Autor(es): Choy, Milly M.; Sessions, October M.; Gubler, Duane J.; Ooi, Eng Eong

Resumo: Dengue virus (DENV) relies on host factors to complete its life cycle in its mosquito host for subsequent transmission to humans. DENV first establishes infection in the midgut of Aedes aegypti and spreads to various mosquito organs for lifelong infection. Curiously, studies have shown that infectious DENV titers peak and decrease thereafter in the midgut despite relatively stable viral genome levels. However, the mechanisms that regulate this decoupling of infectious virion production from viral RNA replication have never been determined. We show here that the ubiquitin proteasome pathway (UPP) plays an important role in regulating infectious DENV production. Using RNA interference studies, we show in vivo that knockdown of selected UPP components reduced infectious virus production without altering viral RNA replication in the midgut. Furthermore, this decoupling effect could also be observed after RNAi knockdown in the head/thorax of the mosquito, which otherwise showed direct correlation between infectious DENV titer and viral RNA levels. The dependence on the UPP for successful DENV production is further reinforced by the observed up-regulation of key UPP molecules upon DENV infection that overcome the relatively low expression of these genes after a blood meal. Collectively, our findings indicate an important role for the UPP in regulating DENV production in the mosquito vector. DENV is a re-emerging mosquito-borne flavivirus and the lack of sustainable preventative or therapeutic measures renders it a significant health burden globally. Although suppression of mosquito populations represents the most widely used dengue control strategy, there has been limited efficacy with this method. Blocking host factors required for DENV replication in mosquitoes may thus serve as an effective anti-transmission strategy. We have recently observed that the UPP plays a critical role in regulating DENV egress from infected cells, but how the UPP contributes to DENV life cycle in mosquitoes remain ill-defined. We show here that the Aedes aegypti midgut has evolved to control persistent DENV infection by differentially regulating key genes in the UPP, without harm to itself. Using RNAi, knockdown of proteasome subunits, beta 1, beta 2 and beta 5, as well as other UPP-specific genes in vivo reduced the production of infectious virus without altering viral RNA replication in the mosquito. Targeting these host factors via dsRNA-mediated or chemical inactivation in the mosquito salivary glands may serve as a viable anti-dengue transmission strategy from mosquitoes to humans.

Palavras-Chave: Human diseases; Viral diseases; Replication; Life cycle; Pest control; Hosts; Aquatic insects; Disease transmission; Public health; Virions; Genomes; Head; Blood meals; Infection; Salivary gland; RNA; Dengue; Thorax; RNA-mediated interference; Midgut; Ubiquitin; Inactivation; Organs; Dengue virus; Aedes aegypti; Flavivirus

Imprenta: Plos Neglected Tropical Diseases, v. 9, n. 11, 2015.

Descritores: Aedes aegypti - Infectious diseases ; Aedes aegypti - Viral infections ; Aedes aegypti - Virus ; Aedes aegypti - Transmission ; Aedes aegypti - Dengue

Data de publicação: 2015