CHINESE JOURNAL OF PARASITOLOGY AND PARASITIC DISEASES ›› 2018, Vol. 36 ›› Issue (2): 103-111.

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Analysis of genes associated with antifolate drug resistance in Plasmodium vivax from different infection sources

Ying DONG1,*(), Yan DENG1, Meng-ni CHEN1, Yan-chun XU1, Xiang-hua MAO1, Jian WANG1, Ai-ming SUN2, Jing-bo XUE3   

  1. 1 Yunnan Institute of Parasitic Diseases, Yunnan Center of Malaria Research, Yunnan Provincial Key Laboratory of Vector-borne Diseases Control and Research, Puer 665000, China
    2 Hubei International Travel Healthcare Center, Wuhan 430000, China
    3 National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention; WHO Collaborating Centre for Tropical Diseases; National Center for International Research on Tropical Diseases, Ministry of Science and Technology; Key Laboratory of Parasite and Vector Biology, Ministry of Health,Shanghai 200025, China
  • Received:2017-08-17 Online:2018-04-28 Published:2018-04-24
  • Contact: Ying DONG E-mail:luxidongying@126.com
  • Supported by:
    Supported by National Natural Science Foundation of Chian(No. 81220108019, No. 81660559)and the Youth Project of Yunnan Province Basic Research Program (No. 2017FD007, No. 2017FD190)

Abstract:

Objective To analyze the mutation characteristics of dihydrofolate reductase gene (Pvdhfr) and dihydropterroate synthase gene (Pvdhps), which are associated with antifolate drug resistance, in Plasmodium vivax from different infection sources in Yunnan Province. Methods Dry blood spots on filter papers were collected from vivax malaria patients reported through the Reporting System of Chinese Center for Disease Control and Prevention from August 2012 to December 2016 and the corresponding epidemiology data of the patients were collected as well. DNA was extracted from P. vivax, and the Pvdhfr and Pvdhps fragments were amplified with nest-PCR. The PCR products were sequenced, and all sequences were aligned with the reference sequences (GenBank ID: X98123 and PVX_123230). The haplotype number, expected heterozygsity (He), and genetic differentiation (Fixation index) of the two genes in different Plasmodium populations were analyzed with MEGA 5.04 and Arlequin 3.5.1 softwares. The haplotype media evolution tree was constructed with the Network 4.6.0 software. Results A total of 1 203 blood samples were collected, including 1 060 with an infection source in Myanmar, 70 in Africa and 64 from indigenous patients in Yunnan. The PCR results showed that Pvdhfr and Pvdhps were amplified and sequenced in 272 and 708 samples, respectively. There were 53 haplotyes for Pvdhfr in the 272 DNA sequences, with an He of 0.243, and the Yunnan indigenous isolates had the highest He value (0.667). The case of all 12 loci of Pvdhfr gene being wild-type had a frequency of 8.1% (22/272). All the other 52 haplotypes harbored various types of missense mutations at the 12 loci, including single-locus, double-loci, triple-loci, quadruple-loci, quintuple-loci and sixfold-loci mutations. There were 35 haplotyes in 708 DNA sequences of Pvdhps gene, with an He of 0.153, and the Myanmar-source isolates had the highest He (0.142). The case of all the 5 loci of Pvdhps gene being wild-type had a frequency of 36.2% (256/708). All the other 34 haplotypes harbored 29 types of missense mutations at the 5 loci, including single-locus, double-loci, triple-loci, and quadruple-loci mutations. The media network diagram constructed from all the haplotypes of the two P. vivax genes showed that the haplotypes occurred initially as wild-type, and then evolved from single mutation to multiple mutations. In blood samples with wild-type and mutated Pvdhfr, the percentages of Pvdhps mutations were 18.2% (4/22) and 65.6% (147/224), respectively. The blood samples confirmed with Pvdhps mutations and Pvdhfr mutations were from 14 and 9 prefectures, respectively, and predominated by the Myanmar source samples that constituted 97.3% (442/452) and 95.4% (144/151), respectively. Conclusion Both Pvdhfr and Pvdhps have a high mutation frequency and a high degree of mutation in P. vivax from different infection sources in Yunnan Province.

Key words: Plasmodium vivax, Antifolate drug, Dihydrofolate reductase, Dihydropterroate synthase, Resistance-associated gene, Mutation, Analysis

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