Table 4

Inverse relationship of rPA and rLF concentrations achieving 95 to 99% cytotoxicity in the MLAa

rLF preparationbrLF concn (ng/ml) causing 95 to 99% MLA cytotoxicity at the indicated rPA concn (ng/ml)c:
140120100805030201510
rLF-AND3334–6812–1624–64NA
rLF-HMAE6464–8080–112NANANANANANA
rLF-HMALND16162432–40NANANANA
rLF-dNDND3ND6–81013–1624NA
  • a Evaluation of different rLF concentrations in combination with those of rPA demonstrated unique rPA and rLF combinations that achieved optimal cytotoxicity between 95 and 99% for use in the anthrax toxin neutralization assay (TNA).

  • b rLF-A, native LF sequence. rLF-HMAE and rLF-HMAL, containing additional N-terminal Met and His residues, were produced by Emergent BioSolutions and List Biological Laboratories, respectively. rLF-d was derived from rLF-HMAE digested with N-terminal dipeptidase, which removed 2 or 4 N-terminal residues.

  • c ND, not determined; NA, not applicable (rLF concentration did not induce at least 95% cytotoxicity).