Conserved and distinct morphological aspects of the salivary glands of sand fly vectors of leishmaniasis: an anatomical and ultrastructural study

Rafael Nacif-Pimenta,Petr Volf,Vera Volfova,Nagila F C Secundino,Luciana C Pinto,Paulo F P Pimenta

doi:10.1186/s13071-020-04311-y

Rafael Nacif-Pimenta, Petr Volf + Show 4 more

Open Access

https://doi.org/10.1186/s13071-020-04311-y

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Journal: Parasites & Vectors	Publication Date: Sep 3, 2020
Citations: 3	License type: open-access

Affiliation: Fundação Oswaldo Cruz, Charles University

Abstract

BackgroundSand flies are vectors of Leishmania spp., the causative agents of leishmaniasis in vertebrates, including man. The sand fly saliva contains powerful pharmacologically active substances that prevent hemostasis and enhance Leishmania spp. infections. On the other hand, salivary proteins can protect vaccinated mice challenged with parasites. Therefore, sand fly salivary proteins are relevant for the epidemiology of leishmaniasis and can be a potential target for a vaccine against leishmaniasis. Despite this, studies on sand fly salivary glands (SGs) are limited.MethodsThe present study analyzes, in detail, the morphology, anatomy and ultrastructure of the SGs of sand fly vectors of the genera Lutzomyia and Phlebotomus. We used histology, transmission and scanning electron microscopy and lectin labeling associated with confocal laser microscopy.ResultsThe SGs have conserved and distinct morphological aspects according to the distinct sand fly species. Each SG has a single rounded lobe constituting of c.100–120 secretory cells. The SG secretory cells, according to their ultrastructure and lectin binding, were classified into five different subpopulations, which may differ in secretory pathways.ConclusionsTo the best of our knowledge, these morphological details of sand fly salivary glands are described for the first time. Further studies are necessary to better understand the role of these different cell types and better relate them with the production and secretion of the saliva substances, which has a fundamental role in the interaction of the sand fly vectors with Leishmania.

Highlights

Sand flies are vectors of Leishmania spp., the causative agents of leishmaniasis in vertebrates, includ‐ ing man
The present study focuses on analyzing in detail the morphology, microanatomy and ultrastructure of the salivary gland (SG) of some important species of sand fly vectors of leishmaniasis of the genera Lutzomyia and Phlebotomus
Using morphological techniques such as scanning electron microscopy (SEM) and transmission electron microscopy (TEM) associated with lectin labeling visualized by laser scanning confocal microscopy (LSM), we showed conserved morpho-structural aspects among the sand fly SGs as well as the presence of different subpopulations of secretory cells which can be distinct according to the sand fly species

Summary

Introduction

Sand flies are vectors of Leishmania spp., the causative agents of leishmaniasis in vertebrates, includ‐ ing man. The sand fly saliva contains powerful pharmacologically active substances that prevent hemostasis and enhance Leishmania spp. infections. Sand fly salivary proteins are relevant for the epidemiology of leishmaniasis and can be a potential target for a vaccine against leishmaniasis. Female sand flies (Diptera: Psychodidae) are blood-feeding insects and the main vectors of the parasite Leishmania (Ross, 1903), the causative agent of leishmaniasis and a neglected tropical disease with worldwide distribution. The bite of infected female sand flies transmits Leishmania parasites. The sand fly uses the saliva to counter these defenses to accomplish a successful blood meal via powerful pharmacologically active substances; the saliva plays an essential role in infection establishment. The proteins described in the sand fly saliva facilitate entry and survival of the parasite [7, 8]

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