Fig. 4.

Immune responses in mice 5 wk after oral primary immunization and protection with RASV strains χ9354(pYA4545) (vector control), χ9354(pYA4859) (pYA4545 encoding WSN HA), χ11214(pYA4859) (∆P_hilA::P_trcΔlacO888 hilA), χ11215(pYA4859) (∆tlpA, ∆sseL), and χ11218(pYA4859) (∆P_hilA::P_trcΔlacO888 hilA, ∆tlpA, ∆sseL), or BSG. Induction of IgG titers against S. Typhimurium LPS (A) and inactivated WSN virus (B) detected by ELISA. Pooled serum samples (n = 8) from mice within a group were assayed and analyzed by ANOVA followed by Tukey’s range test, **P < 0.001. (C) Weight loss, *P < 0.01 and (D) percent survival of mice (n = 8) after an intranasal challenge with 100 LD₅₀ of rWSN influenza virus at 8 wk PPI. Survival curve has a P < 0.0002 by log-rank (Mantel–Cox) test.