title: Quantitative analysis of HBsAg, IgM anti-HBc and anti-HBc avidity in acute and chronic hepatitis B.
abstract: OBJECTIVE
  We evaluated hepatitis B virus (HBV) serological markers by novel, quantitative immunoassays in order to study their behaviours and possible role in the various phases of HBV infection.
  
  
  METHODS
  The quantitative determination of HBsAg and anti-HBc/IgM by chemiluminescent immunoassays (Abbott Architect) and the calculation of anti-HBc avidity index have been carried out on repository specimens from patients with acute or chronic hepatitis B.
  
  
  RESULTS
  In acute hepatitis the levels of HBsAg were generally >10,000 UI/mL and decreased sharply in the recovery phase. In 35 anti-HBe-positive chronic hepatitis cases HBsAg levels were generally lower than 10,000 UI/mL (mean: 2655), whereas in five HBeAg-positive chronic hepatitis patients the mean value was 78,756 UI/mL and 90% of specimens exceeded 10,000 UI/mL. The lowest values (mean: 1029 IU/mL) were found in the seven patients with minimal hepatic damage. IgM anti-HBc antibodies were positive in all acute cases and in 68/207 samples (32.85%) from patients with chronic hepatitis, with significantly lower levels (average sample/cutoff (S/CO) ratio: 2.95 in chronic cases versus 25.96 in acute cases; p<0.005). A S/CO value of 10 for anti-HBc IgM had a 100% negative predictive value and a 99.13% positive predictive value for acute hepatitis B. The study of anti-HBc avidity by an experimental procedure showed that an avidity index (AI) threshold of 0.7 had a good efficacy to discriminate the cases of chronic hepatitis, among whom only 2 specimens out of 193 (1.04%) had an AI<0.7.
  
  
  CONCLUSIONS
  The quantitative determination of HBsAg, anti-HBc/IgM and anti-HBc avidity provides additional information and may be useful in the differential diagnosis of acute and chronic HBV infections and in the follow-up of chronically infected patients.
authors.affiliation: Department of Microbiology and Virology, University of Brescia, Spedali Civili Brescia, Piazza Spedali Civili 1, 25123 Brescia, Italy.
authors.forename: Anna
authors.initials: A
authors.lastname: Rodella
authors.forename: Claudio
authors.initials: C
authors.lastname: Galli
authors.forename: Luigina
authors.initials: L
authors.lastname: Terlenghi
authors.forename: Francesca
authors.initials: F
authors.lastname: Perandin
authors.forename: Carlo
authors.initials: C
authors.lastname: Bonfanti
authors.forename: Nino
authors.initials: N
authors.lastname: Manca
mesh_terms: D000208:Acute Disease; D000915:Antibody Affinity; D015415:Biomarkers; D002908:Chronic Disease; D003937:Diagnosis, Differential; D006509:Hepatitis B / Q000175:diagnosis*; D006510:Hepatitis B Antibodies / Q000032:analysis*; D006512:Hepatitis B Core Antigens / Q000032:analysis*; D006514:Hepatitis B Surface Antigens / Q000032:analysis*; D006801:Humans; D007075:Immunoglobulin M / Q000032:analysis*; D008163:Luminescent Measurements / Q000379:methods*; D012189:Retrospective Studies
chemical_list: D015415:Biomarkers; D006510:Hepatitis B Antibodies; D006512:Hepatitis B Core Antigens; D006514:Hepatitis B Surface Antigens; D007075:Immunoglobulin M