AUTHOR=Vomáčková Kykalová Barbora , Sassù Fabiana , Volf Petr , Telleria Erich Loza 

TITLE=RNAi-mediated gene silencing of Phlebotomus papatasi defensins favors Leishmania major infection

JOURNAL=Frontiers in Physiology

VOLUME=14

YEAR=2023

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2023.1182141

DOI=10.3389/fphys.2023.1182141

ISSN=1664-042X

ABSTRACT=<p><bold>Introduction:</bold> Production of different antimicrobial peptides (AMPs) is one of the insect’s prominent defense strategies, regulated mainly by Toll and immune deficiency (IMD) humoral pathways. Here we focused mainly on two AMPs of <italic>Phlebotomus papatasi</italic>, vector of <italic>Leishmania major</italic> parasites, their association with the relish transcription factor and the effective participation on <italic>Leishmania</italic> infection.</p><p><bold>Methods and results:</bold> We further characterized the role of previously described gut-specific <italic>P. papatasi</italic> defensin (PpDef1) and identified the second defensin (PpDef2) expressed in various sand fly tissues. Using the RNAi-mediated gene silencing, we report that the silencing of <italic>PpDef1</italic> gene or simultaneous silencing of both defensin genes (<italic>PpDef1</italic> and <italic>PpDef2</italic>) resulted in increased parasite levels in the sand fly (detectable by PCR) and higher sand fly mortality. In addition, we knocked down relish, the sole transcription factor of the IMD pathway, to evaluate the association of the IMD pathway with AMPs expression in <italic>P. papatasi</italic>. We demonstrated that the relish gene knockdown reduced the expression of <italic>PpDef2</italic> and <italic>attacin</italic>, another AMP abundantly expressed in the sand fly body.</p><p><bold>Conclusions:</bold> Altogether, our experiments show the importance of defensins in the sand fly response toward <italic>L. major</italic> and the role of the IMD pathway in regulating AMPs in <italic>P. papatasi</italic>.</p>