Analysis of the neutralizing capacity of purified M1A by MNT. (A) Vero E6 cell control; (B) cells treated with 100 PFU of SARS-CoV; (C) cells treated with 100 PFU of SARS-CoV and 0.5 mg/ml M1A Fab. a, b, and c, CPE of cells on the 2nd, 3rd, and 6th days of virus infection, respectively.