A method for the detection of virus infectivity in single cells and real time: Towards an automated fluorescence neutralization test

- A novel method to measure virus infectivity is proposed.
- This method is applied to a semi-automated neutralization test.
- Real time imaging of virus infectivity is also demonstrated.

Virus neutralizing antibodies are critical correlates of protection in vaccine development and are discriminatory in the plaque reduction neutralization test when used for the diagnosis of viral infections. However, neutralization assays are time consuming, labor intensive and highly variable, thus limiting their use. Advances in automated live imaging of cells opened new possibilities for standard virus diagnostic techniques such as neutralization assays. To this end, a reporter cell line based on the translocation of the transcription factor IRF3 in response to infection is proposed. Image acquisition of signal in a microplate format allowed the setup of a rapid, semi-automated and high-throughput fluorescent neutralization test. The study is extended to the live imaging of IRF3 translocations that could potentially cut the time of analysis to few hours. The fluorescent neutralization test is suitable for high-throughput assays and expandable to other viruses of global importance such as Zika virus.