Genetic diversity of three surface protein genes in Plasmodium malariae from three Asian countries

• Published in: Malaria Journal
• Main Authors: Suttipat Srisutham, Naowarat Saralamba, Kanlaya Sriprawat, Mayfong Mayxay, Frank Smithuis, Francois Nosten, Sasithon Pukrittayakamee, Nicholas P. J. Day, Arjen M. Dondorp, Mallika Imwong
• Format: Article in Journal/Newspaper
• Language: English
• Published: BMC 2018
• Subjects: Plasmodium malariae; TRAP; AMA1; P48/45; Arctic medicine. Tropical medicine; RC955-962; Infectious and parasitic diseases; RC109-216; Arctic
• Online Access: https://doi.org/10.1186/s12936-018-2176-x; https://doaj.org/article/d903ba15d12340939854ba1f4b4cce3f

Abstract Background Genetic diversity of the three important antigenic proteins, namely thrombospondin-related anonymous protein (TRAP), apical membrane antigen 1 (AMA1), and 6-cysteine protein (P48/45), all of which are found in various developmental stages of Plasmodium parasites is crucial for targeted vaccine development. While studies related to the genetic diversity of these proteins are available for Plasmodium falciparum and Plasmodium vivax, barely enough information exists regarding Plasmodium malariae. The present study aims to demonstrate the genetic variations existing among these three genes in P. malariae by analysing their diversity at nucleotide and protein levels. Methods Three surface protein genes were isolated from 45 samples collected in Thailand (N = 33), Myanmar (N = 8), and Lao PDR (N = 4), using conventional polymerase chain reaction (PCR) assay. Then, the PCR products were sequenced and analysed using BioEdit, MEGA6, and DnaSP programs. Results The average pairwise nucleotide diversities (π) of P. malariae trap, ama1, and p48/45 were 0.00169, 0.00413, and 0.00029, respectively. The haplotype diversities (Hd) of P. malariae trap, ama1, and p48/45 were 0.919, 0.946, and 0.130, respectively. Most of the nucleotide substitutions were non-synonymous, which indicated that the genetic variations of these genes were maintained by positive diversifying selection, thus, suggesting their role as a potential target of protective immune response. Amino acid substitutions of P. malariae TRAP, AMA1, and P48/45 could be categorized to 17, 20, and 2 unique amino-acid variants, respectively. For further vaccine development, carboxyl terminal of P48/45 would be a good candidate according to conserved amino acid at low genetic diversity (π = 0.2–0.3). Conclusions High mutational diversity was observed in P. malariae trap and ama1 as compared to p48/45 in P. malariae samples isolated from Thailand, Myanmar, and Lao PDR. Taken together, these results suggest that P48/45 might be a good vaccine candidate ...