TABLE 2

Serum antibody response of BALB/c mice i.n. vaccinated with B. mallei live attenuated strains

Vaccine/dosage (P, B, or 2B)aSerum titerbIgG2a/IgG1 serum ratio
IgGIgG2aIgG1
PBSNDNDND
TMM001/1.5 × 104 CFU (P)51,200 ± 0136,533 ± 48,27231,289 ± 14,5044.4
CLH001/1.5 × 104 CFU (P)400 ± 0NDND
CLH001/1.5 × 105 CFU (P)3,733 ± 2,325944 ± 163ND
CLH001/1.5 × 104 CFU (B)4,267 ± 2,1335,511 ± 4731,422 ± 1543.9
CLH001/1.5 × 105 CFU (B)19,200 ± 7,69231,259 ± 7,8538,533 ± 1,7423.7
CLH001/1.5 × 104 CFU (2B)19,911 ± 5,32118,489 ± 6,5178,533 ± 3,6952.2
CLH001/1.5 × 105 CFU (2B)42,667 ± 6,96796,711 ± 8,53324,178 ± 2,0114
  • a Antibody titers were determined at 2 weeks after primary vaccination (P), 2 weeks after first boost (B), and 3 weeks after second boost (2B). PBS control animals were vaccinated with 50 μl of PBS. Data from TMM001-vaccinated animals (prime vaccination only) are included for comparison.

  • b To determine serum antibody titers, sera from 3 mice/group were tested by indirect ELISA with irradiated B. mallei ATCC 23344 whole cells used as the antigen. Titer determinations were performed in triplicate, and data are reported as the mean reciprocal endpoint titers ± standard deviations (SD). ND, not detected, because titers less than or equal to 100 were considered to represent negative results.