A group from Department of Gastroenterology and Hepatology, Juntendo University Shizuoka Hospital, 1129 Nagaoka, Izunokuni-shi, Shizuoka, 410-2295, Japan, etc. has reported that the serum O-glycosylated hepatitis B surface antigen (HBsAg) level can be used to evaluate serum HBV virion levels through conventional immunoassay and may be a novel potential biomarker of viral kinetics, especially in patients receiving NA therapy.
Currently, oral administration of nucleos(t)ide analogs (NAs) is the most popular treatment strategy for patients with CHB because of the excellent virologic efficacy and safety profile of NAs. Long-term administration of NAs suppresses HBV replication in most patients, resulting in biochemical remission and histological improvement, including the regression of fibrosis and cirrhosis. However, HBV infection cannot be completely eliminated because of the persistence of intrahepatic covalently closed circular DNA (cccDNA). Measuring the intrahepatic cccDNA concentration would be the most direct way to assess the replication-competent viral reservoir. However, there are limitations, including the need for liver biopsy and the lack of a standardized method to quantify cccDNA.
HBsAg has long served as a qualitative serological marker for the diagnosis of HBV infection. Quantitative HBsAg assay has demonstrated that serum HBsAg levels are correlated with serum HBV DNA levels and intrahepatic cccDNA levels, and show prognostic significance. However, currently available HBsAg assays cannot distinguish between HBV virions and non-infectious subviral particles (SVPs). Recently, O-glycosylation of the PreS2 domain of M-HBsAg was identified as a distinct characteristic of genotype C HBV virions via a glycan-based immunoassay, and a recombinant antibody that specifically recognizes O-glycosylated M-HBsAg (anti-Glyco-PreS2 antibody) was developed.
Authors have found that the serum O-glycosylated HBsAg level can be used to evaluate serum HBV virion levels through conventional immunoassay and may be a novel potential biomarker of viral kinetics, especially in patients receiving NA therapy.