Rapid evolution of knockdown resistance haplotypes in response to pyrethroid selection in Aedes aegypti.
Ontology highlight
ABSTRACT:
SUBMITTER: Baltzegar J
PROVIDER: S-EPMC8372076 | biostudies-literature |
REPOSITORIES: biostudies-literature
Similar Datasets
Project description:BACKGROUND:Understanding mechanisms driving insecticide resistance in vector populations remains a public health priority. To date, most research has focused on the genetic mechanisms underpinning resistance, yet it is unclear what role environmental drivers may play in shaping phenotypic expression. One of the key environmental drivers of Aedes aegypti mosquito population dynamics is resource-driven intraspecific competition at the larval stage. We experimentally investigated the role of density-dependent larval competition in mediating resistance evolution in Ae. aegypti, using knockdown resistance (kdr) as a marker of genotypic resistance and CDC bottle bioassays to determine phenotype. We reared first-instar larvae from susceptible and pyrethroid-resistant field-derived populations of Ae. aegypti at high and low density and measured the resulting phenotypic resistance and population kdr allele frequencies. RESULTS:At low density, only 48.2% of the resistant population was knocked down, yet at high density, the population was no longer phenotypically resistant - 93% were knocked down when exposed to permethrin, which is considered susceptible according to WHO guidelines. Furthermore, the frequency of the C1534 kdr allele in the resistant population at high density decreased from 0.98 ± 0.04 to 0.69 ± 0.04 in only one generation of selection. CONCLUSIONS:Our results indicate that larval conditions, specifically density, can impact both phenotype and genotype of pyrethroid-resistant populations. Furthermore, phenotypic susceptibility to pyrethroids may be re-established in a resistant population through a gene x environment interaction, a finding that can lead to the development of novel resistance management strategies that capitalize on density-induced costs.
| S-EPMC5934844 | biostudies-literature
Project description:Aedes aegypti vectors the pathogens that cause dengue, yellow fever, Zika virus, and chikungunya and is a serious threat to public health in tropical regions. Decades of work has illuminated many aspects of Ae. aegypti's biology and global population structure and has identified insecticide resistance genes; however, the size and repetitive nature of the Ae. aegypti genome have limited our ability to detect positive selection in this mosquito. Combining new whole genome sequences from Colombia with publicly available data from Africa and the Americas, we identify multiple strong candidate selective sweeps in Ae. aegypti, many of which overlap genes linked to or implicated in insecticide resistance. We examine the voltage-gated sodium channel gene in three American cohorts and find evidence for successive selective sweeps in Colombia. The most recent sweep encompasses an intermediate-frequency haplotype containing four candidate insecticide resistance mutations that are in near-perfect linkage disequilibrium with one another in the Colombian sample. We hypothesize that this haplotype may continue to rapidly increase in frequency and perhaps spread geographically in the coming years. These results extend our knowledge of how insecticide resistance has evolved in this species and add to a growing body of evidence suggesting that Ae. aegypti has an extensive genomic capacity to rapidly adapt to insecticide-based vector control.
| S-EPMC10118305 | biostudies-literature
Project description:Mutation of the voltage-gated sodium channel (VGSC) gene, or knockdown resistance (kdr) gene, is an important resistance mechanism of the dengue vector Aedes aegypti mosquitoes against pyrethroids. In many countries in Asia, a valine to glycine substitution (V1016G) and a phenylalanine to cysteine substitution (F1534C) are common in Ae. aegypti populations. The G1016 and C1534 allele frequencies have been increasing in recent years, and hence there is a need to have a simple and inexpensive tool to monitor the alleles in large scale.A multiplex PCR to detect V1016G and F1534C mutations has been developed in the current study. This study utilized primers from previous studies for detecting the mutation at position 1016 and newly designed primers to detect variants at position 1534. The PCR conditions were validated and compared with DNA sequencing using known kdr mutant laboratory strains and field collected mosquitoes. The efficacy of this method was also compared with allele-specific PCR (AS-PCR).The results of our multiplex PCR were in complete agreement with sequencing data and better than the AS-PCR. In addition, the efficiency of two non-toxic DNA staining dyes, Ultrapower™ and RedSafe™, were evaluated by comparing with ethidium bromide (EtBr) and the results were satisfactory.Our multiplex PCR method is highly reliable and useful for implementing vector surveillance in locations where the two alleles co-occur.
| S-EPMC5634894 | biostudies-literature
Project description:Pyrethroid insecticides are widely used to control insect pests and human disease vectors. Voltage-gated sodium channels are the primary targets of pyrethroid insecticides. Mutations in the sodium channel have been shown to be responsible for pyrethroid resistance, known as knockdown resistance (kdr), in various insects including mosquitoes. In Aedes aegypti mosquitoes, the principal urban vectors of dengue, zika, and yellow fever viruses, multiple single nucleotide polymorphisms in the sodium channel gene have been found in pyrethroid-resistant populations and some of them have been functionally confirmed to be responsible for kdr in an in vitro expression system, Xenopus oocytes. This mini-review aims to provide an update on the identification and functional characterization of pyrethroid resistance-associated sodium channel mutations from Aedes aegypti. The collection of kdr mutations not only helped us develop molecular markers for resistance monitoring, but also provided valuable information for computational molecular modeling of pyrethroid receptor sites on the sodium channel.
| S-EPMC5198208 | biostudies-literature
Project description:BackgroundControl of Aedes aegypti, the mosquito vector of dengue, chikungunya and yellow fever, is a challenging task. Pyrethroid insecticides have emerged as a preferred choice for vector control but are threatened by the emergence of resistance. The present study reports a focus of pyrethroid resistance and presence of two kdr mutations--F1534C and a novel mutation T1520I, in Ae. aegypti from Delhi, India.Methodology/principal findingsInsecticide susceptibility status of adult-female Ae. aegypti against DDT (4%), deltamethrin (0.05%) and permethrin (0.75%) was determined using WHO's standard insecticide susceptibility kit, which revealed resistance to DDT, deltamethrin and permethrin with corrected mortalities of 35%, 72% and 76% respectively. Mosquitoes were screened for the presence of kdr mutations including those reported earlier (I1011V/M, V1016G/I, F1534C, D1794Y and S989P), which revealed the presence of F1534C and a novel mutation T1520I. Highly specific PCR-RFLP assays were developed for genotyping of these two mutations. Genotyping using allele specific PCR and new PCR-RFLP assays revealed a high frequency of F1534C (0.41-0.79) and low frequency of novel mutation T1520I (0.13). The latter was observed to be tightly linked with F1534C and possibly serve as a compensatory mutation. A positive association of F1534C mutation with DDT and deltamethrin resistance in Ae. aegypti was established. However, F1534C-kdr did not show significant protection against permethrin.Conclusions/significanceThe Aedes aegypti population of Delhi is resistant to DDT, deltamethrin and permethrin. Two kdr mutations, F1534C and a novel mutation T1520I, were identified in this population. This is the first report of kdr mutations being present in the Indian Ae. aegypti population. Highly specific PCR-RFLP assays were developed for discrimination of alleles at both kdr loci. A positive association of F1534C mutation with DDT and deltamethrin resistance was confirmed.
| S-EPMC4287524 | biostudies-literature
Project description:In Colombia Aedes (Stegomyia) aegypti is the main vector of urban arboviruses such as dengue, chikungunya and Zika. This urban mosquito has a well-established capacity to develop insecticide resistance to different types of insecticides (pyrethroids, organochlorides, organophosphates), using multiple resistance mechanisms. An understanding of ongoing resistance mechanisms is critical to determining the activities of vector control programs. In order to identify the biochemical and molecular mechanisms associated with pyrethroid resistance in Colombia, three laboratory-selected strains resistant to DDT, Propoxur and lambdacyhalothrin, and 7 field-collected strains were evaluated. CDC bioassays were performed to measure the susceptibility status to pyrethroid type I (permethrin) and II (deltamethrin and lambdacyhalothrin), and potential cross-resistance to different types of insecticides; organochlorine (DDT), carbamates (propoxur) and organophosphates (malathion). The enzymatic activity of esterases, glutathione S-transferases (GST) and P450 monooxygenases were biochemically determined. Frequencies of kdr mutations Val1016Ile and Phe1534cys were determined through real-time PCR. The Rockefeller strain of Aedes (Stegomyia) aegypti was used as the susceptible control. The laboratory-selected strains "propoxur" and "lambdacyhalothrin" and one field population (Medellín (BF) F2 were resistant to all evaluated pyrethroids. Six of the seven field populations as well as the laboratory- selected "DDT" strain were resistant to permethrin. All the evaluated strains were resistant to DDT. Cross-resistance between lambdacyhalothrin and propoxur was observed in the laboratory-selected strains; however, all field-collected strains were susceptible to propoxur and no evidence of malathion resistance was found. The main biochemical mechanism for resistance observed in the field-collected strains was related to the enzyme GST. Further, the frequencies of kdr mutations alleles associated with insecticide resistance were high and ranged from 0.02 to 0.72 for Ile1016 and from 0.44 to 0.99 for Cys1534. Strains with high frequencies of both kdr mutations were resistant to both type I and II pyrethroids. These results suggest that Ae. aegypti from Colombia have developed multiple resistance mechanisms associated with pyrethroid resistance; therefore a resistance management strategy against these field populations of Ae. Aegypti, incorporating these findings is strongly recommended.
| S-EPMC6447284 | biostudies-literature
Project description:The mosquito Aedes aegypti is the major vector of the four serotypes of dengue virus (DENV1-4). Previous studies have shown that Ae. aegypti in Mexico have a high effective migration rate and that gene flow occurs among populations that are up to 150 km apart. Since 2000, pyrethroids have been widely used for suppression of Ae. aegypti in cities in Mexico. In Yucatan State in particular, pyrethroids have been applied in and around dengue case households creating an opportunity for local selection and evolution of resistance. Herein, we test for evidence of local adaptation by comparing patterns of variation among 27 Ae. aegypti collections at 13 single nucleotide polymorphisms (SNPs): two in the voltage-gated sodium channel gene para known to confer knockdown resistance, three in detoxification genes previously associated with pyrethroid resistance, and eight in putatively neutral loci. The SNPs in para varied greatly in frequency among collections, whereas SNPs at the remaining 11 loci showed little variation supporting previous evidence for extensive local gene flow. Among Ae. aegypti in Yucatan State, Mexico, local adaptation to pyrethroids appears to offset the homogenizing effects of gene flow.
| S-EPMC4347380 | biostudies-literature
Project description:Association mapping of factors that condition pyrethroid resistance in Aedes aegypti has consistently identified genes in multiple functional groups. Toward better understanding of the mechanisms involved, we examined high throughput sequencing data (HTS) from two Aedes aegypti aegypti collections from Merida, Yucatan, Mexico treated with either permethrin or deltamethrin. Exome capture enrichment for coding regions and the AaegL5 annotation were used to identify genes statistically associated with resistance. The frequencies of single nucleotide polymorphisms (SNPs) were compared between resistant and susceptible mosquito pools using a contingency χ2 analysis. The -log10(χ2 p value) was calculated at each SNP site, with a weighted average determined from all sites in each gene. Genes with -log10(χ2 p value) ≥ 4.0 and present among all 3 treatment groups were subjected to gene set enrichment analysis (GSEA). We found that several functional groups were enriched compared to all coding genes. These categories were transport, signal transduction and metabolism, in order from highest to lowest statistical significance. Strikingly, 21 genes with demonstrated association to synaptic function were identified. In the high association group (n = 1,053 genes), several genes were identified that also genetically or physically interact with the voltage-gated sodium channel (VGSC). These genes were eg., CHARLATAN (CHL), a transcriptional regulator, several ankyrin-domain proteins, PUMILIO (PUM), a translational repressor, and NEDD4 (E3 ubiquitin-protein ligase). There were 13 genes that ranked among the top 10%: these included VGSC; CINGULIN, a predicted neuronal gap junction protein, and the aedine ortholog of NERVY (NVY), a transcriptional regulator. Silencing of CHL and NVY followed by standard permethrin bottle bioassays validated their association with permethrin resistance. Importantly, VGSC levels were also reduced about 50% in chl- or nvy-dsRNA treated mosquitoes. These results are consistent with the contribution of a variety of neuronal pathways to pyrethroid resistance in Ae. aegypti.
| S-EPMC6350986 | biostudies-literature
Project description:Aedes aegypti is the primary mosquito vector of dengue, yellow fever, Zika and chikungunya. Current strategies to control Ae. aegypti rely heavily on insecticide interventions. Pyrethroids are a major class of insecticides used for mosquito control because of their fast acting, highly insecticidal activities and low mammalian toxicity. However, Ae. aegypti populations around the world have begun to develop resistance to pyrethroids. So far, more than a dozen mutations in the sodium channel gene have been reported to be associated with pyrethroid resistance in Ae. aegypti. Co-occurrence of resistance-associated mutations is common in pyrethroid-resistant Ae. aegypti populations. As global use of pyrethroids in mosquito control continues, new pyrethroid-resistant mutations keep emerging. In this microreview, we compile pyrethroid resistance-associated mutations in Ae. aegypti in a chronological order, as they were reported, and summarize findings from functional evaluation of these mutations in an in vitro sodium channel expression system. We hope that the information will be useful for tracing possible evolution of pyrethroid resistance in this important human disease vector, in addition to the development of methods for global monitoring and management of pyrethroid resistance in Ae. aegypti.
| S-EPMC8060125 | biostudies-literature
Project description:BACKGROUND:Resistance to pyrethroid insecticides in Aedes aegypti has become widespread after almost two decades of the frequent use of these pesticides to reduce arbovirus transmission. Despite this resistance, pyrethroids continue to be used because they are relatively inexpensive and have low human toxicity. Resistance management has been proposed as a way to retain the use of pyrethroids in natural populations. A key component of resistance management is the assumption that negative fitness is associated with resistance alleles such that resistance alleles will decline in frequency when the insecticides are removed. At least three studies in Ae. aegypti have demonstrated a decrease in pyrethroid resistance once the insecticide has been removed. METHODS/PRINCIPAL FINDINGS:The present study aims to evaluate variation in the loss of pyrethroid resistance among newly established laboratory populations of Ae. aegypti from Mexico. Eight field collections were maintained for up to eight generations, and we recorded changes in the frequencies of the mutations at the V1,016I locus and at the F1,534C locus in the voltage-gated sodium channel gene (VGSC). I1,016 and C1,534 confer resistance. We also examined resistance ratios (RR) with type 1 and 2 pyrethroids. CONCLUSIONS/SIGNIFICANCE:We demonstrate that, in general, the frequency of the Ae. aegypti pyrethroid-resistance alleles I1,016 and C1,534 decline when they are freed from pyrethroid pressure in the laboratory. However, the pattern of decline is strain dependent. In agreement with earlier studies, the RR was positively correlated with the frequencies of the resistance allele I1,016 and showed significant protection against permethrin, and deltamethrin, whereas F1,534C showed protection against permethrin but not against deltamethrin.
| S-EPMC7117762 | biostudies-literature