Genetic diversity of the merozoite surface protein-3 gene in Plasmodium falciparum populations in Thailand

Malaria Journal

Research

Napaporn Siripoon¹  Phumin Simpalipan²  Sittiporn Pattaradilokrat²  Pongchai Harnyuttanakorn²  Vorthon Sawaswong²  Morakot Kaewthamasorn³ 

[1] College of Public Health Sciences, Chulalongkorn University, 10330, Bangkok, Thailand;Department of Biology, Faculty of Science, Chulalongkorn University, 10330, Bangkok, Thailand;Department of Pathology, Faculty of Veterinary Science, Chulalongkorn University, 10330, Bangkok, Thailand;

关键词: DNA sequencing;    Genetic diversity;    Vaccine;    Merozoite surface protein;    Southeast Asia;   

DOI  :  10.1186/s12936-016-1566-1

 received in 2016-07-15, accepted in 2016-10-07,  发布年份 2016

来源: Springer

【 摘 要 】

BackgroundAn effective malaria vaccine is an urgently needed tool to fight against human malaria, the most deadly parasitic disease of humans. One promising candidate is the merozoite surface protein-3 (MSP-3) of Plasmodium falciparum. This antigenic protein, encoded by the merozoite surface protein (msp-3) gene, is polymorphic and classified according to size into the two allelic types of K1 and 3D7. A recent study revealed that both the K1 and 3D7 alleles co-circulated within P. falciparum populations in Thailand, but the extent of the sequence diversity and variation within each allelic type remains largely unknown.MethodsThe msp-3 gene was sequenced from 59 P. falciparum samples collected from five endemic areas (Mae Hong Son, Kanchanaburi, Ranong, Trat and Ubon Ratchathani) in Thailand and analysed for nucleotide sequence diversity, haplotype diversity and deduced amino acid sequence diversity. The gene was also subject to population genetic analysis (Fst) and neutrality tests (Tajima’s D, Fu and Li D* and Fu and Li’ F* tests) to determine any signature of selection.ResultsThe sequence analyses revealed eight unique DNA haplotypes and seven amino acid sequence variants, with a haplotype and nucleotide diversity of 0.828 and 0.049, respectively. Neutrality tests indicated that the polymorphism detected in the alanine heptad repeat region of MSP-3 was maintained by positive diversifying selection, suggesting its role as a potential target of protective immune responses and supporting its role as a vaccine candidate. Comparison of MSP-3 variants among parasite populations in Thailand, India and Nigeria also inferred a close genetic relationship between P. falciparum populations in Asia.ConclusionThis study revealed the extent of the msp-3 gene diversity in P. falciparum in Thailand, providing the fundamental basis for the better design of future blood stage malaria vaccines against P. falciparum.

【 授权许可】

CC BY   
© The Author(s) 2016