Fig. 4.

The effects of cathepsins on the cleavage of VP1 of FCV or MNV-1. Concentrated FCV (left panel) or MNV-1 (right panel) was incubated with a recombinant cathepsin L or cathepsin B in a cathepsin reaction buffer at pH 4.0 or pH 5.5, respectively, for 2 h at 37 °C. Mock-treatment samples were incubated in PBS at pH 4, 5.5 or 7.0. The samples were then subjected to SDS-PAGE, transferred to nitrocellulose membrane, probed with antibodies against FCV or MNV-1 VP1 visualized by chemiluminescence. Uncleaved or cleaved VP1 is indicated by an arrow.