BACKGROUND: Despite intensive use of Bromadiolone, rodent control was inefficient in a farm in Zaragoza (Spain) infested by rats. While metabolic resistance was previously described in this rodent species, the observation of a target resistance to vitamin K rodenticides had been poorly documented in Rattus rattus.RESULTS: From rats trapped in the farm, cytochrome b and Vkorc1 gene were amplified by PCR and sequenced in order to identify species and detect potential Vkorc1 mutations. VKORC1 deduced amino acids sequences were thus expressed in Pichia pastoris and inhibition constants towards various rodenticides were determined. The 10 rats trapped in the farm were all identified as Rattus rattus. They were found... More
BACKGROUND: Despite intensive use of Bromadiolone, rodent control was inefficient in a farm in Zaragoza (Spain) infested by rats. While metabolic resistance was previously described in this rodent species, the observation of a target resistance to vitamin K rodenticides had been poorly documented in Rattus rattus.RESULTS: From rats trapped in the farm, cytochrome b and Vkorc1 gene were amplified by PCR and sequenced in order to identify species and detect potential Vkorc1 mutations. VKORC1 deduced amino acids sequences were thus expressed in Pichia pastoris and inhibition constants towards various rodenticides were determined. The 10 rats trapped in the farm were all identified as Rattus rattus. They were found to be homozygous for the g.74A>T nucleotide replacement in exon 1 of the Vkorc1 gene leading to p.Y25F mutation. This mutation led to increase in Ki towards various rodenticides probably caused by a partial loss of helical structure of TM4.CONCLUSION: The p.Y25F mutation detected in Vkorc1 gene in Rattus rattus trapped in the Spanish farm is associated to the resistance phenotype to bromadiolone that has been observed. It is the first evidence of target resistance to AVKs in Rattus rattus.This article is protected by copyright. All rights reserved.
