Neutralization of wild-type iota-toxin (2 nM Ia plus 2 nM Ib) by various concentrations of each MAb in a Vero cell protection assay. MAbs 1D11 (○) and 4F6 (▵) afforded protection against iota-toxin versus MAbs lE12, 10A6, and 4H7, or a negative-control MAb, 1G6 (each designated by a square), developed against staphylococcal enterotoxin A.