TABLE 2.

Number of mice with serum antibodies enhanced by oral administration of B. breve YIT4064^a

Mouse group	No. of mice with >400 U of anti-PR8/total no. testedb	% of mice with >400 U of anti-PR8 IgG
1	0/10	0
2	0/10	0
3	3/10	30
4	2/10	20
5	0/10	0
6	1/10	10
7	0/10	0
8	3/9*	33
9	0/10	0
10	5/10**	50

^aMice were not immunized (groups 1 and 2), were immunized orally with a single dose of 10^5.9 EID₅₀ of PR8 at 6 (groups 3 and 4), 8 (groups 5 and 6), and 10 weeks (groups 7 and 8) before nasal inoculation (10^3.5 EID₅₀ of PR8), or were immunized orally with two doses of 10^4.9 EID₅₀ of PR8 at 6 and 2 weeks before nasal inoculation (10^3.5 EID₅₀ of PR8) (groups 9 and 10). Mice were not fed (groups 1, 3, 5, 7, and 9) or were fed (groups 2, 4, 6, 8 and 10) B. breve YIT4064 throughout these experiments. The anti-PR8 IgG titer in serum was measured just before nasal inoculation (10^3.5 EID₅₀ of PR8), and the number of mice with anti-PR8 IgG levels of >400 U was determined. 

^b**, P < 0.02 versus number of antibody-enhanced mice in group 9, by Fisher’s exact test. *, P < 0.05 versus number of antibody-enhanced mice in group 7, by χ² test.