Use of hepatitis B core antigen produced in Escherichia coli to detect immunoglobulin M specific antibodies in an enzyme-linked immunosorbent assay.

The antigenic activity of HBcAg produced in Escherichia coli and HBcAg from human liver was compared in a mu-specific solid-phase antibody-capture assay for detection of anti-HBc-IgM. HBcAg from liver could be detected in dilutions up to 1:3, HBcAg from Escherichia coli in dilutions up to 1:10,000. Using HBcAg from Escherichia coli, sera from five patients with acute resolving hepatitis B and sera from four patients with acute hepatitis B who had developed chronic liver disease were tested for anti-HBc-IgM in ELISA. IgM fractions separated out of the same sera by immunoaffinity chromatography were tested for anti-HBc-IgM using a commercially available test. The results were in good agreement with those obtained by ELISA. Anti-HBc-IgM could be detected up to 900 days after onset of disease. Different groups of patients were tested for presence of anti-HBc-IgM in ELISA. Fifty-nine of 60 patients with acute hepatitis B were positive for anti-HBc-IgM at onset of illness. Ten of 16 patients with chronic aggressive hepatitis and seven of 23 HBsAg positive dialysis patients were also positive for anti-HBc-IgM, whereas only two of 12 patients with chronic persistent hepatitis and one of 15 HBsAg positive blood donors ("healthy" carriers of HBsAg) had detectable anti-HBc-IgM.