ERK signaling couples nutrient status to antiviral defense in the insect gut

• Published in: Proceedings of the National Academy of Sciences - PNAS 2013-09, Vol.110 (37), p.15025-15030
• Main Authors: Xu, Jie, Hopkins, Kaycie, Sabin, Leah, Yasunaga, Ari, Subramanian, Harry, Lamborn, Ian, Gordesky-Gold, Beth, Cherry, Sara
• Format: Article
• Language: English
• Subjects: Aedes; Aedes - immunology; Aedes - metabolism; Aedes - virology; Animal Nutritional Physiological Phenomena; Animals; Antivirals; Arbovirus; Arboviruses - immunology; Arboviruses - pathogenicity; Biological Sciences; Cells; Digestive System - immunology; Digestive System - metabolism; Digestive System - virology; Drosophila; Drosophila melanogaster - immunology; Drosophila melanogaster - metabolism; Drosophila melanogaster - virology; Female; Host-Pathogen Interactions - immunology; Immunity, Innate; Infections; Insect genetics; Insect vectors; Insect Vectors - immunology; Insect Vectors - metabolism; Insect Vectors - virology; Insulin; Insulin - pharmacology; MAP Kinase Signaling System - genetics; MAP Kinase Signaling System - immunology; Midgut; Mosquitoes; Mosquitos; Pharmacology; RNA Interference; Sindbis virus; Vesicular stomatitis virus; Viral infections; Viruses
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.1303193110

A unique facet of arthropod-borne virus (arbovirus) infection is that the pathogens are orally acquired by an insect vector during the taking of a blood meal, which directly links nutrient acquisition and pathogen challenge. We show that the nutrient responsive ERK pathway is both induced by and restricts disparate arboviruses in Drosophila intestines, providing insight into the molecular determinants of the antiviral “midgut barrier.” Wild-type flies are refractory to oral infection by arboviruses, including Sindbis virus and vesicular stomatitis virus, but this innate restriction can be overcome chemically by oral administration of an ERK pathway inhibitor or genetically via the specific loss of ERK in Drosophila intestinal epithelial cells. In addition, we found that vertebrate insulin, which activates ERK in the mosquito gut during a blood meal, restricts viral infection in Drosophila cells and against viral invasion of the insect gut epithelium. We find that ERK’s antiviral signaling activity is likely conserved in Aedes mosquitoes, because genetic or pharmacologic manipulation of the ERK pathway affects viral infection of mosquito cells. These studies demonstrate that ERK signaling has a broadly antiviral role in insects and suggest that insects take advantage of cross-species signals in the meal to trigger antiviral immunity.