Journal Article

The anti-immune dengue subgenomic flaviviral RNA is present in vesicles in mosquito saliva and is associated with increased infectivity

Chowdhury, Avisha, Strilets, Tania, Rey-Cadilhac, Félix, Rachenne, Florian, Garcia-Blanco, Mariano A., Marti-Renom, Marc A., Singh, Moirangthem Kiran, Azar, Sasha R., Missé, Dorothée, Nir, Guy, Castillo, David, Vasilakis, Nikos, Pompon, Julien, Serrato-Pomar, Idalba M., Chuo, Vanessa, Kenney, Linda J., Kini, R. Manjunatha, Tan, Wei-Lian, Medkour, Hacène, Hamel, Rodolphe, Yeh, Shih-Chia

2023

Overview

Mosquito transmission of dengue viruses to humans starts with infection of skin resident cells at the biting site. There is great interest in identifying transmission-enhancing factors in mosquito saliva in order to counteract them. Here we report the discovery of high levels of the anti-immune subgenomic flaviviral RNA (sfRNA) in dengue virus 2-infected mosquito saliva. We established that sfRNA is present in saliva using three different methods: northern blot, RT-qPCR and RNA sequencing. We next show that salivary sfRNA is protected in detergent-sensitive compartments, likely extracellular vesicles. In support of this hypothesis, we visualized viral RNAs in vesicles in mosquito saliva and noted a marked enrichment of signal from 3’UTR sequences, which is consistent with the presence of sfRNA. Furthermore, we show that incubation with mosquito saliva containing higher sfRNA levels results in higher virus infectivity in a human hepatoma cell line and human primary dermal fibroblasts. Transfection of 3’UTR RNA prior to DENV2 infection inhibited type I and III interferon induction and signaling, and enhanced viral replication. Therefore, we posit that sfRNA present in salivary extracellular vesicles is delivered to cells at the biting site to inhibit innate immunity and enhance dengue virus transmission.

• Publisher: Public Library of Science,Public Library of Science (PLoS)
• Subject: 3' Untranslated Regions / Aedes / Animals / Aquatic insects / Biochemistry, Molecular Biology / Biological response modifiers / Biology and Life Sciences / Biting / Composition / Culicidae / Dengue / Dengue fever / Dengue viruses / Detergents, Synthetic / Disease transmission / Exocrine glands / Extracellular vesicles / Fibroblasts / Flavivirus / Flavivirus - genetics / Gene sequencing / Genetic aspects / Genomics / Health aspects / Hepatoma / Human health and pathology / Humans / Identification and classification / Immunity / Incubation / Infection / Infections / Infectious diseases / Infectivity / Innate immunity / Interferon / Life Sciences / Liver cancer / Medicine and Health Sciences / Microbiology and Parasitology / Mosquitoes / Physiological aspects / Research and Analysis Methods / Ribonucleic acid / Risk factors / RNA / RNA sequencing / RNA viruses / RNA, Viral / RNA, Viral - genetics / RNA, Viral - metabolism / Saliva / Saliva - metabolism / Salivary glands / Scientific equipment and supplies industry / secretions / Subgenomic RNA / Transfection / Vector-borne diseases / Vesicles / Viral infections / Virology / Virus Replication / Viruses