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Persistent infection of cultured mammalian cells by Japanese encephalitis virus
Abstract:
Persistent infections were established by serial undiluted passage of flavivirus Japanese encephalitis virus in a line of rabbit kidney cells (MA-111). The persistently infected cells resembled uninfected cells in most respects. Low levels of infectious virions were released from a small percentage of cells, and a larger and more variable percentage was shown to possess viral antigen by fluorescent-antibody staining. Released viruses were shown to interfere with replication of wild-type Japanese encephalitis virus. Persistently infected MA-111 cells could not be superinfected with homologous wild-type Japanese encephalitis virus but could be superinfected with two heterologous viruses. Transfer of cell culture medium from persistently infected MA-111 cells to a line of African green monkey kidney cells (Vero) resulted in similar persistent infections in the latter cells. Temperature sensitivity and host-cell interferon production were not involved in establishment or maintenance of persistence. Determination of ratios of physical particles to infectious particles revealed that many defective, noninfectious viruses were present, suggesting that defective interfering particles may be responsible for persistency.
Insights
Researchers established persistent Japanese encephalitis virus infections in rabbit kidney cells. Defective interfering particles, which hinder virus replication, likely cause this persistent flavivirus infection.
Area of Science:
- Virology
- Cell Biology
- Infectious Diseases
Background:
- Persistent viral infections pose significant challenges in healthcare.
- Understanding the mechanisms of viral persistence is crucial for developing effective treatments.
Purpose of the Study:
- To establish and characterize persistent infections of Japanese encephalitis virus (JEV) in cell culture.
- To investigate the potential role of defective interfering particles (DIPs) in maintaining viral persistence.
Main Methods:
- Serial undiluted passage of JEV in MA-111 rabbit kidney cells to establish persistent infection.
- Fluorescent-antibody staining to detect viral antigen expression.
- Superinfection assays with homologous and heterologous viruses.
- Transference of cell culture medium to Vero cells to assess infectivity.
- Determination of physical particle to infectious particle ratios.
Main Results:
- Persistently infected MA-111 cells showed low-level virion release and variable viral antigen presence.
- Released viruses interfered with wild-type JEV replication.
- Cells resisted superinfection by homologous JEV but not heterologous viruses.
- Persistent infection was transferable via cell culture medium.
- High ratios of physical to infectious particles indicated the presence of defective viruses.
Conclusions:
- Defective interfering particles are strongly implicated as the causative agents of persistent Japanese encephalitis virus infection in this model.
- The findings provide insights into the mechanisms of flavivirus persistence and potential strategies for intervention.