title: Differential sequence diversity at merozoite surface protein-1 locus of Plasmodium knowlesi from humans and macaques in Thailand.
abstract: To determine the genetic diversity and potential transmission routes of Plasmodium knowlesi, we analyzed the complete nucleotide sequence of the gene encoding the merozoite surface protein-1 of this simian malaria (Pkmsp-1), an asexual blood-stage vaccine candidate, from naturally infected humans and macaques in Thailand. Analysis of Pkmsp-1 sequences from humans (n=12) and monkeys (n=12) reveals five conserved and four variable domains. Most nucleotide substitutions in conserved domains were dimorphic whereas three of four variable domains contained complex repeats with extensive sequence and size variation. Besides purifying selection in conserved domains, evidence of intragenic recombination scattering across Pkmsp-1 was detected. The number of haplotypes, haplotype diversity, nucleotide diversity and recombination sites of human-derived sequences exceeded that of monkey-derived sequences. Phylogenetic networks based on concatenated conserved sequences of Pkmsp-1 displayed a character pattern that could have arisen from sampling process or the presence of two independent routes of P. knowlesi transmission, i.e. from macaques to human and from human to humans in Thailand.
authors.affiliation: Molecular Biology of Malaria and Opportunistic Parasites Research Unit, Department of Parasitology, Faculty of Medicine, Chulalongkorn University, Bangkok 10330, Thailand. p.chaturong@gmail.com
authors.forename: Chaturong
authors.initials: C
authors.lastname: Putaporntip
authors.forename: Siriporn
authors.initials: S
authors.lastname: Thongaree
authors.forename: Somchai
authors.initials: S
authors.lastname: Jongwutiwes
mesh_terms: D000818:Animals; D016054:DNA, Protozoan / Q000235:genetics; D014644:Genetic Variation; D006239:Haplotypes; D006801:Humans; D008251:Macaca / Q000469:parasitology; D008288:Malaria / Q000469:parasitology* / Q000662:veterinary*; D020066:Merozoite Surface Protein 1 / Q000737:chemistry / Q000235:genetics*; D008992:Monkey Diseases / Q000469:parasitology*; D010802:Phylogeny; D016790:Plasmodium knowlesi / Q000235:genetics*; D011995:Recombination, Genetic; D013785:Thailand
chemical_list: D016054:DNA, Protozoan; D020066:Merozoite Surface Protein 1
keywords: Human-to-human transmission; Merozoite surface protein 1; Mosaic organization; Phylogenetic networks; Plasmodium knowlesi; Recombination