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Transforming genes among three different oncogenic subgroups of human adenoviruses have similar replicative functions
Abstract:
We have examined the functional similarity of the transforming genes for replicative functions among three different subgroups of human adenoviruses (A, B, and C), using mutant complementation as an assay. A host range deletion mutant (dl201.2) of Ad2 (nononcogenic subgroup C) lacking about 5% of the viral DNA covering two early gene blocks (E1a and E1b) involved in cellular transformation was isolated and tested for its ability to replicate in nonpermissive KB cells in the presence of Ad7 (weakly oncogenic group B) or ad12 (highly oncogenic group A). The complementation of the mutant defect was demonstrated by cleaving the viral DNA extracted from mixed infected cells or the DNA extracted from purified virions from mixed infected cells with restriction endonuclease BamHI, which produces a different cleavage pattern with the DNA of each serotype. It was found that the defects in E1a plus E1b of dl201.2 could be complemented by Ad7 and Ad12, indicating that these genes in Ad2, Ad7, and Ad12 have similar functions during productive infection.
Insights
Human adenoviruses from subgroups A, B, and C share similar transforming genes essential for replication. Mutant complementation assays confirmed functional conservation of early gene blocks (E1a and E1b) across these adenovirus subgroups.
Area of Science:
- Virology
- Molecular Biology
- Genetics
Background:
- Human adenoviruses are classified into subgroups A, B, and C.
- Early gene regions E1a and E1b are critical for viral replication and cellular transformation.
- Functional differences in these genes can impact oncogenicity and host range.
Purpose of the Study:
- To investigate the functional similarity of transforming genes in human adenoviruses (subgroups A, B, and C).
- To determine if early gene blocks E1a and E1b are functionally conserved across different adenovirus subgroups for replicative functions.
Main Methods:
- Utilized mutant complementation assays to assess gene function.
- Isolated a host range deletion mutant (dl201.2) of adenovirus type 2 (Ad2) lacking E1a and E1b gene blocks.
- Performed mixed infections with Ad2 mutant and other adenovirus serotypes (Ad7, Ad12).
- Analyzed viral DNA using restriction endonuclease BamHI to confirm complementation.
Main Results:
- The E1a and E1b gene defects in the Ad2 mutant (dl201.2) were successfully complemented by adenovirus type 7 (Ad7) and adenovirus type 12 (Ad12).
- BamHI restriction enzyme digestion patterns confirmed the presence of DNA from both infecting viruses in mixed infections.
- Complementation indicates that the E1a and E1b genes of Ad2, Ad7, and Ad12 share similar functions in productive viral infection.
Conclusions:
- The early transforming genes (E1a and E1b) of human adenoviruses exhibit functional similarity across subgroups C, B, and A.
- These conserved gene functions are crucial for the replicative cycle of adenoviruses.
- Findings support the hypothesis of conserved molecular mechanisms underlying adenovirus replication and transformation.