title: Novel and highly sensitive immunoassay for total hepatitis B surface antigen, including that complexed with hepatitis B surface antibody.
abstract: BACKGROUND
  Hepatitis B surface antigen (HBsAg) is used as a clinical marker of hepatitis B virus (HBV) infection. However, conventional HBsAg assays have so far failed to accurately detect HBsAg in blood because of interference by patient-derived antibodies against HBsAg (HBsAb).
  
  
  METHODS
  We developed a novel, fully automated assay system that can detect total HBsAg in blood, including antigens complexed with HBsAb. The immunoassay inactivates HBsAb via a simple pretreatment step to dissociate the HBsAg molecule from HBsAg-HBsAb complexes and thereby estimate total HBsAg. Accordingly, the test has been termed the "immunoassay for total antigen including complex via pretreatment (iTACT)-HBsAg."
  
  
  RESULTS
  The recovery rate of HBsAg in the presence of HBsAb was greater than 87 % at a cutoff value set at 5.0 mIU/mL on the basis of data from 545 healthy controls. Analyses using serial serum samples from 25 HBV carriers who became negative for HBsAg during follow-up showed that the iTACT-HBsAg could detect HBsAg over a period of years despite a loss in detection by conventional assays and was able to detect HBsAg in 39 (53 %) of 73 samples with HBsAb.
  
  
  CONCLUSIONS
  The new iTACT-HBsAg assay appears to detect total HBsAg with high sensitivity, even in the presence of HBsAb, and may useful in identifying subclinical or occult HBV carriers.
authors.affiliation: Department of Medicine, Shinshu University School of Medicine, Asahi 3-1-1, Matsumoto, 390-8621, Japan.
authors.forename: Akihiro
authors.initials: A
authors.lastname: Matsumoto
authors.affiliation: New Product Development Department, Fujirebio Inc., Hachioji, Tokyo, Japan.
authors.forename: Masayasu
authors.initials: M
authors.lastname: Imaizumi
authors.affiliation: Department of Virology and Liver Unit, Nagoya City University Graduate School of Medical Sciences, Nagoya, Aichi, Japan.
authors.forename: Yasuhito
authors.initials: Y
authors.lastname: Tanaka
authors.affiliation: Division of Hepatobiliary and Pancreatic Disease, Department of Internal Medicine, Hyogo College of Medicine, Nishinomiya, Hyogo, Japan.
authors.forename: Shuhei
authors.initials: S
authors.lastname: Nishiguchi
authors.affiliation: Clinical Research Center, National Hospital Organization, Nagasaki Medical Center, Omura, Nagasaki, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Yatsuhashi
authors.affiliation: Research and Development Department, Advanced Life Science Institute Inc., Wako, Saitama, Japan.
authors.forename: Takehiko
authors.initials: T
authors.lastname: Ishida
authors.affiliation: New Product Development Department, Fujirebio Inc., Hachioji, Tokyo, Japan.
authors.forename: Kazushige
authors.initials: K
authors.lastname: Moriyama
authors.affiliation: New Product Development Department, Fujirebio Inc., Hachioji, Tokyo, Japan.|Research and Development Department, Advanced Life Science Institute Inc., Wako, Saitama, Japan.
authors.forename: Katsumi
authors.initials: K
authors.lastname: Aoyagi
authors.affiliation: Department of Medicine, Shinshu University School of Medicine, Asahi 3-1-1, Matsumoto, 390-8621, Japan. etanaka@hsp.md.shinshu-u.ac.jp.
authors.forename: Eiji
authors.initials: E
authors.lastname: Tanaka
mesh_terms: D000328:Adult; D000368:Aged; D000936:Antigen-Antibody Complex / Q000097:blood*; D015415:Biomarkers / Q000097:blood; D002353:Carrier State / Q000175:diagnosis; D002850:Chromatography, Gel / Q000379:methods; D005260:Female; D006509:Hepatitis B / Q000175:diagnosis*; D006510:Hepatitis B Antibodies / Q000097:blood*; D006514:Hepatitis B Surface Antigens / Q000097:blood*; D006801:Humans; D007124:Immunoenzyme Techniques / Q000379:methods*; D008297:Male; D008875:Middle Aged; D012680:Sensitivity and Specificity; D013048:Specimen Handling / Q000379:methods
chemical_list: D000936:Antigen-Antibody Complex; D015415:Biomarkers; D006510:Hepatitis B Antibodies; D006514:Hepatitis B Surface Antigens
keywords: Hepatitis B surface antigen; Immunoassay; Immunoassay for total antigen including complex via pretreatment