Haplotyping of Plasmodium falciparum Thrombospondin-Related Adhesive Protein Coding Gene in Isolates from Buea, Cameroon

Knowledge of the genetic diversity of leading malaria vaccine candidate genes in various geographical regions is very essential for the development of a very successful malaria vaccine. This study aimed at assessing the haplotype variation of Plasmodium falciparum thrombospondin-related adhesive protein (PfTRAP) gene in malaria isolates from Buea, Cameroon. Parasitized blood samples were collected on whatmann filter papers by finger pricks from 291 participants. Plasmodium infection was assessed by thick and thin blood films. DNA samples were isolated from blood spots using the chelex method and used for falciparum speciation and PfTRAP gene amplification by polymerase chain reaction. PfTRAP amplicons were digested using four different restriction enzymes. The PfTRAP sequences were amplified from 83 of 172 falciparium positive DNA extracts. Digestion of the gene with the BglII gave two of four possible variants {(+-; 2.4%), (--; 100%)}, three with SspI {(+-; 1.2%), (-+; 15%), (--; 80.7%)} and all four with AflII {(+-; 71.1%), (++; 16.9%), (-+; 4.8%); (--; 7.2%)}. The single TaqαI site on the gene was present in 65% of the samples. Haplotype analysis showed that 14 of the 96 possible PfTRAP haplotypes were present in our isolates with haplotype 91 (----+-+) being the most prevalent (32%). We have demonstrated the various PfTRAP haplotypes circulating with low frequency in the malaria endemic region of Buea. These findings will add to the knowledge of the PfTRAP haplotypes circulating worldwide which is very vital for a TRAP-based/multi-antigen malaria vaccine development that will be globally effective.