Next generation sequencing to detect variation in the Plasmodium falciparum circumsporozoite protein.

The malaria vaccine RTS,S/AS01, based on immunogenic regions of the Plasmodium falciparum circumsporozoite protein (CSP), has partial efficacy against clinical malaria in African children. Understanding how sequence diversity in CSP T- and B-cell epitopes relates to naturally acquired and vaccine-induced immunity may be useful in efforts to improve the efficacy of CSP-based vaccines. However, limitations in sequencing technology have precluded thorough evaluation of diversity in the immunogenic regions of this protein. In this study, 454, a next generation sequencing technology, was evaluated as a method for assessing diversity in these regions. Portions of the circumsporozoite gene (cs) were sequenced both by 454 and Sanger sequencing from samples collected in a study in Bandiagara, Mali. 454 detected more single nucleotide polymorphisms and haplotypes in the T-cell epitopes than Sanger sequencing, and it was better able to resolve genetic diversity in samples with multiple infections; however, it failed to generate sequence for the B-cell epitopes.