Long-term efficacy and safety of tenofovir disoproxil fumarate in Chinese patients with chronic hepatitis B: 5-year results

Five-year results of a treatment program for chronic hepatitis B in Ethiopia

BACKGROUND

In sub-Saharan Africa, less than 1% of treatment-eligible chronic hepatitis B (CHB) patients receive antiviral therapy. Experiences from local CHB programs are needed to inform treatment guidelines and policies on the continent. Here, we present 5-year results from one of the first large-scale CHB treatment programs in sub-Saharan Africa.

METHODS

Adults with CHB were enrolled in a pilot treatment program in Addis Ababa, Ethiopia, in 2015. Liver enzymes, viral markers, and transient elastography were assessed at baseline and thereafter at 6-month intervals. Tenofovir disoproxil fumarate was initiated based on the European Association for the Study of the Liver (EASL) criteria, with some modifications. Survival analysis was performed using the Kaplan-Meier method.

RESULTS

In total, 1303 patients were included in the program, of whom 291 (22.3%) started antiviral therapy within the initial 5 years of follow-up. Among patients on treatment, estimated 5-year hepatocellular carcinoma-free survival was 99.0% in patients without cirrhosis at baseline, compared to 88.8% in patients with compensated cirrhosis, and 54.2% in patients with decompensated cirrhosis (p < 0.001). The risk of death was significantly higher in patients with decompensated cirrhosis at baseline (adjusted hazard ratio 44.6, 95% confidence interval 6.1-328.1) and in patients older than 40 years (adjusted hazard ratio 3.7, 95% confidence interval 1.6-8.5). Liver stiffness declined significantly after treatment initiation; the median change from baseline after 1, 3, and 5 years of treatment was - 4.0 kPa, - 5.2 kPa, and - 5.6 kPa, respectively.

CONCLUSIONS

This pilot program demonstrates the long-term benefits of CHB therapy in a resource-limited setting. The high mortality in patients with cirrhosis underscores the need for earlier detection of CHB and timely initiation of antiviral treatment in sub-Saharan Africa.

TRIAL REGISTRATION

The study was registered at ClinicalTrials.gov (NCT02344498) on January 26, 2015.

The expression of interleukin-1β in patients with chronic hepatitis B treated with pegylated-interferon-alpha combined with tenofovir disoproxil fumarate and monotherapy

BACKGROUND

Anti-hepatitis B virus (HBV) treatment uses tenofovir disoproxil fumarate (TDF) along with Pegylated-interferon-alpha (Peg-IFN-α), which is more effective than TDF/Peg-IFN-α monotherapy. We have previously shown that interleukin-1beta (IL-1β) is related to the effectiveness of IFN-α treatment in chronic hepatitis B (CHB) patients. The aim was to investigate the expression of IL-1β in CHB patients treated with Peg-IFN-α combination with TDF and TDF/Peg-IFN-α monotherapy.

METHODS

Huh7 cells infected with HBV were stimulated by Peg-IFN-α and/or Tenofovir (TFV) for 24h. A single-center cohort study of prospective recruitment of CHB patients: untreated CHB (Group A), TDF combined with Peg-IFN-α therapy (Group B), Peg-IFN-α monotherapy (Group C), TDF monotherapy (Group D). Normal donors served as controls. The clinical datas and blood of patients were collected at 0, 12, and 24 weeks. According to the early response criteria, Group B and C were divided into two subgroups: the early response group (ERG) and the non-early response group (NERG). Stimulation of HBV-infected hepatoma cells with IL-1β to validate the antiviral activity of IL-1β. To test the blood sample, cell culture supernatant, and cell lysates and to assess the expression of IL-1β and HBV replication levels in various treatment protocols, Enzyme-Linked Immunosorbent Assay (ELISA) and quantitative reverse transcription polymerase chain reaction (qRT-PCR) were used. SPSS 26.0 and GraphPad Prism 8.0.2 software were used for statistical analysis. P values < 0.05 was considered to be statistically significant.

RESULTS

In vitro experiments, Peg-IFN-α plus TFV treatment group expressed higher IL-1β and inhibited HBV more effectively than monotherapy. Finally, 162 cases were enrolled for observation (Group A (n = 45), Group B (n = 46), Group C (n = 39), and Group D (n = 32)), and normal donors (n = 20) were enrolled for control. The early virological response rates of Group B, C, and D were 58.7%, 51.3%, and 31.2%. At 24 weeks, IL-1β in Group B(P = 0.007) and C(P = 0.034) showed higher than at 0 week. In Group B, the IL-1β showed an upward trend at 12w and 24w in the ERG. IL-1β significantly reduced HBV replication levels in hepatoma cells.

CONCLUSION

The increased expression of IL-1β may enhance the efficacy of TDF combined with Peg-IFN-α therapy in achieving an early response for CHB patients.

Getting to HBV cure: The promising paths forward

Chronic HBV infection is a global public health burden estimated to impact nearly 300 million persons worldwide. Despite the advent of potent antiviral agents that effectively suppress viral replication, HBV cure remains difficult to achieve because of the persistence of covalently closed circular DNA (cccDNA), HBV-DNA integration into the host genome, and impaired immune response. Indefinite treatment is necessary for most patients to maintain level of viral suppression. The success of direct-acting antivirals (DAAs) for hepatitis C treatment has rejuvenated the search for a cure for chronic hepatitis B (CHB), though an HBV cure likely requires an additional layer: immunomodulators for restoration of robust immune responses. DAAs such as entry inhibitors, capsid assembly modulators, inhibitors of subviral particle release, cccDNA silencers, and RNA interference molecules have reached clinical development. Immunomodulators, namely innate immunomodulators (Toll-like receptor agonists), therapeutic vaccines, checkpoint inhibitors, and monoclonal antibodies, are also progressing toward clinical development. The future of the HBV cure possibly lies in triple combination therapies with concerted action on replication inhibition, antigen reduction, and immune stimulation. Many obstacles remain, such as overcoming translational failures, choosing the right endpoint using the right biomarkers, and leveraging current treatments in combination regimens to enhance response rates. This review gives an overview of the current therapies for CHB, HBV biomarkers used to evaluate treatment response, and development of DAAs and immune-targeting drugs and discusses the limitations and unanswered questions on the journey to an HBV cure.

Tenofovir disoproxil fumarate for multiple nucleos(t)ide analogues treatment failure hepatitis B: Is monotherapy enough?

BACKGROUND AND AIM

Tenofovir disoproxil fumarate (TDF) is a first-line treatment for chronic hepatitis B virus (HBV) infection for its high potency and a low rate of drug resistance. This study investigated the efficacy and safety of TDF in Chinese patients with chronic hepatitis B (CHB) infection after treatment failure with multiple nucleos(t)ide analogues (NAs).

METHODS

Patients included were aged 18-65 years, with treatment failure with multiple NAs (serum HBV DNA > 200 IU/mL after more than two different NA treatments). The primary endpoint was proportion of patients with serum HBV DNA < 20 IU/mL at Week 144 of TDF monotherapy. Secondary endpoints and safety were also assessed.

RESULTS

Overall, 213 patients were enrolled. At Week 144, mean HBV DNA decreased significantly from baseline (4.4 vs 1.4 log₁₀ IU/mL), with 77.0% patients (95% confidence interval: 71.1, 82.9) achieving serum HBV DNA < 20 IU/mL. Three (1.4%) patients experienced virological breakthrough during TDF monotherapy, without hepatitis flare. At Week 144, 15.3% and 4.7% patients (hepatitis B e antigen [HBeAg]-positive at baseline) experienced HBeAg loss and HBeAg seroconversion, respectively; 68.3% patients achieved normalized alanine aminotransferase levels. Overall, 58.7% patients experienced more than one adverse event (AE). Most common AEs were upper respiratory tract infection and blood creatine phosphokinase increase; 8.5% patients experienced study drug-related AEs; 9.4% patients experienced serious AEs (none were TDF-related). Among renal safety parameters, overall trend of mean serum phosphorous level remained stable, while mean estimated glomerular filtration rate increased slightly.

CONCLUSIONS

Tenofovir disoproxil fumarate monotherapy is efficacious in CHB patients with multiple NAs treatment failure with no new safety findings.

Evaluation of Tenofovir Disoproxil Fumarate Treatment in Patients with Chronic Hepatitis B

Objective

The main purpose of chronic hepatitis B (CHB) treatment is to improve the patients' life quality and prevent the disease from progressing to cirrhosis or hepatocellular carcinoma. Continuous suppression of hepatitis B virus (HBV) DNA with nucleoside or nucleotide analogues is the most critical way to achieve this goal. This study aimed to evaluate the CHB patients retrospectively followed up with tenofovir disoproxil fumarate (TDF) treatment.

Materials and Methods

The study was planned as retrospective research by Afyonkarahisar Health Sciences University, Faculty of Medicine, Department of Infectious Diseases and Clinical Microbiology between January 2001 and December 2020. We evaluated all treatment-naive and treatment-experienced patients who received TDF (245 mg/day) treatment with the diagnosis of CHB. The data were obtained by reviewing the file information registered in the hospital automation system. HBsAg, Anti-HBs, HBeAg, Anti-HBe, HBV DNA, aspartate aminotransferase (AST), alanine aminotransferase (ALT) values of the patients were evaluated at 1st, 3rd, 6th, 12th months, and 6-month follow-ups throughout the treatment. Virological (HBV-DNA of < 50 IU/ml), biochemical (decrease below 40 IU/Ml in patients with pre-treatment value of ALT >40 IU/ml) and serological (Anti-HBe seroconversion in HBeAg positives and HBsAg negative and anti-HBs seroconversion in all patients) responses were examined. Adverse effects were also assessed during the treatment.

Results

Data from 131 patients who received TDF treatment were evaluated. Virological responses were determined as 78.6%, 81.3%, 94.2%, and 100% in the patients at 24th week, 48th week, 4th year, and 8th year, respectively. While there was no Anti-HBs seroconversion in any patients in four years of the treatment, it was observed at a rate of 10.5% in the eighth year. We did not determine any significant adverse effects requiring discontinuation of the treatment in the long-term follow-up of 131 patients under TDF treatment.

Conclusion

As a result of our study, TDF was an effective and well-tolerated choice for CHB treatment.

Efficacy and Safety of Tenofovir Disoproxil Orotate in Chronic Hepatitis B Patients Previously Treated with Tenofovir Disoproxil Fumarate: Multicenter, Open-Label, Prospective Study

Background/Aim: We aimed to demonstrate the efficacy and safety of tenofovir disoproxilorotate (TDO) compared with that of tenofovir disoproxil fumarate (TDF) in patients with chronic hepatitis B. Methods: This multicenter, open-label, prospective clinical trial (KCT0004185) was conducted to evaluate the efficacy and safety of TDO on switching from TDF for 24 weeks in virologically suppressed chronic hepatitis B patients. The primary efficacy endpoint was the maintenance of virologic response. Safety was assessed by evaluating major adverse events, changes in renal function, and occurrence of hepatocellular carcinoma (HCC). Results: TDO treatment was not inferior in terms of virological response when compared with that on TDF treatment, with a noninferiority margin of −10% (risk difference, −3.17%; 95% confidence interval, −7.5–1.15%). The biological response of TDO was also comparable to that of TDF, with no significant difference in the proportion of patients with normalized alanine transaminase levels. After 24 weeks of treatment, hepatitis B core-related antigen (HBcrAg) significantly decreased to a mean titer of 3.91 log U/mL from 4.15 log U/mL at baseline (p = 0.01). There were no cases of grade 3 or higher adverse events and HCC. The mean estimated glomerular filtration rate increased from 91.09 mL/min to 93.34 mL/min (p = 0.056), and the mean serum level of phosphorus increased from 3.33 mg/dL to 3.44 mg/dL (p = 0.045), suggesting improvement in renal function with TDO treatment. Conclusion: In patients with chronic hepatitis B, the efficacy of TDO was noninferior to that of TDF, with a significant decrease in the HBcrAg titer and improved renal function.

Guidelines for Prevention and Treatment of Chronic Hepatitis B

To achieve the goal of the World Health Organization to eliminate viral hepatitis as a major public health threat by 2030, the Chinese Society of Infectious Diseases and the Chinese Society of Hepatology convened an expert panel in 2019 to update the guidelines for the prevention and treatment of chronic hepatitis B (CHB). The current guidelines cover recent advances in basic, clinical, and preventive studies of CHB infection and consider the actual situation in China. These guidelines are intended to provide support for the prevention, diagnosis, and treatment of CHB.

Efficacy and safety of tenofovir alafenamide fumarate in nucleoside analogue treatment-naïve patients with chronic hepatitis B

Tenofovir alafenamide fumarate (TAF) is a first-line drug for the antiviral treatment of patients with chronic hepatitis B (CHB) in China. In the present study, the efficacy and renal safety of TAF were evaluated in treatment-naive patients with CHB. Patients with CHB who had not been previously treated with nucleoside analogues (NAs) were recruited before TAF treatment was initiated. Changes in the levels of hepatitis B virus (HBV) DNA, hepatitis B e antigen (HBeAg) and hepatitis B surface antigen (HBsAg) were analyzed at 24 and 48 weeks using immunoassays. In addition, liver stiffness measurement (LSM) and controlled attenuation parameter (CAP) were analyzed using transient elastography, while alanine aminotransferase (ALT), triglyceride (TG), total cholesterol (TC) and low-density lipoprotein-cholesterol (LDL-C) levels, calcium (Ca) and inorganic phosphorus (IP) levels were measured using biochemistry assay. In addition, the estimated glomerular filtration rate (eGFR) was calculated. After 48 weeks, the ALT normalization rate was 95.24% (40/42), the complete virological response (HBV DNA <20 IU/ml) rate was 69.05% (29/42) and the HBeAg seroconversion rate was 8.57% (3/35). The levels of HBV DNA and HBsAg were significantly decreased from the baseline at 5.49±1.95 to 1.26±0.66 log₁₀ IU/ml and from 3.59±0.81 to 3.32±0.55 log₁₀ IU/ml after 48 weeks of treatment, respectively. Compared with that in the baseline measurements, LSM at 48 weeks was significantly decreased from 13.00±8.15 to 8.66±4.45 kPa. No significant differences were observed in the TG, TC, LDL-C, CAP, eGFR, Ca and IP measurements. According to the baseline ALT levels, patients were divided into group A [ALT ≤1 x upper limit of normal (ULN); ULN=50 U/l; n=21], group B (1 x ULN < ALT <2 x ULN; n=22) and group C (ALT ≥2 x ULN; n=18). A significant decrease in HBsAg levels was observed in group B (3.63±0.68 vs. 3.53±0.63 log₁₀ IU/ml) and group C (4.15±0.57 vs. 3.66±0.48 log₁₀ IU/ml) at 24 weeks compared with the baseline. In conclusion, TAF was found to be effective and safe in NA treatment-naive patients with CHB. Moreover, the higher the ALT levels, the more prominent the curative effect from TAF treatment. Therefore, NA treatment-naive CHB patients could benefit from TAF treatment in real world.

Review of Current and Potential Treatments for Chronic Hepatitis B Virus Infection

Chronic hepatitis B virus (HBV) infection remains a major global health burden. Millions of people are at risk for complications of chronic HBV infection, despite the widespread availability of an effective prophylactic vaccine. The current available treatments for HBV infection-interferon and nucleos(t)ide analogues-are effective at suppressing viral replication and decreasing the risk of cirrhosis. However, these treatments have a number of limitations, creating the need for alternative therapeutic agents. Recent advances in drug therapy have heralded a new horizon of novel therapeutic approaches for chronic HBV infection, with several promising antiviral and immunomodulatory agents currently in preclinical or clinical testing. This article reviews the current landscape of HBV treatments and highlights the most recent therapeutic strategies designed to directly target HBV or to improve immune response during chronic infection.

APASL guidance on stopping nucleos(t)ide analogues in chronic hepatitis B patients

Chronic hepatitis B virus (HBV) infection is currently incurable. Long-term treatment with potent and safe nucleos(t)ide analogs (NAs) can reduce hepatocellular carcinoma (HCC) and cirrhosis-related complications through profound viral suppression. However, indefinite therapy raises several crucial issues with pros and cons. Because seroclearance of hepatitis B surface (HBsAg) as functional cure is not easily achievable, a finite therapy including sequential 48-week pegylated interferon therapy may provide an opportunity to facilitate HBsAg seroclearance by the rejuvenation of exhausted immune cells. However, the cost of stopping NA is the high incidence of virological relapse and surge of alanine aminotransferase (ALT) levels, which may increase the risk of adverse outcomes (e.g., decompensation, fibrosis progression, HCC, or liver-related mortality). So far, the APASL criteria to stop NA treatment is undetectable HBV DNA levels with normalization of ALT; however, this criterion for cessation of treatment is associated with various incidence rates of virological/clinical relapse and more than 40% of NA-stoppers eventually receive retreatment. A very intensive follow-up strategy and identification of low-risk patients for virological/clinical relapse by different biomarkers are the keys to stop the NA treatment safely. Recent studies suggested that decreasing HBsAg level at the end-of-treatment to < 100-200 IU/mL seems to be a useful marker for deciding when to discontinue NAs therapy. In addition, several viral and host factors have been reviewed for their potential roles in predicting clinical relapse. Finally, the APASL guidance has proposed rules to stop NA and the subsequent follow-up strategy to achieve a better prognosis after stopping NA. In general, for both HBeAg-positive and HBeAg-negative patients who have stopped treatment, these measurements should be done every 1-3 months at the minimum until 12 months.

Development and validation of a hepatitis B-specific health-related quality-of-life instrument: CLDQ-HBV

Hepatitis B virus (HBV) carries a large global burden. Efforts abound to decrease the burden, which necessitates reporting of patient-reported outcomes (PROs). We aimed to develop and validate an HBV-specific PRO instrument using the Chronic Liver Disease Questionnaire (CLDQ). Data were obtained from patients enrolled in our HBV registries who completed the CLDQ, Short Form-36 (SF-36) and FACIT-F. The sample was split randomly 1:1 into training and testing groups. A standard PRO instrument validation pipeline was used to develop and validate the new CLDQ-HBV instrument. HBV patients (n = 1,339) were 48 ± 13 years old, 60% male, 8% cirrhosis, with 53% receiving oral antivirals (OAV). After reduction of 10 redundant items, exploratory factor analysis for the remaining 19 items found 95% of variance was explained by five factors-emotional function, fatigue, systemic symptoms, worry and sleep. Good-to-excellent internal consistency was found: Cronbach's alphas 0.70-0.90 and item-to-own-domain correlations >0.50 for 18/19 items. Known-group validity tests discriminated between HBV patients with and without cirrhosis, with FIB-4 ≥ 3.25 vs <3.25, with and without history of depression or clinically overt fatigue (all p < 0.0001), and treatment (all p < 0.05, all but one <0.0001). After 48-week follow-up, HBV patients receiving OAV (N = 144) with ≥2.7 log 10/mL decline in HBV viral load experienced significant improvements in fatigue, worry and total CLDQ-HBV scores (p < 0.05). The newly developed CLDQ-HBV is a short, disease-specific PRO instrument for HBV patients which was developed and validated using large data set and an established methodology showing excellent psychometric characteristics.

Continuing besifovir dipivoxil maleate versus switching from tenofovir disoproxil fumarate for treatment of chronic hepatitis B: Results of 192-week phase 3 trial

Background/Aims

Besifovir dipivoxil maleate (BSV), an acyclic nucleotide phosphonate, shows potent antiviral activity against hepatitis B virus. Our previous 48-week trial revealed that BSV has comparable antiviral efficacy to tenofovir disoproxil fumarate (TDF) and better safety profiles in terms of improved renal and bone safety. This extension study evaluated the prolonged efficacy and safety of BSV in treatment-naive chronic hepatitis B patients.

Methods

Patients continued to participate in an open-label BSV study after an initial 48-week double-blind comparison of BSV and TDF treatment. The antiviral efficacy and drug safety was evaluated up to 192 weeks in two groups: patients continuing BSV treatment (BSV-BSV) and patients switching from TDF to BSV after 48 weeks (TDF-BSV).

Results

Among 197 patients receiving randomized treatments, 170 (86%) entered the open-label phase and 152 (77%) entered the 192-week extension study. Virological response rates over 192 weeks were 92.50% and 93.06% in the BSV-BSV and TDF-BSV groups, respectively (P=0.90). Hepatitis B envelop antigen seroconversion and alanine aminotransferase normalization rates were similar between the groups (P=0.75 and P=0.36, respectively). There were no drug-resistant mutations to BSV. Bone mineral density and renal function were well preserved in the BSV-BSV group, whereas these initially worsened then recovered after switching therapy in the TDF-BSV group.

Conclusions

BSV maintained potent antiviral efficacy after 192 weeks and showed no evidence of drug resistance. BSV was safe, well tolerated, and effective in patients who switched from TDF to BSV. Trial Registration Number: NCT01937806 (date: 10 Sep 2013).

Early renal injury indicators can help evaluate renal injury in patients with chronic hepatitis B with long-term nucleos(t)ide therapy

BACKGROUND

Patients with chronic hepatitis B (CHB) with long-term nucleos(t)ide therapy may experience renal insufficiency. Traditional renal function indicators, such as urine protein, serum urea nitrogen (BUN), and serum creatinine, are normal when early mild lesions occur. Therefore, more sensitive renal function indicators are needed.

AIM

To investigate the significance of early renal injury indicators in evaluating renal injury in patients with CHB with long-term nucleos(t)ide therapy.

METHODS

We collected the clinical data of 69 outpatients with CHB at Peking University First Hospital from March 2018 to January 2020 who had been treated with long-term nucleos(t)ide therapy and analyzed the results of early renal injury indicators. Continuous normal distribution data were analyzed by the t-test to determine the difference between two groups. Continuous non-normally distributed data were analyzed by the Mann-Whitney U-test between two groups. The Kruskal-Wallis H test was used to determine the differences among multiple groups. Enumeration data were analyzed by the chi-square test. The related factors of early renal injury indicators were analyzed by logistic regression analysis.

RESULTS

The average treatment duration with nucleos(t)ide analogs of the 69 patients with CHB was 99.7 ± 28.7 mo. The cases of patients with elevated BUN and hypophosphatemia were 6 (8.7%) and 13 (18.8%), respectively; 31 (44.9%) patients had abnormal early renal injury indicators, including 9 patients with abnormal urine microalbumin, 7 patients with abnormal urine immunoglobulin, 6 patients with abnormal urine transferrin, and 19 patients with abnormal α1 microglobulin. There were no significant differences in the mean values of age, sex, BUN, estimated glomerular filtration rate (eGFR), serum uric acid, serum calcium, or serum phosphorus between the two groups of patients with and without early renal injury indicators. However, the mean levels of serum creatinine and urine creatinine, N-acetyl-β-D-glucosidase enzyme, α1 microglobulin, and urine immunoglobulin in the former group of patients were significantly higher than those in the latter group of patients (P < 0.05). The incidence of early renal injury in patients with eGFR ≥ 90, 60-89, and 30-59 mL/(min·1.73 m²) was 36.4% (8/22), 47.6% (20/42), and 60% (3/5), respectively. Logistic regression analysis results showed that gamma-glutamyl transpeptidase [odds ratio (OR) = 1.05 (1.008-1.093), P = 0.020], direct bilirubin [OR = 1.548 (1.111-2.159), P = 0.010], serum creatinine [OR = 1.079 (1.022-1.139), P = 0.006], and age [OR = 0.981 (0.942-1.022), P = 0.357] were independent predictors of early renal injury.

CONCLUSION

Patients with CHB treated with long-term nucleos(t)ide analog therapy had a high probability of early renal injury, and early renal injury indicators were highly sensitive and could be used to monitor early renal impairment.

Impact of Hepatitis B Virus Genetic Variation, Integration, and Lymphotropism in Antiviral Treatment and Oncogenesis

Chronic Hepatitis B Virus (HBV) infection poses a significant global health burden. Although, effective treatment and vaccinations against HBV are available, challenges still exist, particularly in the development of curative therapies. The dynamic nature and unique features of HBV such as viral variants, integration of HBV DNA into host chromosomes, and extrahepatic reservoirs are considerations towards understanding the virus biology and developing improved anti-HBV treatments. In this review, we highlight the importance of these viral characteristics in the context of treatment and oncogenesis. Viral genotype and genetic variants can serve as important predictive factors for therapeutic response and outcomes in addition to oncogenic risk. HBV integration, particularly in coding genes, is implicated in the development of hepatocellular carcinoma. Furthermore, we will discuss emerging research that has identified various HBV nucleic acids and infection markers within extrahepatic sites (lymphoid cells). Intriguingly, the presence of hepatocellular carcinoma (HCC)-associated HBV variants and viral integration within the lymphoid cells may contribute towards the development of extrahepatic malignancies. Improved understanding of these HBV characteristics will enhance the development of a cure for chronic HBV infection.

A novel one-step quantitative reverse transcription PCR assay for selective amplification of hepatitis B virus pregenomic RNA from a mixture of HBV DNA and RNA in serum

Current antiviral therapies against hepatitis B virus (HBV) infections, such as treatment with nucleos(t)ide analogs (NAs) and interferon alpha, can significantly lower HBV DNA titers, eventually to undetectable levels. However, it is still difficult to completely eliminate the stable template of HBV, the covalently closed circular DNA (cccDNA), and this contributes to viral rebound when treatment is discontinued. HBV pregenomic RNA (pgRNA), which was recently found to be present in the enveloped mature HBV viral particle in blood, is tentatively regarded, with still accumulating clinical evidence, as a novel bona fide virological marker reflecting the amount and status of cccDNA when serum HBV DNA becomes undetectable. HBV pgRNA and DNA share almost identical sequences, and it is therefore difficult to differentiate pgRNA from viral DNA using normal PCR methods. To exclude interference from viral DNA, methods for measuring pgRNA usually require a selective DNA degradation step, which is complicated and time-consuming and also compromises the accuracy of detection. In this study, we developed a simplified quantitative reverse transcription polymerase chain reaction (qRT-PCR) assay with improved accuracy achieved by probing the polyA tail of pgRNA. Using clinical serum samples, we observed that not all patients share the same 3' sequence, suggesting slight differences between HBV strains in the way they end transcription. We then designed and evaluated a universal primer and probe set for distinguishing HBV pgRNA from HBV DNA. Our results demonstrated that a one-step qRT-PCR assay could selectively amplify HBV pgRNA from a mixture of HBV RNA and DNA, which is valuable for clinical applications.