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Matrix protein of cell-associated subacute sclerosing panencephalitis viruses
1Department of Measles Virus, National Institute of Health Gakuen, Tokyo, Japan.
Abstract:
The nucleotide sequence has been determined for the matrix (M) protein gene of three strains, Niigata-1, ZH and Biken, of cell-associated subacute sclerosing panencephalitis (SSPE) virus. The M proteins of the Niigata-1 and ZH strains were found to terminate prematurely as a result of nonsense mutations at nucleotide positions 68 and 96 respectively. On the other hand it was predicted that the Biken strain would express M protein with 22 amino acid differences and eight additional amino acids at its C terminus in comparison to the M protein of the Edmonston strain of measles virus. Radiolabelling of cells carrying the Biken strain showed the production of an M protein with considerably altered immunoreactivity and a marked reduction in intracellular stability. Either premature termination or rapid degradation of the M protein may underlie the defectiveness of these three strains of SSPE virus.
Insights
The matrix (M) protein gene of three subacute sclerosing panencephalitis (SSPE) virus strains was sequenced. Two strains showed premature M protein termination, while the third exhibited altered M protein characteristics, potentially explaining SSPE virus defectiveness.
Area of Science:
- Virology
- Molecular Biology
- Genetics
Background:
- Subacute sclerosing panencephalitis (SSPE) is a rare, chronic, and fatal neurological complication of measles virus infection.
- Cell-associated SSPE viruses are characterized by defective replication, but the underlying genetic defects remain incompletely understood.
Purpose of the Study:
- To determine the nucleotide sequence of the matrix (M) protein gene in three distinct strains of cell-associated SSPE virus.
- To investigate potential molecular mechanisms contributing to the defectiveness of these SSPE virus strains.
Main Methods:
- Nucleotide sequencing of the M protein gene from Niigata-1, ZH, and Biken SSPE virus strains.
- Bioinformatic analysis to compare M protein sequences with measles virus.
- Radiolabelling and analysis of M protein expression and stability in infected cells.
Main Results:
- The Niigata-1 and ZH SSPE virus strains possess nonsense mutations in the M gene, leading to premature M protein termination.
- The Biken SSPE virus strain is predicted to express an M protein with significant amino acid differences and altered C-terminus compared to measles virus.
- Radiolabelling studies revealed that the Biken strain produces M protein with altered immunoreactivity and reduced intracellular stability.
Conclusions:
- Premature termination or rapid degradation of the matrix (M) protein is implicated as a key factor underlying the defectiveness of these three SSPE virus strains.
- Understanding these M gene defects provides insights into the pathogenesis of SSPE and viral persistence.