DNA laddering after ISAV infection. Agarose gel electrophoresis of DNA from ASK cells. Lane 1, 1 kb ladder; lane 2, positive control; lane 3, cells treated with 1 μM SS 24 h; lane 4, mock infected cells day 5 p.i.; lane 5; ISAV infected cells day 5 p.i. Laddering pattern was demonstrated by SS treated cells, in addition to positive control.