云南省埃及伊蚊击倒抗性基因流行特征研究

Prevalence characteristics of knockdown resistance gene of Aedes aegypti in Yunnan Province,China

目的 在云南省埃及伊蚊重点分布区,检测埃及伊蚊引起击倒抗性(kdr)的电压门控钠离子通道基因(VGSC)突变并分析,阐明VGSC基因流行特征。方法 收集云南省盈江县、瑞丽市、镇康县、耿马傣族佤族自治县(耿马县)、勐海县、景洪市和勐腊县共7个重点县(市)野生埃及伊蚊成蚊或幼蚊样本,直接测序法扩增VGSC部分基因片段,分析各位点突变率和联合突变构成情况。χ^(2)检验比较不同位点突变率和不同性别成蚊VGSC基因kdr突变的差异等。结果 7个县(市)共计561只(雌蚊276只、雄蚊242只和幼蚊43只)埃及伊蚊样本成功提取蚊DNA基因组并被用于kdr突变的检测,共发现VGSC中4个位点突变。每个县(市)均存在S989P、V1016G和F1534C突变,S989P突变率为71.43%~100%,均值为92.51%[95%置信区间(CI)90.33%~94.70%];V1016G突变率均为100%;F1534C突变率为55.81%~100%,均值为85.38%(95%CI:82.45%~88.32%);首次发现瑞丽市、耿马县和镇康县3个县(市)存在Y1527F位点突变(0~35.45%),均值为8.73%(95%CI:6.39%~11.08%)。同时存在4种联合突变类型:S989P+V1016G、V1016G+F1534C、S989P+V1016G+F1534C和S989P+V1016G+Y1527F+F1534C,未发现单个位点突变情况。除盈江县外的6个县(市)雌蚊与雄蚊分别进行989、1016、1527和1534位点突变率以及联合突变构成比的比较,差异均无统计学意义(均P>0.05)。结论 云南省埃及伊蚊VGSC基因中kdr突变以多位点联合突变为主,且出现Y1527F新突变,应定期开展埃及伊蚊kdr突变监测,及时掌握其对杀虫剂靶标抗性变化规律。

Objective To investigate mutations in the voltage-gated sodium channel gene(VGSC)responsible for knockdown resistance(kdr)in Aedes aegypti and analyze the prevalence characteristics of the VGSC gene in the key areas of Ae.aegypti distribution in Yunnan Province,China.Methods Wild adult or larval Ae.aegypti samples were collected from 7 counties/cities(Yingjiang County,Ruili City,Zhenkang County,Gengma Dai and Va Autonomous County,Menghai County,Jinghong Municipality,and Mengla County)in Yunnan Province.The gene VGSC was amplified by direct sequencing to analyze the point mutation rate and the composition of combined mutations.The Chi-square test was used to compare the differences in the kdr mutation rate of VGSC gene between different loci and between different sexes of Aedes albopictus.Results The DNA was successfully extracted and VGSC gene were sequenced for a total of 561 Ae.aegypti mosquitoes(276 females,242 males,and 43 larvae)in 7 counties/cities.Four point mutations were found in the VGSC gene.S989P,V1016G,and F1534C mutations were present in every county/city.The S989P mutation rate ranged from 71.43%to 100%,with a mean of 92.51%(95%confidence interval[CI]:90.33%-94.70%).The V1016G mutation rate was 100%.The F1534C mutation rate was 55.81%-100%,with a mean of 85.38%(95%CI:82.45%-88.32%).The Y1527F mutation was first detected in Ruili Municipality,Gengma and Zhenkang County,and the mutation rate ranged from 0 to 35.45%,with a mean of 8.73%(95%CI:6.39%-11.08%).There were 4 types of co-occurring mutations:S989P+V1016G,V1016G+F1534C,S989P+V1016G+F1534C,and S989P+V1016G+Y1527F+F1534C.Single point mutations were not found.There were no significant differences in the mutation rates of 989,1016,1527,and 1534 loci and the composition ratios of combined mutations in female and male mosquitoes in six counties/cities except Yingjiang County.Conclusions The kdr mutation in the VGSC gene of Ae.aegypti in Yunnan Province is mainly characterized by multiple-point joint mutations,and a new Y1527F mutation appears.Kdr mutations surveillance in Ae.aegypti should be carried out regularly to grasp the changes in its resistance to insecticide targets in time.