2.4. Inactivated virus
FMDV strain O2016 was propagated in BHK-21 cell suspension cultures at industrial scale bioreactor, and finally inactivated by BEI. Then, cell debris were primarily removed by centrifuge at 4500 rpm in 20-min filtration through a 0.45 µm membrane from Sartorius Stedim Biotech (Gottingen, Germany). Finally, the crude virus bulk was concentrated about 23-fold using a 100-kDa cut-off diafiltration membrane in a tangential flow filter cassette from Sartorius Stedim Biotech (Gottingen, Germany). The FMDV concentrate samples were originally obtained from Vaccine and Serum Research Razi Institute  (Karaj Iran) after the aforementioned cultivation and pretreatment procedure.