TABLE 2.

Effectiveness of s.c. or oral immunization with recombinant S. enterica serovar Choleraesuis vaccine strain C501(pYA-F1P2) in protecting BALB/c mice against i.n. challenge with wild-type B. bronchiseptica HH0809

Strain (genotype) or controlaInoculation routeImmunization dose (CFU)Challenge dose (CFU)bNo. of survivors/ total no. of mice
C501(pYA3493)s.c.2.1 × 1085.2 × 1064/20
C501(pYA-F1P2)s.c.2.1 × 1085.2 × 10620/20c
PBSs.c.200d5.2 × 1061/18
C501(pYA3493)Oral2.1 × 10105.2 × 1064/18
C501(pYA-F1P2)Oral2.1 × 10105.2 × 1064/20
PBSOral200d5.2 × 1063/18
  • a Mice were s.c. or orally immunized twice at 2-week intervals with the indicated vaccine strains or with PBS and challenged 30 days after the primary immunization with wild-type B. bronchiseptica HH0809. Morbidity and mortality observations were recorded daily for 30 days postchallenge.

  • b A total of 5.2×106 CFU represents about four times the LD50 of HH0809 in nonimmunized BALB/c mice.

  • c P < 0.0001 by Fisher's exact test for vector versus vaccine, PBS versus vaccine, and s.c. versus oral vaccination.

  • d Value in microliters.