Salivary Gland Transcriptomes and Proteomes of Phlebotomus tobbi and Phlebotomus sergenti, Vectors of Leishmaniasis

Petr Volf,Věra Volfová,Jesus G Valenzuela,Sreenath Subrahmanyam,Cheng-Chen Chen,Ryan C Jochim,Jianbing Mu,Iva Rohoušová

doi:10.1371/journal.pntd.0001660

Abstract

Background Phlebotomus tobbi is a vector of Leishmania infantum, and P. sergenti is a vector of Leishmania tropica. Le. infantum and Le. tropica typically cause visceral or cutaneous leishmaniasis, respectively, but Le. infantum strains transmitted by P. tobbi can cause cutaneous disease. To better understand the components and possible implications of sand fly saliva in leishmaniasis, the transcriptomes of the salivary glands (SGs) of these two sand fly species were sequenced, characterized and compared.Methodology/Principal FindingscDNA libraries of P. tobbi and P. sergenti female SGs were constructed, sequenced, and analyzed. Clones (1,152) were randomly picked from each library, producing 1,142 high-quality sequences from P. tobbi and 1,090 from P. sergenti. The most abundant, secreted putative proteins were categorized as antigen 5-related proteins, apyrases, hyaluronidases, D7-related and PpSP15-like proteins, ParSP25-like proteins, PpSP32-like proteins, yellow-related proteins, the 33-kDa salivary proteins, and the 41.9-kDa superfamily of proteins. Phylogenetic analyses and multiple sequence alignments of putative proteins were used to elucidate molecular evolution and describe conserved domains, active sites, and catalytic residues. Proteomic analyses of P. tobbi and P. sergenti SGs were used to confirm the identification of 35 full-length sequences (18 in P. tobbi and 17 in P. sergenti). To bridge transcriptomics with biology P. tobbi antigens, glycoproteins, and hyaluronidase activity was characterized.ConclusionsThis analysis of P. sergenti is the first description of the subgenus Paraphlebotomus salivary components. The investigation of the subgenus Larroussius sand fly P. tobbi expands the repertoire of salivary proteins in vectors of Le. infantum. Although P. tobbi transmits a cutaneous form of leishmaniasis, its salivary proteins are most similar to other Larroussius subgenus species transmitting visceral leishmaniasis. These transcriptomic and proteomic analyses provide a better understanding of sand fly salivary proteins across species and subgenera that will be vital in vector-pathogen and vector-host research.

Highlights

Sand flies are bloodsucking nematoceran Diptera that transmit the protozoan parasites of the genus Leishmania
P. tobbi transmits a cutaneous form of leishmaniasis, its salivary proteins are most similar to other Larroussius subgenus species transmitting visceral leishmaniasis
In the P. tobbi cDNA library, 997 high-quality sequences were grouped into 68 contigs and 125 singletons; in P. sergenti, 853 high-quality sequences were grouped into 56 contigs and 196 singletons

Summary

Introduction

Sand flies are bloodsucking nematoceran Diptera that transmit the protozoan parasites of the genus Leishmania. Similar to that of other bloodsucking arthropods, sand fly saliva comprises antihemostatic, immunomodulatory, and antigenic components. During the bite by an infected sand fly, Leishmania parasites are egested into the wound with the saliva. Sand fly saliva can enhance Leishmania infection in naive mice [1,2]. Pre-exposure of mice to sand fly saliva conferred a protective effect against Leishmania infection [3,4]. Le. infantum and Le. tropica typically cause visceral or cutaneous leishmaniasis, respectively, but Le. infantum strains transmitted by P. tobbi can cause cutaneous disease. To better understand the components and possible implications of sand fly saliva in leishmaniasis, the transcriptomes of the salivary glands (SGs) of these two sand fly species were sequenced, characterized and compared

Methods

Results

Conclusion