TABLE 2.

Reactivity of H. influenzae strains with antipilus antisera in a dot blot assay^a

hifA RFLP pattern	Strain (capsular type)b	Hemagglu- tination titer	Reactivity with antiserumc
			R1 (anti-M43 pili)	R19 (anti-Eagan pili)
1	E1ap+ (b)	1:16	0	4+
	E1ap− (b)d	0		0
	R9p+ (b)	1:16	3+	4+
	AA61p+ (b)	1:16	2+	2+
	AAr108p+ (b)	1:16	0	2+
	AAr176 (NT)	1:16	0	0
	AAr39 (NT)	1:16	0	0
	AAr169 (NT)	1:16	0	0
3	M43p+ (b)	1:16	4+	1+
	M42p− (b)e	0	0	0
	AAr122p+ (b)	1:32	4+	0
	AAr7p+ (b)	1:16	4+	2+
	AAr119p+ (b)	1:32	4+	0
	AAr103p+ (b)	1:32	2+	4+
	SL2p+ (b)	1:32	4+	0
	AAr45 (NT)	1:64	0	0

^aTable generated with data from Gilsdorf et al. (11, 13). 

^bAn enrichment technique that depends upon erythrocyte agglutination by piliated H. influenzae type b strains was used to select piliated variants from the clinical isolates. NT, nontypeable H. influenzae. 

^cThe reactivities of the antibodies with native pili on the surfaces of intact bacteria were assessed visually with a dot blot assay and compared with reactivities of positive (homologous strains) and negative (nonpiliated variants) controls included in each assay by using a grading scale ranging from 0 (identical to negative controls) to 4⁺ (identical to homologous strains). 

^dNonpiliated phase variant of E1ap⁺. 

^eNonpiliated variant of strain M43p⁺; used as a negative control.