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Expression of hepatitis B virus large envelope polypeptide inhibits hepatitis B surface antigen secretion in
Abstract:
The outer membrane of the hepatitis B virus consists of host lipid and the hepatitis B virus major (p25, gp28), middle (gp33, gp36), and large (p39, gp42) envelope polypeptides. These polypeptides are encoded by a large open reading frame that contains three in-phase translation start codons and a shared termination signal. The influence of the large envelope polypeptide on the secretion of hepatitis B surface antigen (HBsAg) subviral particles in transgenic mice was examined. The major polypeptide is the dominant structural component of the HBsAg particles, which are readily secreted into the blood. A relative increase in production of the large envelope polypeptide compared with that of the major envelope polypeptide led to profound reduction of the HBsAg concentration in serum as a result of accumulation of both envelope polypeptides in a relatively insoluble compartment within the cell. We conclude that inhibition of HBsAg secretion is related to a hitherto unknown property of the pre-S-containing domain of the large envelope polypeptide.
Insights
The large envelope polypeptide of hepatitis B virus inhibits secretion of hepatitis B surface antigen (HBsAg) particles. Increased large polypeptide production causes HBsAg accumulation within cells, reducing serum levels.
Area of Science:
- Virology
- Molecular Biology
- Immunology
Background:
- The hepatitis B virus (HBV) outer membrane comprises host lipids and HBV envelope polypeptides: major (p25, gp28), middle (gp33, gp36), and large (p39, gp42).
- These polypeptides originate from a single large open reading frame with three translation start codons.
Purpose of the Study:
- To investigate the role of the large envelope polypeptide in the secretion of hepatitis B surface antigen (HBsAg) subviral particles.
- To understand the mechanism by which the large envelope polypeptide influences HBsAg secretion.
Main Methods:
- Utilized transgenic mouse models to study HBsAg secretion.
- Analyzed the impact of varying ratios of large to major envelope polypeptide production on HBsAg levels.
Main Results:
- The major envelope polypeptide is the primary structural component of secreted HBsAg particles.
- Elevated production of the large envelope polypeptide relative to the major polypeptide significantly reduced serum HBsAg concentrations.
- Accumulation of both envelope polypeptides in an insoluble cellular compartment was observed.
Conclusions:
- Inhibition of HBsAg secretion is linked to an uncharacterized property of the pre-S-containing domain of the large envelope polypeptide.
- The balance between large and major envelope polypeptide production is critical for efficient HBsAg secretion.