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Measles virus persistent infection: modification of the virus nucleocapsid protein
Abstract:
The synthesis of intracellular measles virus proteins in persistently infected human cell cultures was studied. The virus-induced proteins were analysed after radioimmunoprecipitation by one- and two-dimensional polyacrylamide gel electrophoresis. The measles virus-induced nucleoprotein (NP) synthesized in persistently infected cells had a reduced binding capacity with measles virus antibodies (human convalescent serum) compared to the NP protein induced by the virus used to initiate the infection. In contrast, monospecific rabbit serum prepared against the original virus NP, or monoclonal anti-NP antibodies, precipitated NP proteins from acutely and persistently infected cells with equal efficiency. When the NP in acutely or persistently infected cells was labelled with either 14C- or 3H-amino acids and subjected to two-dimensional gel analysis, significant charge differences were observed between the virus proteins. When measles virus-infected cells were examined for virus protein synthesis at 40 degrees C, although no change was found in acutely infected cells, NP was not detected in the persistent infection.
Insights
Measles virus nucleoprotein (NP) in persistent infections shows altered antibody binding and charge differences. This viral protein was undetectable at 40°C in persistently infected cells, unlike in acute infections.
Area of Science:
- Virology
- Immunology
- Cell Biology
Background:
- Persistent measles virus infections can alter viral protein synthesis and antigenicity.
- Understanding these changes is crucial for diagnosing and managing chronic viral infections.
Purpose of the Study:
- To investigate the synthesis and characteristics of intracellular measles virus proteins in persistently infected human cell cultures.
- To compare measles virus nucleoprotein (NP) from acute and persistent infections.
Main Methods:
- Radioimmunoprecipitation followed by one- and two-dimensional polyacrylamide gel electrophoresis.
- Analysis of NP protein binding with human convalescent serum, rabbit antiserum, and monoclonal antibodies.
- Metabolic labeling with 14C- or 3H-amino acids and 2D gel electrophoresis to detect charge differences.
- Assessment of viral protein synthesis at elevated temperatures (40°C).
Main Results:
- Measles virus nucleoprotein (NP) from persistently infected cells exhibited reduced binding to human convalescent serum compared to NP from acutely infected cells.
- Monospecific rabbit anti-NP serum and monoclonal anti-NP antibodies precipitated NP from both acute and persistent infections equally.
- Two-dimensional gel analysis revealed significant charge differences in NP proteins synthesized during acute versus persistent measles virus infections.
- Measles virus NP was not detected in persistently infected cells incubated at 40°C, whereas it remained detectable in acutely infected cells.
Conclusions:
- Persistent measles virus infection induces alterations in nucleoprotein (NP) antigenicity and charge.
- These modifications may affect antibody recognition and diagnostic assays.
- The absence of NP at 40°C in persistent infections suggests temperature-sensitive defects in viral protein synthesis or stability.