Stability of hepatitis B virus pregenomic RNA in plasma specimens under various temperatures and storage conditions

Measuring hepatitis B pgRNA stability using an updated automated HBV pgRNA assay with increased sensitivity

BACKGROUND

HBV pregenomic RNA (pgRNA) is a circulating biomarker for covalently closed circular DNA activity in HBV-infected individuals and has been studied for treatment efficacy, disease staging, and off-therapy outcomes; however, data on the stability are scarce. Increasing HBV pgRNA assay sensitivity may improve its predictive value and provide additional insights at low viral levels.

METHODS

Modifications to a fully automated first (v1) generation HBV pgRNA assay improved sensitivity up to 15-fold over the previous assay. Flexible sample input volumes yielded lower limits of quantitation of 10 and 22 copies/mL for 0.6 and 0.2 mL assays, respectively. Results are standardized to secondary standards that are traceable to the WHO HBV DNA standard, and internal and external controls are included.

RESULTS

Comparison between v1 and modified v2 assays showed increased sensitivity from 152 copies/mL with v1 to 10 (0.6 mL) and 22 (0.2 mL) copies/mL with v2, respectively. Quantitated v2 results were indistinguishable from v1, indicating that comparisons can be made to previous studies. Single timepoint treatment-naive blood donors or longitudinal draws from patients with chronic hepatitis B on AB-729, an investigational siRNA therapy, showed improved detection and quantifiable pgRNA with v2 compared with v1. Stability testing demonstrated excellent HBV pgRNA plasma stability after 3 freeze-thaw cycles, for at least 7 days at 25-37 °C and at least 30 days at 4°C, with ≤0.25 Log U/mL decrease.

CONCLUSION

HBV pgRNA v2 assays with increased sensitivity and flexible input volumes demonstrated increased detection and quantitation of low viral titer samples. Highly sensitive HBV pgRNA assays may be useful in refining predictive treatment outcomes based on this marker. HBV pgRNA was stable under multiple conditions, which increases the reliability of this marker.

Dynamics of Hepatitis B Virus Pregenomic RNA in Chronic Hepatitis B Patients With Antiviral Therapy Over 9 Years

Serum hepatitis B virus pregenomic RNA (HBV pgRNA) is a potential biomarker that is correlated with covalently closed circular DNA. The long-term dynamics of HBV pgRNA in patients with chronic hepatitis B need to be explored. One hundred naïve nucleos(t)ide analog-treated patients with chronic hepatitis B were enrolled to analyze the dynamics of HBV pgRNA over 9 years. The positive rates of HBV pgRNAs declined gradually and showed biphasic kinetics. Serum HBV pgRNA levels in patients treated with entecavir became negative later than those treated with adefovir or lamivudine. Patients who remain positive for HBV pgRNA after 9 years of treatment may have higher viral transcription efficiencies. The reverse transcription efficiency of hepatitis B e-antigen (HBeAg)-positive patients was higher than that of HBeAg-negative patients at baseline and showed no difference after 24-week nucleos(t)ide analog treatment. The trajectory of serum HBV pgRNA-negative transformation differs in patients with different characteristics. Long-term dynamic monitoring of serum HBV pgRNA levels has significance in hepatitis B treatment.

One-Step RT-qPCR for Viral RNA Detection Using Digital Analysis

The rapid detection of viruses is becoming increasingly important to prevent widespread infections. However, virus detection via reverse transcription-quantitative polymerase chain reaction (RT-qPCR) is time-consuming, as it involves independent nucleic acid extraction and complementary DNA synthesis. This process limits the potential for rapid diagnosis and mass analysis, which are necessary to curtail viral spread. In this study, a simple and rapid thermolysis method was developed to circumvent the need for extraction and purification of viral RNA. The developed protocol was applied to one-chip digital PCR (OCdPCR), which allowed thermolysis, RT, and digital PCR in a single unit comprising 20,000 chambers of sub-nanoliter volume. Two viruses such as tobacco mosaic virus and cucumber mosaic virus were tested as model viral particles. First, the temperature, exposure time, and template concentration were optimized against tobacco mosaic viral particles, and the most efficient conditions were identified as 85°C, 5 min, and 0.01 μg/nL with a cycle threshold of approximately 33. Finally, the OCdPCR analysis yielded 1,130.2 copies/µL using 10⁻² μg/nL of viral particles in a 30 min thermolysis-RT reaction at 70°C. This novel protocol shows promise as a quick, accurate, and precise method for large-scale viral analysis in the future.