Table 2.

Number of mice with serum antibodies enhanced by oral administration of B. breve YIT4064a

Mouse groupNo. of mice with >400 U of anti-PR8/total no. testedb% of mice with >400 U of anti-PR8 IgG
10/100
20/100
33/1030
42/1020
50/100
61/1010
70/100
83/9* 33
90/100
105/10** 50
  • a Mice were not immunized (groups 1 and 2), were immunized orally with a single dose of 105.9EID50 of PR8 at 6 (groups 3 and 4), 8 (groups 5 and 6), and 10 weeks (groups 7 and 8) before nasal inoculation (103.5EID50 of PR8), or were immunized orally with two doses of 104.9 EID50 of PR8 at 6 and 2 weeks before nasal inoculation (103.5 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 (103.5 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.