Abstract: Objective:To evaluate which rat age segment of Kunming mice is the best model of influenza A virus FM1 strains. Methods:A total 150 Kunming mice of clean grade, half male and half female, with equal age, were randomly divided into young model group (40 rats), mature model group (40 rats), aged model group (40 rats), young normal group (10 rats), mature normal group (10 rats), and aged normal group (10 rats). The mice were observed, and respectively at the end of 3,5 and 7 days of infection were detected lung wet weight;lung tissue pathology score with naked eyes, lung histopathology and lung tissue FQ-PCR viral load testing were also performed.Results:In the young model group, the highest death occurred in 14 days, the overall state was the worst with most severe lung disease, and viral load in lung tissue showed an increasing trend. In mature model group, the death was the least in 14 days, the overall state was the best, basically there was no lung disease, and lung tissue viral load had no copying phenomenon. In aged rats, the overall state showed lung tissue lesions in the first three days, but there was a tendency to recover and after 5 days, viral load tended to decline.Conclusion:The young mice are the idealest model of influenza A virus.

Key words: pneumonia；influenza virus；animal, experiment；mouse