The formation of crystalline arrays of foot-and-mouth disease virus (FMDV) particles in swine kidney tissue culture cells has been examined in greater detail following the initial report of strain A119 in pig kidney cell line cultures, PK15. In the present experiments, FMDV strains recently isolated from field outbreaks in Argentina (A1, O2 and C3 CANEFA) were inoculated into primary swine kidney tissue cultures and samples at suitable intervals for embedding, sectioning and electron microscopy.The three strains of FMDV were stored at -20°C as the sixth bovine kidney tissue culture passage of original tongue tissue suspension. Immediately prior to use, they were inoculated into bovine kidney cultures and 1 ml of infected cell suspension was used in each swine kidney prescription bottle. After l/2 hr incubation at 37°C, 5 to 10 ml of maintenance medium was added and the bottles stored at 37°C. At intervals of 90 min, 3, 4, 5 and 6 hr after inoculation, bottles were processed for electron microscopy. Fluids were removed and the cells gently scraped from the glass into a few ml of Sorenson’s buffer at pH 7.2. Fixation was in 1% glutaraldehyde followed by 2% osmium tetroxide, dehydration, and embedment in epon. Sections were examined in an RCA-EMU-3-G microscope.
Cytoplasmic microtubular images in glutaraldehyde-fixed tissue culture cells by electron microscopy and by immunofluorescence microscopy