2.3 Cell preparation for transmission electron microscopy (TEM)
BHK-21 cells infected with SVV-CH-09-2018 for 18 h, were washed twice with pre-cooled PBS and fixed with glutaraldehyde at 4°C. The cells were recovered by scraping and were centrifuged at 12000 g for 10 min. The supernatant was discarded. The cells were post-fixed in OsO4, embedded in epoxy resin, and polymerized at 80°C for at least 3 days. Finally, the cell samples were cut into 60-nm slices and stained with uranyl acetate(Malenovska, 2013).The sections mounted on grids were observed by TEM, using a model HT7600 microscope (Hitachi, Japan).