Circumsporozoite Protein from <em>Plasmodium vivax</em> and its Relationship to Human Malaria

The circumsporozoite surface protein (CSP) is the most abundant polypeptide in the sporozoite covering. This protein is involved in the motility and invasion of the sporozoite during its entrance in the hepatocyte. Plasmodium vivax CSP sequences analyses revealed that parasites have repeats belonging to three types of peptide repeat units, named VK210, VK247 or P. vivax-like, this last differ from the two previously described variants. All P. vivax CS genotypes have a worldwide distribution by genetic and serological evaluation. Studies have also reported differences in the infectivity of anophelines to the variant genotypes, indicating that different malaria vectors were more susceptible to the infection by VK210. These findings could be a consequence of differences in the emergence of this genotype in specific regions around the world. These polymorphisms are associated to the increase of nonregulated inflammatory immune responses, which in turn may be associated with the outcome of infection. Geographic coexistence of these variants increase drug resistance and also recurrent parasite behavior. Knowledge of the P. vivax genome contributed to several discoveries, however, new studies are still needed to evaluate its potential as a promising vaccine target.