Table 2. B. anthracis inhalation spore challenge results.
| Group | Vaccination | Survival | Prechallenge Letx neut titer, median ± SD | Inhaled spore dose, median LD50* ± SD (LD50 Range) | Days to death, median ± SD |
|---|---|---|---|---|---|
| 1 | PA83Δfurin | 8/8 | 5120 ± 6110 | 98 ± 28 (56-129) | >21 |
| 2 | PA83Δfurin/DM-DP | 8/8 | 2560 ± 3055 | 116 ± 69 (56-238) | >21 |
| 3 | PA83Δfurin, 2 inj. | 8/8 | 1076 ± 634 | 94 ± 74 (52-252) | >21 |
| 4† | PA83Δfurin | 10/10 | 844 ± 843 | 93 ± 40 (27-155) | >21 |
| 5 | PA83Δfurin plus LF[I], 2inj. | 8/8 | 415 ± 199 | 95 ± 43 (72-205) | >21 |
| 6 | PA83Δfurin plus LF[I-III] | 8/8 | 3948 ± 1325 | 113 ± 47 (65-192) | >21 |
| 7 | LF[I-III] | 5/9 | 453 ± 339 | 112 ± 67 (46-241) | 5.3 ± 1.5 |
| 8 | Vector | 0/5 | <20 | 90 ± 35 (58-144) | 2.6 ± 0.5 |
| 9 | AVA, 2 inj. | 4/4 | 1280 ± 805 | 135 ± 34 (107-176) | >21 |
| Naive rabbits | 0/12 | ND | 110 ± 49 (57-208) | 2.6 ± 0.7 | |
| † | Naive rabbits | 0/5 | ND | 112 ± 72 (34-198) | 2.8 ± 1.4 |
Rabbits were selected for challenge on week 13 by calculating the mean Letx neutralization (neut) titer for each group and excluding one rabbit with a higher and lower titer than the mean but always including the highest and lowest titer animals. DM-DP, DMRIE-DOPE; inj, injections.
*
1 LD50 = 105,000 Ames spores.
†
All 10 group 4 rabbits and five naive animals were challenged on week 40.