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Persistent and lytic infections with SSPE virus: a comparison of the synthesis of virus-specific polypeptides
Abstract:
The synthesis of virus-specific polypeptides and messenger RNA in cell cultures persistently infected with an isolate of measles virus from a patient with subacute sclerosing panencephalitis (SSPE) has been compared to that found in a lytic infection with the homologous virus. The persistent infection described here was chosen as its biological characteristics reflect those of virus-infected brain cells from SSPE patients. The synthesis of H, N and possibly F protein was seen in both lytic and persistent infections, but the synthesis of M protein was only detected in the lytic infection. However, messenger RNA isolated from either the lytic or persistent infection directed the synthesis in a cell-free translation system of all structural polypeptides, including M, and also three non-structural polypeptides, with mol. wt. of 34 000, 30 000 and 18 000. Messenger RNAs coding for the virus-specific polypeptides were also shown to be polyadenylated. In addition, those polypeptides made in vitro which were antigenically related to the haemagglutinin, demonstrated structural changes after passage through a persistent infection.
Insights
Measles virus protein synthesis differs between lytic and persistent infections. Messenger RNA from both infection types directs the synthesis of all viral proteins, including M protein, in cell-free systems.
Area of Science:
- Virology
- Molecular Biology
- Neuroscience
Background:
- Subacute sclerosing panencephalitis (SSPE) is a chronic, fatal neurological disease caused by measles virus.
- Persistent measles virus infections in cell cultures mimic aspects of SSPE, offering a model for studying viral replication in the central nervous system.
Purpose of the Study:
- To compare measles virus protein and messenger RNA synthesis in persistently infected cells versus lytic infections.
- To investigate the role of messenger RNA in directing viral protein synthesis during different infection phases.
Main Methods:
- Comparison of measles virus polypeptide and messenger RNA synthesis in persistently infected and lytically infected cell cultures.
- Cell-free translation systems to analyze messenger RNA coding capacity.
- Polyadenylation analysis of viral messenger RNAs.
- Immunological analysis of viral proteins.
Main Results:
- H, N, and possibly F proteins were synthesized in both lytic and persistent infections.
- M protein synthesis was detected only in lytic infections, but its corresponding messenger RNA was present in both.
- Cell-free translation of messenger RNA from both infection types produced all structural polypeptides, including M, and three non-structural polypeptides.
- Viral messenger RNAs were polyadenylated, and haemagglutinin-related polypeptides showed structural changes after persistent infection.
Conclusions:
- Persistent measles virus infection alters viral protein synthesis, but messenger RNA remains capable of directing the synthesis of all viral proteins.
- Structural changes in viral proteins, particularly haemagglutinin, may occur during persistent infections and contribute to SSPE pathogenesis.