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Identification and characterization of a double-stranded RNA- reovirus temperature-sensitive mutant defective in
1Department of Medical Microbiology and Infectious Diseases, University of Manitoba, Winnipeg, Manitoba, Canada. coombs@bldghsc.lanl.umanitoba.ca
Abstract:
A newly identified temperature-sensitive mutant whose defect was mapped to the reovirus M1 gene (minor core protein mu2) was studied to better understand the functions of this virion protein. Sequence determination of the Ml gene of this mutant (tsH11.2) revealed a predicted methionine-to-threonine alteration at amino acid 399 and a change from proline to histidine at amino acid 414. The mutant made normal amounts of single-stranded RNA, both in in vitro transcriptase assays and in infected cells, and normal amounts of progeny viral protein at early times in a restrictive infection. However, tsH11.2 produced neither detectable progeny protein nor double-stranded RNA at late times in a restrictive infection. These studies indicate that mu2 plays a role in the conversion of reovirus mRNA to progeny double-stranded RNA.
Insights
Reovirus M1 gene protein mu2 is essential for converting viral mRNA to double-stranded RNA. A temperature-sensitive mutant (tsH11.2) showed this protein
Area of Science:
- Virology
- Molecular Biology
- Genetics
Background:
- Reoviruses are double-stranded RNA viruses.
- Viral gene products are crucial for viral replication.
- The reovirus M1 gene encodes the minor core protein mu2.
Purpose of the Study:
- To investigate the function of the reovirus M1 gene product, mu2.
- To characterize a temperature-sensitive mutant affecting mu2 function.
Main Methods:
- Isolation and characterization of a temperature-sensitive reovirus mutant (tsH11.2).
- Sequence analysis of the M1 gene in the mutant.
- Analysis of viral RNA and protein synthesis in infected cells at restrictive temperatures.
Main Results:
- The tsH11.2 mutant has mutations in the M1 gene predicting amino acid changes in mu2.
- At restrictive temperatures, the mutant synthesizes normal amounts of single-stranded RNA and early viral proteins.
- The mutant fails to produce progeny double-stranded RNA and late viral proteins at restrictive temperatures.
Conclusions:
- The reovirus mu2 protein plays a critical role in the conversion of viral single-stranded mRNA to double-stranded RNA genomes.
- This function of mu2 is essential for the late stages of reovirus replication.