Figure 5. OVA-conjugate vaccine confers protection against L. monocytogenes challenge.

(A) Mice (n = 4-5) were immunized twice, 3 weeks apart, with PBS, 20 μg OVA, OVA plus free TLR7/8 agonist, or the OVA-conjugate vaccine. Fourteen days after the second immunization mice were challenged i.v. with 3 × 10⁴ CFUs of recombinant L. monocytogenes OVA. Bacterial loads in spleen and liver were enumerated 3 days after the challenge. (B) Mice (n = 4–5) were immunized once with 20 μg OVA plus free TLR7/8 agonist or the OVA-conjugate vaccine or were left untreated. Six weeks after immunization mice were challenged i.v. with 6 × 10⁴ CFUs of recombinant L. monocytogenes OVA. Bacterial loads in spleen and liver were enumerated 3 days after the challenge. Solid lines represent the geometrical mean. Dotted lines represents the level of detection. *P < 0.05, Mann-Whitney test, comparing OVA-conjugate with all other vaccine groups. Each symbol represents an individual mouse.