Influenza viruses cause seasonal epidemics and frequent pandemics such as avian influenza viruses H5N1 and H7N9 that resulted in significant morbidity and fatality in humans. We engineered influenza A viruses to carry a gene encoding Gaussia luciferase (IAV-luci) while remaining replication competent. Influenza A virus has 17 serological hemagglutinin (HA) subtypes, we thus generated a series of IAV-luci with different HAs including pandemic H1/California/7/2009, avian influenza H5/Hongkong/482/1997, and H7/Anhui/1/2013. Through the detection of bioluminescent signals, we showed that: 1) Infection of animals with IAV-luci enabled real time visualization of infection status or assessment of drug treatment in living animals; 2) Cultured cells infected with as little as one IAV-luci could be detected for its bioluminescent signals. 3) Neutralizing antibodies to influenza virus from the serum of H7N9 infected patients could be detected within 6 hours for diagnosis and prediction of disease outcome; 4) Neutralizing antibodies secreted by one antibody producing B cell became detectable using IAV-luci, therefore enabled the cloning of monoclonal antibodies at single cell level. 5) An ultrasensitive microneutralization assay was developed that allows the epidemiological study for “hidden” avian influenza virus infections in human population. We believe that engineered bioluminescent influenza viruses will greatly facilitate the serological monitoring of infection, epidemicological study, antiviral drug discovery, especially the search for anti-influenza neutralizing antibodies.
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