Structure-function Analysis of Bacillus Anthracis Edema Factor by Using Monoclonal Antibodies

Biochem Biophys Res Commun. 1994 Mar 15;199(2):676-82. doi: 10.1006/bbrc.1994.1281.


Edema toxin of Bacillus anthracis is composed of protective antigen (PA) and edema factor (EF), a calcium- and calmodulin-dependent adenylate cyclase. At least five different antigenic regions of EF were identified using a competitive-binding, enzyme-linked immunosorbent assay of paired monoclonal antibodies (mAbs). Two mAbs, 9F5 and 7G10, inhibited the binding of 125I-EF to cell-bound PA. However, only 9F5 inhibited the elongation response of Chinese hamster ovary cells in the presence of edema toxin. Cleavage of EF at the two aspartic acid-proline residues by acid hydrolysis resulted in three fragments: a C-terminal 17 kDa fragment, a central 53 kDa fragment, and an N-terminal 18 kDa fragment. Immunoblots of EF cleaved by formic acid mapped mAbs 9F5 and 7G10 to the N-terminal 18 kDa fragment, mAb 1E6 to the C-terminal 17 kDa fragment, and the remaining 7 mAbs to the central 53 kDa fragment. mAbs 7G10 and 9F5 defined an antigenic region within amino acids 1-156 of EF which is involved in interaction with PA in forming edema toxin.

MeSH terms

  • Adenylyl Cyclase Inhibitors*
  • Amino Acid Sequence
  • Animals
  • Antibodies, Monoclonal* / pharmacology
  • Antigens, Bacterial*
  • Bacillus anthracis*
  • Bacterial Toxins / chemistry*
  • Bacterial Toxins / immunology
  • Bacterial Toxins / pharmacology*
  • Biotin
  • CHO Cells
  • Cricetinae
  • Enzyme-Linked Immunosorbent Assay
  • Female
  • Immunoblotting
  • Immunoglobulin G
  • Kinetics
  • Mice
  • Mice, Inbred BALB C / immunology
  • Neutralization Tests
  • Peptide Fragments / chemistry
  • Peptide Fragments / pharmacology


  • Adenylyl Cyclase Inhibitors
  • Antibodies, Monoclonal
  • Antigens, Bacterial
  • Bacterial Toxins
  • Immunoglobulin G
  • Peptide Fragments
  • anthrax toxin
  • Biotin