Relative frequencies of polymorphisms of variation in Block 2 repeats and 5' recombinant types of Plasmodium falciparum msp1 alleles.
The mechanisms producing the genetic polymorphism at Plasmodium falciparum merozoite surface antigen-1 locus (pfmsp1) include the insertion and deletion of the different type of dimorphic Block 2 9-nucleotide repeat units as well as the intragenic recombination. To study relative occurrence frequencies of these two distinct mechanisms, we have developed a sensitive PCR strategy to identify both 5' recombinant types and the number of Block 2 repeats from the same sample. This method can specifically detect the target 5' recombinant type (Blocks 2-6) at the sensitivity of 1-4 copies of the pfmsp1. Applying the new method to field isolates from the Solomon Islands enabled us to identify six different 5' recombinant types and variation in Block 2 repeat number in three of them, thus distinguishing 10 different alleles. Distribution of these alleles in local three villages in the study area suggests that frequencies of variation in the number of Block 2 9-bp repeats and recombination events within Blocks 2-6 are mutually independent and the frequency of repeat variation is relatively high as compared to that of recombination events at the pfmsp1 locus in P. falciparum populations from the Solomon Islands.
Laboratory of Biology, Osaka Institute of Technology, 5-16-1, Ohmiya, Asahi-ku, Osaka 535-8585, Japan.
Naoko
N
Sakihama
Toshiaki
T
Matsuo
Toshihide
T
Mitamura
Toshihiro
T
Horii
Masatsugu
M
Kimura
Masato
M
Kawabata
Kazuyuki
K
Tanabe
D020121:5' Untranslated Regions; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D002648:Child; D002675:Child, Preschool; D005260:Female; D005787:Gene Frequency; D014644:Genetic Variation; D006801:Humans; D016778:Malaria, Falciparum / Q000469:parasitology; D008297:Male; D020066:Merozoite Surface Protein 1 / Q000235:genetics*; D008875:Middle Aged; D010963:Plasmodium falciparum / Q000145:classification* / Q000235:genetics; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D011995:Recombination, Genetic; D012680:Sensitivity and Specificity; D020080:Tandem Repeat Sequences
D020121:5' Untranslated Regions; D020066:Merozoite Surface Protein 1