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

• DOI: 10.3201/eid0810.020380
• Publication Date: 2012-06-27T18:21:28Z
• Authors: Conrad P. Quinn; Vera A. Semenova; Cheryl M. Elie; Sandra Romero-Ste...; Carolyn Greene; Han Li; Karen Stamey; Evelene Steward-C...; 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
• Keywords: 0301 basic medicine; Antigens, Bacterial; bioterrorism; Bacterial Toxins; R; Dispatch; anthrax; Enzyme-Linked Immunosorbent Assay; Infectious and parasitic diseases; RC109-216; assay; Antibodies, Bacterial; Bioterrorism; Sensitivity and Specificity; Disease Outbreaks; 3. Good health; Anthrax; 03 medical and health sciences; antibody; Bacillus anthracis; Immunoglobulin G; Medicine; Humans; ELISA

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 micro g/mL, a reliable lower limit of detection of 0.09 micro g/mL, and a lower limit of quantification in undiluted serum specimens of 3.0 micro g/mL anti-PA IgG. The diagnostic sensitivity of the assay was 97.8%, and the diagnostic specificity was 97.6%. 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.