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Rotavirus temperature-sensitive mutants are genetically stable and participate in reassortment during mixed infection
1Division of Molecular Virology, Baylor College of Medicine, Houston, Texas 77030.
Abstract:
Mixed and single infections of 7-day-old suckling mice with SA11 temperature-sensitive (ts) mutants and RRV wild-type were examined to determine if selection against ts mutations occurred in the suckling mouse model. Single infections with ts mutants indicated that mutant replication was restricted relative to wild-type and that disease was similarly reduced. Revertant (ts+) progeny did not appear to be selected during infection. Mixed infection with ts mutant and RRV wild-type revealed a reduction in the replication of RRV suggesting that the ts mutants displayed an interference phenotype in vivo similar to that observed in vitro. However, reduced replication of the RRV parent in mixed infection did not result in a significant reduction in disease relative to RRV infection. When progeny from the mixed infections were isolated at the permissive temperature both ts and ts+ progeny were observed, and the genome segments of these progeny segregated in a manner consistent with the temperature phenotype of each progeny clone and the location of the ts mutation determined in vitro. Selection of ts+ progeny from mixed infected mice at nonpermissive temperature yielded either the RRV parent or ts+ reassortants. The segregation of genome segments in these ts+ reassortant progeny was consistent with the location of the ts lesion determined previously in vitro. These results indicate the following with respect to infection of suckling mice with ts mutants: (1) ts lesions are genetically stable and are not selected against during in vivo infection, (2) ts mutants cause disease with reduced severity, (3) ts mutants interfere with the replication of wild-type virus in vivo but not with the severity of disease, and (4) mixed infection of suckling mice may be useful in genetic studies with rotaviruses not adapted to growth in cultured cells.
Insights
Temperature-sensitive (ts) rotavirus mutants are genetically stable in suckling mice, causing less severe disease and interfering with wild-type virus replication without affecting disease severity.
Area of Science:
- Virology
- Animal Models
- Molecular Biology
Background:
- Rotaviruses are a leading cause of severe diarrheal disease in infants.
- Temperature-sensitive (ts) mutants are valuable tools for studying viral genetics.
- The suckling mouse model is commonly used to study rotavirus pathogenesis.
Purpose of the Study:
- To investigate the genetic stability of rotavirus ts mutants in suckling mice.
- To assess the in vivo replication and disease potential of ts mutants.
- To determine if ts mutants interfere with wild-type rotavirus replication in vivo.
Main Methods:
- Infection of 7-day-old suckling mice with SA11 ts mutants and RRV wild-type rotaviruses, both singly and in mixed infections.
- Analysis of viral replication and disease severity in infected mice.
- Isolation and genetic characterization of progeny viruses from mixed infections at permissive and non-permissive temperatures.
Main Results:
- Ts mutants replicated less efficiently and caused reduced disease severity compared to wild-type rotavirus.
- No selection against ts mutations was observed in vivo; revertant (ts+) progeny did not appear.
- Mixed infections demonstrated that ts mutants interfere with wild-type RRV replication in vivo, similar to in vitro observations, but did not significantly alter disease severity.
Conclusions:
- Rotavirus ts lesions are genetically stable in the suckling mouse model.
- Ts mutants exhibit an interference phenotype in vivo, impacting wild-type replication but not disease severity.
- Mixed infections with ts mutants offer a potential genetic tool for studying rotaviruses not adapted to cell culture.