HBsAg can be detected in blood even when serum HBV DNA is very low. The reason is that HBsAg is:
- A A structural protein that is secreted only from lysed hepatocytes
- B Produced in excess and secreted as empty subviral particles (SVPs) independently of complete virion assembly ✓
- C Present on circulating Dane particles exclusively
- D Synthesized and secreted by stellate cells in response to HBV infection
Correct answer: B. Produced in excess and secreted as empty subviral particles (SVPs) independently of complete virion assembly
Explanation
HBsAg (hepatitis B surface antigen) is produced in vast excess and secreted as non-infectious subviral particles (SVPs) — both spherical (22 nm) and filamentous forms — which outnumber complete Dane particles by 1000-10,000 fold; SVPs contain surface proteins without nucleocapsid or viral DNA, explaining why HBsAg can persist even when viral DNA is suppressed. HBsAg is secreted from living infected hepatocytes, not just lysed ones. Dane particles are the complete infectious HBV virions. Stellate cells (Ito cells) are not sites of HBV protein synthesis.
Reference: Ananthanarayan & Paniker's Textbook of Microbiology, 11th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.