Table II.

Fab neutralization potency and possible PA interaction domains. Antibody PA neutralization potency was determined in an antibody dose dependent protection assay with lower and higher challenge approaches as stated in the text. In a lower challenge assay, antibody is pre-incubated with PA, added to the RAW264.7 cells, and then LF is applied for the MTT assay. In the higher challenge assay, antibody, PA and LF are mixed and immediately applied to the RAW264.7 cells for the MTT assay. The possible epitopes on PA are defined by a neutralizing antibody as deduced via the assay.

Fab	Neutralization Potency (IC)	Possible Epitope on PA
A8	a65% at 400 μg/mL, 50% at 110 μg/mL	Domain 1’, LF binding site
	b54% at 400 μg/mL, 50% at 300 μg/mL
F1	a100% at 400 μg/mL, 50% at .25μg/mL	Domain 4, ATR binding site
	b80% at 400 μg/mL, 50% at 58 μg/mL
G11c	a80% at 400 μg/mL, 50% at 60 μg/mL	Domain 4, ATR binding site
G12c	a29% at 400 μg/mL	Domain 4, ATR binding site

^aLower challenge assay;

^bHigher challenge assay;

^cLower challenge assay only