Table 5

Effects of rLF preparations on the anthrax TNA serum dilution 4-parameter logistic fit curve characteristics

Serum samplearLF preparation ([rPA]/[rLF], both in ng/ml)nbUpper asymptote (OD)SlopeED50Lower asymptote (OD)
Mean (±SD)PMean (±SD)PMean (±SD)PMean (±SD)P
MS011211rLF-A (50/5)31.88 (0.10)0.452.27 (0.14)0.102.130 (214)0.110.47 (0.04)0.14
rLF-HMAL (50/40)31.89 (0.16)2.06 (0.19)1.914 (106)0.43 (0.03)
MS122010rLF-A (50/5)32.00 (0.18)0.452.30 (0.15)0.1810.363 (949)0.150.46 (0.04)0.20
rLF-HMAL (50/40)31.98 (0.10)2.19 (0.12)9.586 (57)0.44 (0.02)
  • a Anthrax LT neutralization activity of two different lots (MS122010 and MS 011211) of pooled immune sera from CD-1 female mice (immunized with a single injection of 0.5 ml of a 5-fold dilution in normal saline of AVA containing 500 μg/ml CPG 7909) were evaluated in the TNA using 50 ng/ml rPA in the presence of 40 ng/ml rLF-HMAL or 5 ng/ml rLF-A. The rLF-A preparation was expressed from vector constructs containing the native LF sequence, whereas that of rLF-HMAL (produced by List Biological Laboratories, Inc., Campbell, CA) contained two additional N-terminal residues, His and Met.

  • b Serum dilution 4-parameter logistic fit curve parameter values were obtained from 3 independent experiments, each with 4 (MS122010) or 5 (MS011211) replicate measurements. The 3 mean values from the respective experiments were used to derive the composite mean ± SD values for each curve parameter, in which no significant differences were found between the composite means of curve parameters obtained with rLF-A or rLF-HMAL (P > 0.05 by Student's t test with Welch's correction for unequal variance).