Erythrocyte Binding Activity of PkDBPαII of Plasmodium knowlesi Isolated from High and Low Parasitemia Cases

Invasion of Plasmodium knowlesi merozoite into human erythrocytes involves molecular interaction between the parasite's Duffy binding protein (PkDBP alpha II) and the Duffy antigen receptor for chemokines on the erythrocytes. This study investigates the binding activity of human erythrocyte with PkDBP alpha II of P. knowlesi isolates from high and low parasitemic patients in an erythrocyte binding assay. The binding activity was determined by counting the number and measuring the size of rosettes formed in the assay. The protein PkDBP alpha II of P. knowlesi isolated from low parasitemia cases produced significantly higher number of rosettes with human erythrocytes than high parasitemia case isolates (65.5 +/- 12.9 and 17.2 +/- 5.5, respectively). Interestingly, PkDBP alpha II of isolates from high parasitemia cases formed significantly larger rosettes with human erythrocytes than PkDBP alpha II of isolates from low parasitemia cases (18,000 +/- 13,000 mu m(2) and 1,315 +/- 623 mu m(2), respectively).

Automated summary

The binding activity of PkDBP alpha II from P. knowlesi isolates is affected by the parasitemia level of patients' blood, with isolates from low parasitemia cases showing higher binding activity but significantly smaller rosettes compared to isolates from high parasitemia cases.