FIG. 3.

Comparison of the effects of HA doses on antigen-specific serum antibody responses after i.g. administration. Shown are means ± SE of anti-A/Beijing8-9/93 HA antibody titers in the sera of mice immunized either with 20 μg of HA administered alone (HA only) or with 1-, 5-, or 20-μg doses of A/Beijing8-9/93 HA in combination with either 10 or 100 μg of LT-R72 as indicated. Asterisks indicate groups whose values are significantly different from that of the HA only group (P ≤ 0.05). Double asterisks indicate a value that is significantly greater than that of all other groups shown (P ≤ 0.05).