Analysis of in vivo dynamics of influenza virus infection using a GFP reporter virus.

Influenza A virus Is being extensively studied due to its major Impact in human and animal health. However, the dynamics of Influenza virus Infection and the cell types infected In vivo are poorly understood. These characteristics are not easy to determine parUy because currently there Is no replication-competent virus expressing a fluorescent reporter gene. Here, we report the generation of a complete Influenza virus carrying a GFP reporter gene In the NS segment of its genome (NS1-GFP virus). NS1-GFP virus replicates efficiently in cell culture and shows pathogenicity In mice at levels similar to parental virus. We have analyzed the In vivo dynamics of influenza Infection progression in mice by flow cytometry and whole organ Imaging of infected lungs. Using flow cytometric analysis of infected lungs, apart from epithelial cells, we find antigen presenting cells like CD11c+, CD11b+ CD11c+, CD11b+ and B cells to be GFP positive. In addition, NK cells are susceptible to Influenza Infection. Whole organ imaging of lungs show that influenza infection starts In the respiratory tract In areas closer to large conducting airways and with time spreads to deeper sections of the lungs. We have also tested the effects of oseltamivir and amantadine on the kinetics and In vivo infection progression in mice and find Interesting differences In the effects of these antivirals. Treatment with oseltamlvlr dramatically reduces Influenza Infection in all cell types, whereas, Interestingly, amantadine treatment blocks infection In a cell type specific manner.