National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention, Chinese Center for Tropical Diseases Research, 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, 20025, China.
Parasit Vectors. 2019 Aug 9;12(1):396. doi: 10.1186/s13071-019-3657-7.
In the final phase of China's national programme to eliminate malaria by 2020, it is vitally important to monitor the resistance of malaria vectors for developing effective vector control strategies. In 2017 Shanghai declared that it had eliminated malaria; however, the insecticide resistance status of the primary malaria vector Anopheles sinensis remains unknown.
We examined the pyrethroid and organophosphate resistance of An. sinensis via a bioassay of two populations from the Chongming District of Shanghai. The voltage-gated sodium channel (VGSC) and acetylcholinesterase 1 (ace-1) genes were partially sequenced to examine the association between resistance phenotype and target site genotype. In addition, the geographical distribution, polymorphism and genotype frequencies of insecticide resistance genes were examined using samples collected during routine mosquito surveillance in 2016 and 2017 from Chongming, Songjiang, Jiading and Qingpu Districts.
In Chongming District, the An. sinensis population near Dongtan National Nature Reserve showed resistance to pyrethroids, sensitivity to organophosphate, no knockdown resistance (kdr) mutations in the VGSC gene, and a low frequency (1.71%) of the ace-1 119S allele. An An. sinensis population near the Chongming central area (CM-Xinhe population) showed high resistance to pyrethroids and organophosphates and high frequencies of kdr 1014F and 1014C (80.73%) and ace-1 119S (85.98%) alleles. A significant association was detected between the homozygous kdr mutation 1014F/1014F and pyrethroid resistance in the CM-Xinhe population, indicating that the kdr mutation is probably recessive. Eight kdr genotypes with 1014F and 1014C substitutions were detected in the four surveyed districts of Shanghai. TTT and GGC/AGC were the dominant kdr allele and ace-1 genotype, respectively, and were prevalent in most Shanghai An. sinensis populations.
On the basis of our assessment of insecticide resistance gene mutations in Shanghai, we identified a kdr mutation-free population in Chongming Dongtan. However, high frequencies of target-site mutations of insecticide resistance genes were observed in most areas of Shanghai. Bioassays of An. sinensis populations in the central Chongming District indicated the high insecticide resistance status of An. sinensis populations in Shanghai. We accordingly recommend a restriction on insecticide usage and development of effective integrated pest/vector management interventions to support disease control efforts.
在中国 2020 年消除疟疾的国家计划的最后阶段，监测疟疾媒介的抗药性对于制定有效的媒介控制策略至关重要。2017 年，上海宣布已消除疟疾；然而，主要疟疾媒介中华按蚊的杀虫剂抗性状况尚不清楚。
我们通过对来自上海崇明区的两个种群的生物测定来检查中华按蚊的拟除虫菊酯和有机磷抗性。部分测序电压门控钠离子通道（VGSC）和乙酰胆碱酯酶 1（ace-1）基因，以检查抗性表型与靶位基因型之间的关联。此外，使用 2016 年和 2017 年在崇明、松江、嘉定和青浦区进行常规蚊虫监测时收集的样本，检测了杀虫剂抗性基因的地理分布、多态性和基因型频率。
在崇明区，东滩国家自然保护区附近的中华按蚊种群对拟除虫菊酯表现出抗药性，对有机磷敏感，VGSC 基因无击倒抗性（kdr）突变，ace-1 119S 等位基因频率较低（1.71%）。崇明中心区（CM-Xinhe 种群）附近的中华按蚊种群对拟除虫菊酯和有机磷均具有高抗性，kdr 1014F 和 1014C（80.73%）和 ace-1 119S（85.98%）等位基因的频率较高。在 CM-Xinhe 种群中，发现纯合 kdr 突变 1014F/1014F 与拟除虫菊酯抗性之间存在显著关联，表明 kdr 突变可能是隐性的。在上海四个调查区共检测到 8 种带有 1014F 和 1014C 取代的 kdr 基因型。TTT 和 GGC/AGC 分别是优势 kdr 等位基因和 ace-1 基因型，在大多数上海中华按蚊种群中普遍存在。
基于我们对上海杀虫剂抗性基因突变的评估，我们在崇明东滩发现了一个无 kdr 突变的种群。然而，在上海的大多数地区都观察到了抗药性基因的靶位突变的高频。对崇明中部地区中华按蚊种群的生物测定表明，上海中华按蚊种群的杀虫剂抗性状态很高。因此，我们建议限制杀虫剂的使用，并开发有效的综合病虫害/媒介管理干预措施，以支持疾病控制工作。
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