Hepatitis B virus (HBV) infection results in cirrhosis and the development of hepatocellular carcinoma (HCC) in up to 50% of infected people. Timely treatment can reduce the progression to cirrhosis and the risk of HCC, but lifelong treatment is required for most patients, and treatment is currently only recommended for those at highest risk of severe disease. Guidelines for commencing treatment for HBV require the detection of persistently elevated ALT (liver enzyme) and elevated viral DNA titres, both of which require access to specialized laboratory assays, which are expensive in the case of viral DNA assays. A point-of-care (POC) test for HBV treatment eligibility could provide wider access to HBV treatment especially in resource-poor settings. A POC test for ALT has been developed by the Burnet Institute and partners and is under evaluation for clinical use, however, determining HBV DNA titre (viral load) at POC remains a challenge.
Our approach to developing a POC test for HBV viral load involves a three-step process to (1) capture HBV viral particles (2) clear the large excess of HBV-related viral antigens that are not associated with the authentic viral particles, and (3) detection of captured HBV viral particles by antibodies to HBV surface antigen or core antigen.
We have developed several key methodologies using a deconstructed approach that permits optimization of each of the above steps of viral capture, clearance of free antigen, and detection independently. These findings are key progress steps in the development of a POC test to detect viral antigen as a surrogate of HBV DNA quantification. Further work is needed to prove the concept for the development of POC.