Study of influence of metal ions in the diagnosis of recombinant hepatitis B surface antigen (HBsAg) using ELISA technique

Abstract

Objectives: Preliminary diagnosis of hepatitis B is performed by measuring the levels of serological markers using enzyme-linked immunosorbent assay (ELISA). Errors in diagnosis of the disease using serum markers might occur due to the presence of metallic salts in diagnostic samples. The present study was designed to evaluate the effects of various metal ions on the diagnosis of recombinant hepatitis B surface antigen (HBsAg). Methods: A simple step sandwich ELISA technique was used to evaluate the effects of metal ions on the diagnosis of HBsAg. Further, the zeta potential, electrical conductivity and redox potential of solutions with proteins and metal salts were measured to evaluate the interaction of these metal ions with the protein. Results: The results showed that recombinant HBsAg significantly interacted with the tested metal ions, with lithium ion showing the highest interaction, followed by barium, aluminium, and nickel as the percent decrease in the free HBsAg concentration in presence of these metal ions were found to be 95.5, 94.1, 93.5, and 91.6%, respectively. Zeta potential of the protein in reaction mixture also changed considerably and marked decrease in the concentration of free HBsAg was observed. This decrease in the concentration of free HBsAg resulted into error in the ELISA test which was negative in presence of these metal ions due to strong interaction with the HBsAg protein. Conclusions: The findings of this study clearly demonstrated that the presence of metal ions in pathological samples can result in interaction with the antigen leading to possible diagnostic errors.

Keywords

• ELISA
• Diagnostic errors
• Hepatitis B antigen
• Metal ions
• Interaction