Enoxacin Shows Broad-Spectrum Antiviral Activity against Diverse Viruses by Enhancing Antiviral RNA Interference in Insects

Abstract

RNA interference (RNAi) functions as the major host antiviral defense in insects, while less is understood about how to utilize antiviral RNAi in controlling viral infection in insects. Enoxacin belongs to the family of synthetic antibacterial compounds based on a fluoroquinolone skeleton that has been previously found to enhance RNAi in mammalian cells. In this study, we showed that enoxacin efficiently inhibited viral replication of Drosophila C virus (DCV) and Cricket paralysis virus (CrPV) in cultured Drosophila cells. Enoxacin promoted the loading of Dicer-2-processed virus-derived siRNA into the RNA-induced silencing complex, thereby enhancing antiviral RNAi response in infected cells. Moreover, enoxacin treatment elicited an RNAi-dependent in vivo protective efficacy against DCV or CrPV challenge in adult fruit flies. In addition, enoxacin also inhibited replication of flaviviruses, including Dengue virus and Zika virus, in Aedes mosquito cells in an RNAi-dependent manner. Together, our findings demonstrated that enoxacin can enhance RNAi in insects, and enhancing RNAi by enoxacin is an effective antiviral strategy against diverse viruses in insects, which may be exploited as a broad-spectrum antiviral agent to control vector transmission of arboviruses or viral diseases in insect farming. Importance RNAi has been widely recognized as one of the most broadly acting and robust antiviral mechanism in insects. However, the application of antiviral RNAi in controlling viral infections in insects is less understood. Enoxacin is a fluoroquinolone compound that has been previously found to enhance RNAi in mammalian cells, while its RNAi-enhancing activity has not been assessed in insects. Herein, we showed that enoxacin treatment inhibited viral replication of DCV and CrPV in Drosophila cells and in adult fruit flies. Enoxacin promoted the loading of Dicer-generated virus-derived siRNA into Ago2-incorporated RNA-induced silencing complex, and in turn strengthened the antiviral RNAi response in the infected cells. Moreover, enoxacin also displayed effective RNAi-dependent antiviral effects against flaviviruses, such as Dengue virus and Zika virus, in mosquito cells. This study is the first to demonstrate that enhancing RNAi by enoxacin elicits potent antiviral efficacies against diverse viruses in insects.

Infection Defects of RNA and DNA Viruses Induced by Antiviral RNA Interference

“…CrPV infects diverse species of insects and is substantially more virulent than FHV in fruit flies (28). Like FHV, however, CrPV triggers vsiRNA production in S2 cells, accumulates to higher titers, and is more virulent in dicer-2, r2d2, and ago2 mutant flies than in wild-type flies (28,44). Thus, CrPV infection of wild-type flies also induces antiviral RNAi which confers partial protection against wild-type CrPV.…”

The role of genes of the Argonaute family in the effects of the RNA interference activator enoxacin on the lifespan of Drosophila melanogaster

“…Тем не менее на мышах было показано, что эноксацин не влияет на микробиоту кишечника (на содержание бактерий и распределение типов бактерий в кале) [43]. Дополнительно он оказывает противовирусное действие через усиление РНК-интерференции некоторых патогенных молекул с помощью киРНК, вплоть до потенциальной активности против SARS-CoV-2 [46][47][48].…”

Identification of a Novel Densovirus in Aphid, and Uncovering the Possible Antiviral Process During Its Infection

“…In Drosophila , the intact IMD pathway play key role in response to the infections of Cricket Paralysis Virus (CrPV) and Sindbis virus (SINV) ( 2 ). In vivo , cellular RNA interference process (RNAi) can effectively inhibit the proliferation of Drosophila C virus (DCV) and Cricket Paralysis Virus (DCV) ( 3 ). Cyclic GMP-AMP (cGAMP) synthase (cGAS) is known involved into the antiviral immune response in mammals.…”