Analysis of var genes cloned from a Plasmodium falciparum isolate in China.

Objective: To analyse the var gene repertoire and characterise the chondroitin sulphate A (CSA)-binding activity of the Duffy-binding like (DBL) domains encoded by the var2csa gene of a Plasmodium falciparum (P. falciparum) isolate in Hainan Province, China.

Methods: The sequences of var DBL1 regions were PCR-amplified, sequenced and the sequence characteristics was bioinformatically analysed. Recombinant proteins encoded by the var2csa genes were expressed and purified. The binding activities of the recombinant proteins to CSA receptor was detected by ELISA assays.

Results: Fifty six unique DBL α sequences were obtained, and the sequences represented similar diversity to the var genes of the genome parasite 3D7. There are two var2csa genes in the P. falciparum isolated from Hainan Province. Unlike in other falciparum parasites such as HB3, the two var2csa genes are more diverged. The receptor-binding capacity of DBL-5ε and DBL-6ε domains of HN var2CSA was studied.

Conclusions: This work represented the diversity of var genes of a P. falciparum isolate in China.