Low Frequency of Knockdown Resistance Mutations in Musca domestica (Muscidae: Diptera) Collected From Northwestern Iran

ABSTRACTRaltegravir is highly efficacious in the treatment of HIV-1 infection. The prevalence and impact on virologic outcome of low-frequency resistant mutations among HIV-1-infected patients not previously treated with raltegravir have not been fully established. Samples from HIV treatment-experienced patients entering a clinical trial of raltegravir treatment were analyzed using a parallel allele-specific sequencing (PASS) assay that assessed six primary and six secondary integrase mutations. Patients who achieved and sustained virologic suppression (success patients,n= 36) and those who experienced virologic rebound (failure patients,n= 35) were compared. Patients who experienced treatment failure had twice as many raltegravir-associated resistance mutations prior to initiating treatment as those who achieved sustained virologic success, but the difference was not statistically significant. The frequency of nearly all detected resistance mutations was less than 1% of viral population, and the frequencies of mutations between the success and failure groups were similar. Expansion of pre-existing mutations (one primary and five secondary) was observed in 16 treatment failure patients in whom minority resistant mutations were detected at baseline, suggesting that they might play a role in the development of drug resistance. Two or more mutations were found in 13 patients (18.3%), but multiple mutations were not present in any single viral genome by linkage analysis. Our study demonstrates that low-frequency primary RAL-resistant mutations were uncommon, while minority secondary RAL-resistant mutations were more frequently detected in patients naïve to raltegravir. Additional studies in larger populations are warranted to fully understand the clinical implications of these mutations.

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The Pattern of Knockdown Resistance Mutations Correlated to the Annual Average Temperature in Field Populations of Aedes Albopictus (Diptera: Culicidae) in China

10.21203/rs.3.rs-201442/v1 ◽

2021 ◽

Author(s):

Hanming Chen ◽

Qiuming Zhou ◽

Haowei Dong ◽

Hao Yuan ◽

Jie Bai ◽

...

Keyword(s):

Dengue Fever ◽

Mutation Rate ◽

Aedes Albopictus ◽

Mutant Allele ◽

Pearson Correlation ◽

Point Mutations ◽

National Database ◽

Knockdown Resistance ◽

Resistance Mutations ◽

Annual Average

Abstract Background: Aedes albopictus is the main vector of dengue fever in China, distributed from north to south in China. Insecticides are an important method to control the mosquitoes, especially in the outbreak of dengue fever, but insecticide resistance raises the risk of failure to control vector-borne diseases. Knockdown resistance (kdr) caused by point mutations in the VGSC gene is a key mechanism that confers resistance to pyrethroids. To explore the characteristics and possible evolution trend of kdr mutation in Ae. albopictus, we analyzed the kdr mutations of field populations in China in this study.Methods: A total of 1 549 Ae. albopictus were collected from 18 sites in China from 2017 to 2019, as well as 50 individuals from three sites in the 1990s. A fragment of approximately 350 bp from part of S6 segment in the VGSC gene domain III was amplified and sequenced. The haplotypes of VGSC gene were recorded and the parsimony network was constructed using TCS 1.21. The data of annual average temperatures (AAT) of collection sites was acquired from national database. The correlation between AAT of the collection site and the kdr mutation rate was analyzed by Pearson Correlation using SPSS 21.0. Results: The overall frequency of mutant allele F1534 is 45.62%. Nine mutant alleles were detected at codon 1534 in fifteen field populations, namely TCC/TCG (S) (38.86%), TTG/CTG/CTC/TTA (L) (3.71%), TGC (C) (2.68%), CGC (R) (0.27%) and TGG (W) (0.10%). Only one mutant allele ACC (T) was found at codon 1532 with frequency of 6.39% in ten field populations. Moreover, multiple mutations at I1532 and F1534 in a sample appeared in five populations. The 1534 mutation rate was significantly positive related to AAT (Coefficient=0.624, p=0.0056), while the 1532 mutation rate was significantly negative related to AAT (Coefficient=-0.645, p=0.0038). Thirteen haplotypes were inferred, in which six mutant haplotypes were formed by one step, and the other six haplotypes were formed by one more mutations. In the samples from 1990s, no mutant allele was detected at codon 1532 of VGSC gene. However, F1534S/TCC was found in HNHK94 with an unexpected frequency of 100%.ConclusionsKdr mutations are widespread in the field populations of Ae. albopictus in China. Two novel mutant alleles F1534W/TGG and F1534R/CGC were the detected. The 1534 kdr mutation appeared in the population of Ae. albopictus no later than 1990s. F1534 mutation rate is positive correlated to AAT, while I1532 mutation rate is negative correlated to AAT. Insecticide using should be carefully managed to slow down the spread of high-resistance Ae. albopictus populations.

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Molecular Monitoring of Knockdown Resistance in Head Louse (Phthiraptera: Pediculidae) Populations in Iran

Journal of Medical Entomology ◽

10.1093/jme/tjab101 ◽

2021 ◽

Author(s):

Fereshteh Ghahvechi Khaligh ◽

Navid Dinparast Djadid ◽

Mostafa Farmani ◽

Zahra Asadi Saatlou ◽

Samira Frooziyan ◽

...

Keyword(s):

Amino Acid ◽

Head Louse ◽

Molecular Techniques ◽

Common Mechanism ◽

Amino Acid Substitutions ◽

Head Lice ◽

Knockdown Resistance ◽

Resistance Mutations ◽

Accurate Detection ◽

Genotype Frequencies

Abstract Knockdown resistance (kdr) is a common mechanism of insecticide resistance in head lice to the conventionally used pyrethroid pediculosis and can be the result of various amino acid substitutions within the voltage-sensitive sodium channel (VSSC). In this study, 54 sequences from varied specimens were investigated to monitor well-known resistance mutations and probable new mutations. The Pediculus humanus capitis de Geer specimens were collected from 13 provinces in Iran. The specimens were stored in 70% ethanol until DNA extraction and PCR amplification of ~900-bp fragment of VSSC. The sequences were analyzed using different bioinformatics software for the detection of well-known kdr substitutions and additional mutations potentially associated with kdr resistance in head lice. There were six new and an old (haplotype I) kdr haplotypes within the Iranian head louse population. K794E, F815I, and N818D amino acid substitutions were reported for the first time. The P813H mutation was the most prevalent amino acid substitution in eight provinces. Among 53 sequences, 26 (49%) were homozygous susceptible, and 27 (51%) were heterozygotes. Thus, 51% of the head lice collected in Iran harbored only the P813H allele. The exact test for the Hardy–Weinberg (H–W) equilibrium showed that genotype frequencies differed significantly from the expectation in East-Azerbaijan and Tehran provinces. Moreover, these populations had an inbreeding coefficient (Fis) <0, indicating the excess of heterozygotes. This observation suggests that the populations of head lice from Iran are currently under active selective pressure. For the rest of the populations, H–W equilibrium and the expectations were significantly in harmony. The results of the current study highlight molecular techniques in the accurate detection of resistance genotypes before their establishment within the head louse population. Accurate detection of resistant genotypes seems to be helpful in decision-making on lice control programs and resistance monitoring and management.

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High frequency of knockdown resistance mutations in the para gene of cat flea (Ctenocephalides felis) samples collected from goats

Parasitology Research ◽

10.1007/s00436-020-06714-3 ◽

2020 ◽

Vol 119 (7) ◽

pp. 2067-2073 ◽

Cited By ~ 1

Author(s):

Sedef Erkunt Alak ◽

Ahmet Efe Köseoğlu ◽

Çağrı Kandemir ◽

Turğay Taşkın ◽

Samiye Demir ◽

...

Keyword(s):

High Frequency ◽

Ctenocephalides Felis ◽

Knockdown Resistance ◽

Resistance Mutations ◽

Cat Flea

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Widespread distribution of knockdown resistance mutations in the bed bug,Cimex lectularius(Hemiptera: Cimicidae), populations in the United States

Archives of Insect Biochemistry and Physiology ◽

10.1002/arch.20355 ◽

2010 ◽

pp. n/a-n/a ◽

Cited By ~ 17

Author(s):

Fang Zhu ◽

John Wigginton ◽

Alvaro Romero ◽

Ali Moore ◽

Kimberly Ferguson ◽

...

Keyword(s):

United States ◽

The United States ◽

Cimex Lectularius ◽

Knockdown Resistance ◽

Resistance Mutations ◽

Widespread Distribution ◽

Bed Bug

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Low-Frequency Drug Resistance in HIV-Infected Ugandans on Antiretroviral Treatment Is Associated with Regimen Failure

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00038-16 ◽

2016 ◽

Vol 60 (6) ◽

pp. 3380-3397 ◽

Cited By ~ 26

Author(s):

Fred Kyeyune ◽

Richard M. Gibson ◽

Immaculate Nankya ◽

Colin Venner ◽

Samar Metha ◽

...

Keyword(s):

Drug Resistance ◽

Treatment Failure ◽

Sanger Sequencing ◽

Antiretroviral Treatment ◽

Low Frequency ◽

Drug Resistant ◽

Viral Quasispecies ◽

Resistance Mutations ◽

Drug Resistance Mutations ◽

Hiv 1

Most patients failing antiretroviral treatment in Uganda continue to fail their treatment regimen even if a dominant drug-resistant HIV-1 genotype is not detected. In a recent retrospective study, we observed that approximately 30% of HIV-infected individuals in the Joint Clinical Research Centre (Kampala, Uganda) experienced virologic failure with a susceptible HIV-1 genotype based on standard Sanger sequencing. Selection of minority drug-resistant HIV-1 variants (not detectable by Sanger sequencing) under antiretroviral therapy pressure can lead to a shift in the viral quasispecies distribution, becoming dominant members of the virus population and eventually causing treatment failure. Here, we used a novel HIV-1 genotyping assay based on deep sequencing (DeepGen) to quantify low-level drug-resistant HIV-1 variants in 33 patients failing a first-line antiretroviral treatment regimen in the absence of drug-resistant mutations, as screened by standard population-based Sanger sequencing. Using this sensitive assay, we observed that 64% (21/33) of these individuals had low-frequency (or minority) drug-resistant variants in the intrapatient HIV-1 population, which correlated with treatment failure. Moreover, the presence of these minority HIV-1 variants was associated with higher intrapatient HIV-1 diversity, suggesting a dynamic selection or fading of drug-resistant HIV-1 variants from the viral quasispecies in the presence or absence of drug pressure, respectively. This study identified low-frequency HIV drug resistance mutations by deep sequencing in Ugandan patients failing antiretroviral treatment but lacking dominant drug resistance mutations as determined by Sanger sequencing methods. We showed that these low-abundance drug-resistant viruses could have significant consequences for clinical outcomes, especially if treatment is not modified based on a susceptible HIV-1 genotype by Sanger sequencing. Therefore, we propose to make clinical decisions using more sensitive methods to detect minority HIV-1 variants.

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Primary resistance to integrase strand transfer inhibitors in Spain using ultrasensitive HIV-1 genotyping

Journal of Antimicrobial Chemotherapy ◽

10.1093/jac/dkaa349 ◽

2020 ◽

Vol 75 (12) ◽

pp. 3517-3524

Author(s):

M Casadellà ◽

J R Santos ◽

M Noguera-Julian ◽

R Micán-Rivera ◽

P Domingo ◽

...

Keyword(s):

Reverse Transcriptase ◽

Low Frequency ◽

Transmitted Drug Resistance ◽

Strand Transfer ◽

Resistance Mutations ◽

First Line ◽

Primary Resistance ◽

Integrase Strand Transfer Inhibitors ◽

Virological Outcomes ◽

Hiv 1

Abstract Background Transmission of resistance mutations to integrase strand transfer inhibitors (INSTIs) in HIV-infected patients may compromise the efficacy of first-line antiretroviral regimens currently recommended worldwide. Continued surveillance of transmitted drug resistance (TDR) is thus warranted. Objectives We evaluated the rates and effects on virological outcomes of TDR in a 96 week prospective multicentre cohort study of ART-naive HIV-1-infected subjects initiating INSTI-based ART in Spain between April 2015 and December 2016. Methods Pre-ART plasma samples were genotyped for integrase, protease and reverse transcriptase resistance using Sanger population sequencing or MiSeq™ using a ≥ 20% mutant sensitivity cut-off. Those present at 1%–19% of the virus population were considered to be low-frequency variants. Results From a total of 214 available samples, 173 (80.8%), 210 (98.1%) and 214 (100.0%) were successfully amplified for integrase, reverse transcriptase and protease genes, respectively. Using a Sanger-like cut-off, the overall prevalence of any TDR, INSTI-, NRTI-, NNRTI- and protease inhibitor (PI)-associated mutations was 13.1%, 1.7%, 3.8%, 7.1% and 0.9%, respectively. Only three (1.7%) subjects had INSTI TDR (R263K, E138K and G163R), while minority variants with integrase TDR were detected in 9.6% of subjects. There were no virological failures during 96 weeks of follow-up in subjects harbouring TDR as majority variants. Conclusions Transmitted INSTI resistance remains rare in Spain and, to date, is not associated with virological failure to first-line INSTI-based regimens.

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