A Novel Quantitative ELISA Demonstrates Lack of Correlation Between Serum HDV-RNA and Anti-HDV Antibody Levels in Chronic HDV Infection.

Infection with the hepatitis delta virus (HDV) causes the most aggressive type of viral hepatitis and frequently leads to liver cirrhosis and hepatocellular carcinoma. Immunological aspects associated with HDV infection are poorly studied, and quantitative identification of anti-HDV antibodies may be important for understanding the disease. A quantitative, chemiluminescence-based ELISA was developed and validated using 399 serum samples (199 HDV-Ab positive, 200 healthy controls). Serum levels of HDV-RNA, HBV-DNA and hepatic enzymes (ALT, AST) were measured. Statistical analyses included ROC analysis, distribution analysis, Student's t-test and correlation analysis. ELISA demonstrated linear quantification of anti-HDV antibodies with high specificity (Sp = 100%) and sensitivity (Se = 100%), detecting down to 0.5 ng/mL in pure standards. The mean anti-HDV antibody levels were 67,622 ng/mL overall, 70,883 ng/mL in males and 64,043 ng/mL in females. Antibody levels followed a normal distribution, despite population heterogeneity. Student's t-test revealed significant gender differences in antibody levels and ALT (p = 0.0128 and p = 0.0006), whereas HDV-RNA, HBV-DNA and AST did not differ significantly. Comparisons of the high versus low HDV-RNA subgroups showed no significant differences in antibody levels. Correlation analysis indicated no significant associations between anti-HDV antibody levels and HDV-RNA, hepatic enzyme levels. This study presents a robust quantitative ELISA for detecting anti-HDV antibodies. The humoral immune response, as reflected by antibody levels, is independent of the viral load and liver injury markers. Gender-related differences in antibody and ALT levels were observed. These findings provide a foundation for precise evaluation of HDV-specific immunity in chronic infections.