TABLE 3.

Inhibition of anti-tD15 antibody-induced protection by tD15 and D15-derived peptides in the infant rat model of bacteremia^a

Group	Inhibitor	No. bacteremic/7 challenged	Mean CFU/2.5 μl of blood	Pb
1	PBS	1	980
2	tD15	7	3,810	0.0023
3	Peptides	6	760	0.0291

^aAbsorbed immune sera were prepared by mixing 0.5 ml of rabbit anti-tD15 antiserum with either purified tD15 protein (600 μg; group 2) or a mixture of five tD15 peptides (peptides 4 to 8, 250 μg of each peptide; group 3). The final volume of each mixture was adjusted to 1.5 ml with PBS. The mixture was rotated at room temperature for 1 h. Seven-day-old infant rats (seven per group) were injected s.c. with 0.2 ml of the indicated material. After 20 h, animals were challenged i.p. with freshly grown Hib strain MinnA (200 CFU) as described in Materials and Methods. 

^bStatistical significance of the difference in results obtained between group 1 and the other groups, established by Fisher’s exact test.