On the stability of sequences inserted into viral genomes

Willemsen, Anouk; Zwart, Mark P

For members of the Flaviviridae family, such as West Nile virus and hepatitis C virus (HCV), inserted reporter genes appear to be unstable. This instability is related to the size of the insert, and comes about because of the disruption of structural RNA elements required for viral replication (Ruggli and Rice 1999; Pierson et al. 2005) . To cope with these issues, recombinant Flaviviridae viruses carrying the split-luciferase gene were generated (Tamura et al. 2018 ), including dengue virus, Japanese encephalitis virus, HCV and bovine viral diarrhea virus. In vitro, these recombinant viruses appear to be evolutionary stable and propagation was comparable to the wild-type virus, most probably due to the small 11 amino acid insert size. To demonstrate the utility of the split reporter system-to determine in vivo viral dynamics and the efficacy of antiviral reagents-the recombinant HCV was tested in chimeric mice. Chronic infection was established and the luciferase gene was stably maintained in the viral genome (Tamura et al. 2018) .