Abstract:
Objective To investigate the dynamic changes of general status, lung tissue viral loads, pulmonary and intestinal histopathology and gut microbiota in mice infected with influenza A virus.
Methods C57BL/6J mice were infected intranasally with influenza virus A/PR/8(H1N1). Lung and colon tissue of the mice were collected on day 3 and day 7 after infection. Stool samples of the mice were collected on day 0, 3 and 7 after infection. The lung indexes were calculated, and the lengths and weight of colon were measured. The viral loads in lung tissue were detected by real-time quantitative PCR (RT-qPCR). Pathological changes of lung and colon tissue were detected by HE staining. The micorbiota in the stool samples were sequenced by using the V3-V4 variable region of 16S rRNA.
Results Compared with control group, the body weight and activities of mice in infection group decreased. On day 3 after the infection, compared with control group, the lung viral loads and lung index were significantly higher, the lung pathological injury occurred, and the colon length was shorter without remarkable colon pathology injury in the mice in infection group. On day 7 after infection, the lung viral loads in infected mice decreased compared with those on day 3 after infection. The lung index further increased, the lung pathological injury became more severe and the colon length further decreased compared with control group. No obvious colon pathology change (inflammation) was observed. On day 3 after infection, the abundance of Lactobacillus decreased in gut microbiota. On day 7 after infection, the abundance of Lactobacillus significantly decreased, the abundances of Shigella and Enterococcus remarkably increased in gut microbiota.
Conclusion Mice infected with influenza A virus would exhibit weight loss, reduced intake, increased lung viral titers, lung pathological injury, shortened colon length, and gut microbiota alteration.
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