State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China.
University of Chinese Academy of Sciences, Beijing, 100049, China.
Parasit Vectors. 2019 Feb 7;12(1):77. doi: 10.1186/s13071-019-3298-x.
In South Asia, the epidemiology of malaria is complex, and transmission mainly occurs in remote areas near international borders. Vector control has been implemented as a key strategy in malaria prevention for decades. A rising threat to the efficacy of vector control efforts is the development of insecticide resistance, thus it is important to monitor the type and frequency of insecticide resistant alleles in the disease vectors such as An. sinensis along the China-Vietnam border. Such information is needed to synthesize effective malaria vector control strategies.
A total of 208 adults of An. sinensis, collected from seven sites in southwest Guangxi along the China-Vietnam border, were inspected for the resistance-conferring G119S mutation in acetylcholinesterase (AChE) by PCR-RFLP (polymerase chain reaction restriction fragment length polymorphism) and kdr mutations in the voltage-gated sodium channel (VGSC) by sequencing. In addition, the evolutionary origin of An. sinensis vgsc gene haplotypes was analyzed using Network 5.0.
The frequencies of mutant 119S of AChE were between 0.61-0.85 in the seven An. sinensis populations. No susceptible homozygote (119GG) was detected in three of the seven sites (DXEC, LZSK and FCGDX). Very low frequencies of kdr (0.00-0.01) were detected in the seven populations, with most individuals being susceptible homozygote (1014LL). The 1014F mutation was detected only in the southeast part (FCGDX) at a low frequency of 0.03. The 1014S mutation was distributed in six of the seven populations with frequencies ranging from 0.04 to 0.08, but absent in JXXW. Diverse haplotypes of 1014L and 1014S were found in An. sinensis along the China-Vietnam border, while only one 1014F haplotype was detected in this study. Consistent with a previous report, resistant 1014S haplotypes did not have a single origin.
The G119S mutation of AChE was present at high frequencies (0.61-0.85) in the An. sinensis populations along the China-Vietnam border, suggesting that the vector control authorities should be cautious when considering carbamates and organophosphates as chemicals for vector control. The low frequencies (0.00-0.11) of kdr in these populations suggest that pyrethroids remain suitable for use against An. sinensis in these regions.
在南亚，疟疾的流行病学较为复杂，传播主要发生在靠近国际边境的偏远地区。几十年来，病媒控制一直是疟疾预防的关键策略。昆虫对杀虫剂的抗药性不断增强，对病媒控制工作的效果构成了日益严重的威胁，因此，监测中越边境中华按蚊等疾病传播媒介中杀虫剂抗性等位基因的类型和频率非常重要。此类信息有助于综合制定有效的疟疾病媒控制策略。
共检查了来自中越边境广西西南部七个地点的 208 只中华按蚊成虫，采用 PCR-RFLP（聚合酶链反应限制性片段长度多态性）方法检查乙酰胆碱酯酶（AChE）的抗性赋予 G119S 突变，采用测序方法检查电压门控钠通道（VGSC）的 kdr 突变。此外，利用网络 5.0 分析中华按蚊 vgsc 基因单倍型的进化起源。
在七个中华按蚊种群中，AChE 的突变体 119S 的频率在 0.61-0.85 之间。在七个地点中的三个地点（DXEC、LZSK 和 FCGDX）未检测到敏感纯合子（119GG）。在七个种群中，kdr 的频率非常低（0.00-0.01），大多数个体为敏感纯合子（1014LL）。1014F 突变仅在东南部（FCGDX）以 0.03 的低频率检测到。1014S 突变分布在七个种群中的六个，频率在 0.04 到 0.08 之间，但在 JXXW 中未检测到。在中越边境的中华按蚊中发现了多种 1014L 和 1014S 单倍型，但本研究中仅检测到一种 1014F 单倍型。与之前的报告一致，抗性 1014S 单倍型并非单一起源。
在中国-越南边境的中华按蚊种群中，AChE 的 G119S 突变频率较高（0.61-0.85），这表明在考虑将氨基甲酸酯类和有机磷类作为病媒控制化学品时，病媒控制当局应保持谨慎。这些种群中 kdr 的低频率（0.00-0.11）表明拟除虫菊酯类仍适用于这些地区的中华按蚊防治。
