Genetic polymorphism of the Duffy receptor binding domain of Plasmodium vivax in Colombian wild isolates

The Plasmodium vivax Duffy receptor binding protein (DBP) is a member of the protein family localized in the Plasmodium parasite micronemes that binds to erythrocytes carrying this receptor. Given its importance in the parasite life cycle, it is being considered as a potential candidate in vaccine development against P. vivax infection. Its molecular weight is 140 kDa and the primary structure has been previously reported for the Sal-I strain. This protein is divided into five important regions: a leader peptide sequence, two cysteine rich regions separated by a non-homologous hydrophilic region, and a transmembrane domain. The amino terminal cysteine-rich region has been implicated in the binding process to red blood cells (RBCs) carrying the Duffy receptor in a way analagous to what has been demonstrated with the EBA-175 protein of P. falciparum. A previous report showed natural variation within this critical ligand domain in the P. vivax Sal-I strain. Polymorphism studies within this region are highly significant for the rational design vaccines against asexual blood stages of P. vivax.