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High genetic polymorphism of relapsing P. vivax isolates in northwest Colombia.

ABSTRACT: Genetic diversity of Plasmodium populations has been more extensively documented in Colombia for Plasmodium falciparum than for Plasmodium vivax. Recently, highly variable microsatellite markers have been described and used in population-level studies of genetic variation of P. vivax throughout the world. We applied this approach to understand the genetic structure of P. vivax populations and to identify recurrence-associated haplotypes. In this, three microsatellite markers of P. vivax were amplified and the combined size of the fragments was used to establish genotypes. Patients from an ongoing treatment efficacy trial who were kept either in endemic or non-endemic regions in the northwest of Colombia were included in the study. In total 58 paired clinical isolates, were amplified. A total of 54 haplotypes were observed among the two regions. Some haplotypes were exclusive to the endemic region where the highest degree of polymorphism was detected. In addition, we confirmed the different genotypes of recurrent-relapsing and primary infection isolates suggesting the activation of heterologous hypnozoite populations. We conclude that analysis of the three microsatellites is a valuable tool to establish the genetic characteristics of P. vivax populations in Colombia.

SUBMITTER: Restrepo E

PROVIDER: S-EPMC3485554 | biostudies-literature | 2011 Jul

REPOSITORIES: biostudies-literature

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High genetic polymorphism of relapsing P. vivax isolates in northwest Colombia.

Restrepo Eliana E Imwong Mallika M Rojas Winston W Carmona-Fonseca Jaime J Maestre Amanda A

Acta tropica 20110407 1

Genetic diversity of Plasmodium populations has been more extensively documented in Colombia for Plasmodium falciparum than for Plasmodium vivax. Recently, highly variable microsatellite markers have been described and used in population-level studies of genetic variation of P. vivax throughout the world. We applied this approach to understand the genetic structure of P. vivax populations and to identify recurrence-associated haplotypes. In this, three microsatellite markers of P. vivax were amp ...[more]

PMID: 21497586

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Project description:BackgroundPlasmodium vivax is the predominant malaria species in northern Mauritania. Molecular data on P. vivax isolates circulating in West Africa are scarce. The present study analysed molecular markers associated with resistance to antifolates (Pvdhfr and Pvdhps), chloroquine (Pvmdr1), and artemisinin (Pvk12) in P. vivax isolates collected in two cities located in the Saharan zone of Mauritania.MethodsBlood samples were obtained from P. vivax-infected patients recruited for chloroquine therapeutic efficacy study in 2013 and febrile patients spontaneously consulting health facilities in Nouakchott and Atar in 2015-2016. Fragments of Pvdhfr (codons 13, 33, 57, 58, 61, 117, and 174), Pvdhps (codons 382, 383, 512, 553, and 585), Pvmdr1 (codons 976 and 1076) and Pvk12 (codon 552) genes were amplified by PCR and sequenced.ResultsMost of the isolates in Nouakchott (126/154, 81.8%) and Atar (44/45, 97.8%) carried the wild-type Pvdhfr allelic variant (IPFSTSI). In Nouakchott, all mutants (28/154; 18.2%) had double Pvdhfr mutations in positions 58 and 61 (allelic variant IPFRMSI), whereas in Atar only 1 isolate was mutant (S117N, allelic variant IPFSTNI). The wild-type Pvdhps allelic variant (SAKAV) was found in all tested isolates (Nouakchott, n = 93; Atar, n = 37). Few isolates in Nouakchott (5/115, 4.3%) and Atar (3/79, 3.8%) had the mutant Pvmdr1 allele 976F or 1076L, but not both, including in pre-treatment isolates obtained from patients treated successfully with chloroquine. All isolates (59 in Nouakchott and 48 in Atar) carried the wild-type V552 allele in Pvk12.ConclusionsPolymorphisms in Pvdhfr, Pvdhps, Pvmdr1, and Pvk12 were limited in P. vivax isolates collected recently in Nouakchott and Atar. Compared to the isolates collected in Nouakchott in 2007-2009, there was no evidence for selection of mutants. The presence of one, but not both, of the two potential markers of chloroquine resistance in Pvmdr1 in pre-treatment isolates did not influence the clinical outcome, putting into question the role of Pvmdr1 mutant alleles 976F and 1076L in treatment failure. Molecular surveillance is an important component of P. vivax malaria control programme in the Saharan zone of Mauritania to predict possible emergence of drug-resistant parasites.

Project description:BackgroundThe Duffy-binding protein II of Plasmodium vivax (PvDBPII) has been considered as an attractive target for vaccine-mediated immunity despite a possible highly polymorphic nature. Among seven PvDBP domains, domain II has been shown to exhibit a high rate of nonsynonymous polymorphism, which has been suggested to be a potential immune (antibody binding) evasion mechanism. This study aimed to determine the extent of genetic polymorphisms and positive natural selection at domain II of the PvDBP gene among a sampling of Thai P. vivax isolates.MethodsThe PvDBPII gene was PCR amplified and the patterns of polymorphisms were characterized from 30 Thai P. vivax isolates using DNA cloning and sequencing. Phylogenetic analysis of the sequences and positive selection were done using DnaSP ver 4.0 and MEGA ver 4.0 packages.ResultsThis study demonstrated a high rate of nonsynonymous polymorphism. Using Sal I as the reference strain, a total of 30 point-mutations were observed in the PvDBPII gene among the set of Thai P. vivax isolates, of which 25 nonsynonymous and five synonymous were found. The highest frequency of polymorphism was found in five variant amino acids (residues D384G, R390H, L424I, W437R, I503K) with the variant L424I having the highest frequency. The difference between the rates of nonsynonymous and synonymous mutations estimated by the Nei and Gojobori's method suggested that PvDBPII antigen appears to be under selective pressure. Phylogenetic analysis of PvDBPII Thai P. vivax isolates to others found internationally demonstrated six distinct allele groups. Allele groups 4 and 6 were unique to Thailand.ConclusionPolymorphisms within PvDBPII indicated that Thai vivax malaria parasites are genetically diverse. Phylogenetic analysis of DNA sequences using the Neighbour-Joining method demonstrated that Thai isolates shared distinct alleles with P. vivax isolates from different geographical areas. The study reported here will be valuable for the development of PvDBPII-based malaria vaccine.

Project description:BACKGROUND: Assaying for the parasitic lactate dehydrogenase (pLDH) is widely used as a rapid diagnostic test (RDT), but the efficacy of its serological effectiveness in diagnosis, that is antibody detection ability, is not known. The genetic variation of Korean isolates was analysed, and recombinant protein pLDH was evaluated as a serodiagnostic antigen for the detection of Plasmodium vivax malaria. METHODS: Genomic DNA was purified, and the pLDH gene of P. vivax was amplified from blood samples from 20 patients. The samples came from five epidemic areas: Bucheon-si, Gimpo-si, and Paju-si of Gyeonggi Province, Gangwha-gun of Incheon metropolitan city, and Cheorwon-gun of Gangwon Province, South Korea, from 2010 to 2011. The antigenicity of the recombinant protein pLDH was tested by western blot and enzyme-linked immunosorbent assay (ELISA). RESULTS: Sequence analysis of 20 Korean isolates of P. vivax showed that the open reading frame (ORF) of 951 nucleotides encoded a deduced protein of 316 amino acids (aa). This ORF showed 100% identity with the P. vivax Belem strain (DQ060151) and P. vivax Hainan strain (FJ527750), 89.6% homology with Plasmodium falciparum FCC1_HN (DQ825436), 90.2% homology with Plasmodium berghei (AY437808), 96.8% homology with Plasmodium knowlesi (JF958130), and 90.2% homology with Plasmodium reichenowi (AB122147). A single-nucleotide polymorphism (SNP) at nucleotide 456 (T to C) was also observed in the isolate from Bucheon, but it did not change in the amino acid sequence. The expressed recombinant protein had a molecular weight of approximately 32 kDa, as analysed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis. Of the 40 P. vivax patients, 34 (85.0%) were positive by ELISA. CONCLUSIONS: The pLDH genes of 19 isolates of P. vivax were identical, except one for SNP at nucleotide 456. This observation indicates that this gene is relatively stable. Based on these results, the relationship between antibody production against pLDH and the pattern of disease onset should be investigated further before using pLDH for serodiagnosis.

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High genetic polymorphism of relapsing P. vivax isolates in northwest Colombia.

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High genetic polymorphism of relapsing P. vivax isolates in northwest Colombia.

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