The generation of a reverse genetics system for Kyasanur Forest Disease Virus and the ability to antagonize the induction of the antiviral state in vitro

Abstract

Kyasanur Forest Disease Virus (KFDV) is a tick-borne, hemorrhagic fever-causing member of the Flaviviridae virus family. With infections annually ranging from 50 to 1000 people in south-west India and the lack of effective treatments, a better understanding of this virus is needed. The development of a reverse genetics system (RGS) for KFDV would provide the opportunity to address these issues. The KFDV genome sequence was elucidated and the RGS was created. Utilizing this system, live infectious KFDV particles were produced from mammalian cell culture, thereby validating the success of the RGS. Flaviviruses have the ability to suppress the type 1 interferon response and indications are that the non structural (NS) proteins serve this role. Using luciferase bioassays, the NS5 protein of KFDV was determined to be the primary antagonist of the IFN response when compared to the other NS proteins, specifically NS4B and NS4B-2k. Moreover, our results indicate that this is attributed to a region, beginning before and including the RNA-dependent RNA polymerase (RdRp). With evasion of the interferon response by KFDV established, the further implementation of the reverse genetics system will enable investigation into pathogenesis and disease progression of KFDV with respect to the innate immune response, at the IFN and the NS5 protein levels.