title: Sensitive assays enable detection of serum IgG antibodies against Clostridium difficile toxin A and toxin B in healthy subjects and patients with Clostridium difficile infection.
abstract: BACKGROUND
  Pathogenic Clostridium difficile produces two proinflammatory exotoxins, toxin A and toxin B. Low level of serum antitoxin IgG antibodies is a risk factor for the development of primary and recurrent C. difficile infection (CDI).
  
  
  RESULTS
  We developed and validated two sensitive, titer-based electrochemiluminescence assays for the detection of serum antibody levels against C. difficile toxins A and B. These assays demonstrated excellent precision. The sensitivity of the assays allowed the detection of antitoxin A and antitoxin B IgG antibodies in all tested serum samples during assay validation.
  
  
  CONCLUSIONS
  The validated titer-based assays enable assessment of antitoxin A and antitoxin B IgG antibodies as potential biomarkers to identify patients with CDI at increased risk for CDI recurrence.
authors.affiliation: Translational Molecular Biomarkers, Merck Research Laboratories, Rahway, NJ 07065, USA.
authors.forename: Xuemei
authors.initials: X
authors.lastname: Zhao
authors.affiliation: Translational Molecular Biomarkers, Merck Research Laboratories, Rahway, NJ 07065, USA.|Drug Metabolism & Pharmacokinetics, Novartis Institutes for Biomedical Research, Basel 4057, Switzerland.
authors.forename: Florent
authors.initials: F
authors.lastname: Bender
authors.affiliation: Translational Molecular Biomarkers, Merck Research Laboratories, Rahway, NJ 07065, USA.
authors.forename: Rajiv
authors.initials: R
authors.lastname: Shukla
authors.affiliation: Biometrics Research, Merck Research Laboratories, Rahway, NJ 07065, USA.
authors.forename: John J
authors.initials: JJ
authors.lastname: Kang
authors.affiliation: Vaccines Basic Research, Merck Research Laboratories, West Point, PA 19486, USA.|Janssen Research & Development, L.L.C., 1400 McKean Road, PO Box 776, Spring House, PA 19477, USA.
authors.forename: Ivette
authors.initials: I
authors.lastname: Caro-Aguilar
authors.affiliation: Translational Molecular Biomarkers, Merck Research Laboratories, Rahway, NJ 07065, USA.
authors.forename: Omar F
authors.initials: OF
authors.lastname: Laterza
mesh_terms: D000907:Antibodies, Bacterial / Q000097:blood; D001426:Bacterial Proteins / Q000276:immunology*; D001427:Bacterial Toxins / Q000276:immunology*; D015415:Biomarkers / Q000097:blood; D016360:Clostridioides difficile / Q000378:metabolism*; D003015:Clostridium Infections / Q000175:diagnosis; D004768:Enterotoxins / Q000276:immunology*; D064368:Healthy Volunteers; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood*; D008163:Luminescent Measurements / Q000592:standards; D011786:Quality Control
chemical_list: D000907:Antibodies, Bacterial; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D015415:Biomarkers; D004768:Enterotoxins; D007074:Immunoglobulin G; C041348:tcdA protein, Clostridium difficile; C031815:toxB protein, Clostridium difficile
keywords: Clostridium difficile; Clostridium difficile infection; Clostridium difficile recurrence; anti-C. difficile toxin A antibody; anti-C. difficile toxin B antibody; antibody titer assay; assay validation; biomarker; clinical biomarker assay; endogenous antitoxin antibody