Genetic diversity and population structure of genes encoding vaccine candidate antigens of Plasmodium vivax

Genetic variability was assessed in important polymorphic regions of various vaccine candidate antigens in P. vivax among 106 isolates from the Amazon Region of Loreto, Peru. In addition, genetic diversity determined in Peruvian isolates was compared to population studies from various geographical locations worldwide.The structured diversity found in P. vivax populations did not show a geographic pattern and haplotypes from all gene candidates were distributed worldwide. In addition, evidence of balancing selection was found in polymorphic regions of the trap, dbp and ama-1 genes.It is important to have a good representation of the haplotypes circulating worldwide when implementing a vaccine, regardless of the geographic region of deployment since selective pressure plays an important role in structuring antigen diversity.Malaria is one of the major global public health problems that affect most tropical regions of the world. Even though Plasmodium falciparum is the most virulent, it is estimated that Plasmodium vivax produces around 80 to 300 million clinical cases per year [1]. Furthermore, there have been several reports of severe P. vivax malaria cases in the last few years [2-4]. In 2008, 560,221 malaria cases were reported in the Americas [5]; 74.2% of them caused by P. vivax and 25.7% by P. falciparum [1]. About 90% of these malaria cases originated in the Amazon basin shared by Bolivia, Brazil, Colombia, Ecuador, French Guiana, Guyana, Venezuela, Suriname and Peru [5], whereas the other 10% was contributed by non-Amazon regions.Developing a vaccine for P. vivax represents a major challenge especially considering the lack of in vitro cultures. Thus, current efforts focus on orthologs of P. falciparum. Over the past four decades, experiments performed in animals and human subjects have led to the development of several Plasmodium vaccine candidates. Antigenic surface proteins such as the Circumsporozoite protein (CSP), Thrombospondin related anonymous protein