[Objective] To develop a recombinant influenza A virus (IAV) expressing a reporter (enhanced green fluorescent protein, EGFP), study its biological characteristics in vitro, and explore its application in antiviral drug screening and neutralizing antibody (nAb) detection. [Methods] The EGFP gene was inserted into the C-terminus of NA (derived from H1N1-PR8) by reverse genetics of influenza virus, and the recombinant IAV was successfully constructed, rescued, and named PR8NAEGFP/WSN. The EGFP insertion position and genetic stability were analyzed by RT-PCR and sequencing. PR8NAEGFP/WSN and the control virus (PR8NA/WSN, without EGFP insertion) were identified based on EGFP reporter gene expression, replication kinetics, and plaque morphology. The in vitro antiviral efficacy of favipiravir, a positive drug for influenza virus, was evaluated by focus-forming assay (FFA), qPCR, and EGFP fluorescence detection. The focus reduction neutralization test (FRNT) and reporter gene activity detection were conducted for IAV nAb detection. [Results] PR8NAEGFP/WSN remained genetically stable after five passages in chicken embryos. Compared with PR8NA/WSN, PR8NAEGFP/WSN showed a slightly declined titer at the time point of 48 h and similar crystal violet plaque morphology. The EC50 of favipiravir measured with the recombinant virus is consistent with that with the control virus, and the EC50 values obtained through various detection methods, including FFA, qPCR, and EGFP fluorescence, show good correlations. The correlation coefficient r of the nAb titer determined by FRNT and EGFP fluorescence was 0.930 4, which indicated good consistency. [Conclusion] PR8NAEGFP/WSN, a recombinant IAV carrying the reporter gene, might be used as a real-time visualization tool for the basic research on IAV and the evaluation of antivirals and vaccines for IAV.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |