A new solid phase passive hemagglutination test for IgM antibody to hepatitis B core antigen

Abstract

There is a need for a simple, sensitive, specific, and inexpensive test for immunoglobulin M antibody to hepatitis B core antigen (anti-HBc IgM). A solid phase passive hemagglutination test (SP-PHA) was developed for this purpose and compared with the enzyme-linked immunosorbent assay (ELISA) test. Hepatitis B core antigen (HBcAg) used in PHA and SP-PHA was synthesized in Escherichia coli. Human IgM was captured to a microtiter plate coated with anti-human IgM, and the presence of anti-HBc IgM was demonstrated by the adherence of HBcAg-sensitized erythrocytes to the bottom of a U-shaped microtiter plate. ELISA and SP-PHA were made at 1:100 and 1:1,000 serum dilution, respectively. Both were positive in 100% of 36 cases of acute hepatitis B, 68.18% of 22 cases of chronic hepatitis B, and 20% of 75 healthy carriers of hepatitis B surface antigen (HBsAg) but none in 65 anti-HBc-positive blood donors that had negative results for HBsAg. Results of both tests were identical but were false positive because rheumatoid factor was found only in ELISA. End-point titration by SP-PHA and PHA was also found useful for the differentiation of acute hepatitis B from chronic hepatitis B and HBsAg carriers.