Culex pipiens pallens cuticular protein CPLCG5 participates in pyrethroid resistance by forming a rigid matrix

Abstract

BackgroundChemical insecticides have hugely reduced the prevalence of vector-borne diseases around the world, but resistance threatens their continued effectiveness. Despite its importance, cuticle resistance is an under-studied area, and exploring the detailed molecular basis of resistance is critical for implementing suitable resistance management strategies.MethodsWe performed western blotting of cuticular protein CPLCG5 in deltamethrin-susceptible (DS) and laboratory-produced deltamethrin-resistant (DR) strains of Culex pipiens pallens. Immunofluorescence assays using a polyclonal antibody to locate cuticular CPLCG5 in mosquitoes. EM immunohistochemical analysis of the femur segment was used to compare the cuticle in control and CPLCG5-deficient siRNA experimental groups.ResultsThe gene CPLCG5 encodes a cuticle protein that plays an important role in pyrethroid resistance. Based on a prior study, we found that expression of CPLCG5 was higher in the resistant (DR) strain than the susceptible (DS) strain. CPLCG5 transcripts were abundant in white pupae and 1-day-old adults, but expression was dramatically decreased in 3-day-old adults, then remained stable thereafter. Western blotting revealed that the CPLCG5 protein was ~2.2-fold higher in the legs of the DR strain than the DS strain. Immunofluorescence assays revealed CPLCG5 expression in the head, thorax, abdomen, wing, and leg, and expression most abundant in the leg and wing. EM immunohistochemical analysis suggested that the exocuticle thickness of the femur was significantly thinner in the CPLCG5-deficient siCPLCG5 strain (0.717 ± 0.110 μm) than the siNC strain (0.946 ± 0.126 μm). Depletion of CPLCG5 by RNA interference resulted in unorganised laminae and a thinner cuticle.ConclusionsThe results suggest CPLCG5 participates in pyrethroid resistance by forming a rigid matrix and increasing the thickness of the cuticle.Electronic supplementary materialThe online version of this article (doi: 10.1186/s13071-017-2567-9) contains supplementary material, which is available to authorized users.

Transcriptome Analysis and Identification of Insecticide Tolerance-Related Genes after Exposure to Insecticide in Sitobion avenae

“…Increased insecticides cuticular penetration, including cuticle thickening and alteration of cuticle composition, have previously been described [37]. In Culex pipiens pallens, cuticle protein played an important role in deltamethrin resistance [38], and CPLCG5 encoded a cuticle protein that participated in pyrethroid resistance by inducing rigidity and increasing the thickness of the cuticle [39]. There were five cuticle protein genes differentially expressed in deltamethrin-resistant C. pipiens pallens when compared with susceptible strains, with cuticle protein CP14.6 precursors found to be overexpressed in the deltamethrin-resistant strain.…”

Genome-wide gene expression profiling reveals that cuticle alterations and P450 detoxification are associated with pyrethroid resistance in Anopheles arabiensis populations from Ethiopia

“…Higher expression of cuticular genes has previously been reported for pyrethroid resistant mosquito populations 32, 71–75 and in some cases was associated with a thicker cuticula. 73, 74 Further, some of these Anopheles cuticular genes were also shown to be expressed in the limbs, the most frequent site of contact with insecticides. 76 Apart from genes encoding cuticular proteins, cyp4g16 , which encodes a P450 that catalyzes epicuticular hydrocarbon biosynthesis, has also been reported to be frequently overexpressed in insecticide resistant Anopheles mosquitoes, including An.…”

Involvement of integument‐rich CYP4G19 in hydrocarbon biosynthesis and cuticular penetration resistance in Blattella germanica (L.)

“…Moreover, we can not exclude the possibility that in addition to the hexane‐soluble lipids, other cuticle components, such as structural proteins and chitin layers, might contribute to the cuticular resistance in B. germanica . Such a possibility is based on the validated contribution of cuticular proteins to peneration resistance and the thickening of the chitin layers in pyrethroid‐resistant mosquitoes. Whether these cuticular compounds are involved, and further, which genes are involved in peneration resistance in B. germanica are not well understood.…”