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Isolation and characterization of temperature-sensitive mutants of measles virus
Abstract:
Nine temperature-sensitive (ts) mutants of nonattenuated Edmonston strain measles virus were isolated from wild-type virus which was grown in the presence of 5-fluorouracil. Adsorption, temperature shift, and complementation experiments indicated that all these mutants were restricted at an intracellular stage of infection. However, all the mutants were more rapidly inactivated at 41 C than was wild-type virus, suggesting that the ts product of each mutant either influences or is a structural component of the virus. Three complementation groups were found to be represented among the mutants. Group A contained one mutant and it did not induce synthesis of detectable amounts of viral antigen at the nonpermissive temperature (39 C). Group B consisted of six mutants which did not induce viral antigen synthesis at 39 C and one mutant which did. Group C was represented by one mutant and it induced viral antigen synthesis at 39 C. The two mutants which induced sythesis of viral antigen also induced synthesis of relatively small amounts of virus-specific RNA at 39 C. These mutants, while producing cytoplasmic and nuclear accumulations of viral antigen at 39 C, were restricted in production of syncytia and hemadsorption. All the mutants were less neurovirulent than wild-type virus, as indicated by their inability to produce acute disease in newborn hamsters.
Insights
Researchers isolated nine temperature-sensitive (ts) measles virus mutants, finding they are restricted intracellularly and less neurovirulent. These mutants offer insights into measles virus replication and structure.
Area of Science:
- Virology
- Molecular Biology
Background:
- Measles virus is a significant human pathogen.
- Understanding measles virus replication is crucial for developing effective interventions.
Purpose of the Study:
- To characterize temperature-sensitive (ts) mutants of the Edmonston strain of measles virus.
- To investigate the role of specific viral gene products in measles virus replication and pathogenesis.
Main Methods:
- Isolation of ts mutants using 5-fluorouracil mutagenesis.
- Adsorption, temperature shift, and complementation assays.
- Analysis of viral antigen and RNA synthesis at permissive and nonpermissive temperatures.
- Assessment of neurovirulence in newborn hamsters.
Main Results:
- Nine ts measles virus mutants were isolated, all restricted at an intracellular stage.
- Mutants showed increased inactivation at 41°C, suggesting ts products are structural or influence virus structure.
- Three complementation groups were identified, correlating with viral antigen and RNA synthesis.
- Mutants exhibited reduced syncytia and hemadsorption, and significantly lower neurovirulence in hamsters.
Conclusions:
- The ts mutants provide valuable tools for studying measles virus gene function.
- The ts lesions likely affect essential viral proteins involved in replication and assembly.
- These mutants demonstrate a reduced capacity to cause disease, highlighting potential for attenuated vaccine development.