Increased transcription of Glutathione S-transferases in acaricide exposed scabies mites

• Main Authors: Currie Bart J, Holt Deborah C, Morgan Marjorie S, Arlian Larry G, Pasay Cielo J, Mounsey Kate E, Walton Shelley F, McCarthy James S
• Format: Article
• Language: English
• Published: BMC 2010-05-01
• Series: Parasites & Vectors
• Online Access: http://www.parasitesandvectors.com/content/3/1/43

<p>Abstract</p> <p>Background</p> <p>Recent evidence suggests that <it>Sarcoptes scabiei </it>var. <it>hominis </it>mites collected from scabies endemic communities in northern Australia show increasing tolerance to 5% permethrin and oral ivermectin. Previous findings have implicated detoxification pathways in developing resistance to these acaricides. We investigated the contribution of Glutathione S-transferase (GST) enzymes to permethrin and ivermectin tolerance in scabies mites using biochemical and molecular approaches.</p> <p>Results</p> <p>Increased <it>in vitro </it>survival following permethrin exposure was observed in <it>S. scabiei </it>var. <it>hominis </it>compared to acaricide naïve mites (p < 0.0001). The addition of the GST inhibitor diethyl maleate restored <it>in vitro </it>permethrin susceptibility, confirming GST involvement in permethrin detoxification. Assay of GST enzymatic activity in mites demonstrated that <it>S. scabiei </it>var. <it>hominis </it>mites showed a two-fold increase in activity compared to naïve mites (p < 0.0001). Increased transcription of three different GST molecules was observed in permethrin resistant <it>S. scabiei </it>var. <it>canis</it>- mu 1 (p < 0.0001), delta 1 (p < 0.001), and delta 3 (p < 0.0001). mRNA levels of GST mu 1, delta 3 and P-glycoprotein also significantly increased in <it>S. scabiei </it>var. <it>hominis </it>mites collected from a recurrent crusted scabies patient over the course of ivermectin treatment.</p> <p>Conclusions</p> <p>These findings provide further support for the hypothesis that increased drug metabolism and efflux mediate permethrin and ivermectin resistance in scabies mites and highlight the threat of emerging acaricide resistance to the treatment of scabies worldwide. This is one of the first attempts to define specific genes involved in GST mediated acaricide resistance at the transcriptional level, and the first application of such studies to <it>S. scabiei</it>, a historically challenging ectoparasite.</p>