Methods for the Genetic Stabilization of Reporter Flaviviruses and their Applications

Infectious reporter flaviviruses have been reported since 2003, and they have the potential to be utilized in diverse scientific areas such as investigating viral pathology, conducting high-throughput drug screens, running rapid serum neutralization tests, and diagnosing disease. Despite the value of these applications, their utility has been limited due to genetic instability after continued growth in cell culture. Previous studies have hypothesized this partial or complete loss of reporter gene is the result of recombination. This work describes two methods that can be used to stabilize luciferase-carrying flaviviruses: recombination-dependent lethal mutations and optimizing the capsid duplication length. The first of these methods was shown effective for stabilizing Zika and yellow fever viruses to ten passages in cell culture. The effectiveness of the second method to likewise stabilize reporter flaviviruses was demonstrated with Zika, yellow fever, dengue serotypes 1-4, Japanese encephalitis, and West Nile viruses. Notably, these viruses can be used to determine serum neutralization titers in less than twenty-four hours, whereas the traditional assay takes up to a week. The stabilization of flaviviruses bearing reporter or other trans-genes opens doors for their application in vaccine efficacy evaluation, disease diagnosis, pathogenesis studies, and treatment of diverse afflictions.