Glutathione S-transferases play a role in the detoxification of flumethrin and chlorpyrifos in Haemaphysalis longicornis

Emmanuel Pacia Hernandez,Naotoshi Tsuji,Takeshi Hatta,Remil Linggatong Galay,Tetsuya Tanaka,Kozo Fujisaki,Kodai Kusakisako,Melbourne Rio Talactac

doi:10.1186/s13071-018-3044-9

Abstract

BackgroundHaemaphysalis longicornis is a tick of importance to health, as it serves as a vector of several pathogens, including Theileria orientalis, Babesia ovata, Rickettsia japonica and the severe fever with thrombocytopenia syndrome virus (SFTSV). Presently, the major method of control for this tick is the use of chemical acaricides. The glutathione S-transferase (GST) system is one mechanism through which the tick metabolizes these acaricides. Two GSTs from H. longicornis (HlGST and HlGST2) have been previously identified.ResultsEnzyme kinetic studies were performed to determine the interaction of acaricides with recombinant H. longicornis GSTs. Recombinant HlGST activity was inhibited by flumethrin and cypermethrin, while recombinant HlGST2 activity was inhibited by chlorpyrifos and cypermethrin. Using real-time RT-PCR, the upregulation of the HlGST gene was observed upon exposure to sublethal doses of flumethrin, while the HlGST2 gene was upregulated when exposed to sublethal doses of chlorpyrifos. Sex and strain dependencies in the induction of GST gene expression by flumethrin were also observed. Knockdown of the HlGST gene resulted in the increased susceptibility of larvae and adult male ticks to sublethal doses of flumethrin and the susceptibility of larvae against sublethal doses of chlorpyrifos was increased upon knockdown of HlGST2.ConclusionsHlGST could be vital for the metabolism of flumethrin in larvae and adult male ticks, while HlGST2 is important in the detoxification of chlorpyrifos in larval ticks.

Highlights

Haemaphysalis longicornis is a tick of importance to health, as it serves as a vector of several pathogens, including Theileria orientalis, Babesia ovata, Rickettsia japonica and the severe fever with thrombocytopenia syndrome virus (SFTSV)
Coumaphos significantly decreased the Km of recombinant GST of H. longicornis (HlGST), indicating the apparent activation of the enzyme. These results demonstrated that the interactions of the recombinant glutathione S-transferase (GST) with acaricides depend on the variety of acaricide
The knockdown of HlGST2 and both HlGST and HlGST2 caused a significant increase in the mortality of larvae exposed to 10 μM (HlGST2: t(2) = 5.66, P = 0.030; HlGST and HlGST2: t(2) = 5.66, P = 0.030) and 100 μM chlorpyrifos (HlGST2: t(2) = 7.07, P = 0.019; HlGST and HlGST2: t(2) = 7.07, P = 0.019) (Fig. 3a). These results showed that HlGST is vital for the survival of larval ticks against sublethal doses of flumethrin, while HlGST2 is important in larval tick survival against chlorpyrifos

Summary

Introduction

Haemaphysalis longicornis is a tick of importance to health, as it serves as a vector of several pathogens, including Theileria orientalis, Babesia ovata, Rickettsia japonica and the severe fever with thrombocytopenia syndrome virus (SFTSV). The hard tick Haemaphysalis longicornis is a blood-sucking arthropod widely distributed in East Asia and Australia. They are known vectors of Theileria orientalis, Babesia ovata and Rickettsia japonica, as well as the severe fever with thrombocytopenia syndrome virus (SFTSV) [1, 2]. Amitraz is a formamidine acaricide that has been around since the 1960s It acts as an agonist of the octopaminergic receptors of arthropods, leading to the stimulation of monoamine oxidases and G proteins. Their action results in acetylcholine continuous stimulation, causing hyperactivity and, eventually, the death of the arthropods.

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