The analysis of Plasmodium vivax Duffy receptor binding domain gene sequence from resurgent Korea isolates

The Duffy binding domain gene structures of Plasmodium vivax facilitate the invasion of erythrocytes. Human erythrocytes that lack Duffy blood group a ntigens are resistant to invasion by P. vivax. We have sequenced the Duffy binding domain gene from eight P. vivax isolates collected from malaria cas es in South Korea. When compared to isolates from other regions in the worl d, the amino acid sequences of the Korean isolates showed unique variations in region II. From 606 sequenced amino acids, 32 variations were found. Of these, three variations were regularly found in positions 424, 437 and 503 of the Sal-1 amino acid sequence. In region III, six isolates had a loss o f the 30 by (FAESTKSAE) insert. However, six isolates had 6 by (SD) inserts at the end of region III. Two cases had a reverse pattern. Our results sug gest that the P. vi vax currently found in South Korea are unique when comp ared to other isolates and can be divided, by the analysis of their molecul ar structure, into two strains.