Emerging Infectious Diseases (Oct 2002)

Specific, Sensitive, and Quantitative Enzyme-Linked Immunosorbent Assay for Human Immunoglobulin G Antibodies to Anthrax Toxin Protective Antigen

  • Conrad P. Quinn,
  • Vera A. Semenova,
  • Cheryl M. Elie,
  • Sandra Romero-Steiner,
  • Carolyn M. Greene,
  • Han Li,
  • Karen Stamey,
  • Evelene Steward-Clark,
  • Daniel S. Schmidt,
  • Elizabeth Mothershed,
  • Janet Pruckler,
  • Stephanie Schwartz,
  • Robert F. Benson,
  • Leta O. Helsel,
  • Patricia F. Holder,
  • Scott E. Johnson,
  • Molly Kellum,
  • Trudy Messmer,
  • W. Lanier Thacker,
  • Lilah Besser,
  • Brian D. Plikaytis,
  • Thomas H. Taylor,
  • Alison E. Freeman,
  • Kelly J. Wallace,
  • Peter Dull,
  • Jim Sejvar,
  • Erica Bruce,
  • Rosa Moreno,
  • Anne Schuchat,
  • Jairam R. Lingappa,
  • Sandra K. Martin,
  • John Walls,
  • Melinda Bronsdon,
  • George M. Carlone,
  • Mary Bajani-Ari,
  • David A. Ashford,
  • David S. Stephens,
  • Bradley A. Perkins

DOI
https://doi.org/10.3201/eid0810.020380
Journal volume & issue
Vol. 8, no. 10
pp. 1103 – 1110

Abstract

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The bioterrorism-associated human anthrax epidemic in the fall of 2001 highlighted the need for a sensitive, reproducible, and specific laboratory test for the confirmatory diagnosis of human anthrax. The Centers for Disease Control and Prevention developed, optimized, and rapidly qualified an enzyme-linked immunosorbent assay (ELISA) for immunoglobulin G (IgG) antibodies to Bacillus anthracis protective antigen (PA) in human serum. The qualified ELISA had a minimum detection limit of 0.06 µg/mL, a reliable lower limit of detection of 0.09 µg/mL, and a lower limit of quantification in undiluted serum specimens of 3.0 µg/mL anti-PA IgG. The diagnostic sensitivity of the assay was 97.8%, and the diagnostic specificity was 94.2%. A competitive inhibition anti-PA IgG ELISA was also developed to enhance diagnostic specificity to 100%. The anti-PA ELISAs proved valuable for the confirmation of cases of cutaneous and inhalational anthrax and evaluation of patients in whom the diagnosis of anthrax was being considered.

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