Abstract

Background

   Midgut invasion, a major bottleneck for malaria parasites transmission
   is considered as a potential target for vector-parasite interaction
   studies. New intervention strategies are required to explore the midgut
   proteins and their potential role in refractoriness for malaria control
   in Anopheles mosquitoes. To better understand the midgut functional
   proteins of An. culicifacies susceptible and refractory species,
   proteomic approaches coupled with bioinformatics analysis is an
   effective means in order to understand the mechanism of refractoriness.
   In the present study, an integrated in solution- in gel trypsin
   digestion approach, along with Isobaric tag for relative and absolute
   quantitation (iTRAQ)–Liquid chromatography/Mass spectrometry (LC/MS/MS)
   and data mining were performed to identify the proteomic profile and
   differentially expressed proteins in Anopheles culicifacies susceptible
   species A and refractory species B.

Results

   Shot gun proteomics approaches led to the identification of 80 proteins
   in An. culicifacies susceptible species A and 92 in refractory species
   B and catalogue was prepared. iTRAQ based proteomic analysis identified
   48 differentially expressed proteins from total 130 proteins. Of these,
   41 were downregulated and 7 were upregulated in refractory species B in
   comparison to susceptible species A. We report that the altered midgut
   proteins identified in naturally refractory mosquitoes are involved in
   oxidative phosphorylation, antioxidant and proteolysis process that may
   suggest their role in parasite growth inhibition. Furthermore, real
   time polymerase chain reaction (PCR) analysis of few proteins indicated
   higher expression of iTRAQ upregulated protein in refractory species
   than susceptible species.

Conclusion

   This study elucidates the first proteome of the midguts of An.
   culicifacies sibling species that attempts to analyze unique
   proteogenomic interactions to provide insights for better understanding
   of the mechanism of refractoriness. Functional implications of these
   upregulated proteins in refractory species may reflect the phenotypic
   characteristics of the mosquitoes and will improve our understandings
   of blood meal digestion process, parasite vector interactions and
   proteomes of other vectors of human diseases for development of novel
   vector control strategies.

Electronic supplementary material

   The online version of this article (10.1186/s12864-018-4729-3) contains
   supplementary material, which is available to authorized users.

   Keywords: Anopheles culicifacies, Refractory, Midgut, Shot gun
   proteomics, iTRAQ, RT-PCR

Background

   According to World Health Organization (WHO), India accounts for 75% of
   total malaria cases among South East Asia region [[35]1]. Female
   mosquitoes of the genus Anopheles are the major protagonists of malaria
   transmission. Among various Anopheles species, Anopheles culicifacies
   is considered as one of major malaria vector responsible for
   transmitting nearly 65% of total malaria cases in India [[36]2]. This
   rural malaria vector species has been characterized as a sibling
   species complex with five sub species designated as A, B, C, D and E.
   All these sibling species are phylogenetically indistinguishable and
   are discriminated on the basis of vectorial capacity and malaria
   transmission rate [[37]3]. A natural sub species of An. culicifacies,
   species B was detected and isolated from a specific area that is found
   to be refractory (poor vector) against human malaria parasites
   Plasmodium vivax (100% refractory) and Plasmodium falciparum
   (partially) [[38]4]. Both potent and poor vector species however,
   display same distribution and adaptation to environment with similar
   zoophilic feeding preferences for human and cattle [[39]5].