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Enteric adenovirus type 40: complementation of the E4 defect in Ad2 dl808
Virology
|July 1, 1991
Summary
Enteric adenovirus type 40 (Ad40) shows impaired E4 gene function, as it complements an adenovirus type 2 (Ad2) E4 deletion mutant but is not reciprocally complemented. This suggests Ad40 produces functional E4 proteins essential for viral replication.
Area of Science:
- Virology
- Molecular Biology
- Cellular Biology
Background:
- Enteric adenovirus type 40 (Ad40) exhibits limited replication in standard cell lines like HeLa.
- Productive Ad40 replication requires expression of the E1B region from other adenovirus types (e.g., Ad2, Ad5).
- Ad40 infection in permissive cells shows a prolonged lytic cycle and impaired host cell shutoff, suggesting defects in viral gene functions.
Purpose of the Study:
- To investigate potential impairments in the E4 gene functions of enteric adenovirus type 40 (Ad40).
- To determine if Ad40 possesses functional E4 proteins analogous to those in Ad2, specifically ORF 6 and ORF 3.
- To assess the role of Ad40 E4 proteins in viral replication and host cell interaction.
Main Methods:
- Complementation assays were performed between Ad40 and an E4 deletion mutant of adenovirus type 2 (Ad2 dl808).
- Replication and viral protein synthesis were measured in HeLa and Vero cells to assess complementation efficiency.
- Virion-packaged DNA levels and virus titration were used as key indicators of viral replication.
Main Results:
- Ad40 successfully complemented the Ad2 dl808 E4 deletion mutant in HeLa and Vero cells, restoring viral replication to levels comparable to wild-type Ad2 infection.
- Surprisingly, Ad2 dl808 failed to reciprocally complement Ad40, indicating a potential functional difference or requirement.
- The results demonstrate that Ad40 produces functional E4 ORF 6 and/or ORF 3 activity, and these functions are expressed prior to viral DNA replication.
Conclusions:
- Enteric adenovirus type 40 (Ad40) possesses functional E4 gene products (ORF 6 and/or ORF 3) necessary for efficient viral replication.
- The inability of Ad2 dl808 to complement Ad40 suggests unique aspects of Ad40's E4 gene function or its interaction with the viral replication machinery.
- These findings contribute to understanding the complex mechanisms of adenovirus replication and host-pathogen interactions.