the changes over time in the frequency distribution of the polymorphism of these gene products by comparison with the sequences obtained in 1988-1989. We found no difference in the frequency distribution of 18 putatively neutral loci between the 2 groups, evidence that the background of the parasite population structure has remained stable over 14 years. Although the frequency distribution of most of the polymorphic sites in the hypervariable region of Clag2, Clag8, and Clag9 was stable over 14 years, we found that a proportion of the major Clag2 group and one amino acid position of Clag8 changed significantly. This may be a response to a certain type of pressure.
authors.affiliation: Department of Protozoology, Institute of Tropical Medicine (NEKKEN) and the Global COE Program, Nagasaki University, Sakamoto, Nagasaki 852-8523, Japan ; Centro Nacional de Control de Enfermedades Tropicales, Santo Domingo, República Dominicana.
authors.forename: Jean Semé Fils
authors.initials: JS
authors.lastname: Alexandre
authors.forename: Phonepadith
authors.initials: P
authors.lastname: Xangsayarath
authors.forename: Morakot
authors.initials: M
authors.lastname: Kaewthamasorn
authors.forename: Kazuhide
authors.initials: K
authors.lastname: Yahata
authors.forename: Jetsumon
authors.initials: J
authors.lastname: Sattabongkot
authors.forename: Rachanee
authors.initials: R
authors.lastname: Udomsangpetch
authors.forename: Osamu
authors.initials: O
authors.lastname: Kaneko