<i>Lutzomyia longipalpis</i> Antimicrobial Peptides: Differential Expression during Development and Potential Involvement in Vector Interaction with Microbiota and <i>Leishmania</i>

• Main Authors: Erich Loza Telleria, Bruno Tinoco-Nunes, Tereza Leštinová, Lívia Monteiro de Avellar, Antonio Jorge Tempone, André Nóbrega Pitaluga, Petr Volf, Yara Maria Traub-Csekö
• Format: Article
• Language: English
• Published: MDPI AG 2021-06-01
• Series: Microorganisms
• Subjects: <i>Lutzomyia longipalpis</i>; antimicrobial peptides; innate immunity; RNAi gene silencing; <i>Leishmania</i>; microbiota
• Online Access: https://www.mdpi.com/2076-2607/9/6/1271

Antimicrobial peptides (AMPs) are produced to control bacteria, fungi, protozoa, and other infectious agents. Sand fly larvae develop and feed on a microbe-rich substrate, and the hematophagous females are exposed to additional pathogens. We focused on understanding the role of the AMPs attacin (Att), cecropin (Cec), and four defensins (Def1, Def2, Def3, and Def4) in <i>Lutzomyia longipalpis,</i> the main vector of visceral leishmaniasis in the Americas. Larvae and adults were collected under different feeding regimens, in addition to females artificially infected by <i>Leishmania infantum</i>. AMPs’ gene expression was assessed by qPCR, and gene function of Att and Def2 was investigated by gene silencing. The gene knockdown effect on bacteria and parasite abundance was evaluated by qPCR, and parasite development was verified by light microscopy. We demonstrate that <i>L. longipalpis</i> larvae and adults trigger AMPs expression during feeding, which corresponds to an abundant presence of bacteria. Att and Def2 expression were significantly increased in <i>Leishmania</i>-infected females, while Att suppression favored bacteria growth. In conclusion, <i>L. longipalpis</i> AMPs’ expression is tuned in response to bacteria and parasites but does not seem to interfere with the <i>Leishmania</i> cycle.