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

Area of Science:

• Hepatology
• Immunology
• Diagnostic Assay Development

Background:

• A need exists for a simple, sensitive, specific, and inexpensive diagnostic test for immunoglobulin M antibody to hepatitis B core antigen (anti-HBc IgM).
• Current diagnostic methods may lack the desired combination of simplicity, sensitivity, specificity, and cost-effectiveness for anti-HBc IgM detection.

Purpose of the Study:

• To develop and evaluate a novel solid phase passive hemagglutination test (SP-PHA) for the detection of anti-HBc IgM.
• To compare the performance of the developed SP-PHA assay with the established enzyme-linked immunosorbent assay (ELISA) for anti-HBc IgM detection.

Main Methods:

• Hepatitis B core antigen (HBcAg) was synthesized in Escherichia coli for use in passive hemagglutination (PHA) and SP-PHA assays.
• A microtiter plate coated with anti-human IgM was used to capture human IgM, with anti-HBc IgM presence indicated by HBcAg-sensitized erythrocytes.
• Serum samples from patients with acute hepatitis B, chronic hepatitis B, HBsAg carriers, and HBsAg-negative anti-HBc-positive donors were tested using both SP-PHA and ELISA.

Main Results:

• Both SP-PHA and ELISA demonstrated 100% positivity in acute hepatitis B cases (n=36).
• SP-PHA and ELISA showed 68.18% positivity in chronic hepatitis B cases (n=22) and 20% in HBsAg carriers (n=75).
• False positive results, attributed to rheumatoid factor, were observed only in the ELISA, not in SP-PHA, indicating superior specificity.

Conclusions:

• The developed SP-PHA assay is a simple, sensitive, and specific method for detecting anti-HBc IgM.
• End-point titration using SP-PHA and PHA is valuable for differentiating acute hepatitis B from chronic hepatitis B and HBsAg carriers.