Point mutations in domain II of the voltage-gated sodium channel gene in deltamethrin-resistant Aedes aegypti (Diptera: Culicidae)

Abstract

The continuous usage of pyrethroids against insects has provoked the emergence of insecticide resistance that has become a major obstacle to disease vector control. The knockdown resistance (kdr) voltage-gated sodium channel gene is regarded as a key to understanding the mechanism of resistance to pyrethroids. The main purpose of this study is to identify point mutations in the sodium channel gene associated with deltamethrin resistance in Aedes aegypti. Two mutations in the IIS6 domain of the channel, S989P and V1016G, were identified as possible candidates responsible for the emergence of deltamethrin resistance in Ae. aegypti Khu Bua strain. As S989P and V1016G mutations are located within the IIS5-S6 loop and IIS6 near the ion filter and binding site, these mutations might enhance pyrethroid resistance. Allelic variation in the sodium channel gene is thought to be one of the principal molecular mechanisms regulating pyrethroid resistance in mosquitoes.

Co-occurrence of Point Mutations in the Voltage-Gated Sodium Channel of Pyrethroid-Resistant Aedes aegypti Populations in Myanmar

“…The S989P mutation has always been linked to the V1016G mutation; however, V1016G has sometimes been found in the absence of S989P [12]. The observed co-occurrence of the V1016G and S989P mutations with high frequency in Myanmar correspond to the former scenario.…”

“…The observed co-occurrence of the V1016G and S989P mutations with high frequency in Myanmar correspond to the former scenario. Srisawat et al indicated that the co-occurrence of V1016G and S989P enhanced the resistance of Aedes aegypti to deltamethrin [12]. However, the authors were unable to determine the effect of the single S989P mutation on pyrethroid sensitivity, and were therefore unable to provide direct evidence of how the two mutations were associated with resistance.…”

“…Harris et al reported that the F1534C mutation was strongly correlated with resistance to DDT and pyrethroid [11]. The S989P mutation in domain II of the voltage-gated sodium channel gene, which occurs in deltamethrin-resistant Aedes aegypti , is another principal kdr mutation that regulates pyrethroid resistance in mosquitoes [12]. Yanola et al [10] reported the existence of the F1534C mutation in Aedes aegypti from Yangon City, Myanmar.…”

Sodium Channel Mutations and Pyrethroid Resistance in Aedes aegypti

“…Subsequently, an F1534C substitution in IIIS6 was discovered in DDT/permethrin-resistant Aedes aegypti in Thailand and Vietnam [33,34,35,36]. Furthermore, two additional mutations, S989P and D1763Y, were found to coexist with V1016G in permethrin-resistant populations in Thailand [37,38,39] and in Taiwan [40], respectively.…”

“…Similarly, nucleotide sequence polymorphisms in the sodium channel gene from geographically distinct populations potentially influence the contribution of kdr mutations to pyrethroid resistance. For example, the S989P mutation appears to synergize the effects of the V1016G mutation based on analysis of field populations in Thailand [37]. However, genetic addition of the S989P allele in either the homozygous or heterozygous form to V1016G homozygotes did not enhance resistance to permethrin or deltamethrin in another study in Indonesia [45].…”