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Transient replication of human papillomavirus DNAs
A M Del Vecchio1, H Romanczuk, P M Howley
1Laboratory of Tumor Virus Biology, National Cancer Institute, Bethesda, Maryland 20892.
Journal of Virology
|October 1, 1992
Summary
Human papillomaviruses (HPVs) DNA replication is poorly understood. This study shows HPV-11 and HPV-18 DNA replicate transiently in cell lines, identifying key viral replication elements E1 and E2.
Area of Science:
- Virology
- Molecular Biology
- Oncogenesis
Background:
- Human papillomaviruses (HPVs) DNA replication mechanisms remain largely uncharacterized.
- Previous studies relied on bovine papillomavirus type 1 (BPV-1), limiting understanding of HPV replication.
- A robust cell culture system for stable HPV DNA replication has been lacking.
Purpose of the Study:
- To establish a transient replication system for human papillomavirus (HPV) DNA.
- To identify viral cis-acting elements (origins of replication) and trans-acting factors (E1, E2 proteins) essential for HPV DNA replication.
- To investigate the replication capabilities of different HPV types, including HPV-16, HPV-11, and HPV-18.
Main Methods:
- Transfection of full-length genomic DNAs of HPV types 11 and 18 into human squamous cell carcinoma cell lines.
- Localization of viral origins of replication within the viral long control region.
- Cotransfection assays using plasmids expressing HPV E1 and E2 open reading frames (ORFs) from various HPV types.
Main Results:
- HPV-11 and HPV-18 genomic DNAs replicated transiently in tested cell lines, unlike HPV-16.
- Viral origins of replication were mapped to the long control region.
- Shared functions among HPV E1 and E2 proteins and origins were identified, facilitating replication of HPV-11, HPV-16, and HPV-18.
- HPV-16 DNA replication was achieved by expressing its early region genes from a strong promoter, suggesting insufficient endogenous E1/E2 expression limited its replication.
Conclusions:
- A functional transient replication system for HPV DNA in human cell lines was established.
- The study identified essential viral cis (origin) and trans (E1, E2) elements for HPV DNA replication.
- Differences in HPV-16 replication were attributed to insufficient expression of its E1 and E2 genes, highlighting the importance of viral gene expression levels in replication competence.