Akihiro Matsumoto1, Masayasu Imaizumi2, Yasuhito Tanaka3, Shuhei Nishiguchi4, Hiroshi Yatsuhashi5, Takehiko Ishida6, Kazushige Moriyama2, Katsumi Aoyagi2,6, Eiji Tanaka7. 1. Department of Medicine, Shinshu University School of Medicine, Asahi 3-1-1, Matsumoto, 390-8621, Japan. 2. New Product Development Department, Fujirebio Inc., Hachioji, Tokyo, Japan. 3. Department of Virology and Liver Unit, Nagoya City University Graduate School of Medical Sciences, Nagoya, Aichi, Japan. 4. Division of Hepatobiliary and Pancreatic Disease, Department of Internal Medicine, Hyogo College of Medicine, Nishinomiya, Hyogo, Japan. 5. Clinical Research Center, National Hospital Organization, Nagasaki Medical Center, Omura, Nagasaki, Japan. 6. Research and Development Department, Advanced Life Science Institute Inc., Wako, Saitama, Japan. 7. Department of Medicine, Shinshu University School of Medicine, Asahi 3-1-1, Matsumoto, 390-8621, Japan. etanaka@hsp.md.shinshu-u.ac.jp.
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.
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.
Entities:
Keywords:
Hepatitis B surface antigen; Immunoassay; Immunoassay for total antigen including complex via pretreatment