Table 1.

Cooperative bactericidal activity of anti-fHbp mAb, JAR 4 (IgG2a), when tested together with second anti-fHbp mAbs and human complement^a

Second mAb	Ig Isotype	fH Inhibitionb	Location of Residues	Distance (Å)c		Strain (fHbp variant)d	Combination BC50, μg/mle
				D25	G58
mAb 502	G2a	-	R204	27	32	H44/76 (1)	0.5
JAR 5	G2b	++	G121, K122	42	24-26	H44/76 (1)	0.4
JAR 3f	G3	++	G121, K122	42	24-26	NZ98/254 (1)	1
JAR 5f	G2b	++	G121, K122	42	24-26	NZ98/254 (1)	4
JAR 10	G1	-	E180	36	41	8047 (2)	>50
JAR 10	G1	-	K192	39	43	8047 (2)	>50
JAR 11f	G2a	+	A174	39	47	8047 (2)	5
JAR 13f	G2a	++	S216	47	47	8047 (2)	4
JAR 32	G2a	++	K174	39	47	BuFa 1/03 (2)	10
JAR 33	G2a	-	E180	36	41	BuFa 1/03 (2)	>50
JAR 33	G2a	-	R192	39	43	BuFa 1/03 (2)	>50
JAR 35	G2b	++	K174	39	47	BuFa 1/03 (2)	20

^aNone of the mAbs was individually bactericidal against the strains shown (BC₅₀>50 μg/ml).

^bELISA inhibition was performed as described (Beernink et al., 2008) and defined by ++,>75%; +, 25 to 45%; -, <15%.

^cDistances were measured between the alpha-carbon of JAR 4 epitope residue and that of the residue affecting the epitope of the second mAb using SwissPDB Viewer/DeepView (http://spdbv.vital-it.ch/) using coordinates from the NMR solution structure of the entire of fHbp molecule (antigenic variant 1, strain MC58) (Cantini et al., 2009).

^dThe four test strains each expressed different fHbp peptides that were recognized by JAR 4. The strains were selected because they also bound with the respective second mAbs tested.

^eMinimal combined concentration of the two mAbs sufficient for bactericidal activity (50 percent killing after 1 hr of incubation with human complement)

^fData reported previously (Beernink et al., 2008).