Development of ultra-high sensitivity bioluminescent enzyme immunoassay for hepatitis B virus surface antigen using firefly luciferase.

Hepatitis B virus (HBV) infection continues to be a global public health concern. Efficient diagnosis of HBV surface antigen (HBsAg) is useful for identification of infection, treatment and prevention of transfusion-transmitted viral infections. Seronegative window reduction afforded by a highly sensitive measurement methodology is necessary as a small quantity of virus with infection risk exists for the period characterized by undetectable HBsAg following HBV infection. In this study, a bioluminescent enzyme immunoassay (BLEIA) for HBsAg was developed employing firefly luciferase as a labeling enzyme and a two-step sandwich immunoassay method. The cut-off value (10 mIU/mL) was 50-fold more sensitive relative to conventional chemiluminescent enzyme immunoassay based on luminol luminescence involving peroxidase as the labeling enzyme and the identical antibodies. Preliminary clinical data for this BLEIA revealed that the HBV seroconversion panel derived sequentially from HBV-infected human blood was detected 11 days following window closure from the first bleed, whereas detection occurred 14-25 days following window closure with the three conventional commercial kits.