Approved Abstracts

VKORC1 single nucleotide polymorphism in rodents in Spain

Author(s): Bermejo-Nogales A; Navas JM;
Presenter: Azucena Bermejo-Nogales

Rodents are considered one of the animal pests with the greatest impact on agricultural production and public health. The estimated losses caused by rodents range between 5% and 90% of crop production. In addition, rodents can be the vector of zoonoses causing human health problems and they can also affect food security. Therefore, it is essential to control their populations through effective approaches. Strategies based on an Integrated Pest Management (IPM) try to implement an effective reduction in the use of pesticides decreasing the likelihood of the appearance of pesticide resistance. Anticoagulant rodenticides (AR) have been widely used as one of the most effective ways to control rodent populations. AR inhibit the enzyme vitamin K 2,3-epoxide reductase (VKORC1) causing animal death due to internal haemorrhages. Resistance to AR is mainly associated with mutations or single nucleotide polymorphism (SNP) in the vkorc1 gene. In Spain, there is a lack of information on this subject. The aim of this study is to monitor the presence of SNP that can favour resistance in rodent populations in Spain. Furthermore, we aim to characterize binding properties of AR to VKORC1 with new SNP by in silico analysis. The species selected for this study are brown rat (Rattus norvegicus), black rat (Rattus rattus) and mouse (Mus musculus), as considered the most common pests in our latitudes. In coordination with the National Association of Environmental Sanitation Companies (ANECPLA) we designed a kit with the material for the collection of samples and a questionnaire for identification of places where the lack of efficacy of the rodenticides has been reported despite the good consumption of bait. By april 2021 we recibed 118 samples of rodents stool and tails from 12 autonomous communities (regions) in Spain. Additionally, the managing entities of four locations with specific interest on this project sent us also 20-25 prospective samples. We performed the DNA extraction and analysed SNP in the exon 3 of the vkorc1 gene by means of PCR. Determination of pest specie was based on cytochrome b (cytb) sequences and phylogenetic analysis. We found differential distribution of the three species, and intringuly we unexpectedly discovered the presence of black rat in the centre of the Iberian Peninsula. Good quality was obtained in 60% of samples. At least 20% of the analysed faeces samples showed a SNP. We found genotypic variation at various codons of the vkorc1 gene. Indeed, AutoDock Vina virtual screening analysis showed less binding affinity and therefore resistance of specific mutations to some AR. These results have direct implications regarding the treatment and use of AR.

Keywords: rat; mutation; Anticoagulant rodenticides




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