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[The study on heterogeneity of hepatitis B virus DNA]
Jing Dong1, Jun Cheng, Qinhuan Wang
1Gene Therapy Research Center, Institute of Infectious Diseases, The 302 Hospital of PLA, Beijing 100039, China.
Insights
Hepatitis B virus (HBV) quasispecies exist in chronic infections, showing variations in genes like preC/C, S, and X. Specific deletions in the X gene (core promoter) may impact infection prognosis and HBeAg expression.
Area of Science:
- Virology
- Molecular Biology
- Hepatology
Context:
- Chronic Hepatitis B virus (HBV) infection is a global health concern.
- Understanding HBV genetic diversity is crucial for disease management.
- HBV quasispecies represent intra-patient viral variants.
Purpose:
- To investigate the genetic diversity of HBV quasispecies in patients with chronic HBV infection.
- To identify specific mutations and deletions within key HBV genes.
Summary:
- PCR amplification and sequencing of preC/C, polymerase, S, X genes, and whole genomes from 18 chronic HBV patients revealed significant quasispecies diversity.
- High homology was observed within gene regions (e.g., 98.0-99.1% for preC/C), but variations including substitutions, deletions, and frame-shifts were identified.
- Notable findings include frequent A83 substitution and core antigen internal deletion (CID) in the preC/C region, and deletions in the X gene (core promoter) potentially affecting HBeAg expression and viral protein structure.
Impact:
- Identifies specific HBV quasispecies characteristics, including deletions in the X gene (core promoter), that may influence disease prognosis.
- Highlights the significance of amino acid substitutions in viral proteins for further investigation.
- Contributes to a deeper understanding of HBV evolution and pathogenesis in chronic infections.
Objective:
To investigate the HBV quasispecies groups in the patients with chronic HBV infection.
Methods:
Specific primers ware synthesized according to HBV strain found in China, the preC/C gene, reverse transcriptase region, whole S region, X gene and whole genome ware amplified by PCR method from the serum of 18 patients with chronic HBV infection, and then the PCR products were subcloned into pGEM Teasy vectors. Positive clones with target sequences were selected out for sequencing. Sequence comparison of the selected clones ware made to find the difference.
Results:
The homology between clones from one patient of preC/C gene, reverse transcriptase of polymerase region, whole S region, X gene and whole genome are 98.0% approximately 99.1%, 98.7% approximately 99.3%, 97.5% approximately 100%, 93.0% approximately 98.2% and 96.6% approximately 97.5%, respectively. There was a high-frequency A83 substitution and core antigen internal deletion (CID) in preC/C region. Substitution, deletion and frame-shift by insertion or deletion of short sequence were found in 4 open reading frames. Deletion in X gene (Core promoter, CP) will not only result in the polymorphism of X protein at the carboxyl end, but also regulate the expression of HBeAg. Coding sequence of truncated middle surface antigen and defective HBV genome could also be detected in this study.
Conclusion:
There are HBV quasispecies groups in patients with chronic HBV infection. Hot deletion region in X region (CP) will influence the prognosis of the HBV infection. Individually characterized substitutions in amino acid sequence of viral protein is worthy of further study.