Fig. 1
Infection model and microbial abundance analysis. A Fish were infected with LMBV via bath immersion and sacrificed at 1, 4, 7, 14, 21, and 28 DPI for tissue sample collection. B Cumulative survival rate of the Ctrl group and LMBV-infected group. The data are representative of two independent experiments. C Clinical phenotypes observed in largemouth bass infected with LMBV. D qPCR was used to quantify LMBV mcp gene copies (Log10) in the gut samples from the Ctrl, Mild, and Severe groups (n = 6). E Histological examination of the gut in Ctrl, Mild-7, and Severe-7 group fish. F Distribution of bacteria in gut paraffin sections from fish in the Ctrl, Mild, and Severe groups was detected by in situ hybridization. From left to right: Ctrl, Mild, and Severe groups, scale bars: 30 μm. G Bacterial counts per villus in the Ctrl, Mild, and Severe groups (n = 6). Statistical differences were evaluated using a one-way ANOVA test. H Flow cytometry analysis displaying the staining of gut bacteria with SYTO BC Green in the Ctrl, Mild, and Severe groups. I The total gut bacterial count per fish in the Ctrl, Mild, and Severe groups (n = 6). *p < 0.05, **p < 0.01, ***p < 0.001