TABLE 6.

Effect of i.n. immunization with dLOS-CRM conjugate on LOS antibody responses and bacterial clearance of the heterologous strain O35E (serotype A) in mice

Immunization groupa	Antibody class	Anti-LOSb of:				Mean CFU of bacteria recovered/lungb (range)	Bacterial reduction (%)c
		O35E		25238
		Lung lavage fluid	Serum	Lung lavage fluid	Serum
dLOS-CRM	IgA	210 (30-1,355)**d	33 (8-138)*	210 (30-1,355)**	42 (11-165)**	1,674 (900-3,115)**	81
	IgG	40 (10-215)**	72 (14-366)**	45 (10-295)**	90 (12-669)**
	IgM	30 (10-80)**	24 (10-57)**	35 (15-90)**	24 (10-57)**
PBS	IgA	3	10	3	10	8,651 (6,374-11,740)	0
	IgG	3	10	3	10
	IgM	3	10	3	10

^aMice, 20 per group, were i.n. immunized four times at 1-week intervals with 10 μl of PBS containing a mixture of 5 μg of dLOS-CRM and 1 μg of CT or with 10 μl of PBS containing 1 μg of CT, respectively. One week after the last immunization, 10 mice from each group were used to collect samples for antibody measurement. The remaining 10 mice from each group mice were challenged with 2 × 10⁸ CFU of the M. catarrhalis strain O35E per ml in a nebulizer, and mouse lungs were collected 6 h postchallenge.

^bGeometric mean (± SD range) of antibody ELISA titers of 10 mice.

^cCompared with PBS group.

^dStatistical significance for comparison with PBS group: *, P < 0.05; **, P < 0.01.