Salivary Gland Proteome Analysis Reveals Modulation of Anopheline Unique Proteins in Insensitive Acetylcholinesterase Resistant Anopheles gambiae Mosquitoes

Sylvie Cornelie,François Mouchet,Philippe Marin,Edith Demettre,Françoise Mathieu-Daudé,Vincent Corbel,Martial Seveno,Innocent Djègbè,Marie Rossignol,Franck Remoué,Fabrice Chandre

doi:10.1371/journal.pone.0103816

Abstract

Insensitive acetylcholinesterase resistance due to a mutation in the acetylcholinesterase (ace) encoding ace-1 gene confers cross-resistance to organophosphate and carbamate insecticides in Anopheles gambiae populations from Central and West Africa. This mutation is associated with a strong genetic cost revealed through alterations of some life history traits but little is known about the physiological and behavioural changes in insects bearing the ace-1R allele. Comparative analysis of the salivary gland contents between An. gambiae susceptible and ace-1R resistant strains was carried out to charaterize factors that could be involved in modifications of blood meal process, trophic behaviour or pathogen interaction in the insecticide-resistant mosquitoes. Differential analysis of the salivary gland protein profiles revealed differences in abundance for several proteins, two of them showing major differences between the two strains. These two proteins identified as saglin and TRIO are salivary gland-1 related proteins, a family unique to anopheline mosquitoes, one of them playing a crucial role in salivary gland invasion by Plasmodium falciparum sporozoites. Differential expression of two other proteins previously identified in the Anopheles sialome was also observed. The differentially regulated proteins are involved in pathogen invasion, blood feeding process, and protection against oxidation, relevant steps in the outcome of malaria infection. Further functional studies and insect behaviour experiments would confirm the impact of the modification of the sialome composition on blood feeding and pathogen transmission abilities of the resistant mosquitoes. The data supports the hypothesis of alterations linked to insecticide resistance in the biology of the primary vector of human malaria in Africa.

Highlights

Malaria remains one of the most important public health problems worldwide
Differential analysis between salivary gland extracts (SGE) samples from resistant and susceptible mosquitoes Four independent biological repeats corresponding to four SGE samples of each An. gambiae strain, ace-1R Kisumu strain (AceRKis) and Kis, were used for the comparative analysis
Of these spots eight were excised from the preparative Kis and AceRKis gels, whereas the other two spots were too faint for excision

Summary

Introduction

Due to its high anthropophily Anopheles gambiae s.l. constitutes the main vector of malaria and the target of vector control programmes in Africa [1]. Anopheles mosquito has developed resistance to the different classes of insecticides used in vector control stategies through two major mechanisms. Two amino acid substitutions in the protein have been shown to play a role in resistance but the resistant allele encoding the G119S mutation, namely ace-1R, was reported several times in field An. gambiae populations [4,5,6]. D7 long form protein which is known to favor the blood intake was downregulated in resistant Culex mosquitoes whereas some metabolic components were up-regulated in the resistant strain [13].

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Discussion

Conclusion