184 - Critical evaluation of false negative results in competitive EIA tests for hepatitis Delta virus antibodies
Autor(s): A. Martella, M. Martella
Issue: RIMeL - IJLaM, Vol. 6, N. 3, 2010 (MAF Servizi srl ed.)
Page(s): 184-91
Summary
Background. The Hepatitis Delta Virus (HDV) belongs to a group of subviral agents known as Satellites. It needs a helper virus (HBV) in order to replicate its genome and to produce surface antigens. In the literature, some authors reported false positive or negative results in anti-HDV antibodies (HDV-Ab) cases. Methods. The present study is based on the observation of false negative cases in a competitive EIA-test forHDV-Ab, carried out on subjects with high concentrations of HDV antigen (HDV-Ag). Results. We have shown that a high haematic concentration of the antigen creates a “polymerization phenomenon”, with many binding sites for the conjugate, producing an abnormal signal characterized by a highoptical density result (an atypical negative reaction), despite the presence of anti-HDV antibodies in serum. We simply obtained the expected positive results by a mere sample dilution in physiological saline solution. Conclusions. A correct positive or negative reaction for HDV-Ab, in these atypical cases, can be obtained onlyin an empirical way by serum dilution. In these cases, however, the accuracy of quantitative results is uncertain. Key-words: HDV-Ab, HDV-Ag, false negative, false positive, polymerization phenomenon.