Highly Sensitive Glycan Profiling of Hepatitis B Viral Particles and a Simple Method for Dane Particle Enrichment.

Hepatitis B virus (HBV) is a double-stranded DNA virus composed of three types of viral particles. The virions are called Dane particles and the others are noninfectious subviral particles (SVPs). In blood, SVPs are detected in abundance, about 1000-10000 fold higher than Dane particles. Dane particles are hazardous because of their strong infectivity, unlike SVPs. Dane particles are covered with an envelope of glycoprotein called HBV surface antigen (HBsAg). HBsAg glycosylation is involved in viral particle formation and secretion. In this study, we established a novel and highly sensitive method for viral glycan profiling of HBsAg using small aliquots of patient serum. Our lectin microarray system could sensitively profile the glycans exposed on HBV while retaining the intact viral particle structure under nonreducing conditions. Several typical lectins were chosen from the lectin microarray results. Specifically, jacalin, which recognizes O-glycan, showed specific and strong reactivity to the M-HBsAg required for Dane particle secretion. Employing the lectin-fractionation method using jacalin, HBV particles were fractionated into jacalin-bound and unbound fractions from patient serum. We measured HBsAg titer and viral DNA load in each fraction using clinical tests. Interestingly, the jacalin-bound fraction contained a major fraction of the HBV viral DNA load. Thus, in this study we have presented a glycan profiling method for HBsAg on the intact HBV particle and an easy and simple method to enrich Dane particles from patient serum by jacalin fractionation.