title: Dengue virus type 2 infections of Aedes aegypti are modulated by the mosquito's RNA interference pathway.
abstract: A number of studies have shown that both innate and adaptive immune defense mechanisms greatly influence the course of human dengue virus (DENV) infections, but little is known about the innate immune response of the mosquito vector Aedes aegypti to arbovirus infection. We present evidence here that a major component of the mosquito innate immune response, RNA interference (RNAi), is an important modulator of mosquito infections. The RNAi response is triggered by double-stranded RNA (dsRNA), which occurs in the cytoplasm as a result of positive-sense RNA virus infection, leading to production of small interfering RNAs (siRNAs). These siRNAs are instrumental in degradation of viral mRNA with sequence homology to the dsRNA trigger and thereby inhibition of virus replication. We show that although dengue virus type 2 (DENV2) infection of Ae. aegypti cultured cells and oral infection of adult mosquitoes generated dsRNA and production of DENV2-specific siRNAs, virus replication and release of infectious virus persisted, suggesting viral circumvention of RNAi. We also show that DENV2 does not completely evade RNAi, since impairing the pathway by silencing expression of dcr2, r2d2, or ago2, genes encoding important sensor and effector proteins in the RNAi pathway, increased virus replication in the vector and decreased the extrinsic incubation period required for virus transmission. Our findings indicate a major role for RNAi as a determinant of DENV transmission by Ae. aegypti.
authors.affiliation: Department of Microbiology, Arthropod-borne and Infectious Diseases Laboratory, Colorado State University, Fort Collins, Colorado, United States of America.
authors.forename: Irma
authors.initials: I
authors.lastname: Sánchez-Vargas
authors.forename: Jaclyn C
authors.initials: JC
authors.lastname: Scott
authors.forename: B Katherine
authors.initials: BK
authors.lastname: Poole-Smith
authors.forename: Alexander W E
authors.initials: AW
authors.lastname: Franz
authors.forename: Valérie
authors.initials: V
authors.lastname: Barbosa-Solomieu
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Wilusz
authors.forename: Ken E
authors.initials: KE
authors.lastname: Olson
authors.forename: Carol D
authors.initials: CD
authors.lastname: Blair
mesh_terms: D000330:Aedes / Q000235:genetics / Q000276:immunology* / Q000821:virology*; D000704:Analysis of Variance; D000818:Animals; D002478:Cells, Cultured; D016009:Chi-Square Distribution; D003716:Dengue Virus / Q000502:physiology*; D020868:Gene Silencing; D000882:Haplorhini; D034622:RNA Interference; D012330:RNA, Double-Stranded / Q000032:analysis; D012367:RNA, Viral / Q000032:analysis; D016601:RNA-Binding Proteins / Q000235:genetics / Q000276:immunology; D034743:RNA-Induced Silencing Complex / Q000235:genetics / Q000276:immunology; D015398:Signal Transduction; D014779:Virus Replication
chemical_list: D012330:RNA, Double-Stranded; D012367:RNA, Viral; D016601:RNA-Binding Proteins; D034743:RNA-Induced Silencing Complex