Characterization of fungal symbiosis in phlebotomus perniciosus and evaluation of its possible implications for the control of Leishmaniases

The control of vector-borne diseases represents one of the greatest global public health challenges of the 21st century. In this context, biological control methods are an alternative to the use of chemicals, and the use of microorganisms is now well established in biocontrol. While arthropod-associated bacteria are the focus of several research programs aimed at developing strategies to control vector-borne diseases, such as malaria, dengue, and trypanosomiasis, arthropod-associated yeasts and their killer toxins have not yet been deeply investigated. In this work, we studied the yeast community associated with the sand fly Phlebotomus perniciosus, the main vector of leishmaniasis in the western Mediterranean area, with the aim of investigating their potential to interfere with Leishmania development in the insect. To reach the goal we associated culture-based methodology with culture independent methods: we performed yeast isolation and identification, 454 Pyrosequencing, PCR screening and whole mount FISH with specific probes to localize the yeast species. We focused our attention to the yeast Wickerhamomyces anomalus, isolated from both sexes of P. perniciosus; this yeast was phylogenetically characterized and tested against sensitive yeast strains, demonstrating its killer phenotype. Finally, in order to explore the possibility that this yeast could exert inhibitory/killing activity against pathogens, we tested the in vitro activity of W. anomalus strains against Leishmania infantum. This study offers the basis for the development of a method for vector-borne disease control that is environment-friendly and safe for human health. The use of yeast symbionts with antimicrobial proprieties could be included in the integrated approach for the control of leishmaniases, a worldwide re-emerging public health problem