2.6 Pathological and immunofluorescence examinations
Intestinal tissues were collected for the examinations within 10 to 15 min after the death of each mink. Each tissue sample was impregnated with formalin by soaking in 10% formalin for more than 24 h at room temperature, and the samples were then soaked in different concentrations of ethanol from 100% to 70% for 2 h. The samples were then embedded in paraffin wax and sectioned (6 µm). The sections were stained with hematoxylin and eosin for histological examination using light microscopy (Olympus, Tokyo, Japan). The dewaxing sections were used for immunofluorescence assay(Hou et al., 2018). The sections were blocked with 0.3% bovine serum albumin in PBS at room temperature (RT) for 3 h and then washed three times with pre-cooled PBS. This was followed by permeabilization with 0.4% Triton X-100 at RT, after which, the sections were incubated for 45 min at RT with anti-SVV VP1 antibody, which was synthesized in our lab. The sections were then labeled with secondary goat anti-mouse IgG H&L antibody (FITC) (Abcam, Cambridge, UK) for 30 min at RT. Finally, the samples were washed with PBS, and examined by fluorescence microscope (Leica, Wetzlar, Germany).