Modulating Gut Microbiome to Enhance Viral Immunity

To eliminate as much as possible the intestinal microbial background of mice, ampicillin (1 mg/ml), streptomycin (5 mg/ml), vancomycin (0.25 mg/ml), and mycomycin (1 mg/ml; Solarbio) were added to the sterile drinking water of mice for 6 days, followed by FMT. Mouse feces from the PBS + H9N2 and 0111 + H9N2 groups were collected on the seventh day and processed as described previously (Yang et al., 2021 (link)). Briefly, fecal samples were placed in a sterile N₂ incubator, mixed thoroughly, and then plugged into a cell filter to collect bacteria and centrifuged at 12,000 rpm for 10 min. The samples were subsequently added to 10% glycerol, stored at −80°C. FMT before replacing the glycerol with PBS and stained with methylene blue staining to count the number of viable microorganisms. Mice were gavaged in 100 μl volumes (n = 5). One day later, all mice were intranasally attacked with H9N2 (10^6.5 EID₅₀), and their survival and weight loss were monitored 14 days after infection. FMT experiment was repeated twice independently.