Analysis of chloroquine-resistant gene polymorphisms in Plasmodium falciparum imported into China in 2012 and 2018 / 中国血吸虫病防治杂志

ABSTRACT

Objective To detect the chloroquine-resistant molecular marker polymorphisms in Plasmodium falciparum imported into China, investigate the mutation types of P. falciparum chloroquine resistant transporter (Pfcrt) gene at positions 72 to 76, and analyze the specificity of the P. falciparum specimens with different origins. Methods A total of 674 filter paper blood samples were collected from the National Malaria Diagnosis Reference Laboratory of China in 2012 and 2018. The amino acid po- sitions 72 to 76 of the Pfcrt gene on chromosome 7 were amplified using nested PCR assay and sequenced, and the sequencing results of the target gene fragment and the geographical region-specific prevalence of the mutations in the Pfcrt gene were analyzed. Results Among the 674 imported P. falciparum malaria cases in China in 2012 and 2018, 99.5% (644/674) were from Africa, which were predominantly from western and central Africa (80.4%, 518/644), and 4.5% (30/674) from Southeast Asia and Oceania (Papua New Guinea). A total of 4 site mutations (C72S, M74I, N75E and K76T) and 5 haplotypes (CVMNK, CVIET and SVMNT and two mixed types) were identified, with haplotypes CVMNK and CVIET present in parasites of both African and Southeast Asian origins, SVMNT detected in Southeast Asia (Myanmar) and Papua New Guinea isolates, the mixed type of haplo- types CVMNK/CVIET detected in P. falciparum of African and Southeast Asian origins, and the mixed type of haplotypes CVMNK/SVMNT detected only in the Myanmar isolate. Most P. falciparum parasites of the African origin carried the wild-type Pfcrt allele (77.7%, 478/615), and 68.0% (17/25) of the P. falciparum parasites of the Southeast Asian and Papua New Guinea or- igins harbored chloroquine resistant molecular markers (χ2 = 28.5, P < 0.05). The constituent ratio of the wild- and mutant-type Pfcrt allele varied in different geographical regions of Africa (P < 0.01), and the lowest prevalence of the wild-type Pfcrt allele was seen in western Africa. Conclusion Among the 674 imported malaria cases in China in 2012 and 2018, the P. falciparum imported from Sotheast Asia habors a higher proportion of resistance to chloroquine and a higher molecular polymophism at ami- no acid positions 72 to 76 of the Pfcrt gene than the parasite of the African origin.