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Envelope and precore/core variants of hepatitis B virus
1Academic Department of Medicine, St. Mary's Hospital Medical School, Imperial College, University of London, England.
Gastroenterology Clinics of North America
|September 1, 1994
Summary
Hepatitis B virus (HBV) variants arise due to immune selection pressures, particularly when antibody responses occur without T-cell responses. These variants can lead to different clinical outcomes when transmitted to new hosts.
Area of Science:
- Hepatology
- Virology
- Immunology
Background:
- Hepatitis B virus (HBV) replication-competent variants emerge due to immune selection pressures targeting envelope, precore/core, and X proteins.
- An antibody response without a cytotoxic T-lymphocyte (CTL) response creates an optimal environment for variant selection.
Purpose of the Study:
- To investigate the role of immune selection pressures in the emergence of HBV variants.
- To understand how different immune responses influence HBV evolution and clinical outcomes.
Main Methods:
- Analysis of HBV protein mutations under immune selection.
- Evaluation of antibody and CTL responses in HBV-infected individuals and neonates.
- Assessment of variant transmission and clinical presentation in new hosts.
Main Results:
- Mutations in HBV envelope, precore/core, and X proteins are hotspots for immune selection.
- Passive/active immunization in neonates and HBeAg seroconversion in chronic carriers with defective CTLs facilitate variant emergence.
- The timing and type of immune pressure dictate virologic and clinical outcomes.
Conclusions:
- Immune selection pressures, especially antibody responses lacking CTL activity, drive the evolution of clinically significant HBV variants.
- The clinical picture of HBV infection can change upon transmission of these variants due to altered immune pressures in the new host.