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Comparison of two defective hepatitis A virus strains adapted to cell cultures
P Reiner1, M Reinerová, Z Veselovská
1Institute of Preventive and Clinical Medicine, Bratislava, Czechoslovakia.
Abstract:
The replication of two defective hepatitis A virus strains in cell culture was examined. The w.t. HAS-15 strain growing in FRhK-4 cells produced infectious icosahedral virions 27 nm in size as well as round shaped particles with lipids attached to their surface. The morphogenesis of HAV was membrane-dependent and the detected particles were in various degree of maturation. The MBB 11/5 strain growing in PLC/PRF/5 cells produced mainly noninfectious empty procapsids without RNA genome. The translation of viral proteins was uninhibited in both strains. The reason for restricted replication competence of both strains seemed to be different. In HAS-15, highly efficient encapsidation of the progeny RNA positive-strand lowered the formation of replicative intermediate forms. In MBB 11/5, nearly exclusive empty procapsid production gave evidence for the failure of the VPg primer protein attachment to viral RNA. Changes in the efficacy of viral genome replication were a result of the adaptation of HAV to propagation in vitro.
Insights
This study examined defective hepatitis A virus (HAV) replication in cell culture. Different strains showed distinct replication defects, one linked to efficient RNA encapsidation and the other to failed protein attachment.
Area of Science:
- Virology
- Cell Biology
- Molecular Biology
Background:
- Hepatitis A virus (HAV) is a significant human pathogen.
- Understanding HAV replication is crucial for developing antiviral strategies.
- Defective viral strains offer insights into essential replication mechanisms.
Purpose of the Study:
- To investigate the replication mechanisms of two distinct defective hepatitis A virus strains in cell culture.
- To elucidate the molecular basis for the restricted replication competence observed in these strains.
- To explore the role of viral adaptation in vitro.
Main Methods:
- Cell culture propagation of HAV strains (HAS-15 and MBB 11/5).
- Characterization of viral particles using electron microscopy.
- Analysis of viral protein translation and RNA replication intermediates.
- Assessment of viral genome encapsidation and primer protein attachment.
Main Results:
- The HAS-15 strain produced infectious virions and lipid-associated particles, with membrane-dependent morphogenesis and varying maturation stages.
- The MBB 11/5 strain predominantly produced noninfectious empty procapsids lacking RNA.
- Viral protein translation was unaffected in both strains.
- HAS-15 replication was limited by efficient RNA encapsidation, reducing replicative intermediates.
- MBB 11/5 replication failure was attributed to impaired VPg primer protein attachment to viral RNA.
Conclusions:
- Defective HAV replication arises from distinct molecular defects, including RNA encapsidation efficiency and primer protein attachment.
- HAV adaptation to cell culture conditions influences viral genome replication efficacy.
- These findings contribute to understanding HAV pathogenesis and potential therapeutic targets.