A 10% suspension of epithelium is prepared in phosphate-buffered saline (PBS) and inoculated onto susceptible cells. At the world reference laboratory (WRL), samples are inoculated onto primary bovine thyroid cells (BTY) and the swine renal cell line IB-RS-2. Cell cultures are incubated for 48 hours and observed daily for cytopathic effect (CPE). Cultures not showing CPE are blind passaged after this time and incubated for a further 48 hours. The supernatants of all cultures showing CPE are examined in the antigen capture ELISA to confirm the presence of FMD virus and to identify the serotype.