Top Journal Insight | Clinical Features of Serum HBV RNA in Chronic Hepatitis B Patients with Low-Level Viremia and Its Correlation with Virological Response

Background

Low-level viremia (LLV) represents a suboptimal virological response during antiviral therapy and is closely associated with poor prognosis, potentially leading to disease progression and adverse outcomes. Globally, oral nucleos(t)ide analogues (NUCs) such as entecavir (ETV), tenofovir disoproxil fumarate (TDF), and tenofovir alafenamide (TAF) remain the first-line treatment options for chronic hepatitis B. However, more than 20% of patients experience persistent or intermittent LLV despite ongoing NUC therapy. Current evidence is insufficient to clearly determine the impact of LLV on treatment efficacy and long-term outcomes, and clinical guidelines lack consensus on its management. Therefore, identifying reliable biomarkers to assess the risk and treatment outcomes associated with LLV is critical for guiding timely clinical intervention.

Incomplete clearance or silencing of covalently closed circular DNA (cccDNA) may be associated with the occurrence of low-level viremia (LLV) in patients with chronic hepatitis B (CHB). Hepatitis B virus pregenomic RNA (pgRNA), transcribed from intrahepatic cccDNA within infected hepatocyte nuclei, is not inhibited by nucleos(t)ide analogues (NUCs) and accurately reflects the level and transcriptional activity of cccDNA in the body. Although quantitative detection of serum HBV RNA holds clinical promise, evidence supporting its application in LLV management remains limited, especially in pediatric populations. For patients receiving NUC therapy, the degree of viral suppression during treatment is a key determinant of clinical outcomes.

Recently, Nanshan Hospital of Guangxi Zhuang Autonomous Region, in collaboration with Beijing Tiantan Hospital affiliated with Capital Medical University and the School of Basic Medical Sciences of Southern Medical University, published a new article in Virology Journal. By conducting a longitudinal analysis of serum HBV RNA and other biomarkers in children with LLV receiving NUC therapy, the study revealed the predictive value of serum HBV RNA for treatment outcomes in this population.

Methods

Baseline demographic and clinical characteristics were systematically recorded, including sex, age, body mass index (BMI), history of NUC use, family history of hepatitis B, as well as serum biomarkers such as alanine aminotransferase (ALT), hepatitis B e antigen (HBeAg), hepatitis B surface antigen (HBsAg), HBV DNA, and HBV RNA. Serum HBV RNA was quantified using an RNA capture probe detection kit (Rendu Biotech, Shanghai, China), with a lower limit of detection (LLOD) of 50 copies/mL.

Results

1.Baseline Characteristics and Virological Outcomes by Treatment Regimen

There were no statistically significant differences in baseline serum levels of HBV DNA, HBV RNA, and quantitative HBsAg (qHBsAg) among the SwiT, ComT, and ConT groups (P > 0.05). At week 48, serum HBV RNA levels were higher in the SwiT and ComT groups compared to the ConT group (3.95 vs. 3.54 log₁₀ IU/mL, P = 0.008; 3.79 vs. 3.54 log₁₀ IU/mL, P = 0.08). Although serum HBV DNA levels in the SwiT and ComT groups were also higher than those in the ConT group at that time, there was no significant difference in qHBsAg levels.

By week 120, 36.8% of patients had not achieved a virological response (NVR). Patients with NVR tended to have lower BMI, HBV genotype C, HBeAg positivity, and higher baseline HBV DNA levels. At week 48, NVR patients continued to exhibit higher levels of HBV DNA (median 2.89 log₁₀ IU/mL) and HBV RNA (median 4.06 log₁₀ copies/mL).

2. Longitudinal Changes in Serum Biomarkers During Initial Entecavir Treatment

In the ConT group, the median serum HBV RNA levels decreased by 1.32 and 1.83 log₁₀ copies/mL at weeks 12 and 24, respectively, compared with baseline (P < 0.001). Median qHBsAg levels decreased by 0.20 and 0.26 log₁₀ IU/mL at the same time points (P < 0.001), while HBV DNA showed an even more marked decline of 3.50 and 4.34 log₁₀ IU/mL, respectively (P < 0.001).

The SwiT and ComT groups demonstrated similar trends. HBV RNA levels declined by approximately 1.09–1.60 log₁₀ and 1.70–1.99 log₁₀ copies/mL at weeks 12 and 24, respectively. Across all treatment groups, the degree of HBV DNA suppression consistently exceeded that of HBV RNA and qHBsAg (P < 0.001).

By week 120, the rates of undetectable HBV DNA reached 80.0% in the SwiT group and 83.9% in the ComT group, representing a 1.6-fold increase compared to the ConT group (50.7%). Similarly, the rates of undetectable HBV RNA were 60.0% (SwiT) and 54.8% (ComT), both significantly higher than in the ConT group (32.5%).

Despite virological suppression, qHBsAg levels remained elevated in most patients, with HBsAg seroclearance (<0.05 IU/mL) observed in only 3 cases across the entire cohort.

By week 72, compared to week 48 levels, the SwiT group showed additional decreases in HBV DNA, HBV RNA, and qHBsAg of 0.74, 0.77, and 0.15 log₁₀, respectively; the ComT group showed reductions of 0.88, 0.70, and 0.22 log₁₀, respectively. In contrast, the ConT group showed only modest decreases of 0.50, 0.50, and 0.08 log₁₀, respectively—highlighting the advantage of treatment adjustment.

Multivariate regression analysis identified genotype C (adjusted odds ratio [aOR]: 6.89; 95% CI: 1.56–30.49; P = 0.011), continued ETV monotherapy, higher HBV DNA at week 48 (aOR: 63.73; 95% CI: 7.58–535.97; P < 0.001), and higher HBV RNA at week 48 (aOR: 5.86; 95% CI: 1.40–24.62; P = 0.016) as independent risk factors for non-virological response (NVR) (Fig. 4B).

ROC curve analysis (Fig. 5A) demonstrated that at week 48, the area under the curve (AUC) for HBV DNA and HBV RNA were 0.80 (sensitivity 0.88, specificity 0.66) and 0.76 (sensitivity 0.58, specificity 0.88), respectively, with no statistically significant difference between them (P = 0.459). However, combining both markers significantly improved the predictive accuracy, yielding an AUC of 0.82 (sensitivity 0.88, specificity 0.65), which was superior to either single marker alone (P < 0.05).

Stratification based on the optimal HBV RNA cutoff value at week 48 (3.97 log₁₀ copies/mL) revealed that patients below this threshold achieved higher rates of virological suppression across all treatment regimens (P < 0.05; Fig. 5B).

The HBV nucleic acid detection kit independently developed by Rendu Bio is the first to be approved for market launch due to its unique detection technology, high sensitivity, and high specificity. Unlike conventional PCR techniques, this kit utilizes a proprietary SAT technology — RNA real-time fluorescence isothermal amplification — which enables direct amplification and quantification of RNA molecules without interference from HBV DNA in the samples and without requiring DNase treatment. The detection limit reaches as low as 50 copies/mL. Integrated with the AutoSAT fully automated platform, the kit eliminates manual operation errors and saves laboratory manpower and resources, providing reliable support for hepatitis B patient management.