Suphakhonchuwong Nutnicha, Chaijaroenkul Wanna, Rungsihirunrat Kanchana, Na-Bangchang Kesara, Kuesap Jiraporn
Faculty of Allied Health Sciences, Thammasat University, Pathumthani, Thailand.
Chulabhorn International College of Medicine, Thammasat University, Pathumthani, Thailand.
Parasitol Res. 2018 Dec;117(12):3965-3978. doi: 10.1007/s00436-018-6106-1. Epub 2018 Oct 10.
Malaria is a significant public health problem in several tropical countries including Thailand. The prevalence of Plasmodium vivax infection has been increasing in the past decades. Plasmodium vivax merozoite surface protein (PvMSP) gene encodes a malaria vaccine candidate antigen. Its polymorphic nature leads to antigenic variation, the barrier for vaccine development, drug resistance, and potential for multiple-clone infections within the malaria patients. The objective of this study was to investigate the genetic diversity of PvMSP1 and PvMSP3 gene in P. vivax populations in Thailand. A total of 100 P. vivax isolates collected from the western (Kanchanaburi and Tak Provinces) and southern (Ranong Provinces) regions along the Thai-Myanmar border were analyzed using polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP). Analysis of the F1, F2, and F3 regions of PvMSP1 revealed 5, 2, and 3 allelic variants, respectively. Three major types of PvMSP3-α and two major types of PvMSP3-β were identified based on the PCR product sizes. After digestion with restriction enzymes, 29, 25, 26, and 18 patterns were distinguished by RFLP for PvMSP1 (F2, Alu I), PvMSP1 (F2, Mnl I), PvMSP3-α, and PvMSP3-β, respectively. Combination of each family variant (PvMSP1 and PvMSP3) resulted in high genetic polymorphism of P. vivax population. Additionally, using PvMSP1 polymorphic marker revealed a significant association between multiple-genotype infections and P. vivax parasitemia. The results strongly supported that P. vivax populations in the endemic areas along the Thai-Myanmar border are highly diverse.
疟疾是包括泰国在内的几个热带国家的一个重大公共卫生问题。在过去几十年间，间日疟原虫感染率一直在上升。间日疟原虫裂殖子表面蛋白（PvMSP）基因编码一种疟疾疫苗候选抗原。其多态性导致抗原变异，这是疫苗研发的障碍、耐药性产生的原因，也是疟疾患者体内出现多克隆感染的潜在因素。本研究的目的是调查泰国间日疟原虫群体中PvMSP1和PvMSP3基因的遗传多样性。使用聚合酶链反应和限制性片段长度多态性（PCR-RFLP）方法，对从泰国-缅甸边境沿线西部（北碧府和夜丰颂府）和南部（拉廊府）地区收集的100株间日疟原虫分离株进行了分析。对PvMSP1的F1、F2和F3区域分析分别揭示了5个、2个和3个等位基因变体。基于PCR产物大小，鉴定出三种主要类型的PvMSP3-α和两种主要类型的PvMSP3-β。用限制性酶消化后，通过RFLP分别区分出PvMSP1（F2，Alu I）、PvMSP1（F2，Mnl I）、PvMSP3-α和PvMSP3-β的29种、25种、26种和18种模式。每个家族变体（PvMSP1和PvMSP3）的组合导致间日疟原虫群体具有高度的遗传多态性。此外，使用PvMSP1多态性标记揭示了多基因型感染与间日疟原虫血症之间存在显著关联。结果有力地支持了泰国-缅甸边境流行地区的间日疟原虫群体具有高度多样性。
