Diversity of the nucleic acid forms of circulating HBV in chronically infected patients and its impact on viral cycle (Équipe Gautheron/Housset)

Hepatol Int 2022 Vol. 16 Issue 6 Pages 1259-1272

BACKGROUND: Besides the prototypical hepatitis B virus (HBV) infectious particle, which contains a full-length double-stranded DNA (flDNA), additional circulating virus-like particles, which carry pregenomic RNA (pgRNA), spliced1RNA (sp1RNA) or spliced-derived DNA (defDNA) forms have been described. We aimed to determine the level of these four circulating forms in patients and to evaluate their impact on viral lifecycle.

METHODS: Chronic HBV untreated patients (n = 162), included in the HEPATHER cohort, were investigated. Pangenomic qPCRs were set up to quantify the four circulating forms of HBV nucleic acids (HBV(naf)). In vitro infection assays were performed to address the impact of HBV(naf).

RESULTS: Hierarchical clustering individualized two clusters of HBV(naf) diversity among patients: (1) cluster 1 (C1) showing a predominance of flDNA; (2) cluster 2 (C2) showing various proportions of the different forms. HBeAg-positive chronic hepatitis phase and higher viral load (7.0 +/- 6.4 vs 6.6 +/- 6.2 Log(10) copies/ml; p < 0.001) characterized C2 compared to C1 patients. Among the different HBV(naf), pgRNA was more prevalent in C1 patients with high vs low HBV viral load (22.1% +/- 2.5% vs 4.1% +/- 1.8% of HBV(naf), p < 0.0001) but remained highly prevalent in C2 patients, whatever the level of replication. C2 patients samples used in infection assays showed that: (1) HBV(naf) secretion was independent of the viral strain; (2) the viral cycle efficiency differed according to the proportion of HBV(naf) in the inoculum, independently of cccDNA formation. Inoculum enrichment before infection suggests that pgRNA-containing particles drive this impact on viral replication.

CONCLUSION: Besides the critical role of HBV replication in circulating HBV(naf) diversity, our data highlight an impact of this diversity on the dynamics of viral cycle.

CLINICAL TRIAL REGISTRATION: Patients were included from a prospective multicenter French national cohort (ANRS CO22 HEPATHER, NCT01953458).