Abstract
During the blood feeding, sand fly females inject saliva containing immunomodulatory and anti-haemostatic molecules into their vertebrate hosts. The saliva composition is species-specific, likely due to an adaptation to particular haemostatic pathways of their preferred host. Research on sand fly saliva is limited to the representatives of two best-studied genera, Phlebotomus and Lutzomyia. Although the members of the genus Sergentomyia are highly abundant in many areas in the Old World, their role in human disease transmission remains uncertain. Most Sergentomyia spp. preferentially attack various species of reptiles, but feeding on warm-blooded vertebrates, including humans and domestic animals, has been repeatedly described, especially for Sergentomyia schwetzi, of which salivary gland transcriptome and proteome is analyzed in the current study. Illumina RNA sequencing and de novo assembly of the reads and their annotation revealed 17,293 sequences homologous to other arthropods’ proteins. In the sialome, all proteins typical for sand fly saliva were identified–antigen 5-related, lufaxin, yellow-related, PpSP15-like, D7-related, ParSP25-like, and silk proteins, as well as less frequent salivary proteins included 71kDa-like, ParSP80-like, SP16-like, and ParSP17-like proteins. Salivary enzymes include apyrase, hyaluronidase, endonuclease, amylase, lipase A2, adenosine deaminase, pyrophosphatase, 5’nucleotidase, and ribonuclease. Proteomics analysis of salivary glands identified 631 proteins, 81 of which are likely secreted into the saliva. We also compared two S. schwetzi lineages derived from the same origin. These lineages were adapted for over 40 generations for blood feeding either on mice (S-M) or geckos (S-G), two vertebrate hosts with different haemostatic mechanisms. Altogether, 20 and 40 annotated salivary transcripts were up-regulated in the S-M and S-G lineage, respectively. Proteomic comparison revealed ten salivary proteins more abundant in the lineage S-M, whereas 66 salivary proteins were enriched in the lineage S-G. No difference between lineages was found for apyrase activity; contrarily the hyaluronidase activity was significantly higher in the lineage feeding on mice.
Highlights
Phlebotomine sand flies (Diptera, Psychodidae) are bloodsucking insects and vectors of viruses, bacteria and protists, causative agents of several important diseases of humans and animals
Sergentomyia sand flies were considered as insects with possible vector role in the transmission of reptile trypanosomatid parasites belonging to the genera Trypanosoma and Leishmania [5,6,7], but more recently they have been found positive for several human pathogenic viruses, namely Chandipura [8], Toscana [9], and Dashli virus [10], despite that Sergentomyia sand flies vectorial capacity is still under consideration
Total of 339,133,323 trimmed reads generated from six libraries of S. schwetzi salivary glands (S-M 1-3, sources geckos (S-G) 1-3) were subsequently assembled into 88,676 contigs (N50 length 1,104 bp; median contig length 329 bp; average contig length 644 bp; total assembled bases 57,076,819)
Summary
Phlebotomine sand flies (Diptera, Psychodidae) are bloodsucking insects and vectors of viruses, bacteria and protists, causative agents of several important diseases of humans and animals. Out of over 800 described sand fly species, about 100 (all belonging to the two genera: Phlebotomus and Lutzomyia) are proven or suspected vectors of medical importance [1,2]. Sergentomyia sand flies were considered as insects with possible vector role in the transmission of reptile trypanosomatid parasites belonging to the genera Trypanosoma and Leishmania [5,6,7], but more recently they have been found positive for several human pathogenic viruses, namely Chandipura [8], Toscana [9], and Dashli virus [10], despite that Sergentomyia sand flies vectorial capacity is still under consideration. While a number of reports focused on the composition and function of Phlebotomus and Lutzomyia saliva (reviewed in [11]), only a single study dealt with characterization of Sergentomyia salivary enzymes [14]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
