Fig 5. Production of SS2-specific IgG antibodies in immunized mice.

The CD1 mice were immunized with SS2 inactive vaccine, ΔssnA, or PBS, and antibody levels were detected at 14, and 28 days post-inoculation by indirect ELISA. The data are expressed as the mean ± SD, *P < 0.05 and **P < 0.01. Δ, versus the negative control.