Inhibitory experiments of BHV-1-induced apoptosis. (A) MDBK cells were pre-treated with inhibitors for 2 h then infected with 2 MOI BHV-1 for 48 h. After incubation, virus were collected and virus titers are shown as lg TCID50/ml. (B) MDBK cells were pretreated with NH4Cl at different concentrations for 2 h before infection and then infected with 2 MOI BHV-1 for 48 h. Cells infected in the same conditions without NH4Cl were used as positive controls. Virus titers are shown as lg TCID50/ml. (C) DNA fragmentation in the presence of NH4Cl infected cells was examined by DNA fragmentation assay. (D, E) BHV-1 was inactivated by exposing to a 30 W UV germicidal light at a distance of 30 cm for 30 min at 4°C. MDBK cells were infected with UV-inactivated virus at 10 MOI for 24 h at 37°C, and than virus titer (D) and DNA fragmentation (E) were examined.