Mutación asociada a la resistencia a insecticidas piretroides en el mosquito transmisor de dengue ("Aedes aegypti")

CIENCIA-UANL, ISSN 1405-9177, Vol. 11, Nº. 4, 2008
Source: OAI


Pyrethroids are commonly used as mosquito adulticides and evolution of resistance to these compounds is a major threat to public health. ‘Knockdown resistance’ to pyrethroids (kdr) is frequently caused by nonsynonymous mutations in the voltage-gated sodium channel transmembrane protein (para) that reduce pyrethroid binding. Early detection of kdr is critical to the development of resistance management strategies in mosquitoes including Aedes aegypti, the most prevalent vector of dengue and yellow fever viruses. Brengues et al. described seven novel mutations in hydrophobic segment 6 of domain II of para in Aedes aegypti. Assays on larvae from strains bearing these mutations indicated reduced nerve sensitivity to permethrin inhibition. Two of these occurred in codons Iso1011 and Val1016 in exons 20 and 21 respectively. A transition in the third position of Iso1011 encoded a Met1011 replacement and a transversion in the second position of Val1016 encoded a Gly1016 replacement. We have screened this same region in 1318 mosquitoes in 32 additional strains; 30 from throughout Latin America. While the Gly1016 allele was never detected in Latin America, we found two new mutations in these same codons. A transition in the first position of codon 1011 encodes a Val replacement while a transition in the first position of codon 1016 encodes an Iso replacement. We developed PCR assays for these four mutations that can be read either on an agarose gel or as a melting curve. Selection experiments: one with deltamethrin on a field strain from Santiago de Cuba and another with permethrin on a strain from Isla Mujeres, Mexico rapidly increased the frequency of the Iso1016 allele. Bioassays of F3 offspring arising from permethrin susceptible Val1016 homozygous parents and permethrin resistant Iso1016 homozygous parents show that Iso1016 segregates as a recessive allele in conferring kdr. Analysis of segregation between alleles at the 1011 and 1016 codons in the F3 showed a high rate of recombination even though the two codons are only separated by a ~250 bp intron. The tools and information presented provide a means for early detection and characterization of kdr that is critical to the development of strategies for resistance management.

Download full-text


Available from: Adriana E. Flores, Oct 08, 2015
136 Reads
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Some statistical properties of samples of DNA sequences are studied under an infinite-site neutral model with recombination. The two quantities of interest are R, the number of recombination events in the history of a sample of sequences, and RM, the number of recombination events that can be parsimoniously inferred from a sample of sequences. Formulas are derived for the mean and variance of R. In contrast to R, RM can be determined from the sample. Since no formulas are known for the mean and variance of RM, they are estimated with Monte Carlo simulations. It is found that RM is often much less than R, therefore, the number of recombination events may be greatly under-estimated in a parsimonious reconstruction of the history of a sample. The statistic RM can be used to estimate the product of the recombination rate and the population size or, if the recombination rate is known, to estimate the population size. To illustrate this, DNA sequences from the Adh region of Drosophila melanogaster are used to estimate the effective population size of this species.
    Genetics 10/1985; 111(1):147-64. · 5.96 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Dengue fever/dengue hemorrhagic fever is now one of the most important public health problems in tropical developing countries and also has major economic and societal consequences.
    Trends in Microbiology 03/2002; 10(2):100-3. DOI:10.1016/S0966-842X(01)02288-0 · 9.19 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: A sample of Aedes aegypti (L.) from Santiago de Cuba, Cuba, with a high level of temephos resistance (19.58x at the 50% lethal concentration [LC50]), was subjected to temephos selection to evaluate the utility of this organophosphate insecticide for mosquito control. High resistance developed after six generations of selection (200.00x). Little or no cross-resistance was observed to the organophosphates, malathion and fenitrothion, but high cross-resistance was observed for the pyrethroid deltamethrin (337.5x) and the organophosphate fenthion (12.74x). Synergism tests implicated detoxifying esterases in temephos and fenthion resistance and deltamethrin resistance was associated with a cytochrome P450 monooxygenasa. Biochemical tests, polyacrylamide gel electrophoresis (PAGE), and inhibition studies confirmed the presence of elevated esterase activity associated with temephos resistance. Pyrethroid resistance could be associated with a glutathione-S-transferase mechanism but not the esterases. The cross-resistance to deltamethrin from temephos selection could limit the use of both insecticides for Ae. aegypti control.
    Journal of Medical Entomology 12/2002; 39(6):882-8. DOI:10.1603/0022-2585-39.6.882 · 1.95 Impact Factor
Show more