Functional cure in chronic hepatitis B is defined by loss of serum HBsAg, and a falling HBsAg is routinely read as evidence that covalently closed circular DNA has been eliminated or durably silenced. That reading assumes the antigen is coming from cccDNA. It need not be: HBV DNA integrated into the host genome can also be transcribed into full-length envelope transcripts.
This study combined intrahepatic HBsAg immunostaining, quantitative serum HBsAg and droplet digital PCR profiling of HBV DNA and RNA in liver biopsies to separate patients whose antigen production was predominantly cccDNA-driven from those in whom it was integration-driven, then compared them directly. All three envelope proteins were present in liver and serum in both groups. The relative abundance of L and S proteins did not differ. Intrahepatic burden correlated with serum levels across the combined cohort, indicating similar retention and secretion. Every established intrahepatic staining pattern, membranous and cytoplasmic, appeared in both groups, with none unique to either source.
The practical consequence runs in both directions. A patient whose HBsAg remains detectable may have substantial integration and little cccDNA activity — a partial cure state the current endpoint does not recognise. Equally, HBsAg decline under a novel agent cannot be taken as proof that cccDNA has been silenced. For a clinician this changes how trial results should be read rather than what to do on Monday; for anyone counselling a patient about a cure trial, it is the honest caveat.
- Do not interpret a falling HBsAg as evidence that cccDNA has been cleared
- Recognise persistent HBsAg with low viral activity as a possible integration-driven state
- Read HBsAg-loss endpoints in cure trials as a surrogate with a known confounder
- Continue standard nucleos(t)ide management unchanged — this is about endpoints, not treatment
Why it matters
The biomarker defining cure in hepatitis B cannot tell you which viral source produced it.
Don't overread it
This is mechanistic work in liver biopsies — it does not show that any patient was misclassified in a completed trial.
Read the rest in the app
You have read your two free briefings this month. The app carries all 27 specialties, every morning, free — and this finding is waiting in it.
Scan to keep reading on your phone. No account needed to start.
Tomorrow morning, before your first patient
One edition a day for gastroenterology & hepatology, written by the desk, every claim tied to its paper. Six minutes.
Get the app — free