Bovine papillomavirus contains multiple transforming genes

Area of Science:

• Virology
• Molecular Biology
• Oncology

Background:

• Bovine papillomavirus type 1 (BPV-1) DNA transforms rodent cells in vitro.
• BPV-1 DNA exists as extrachromosomal plasmids in transformed cells.
• Previous studies identified five viral RNAs with a shared 3' terminus in BPV-1 transformed cells.

Purpose of the Study:

• To define the structure of BPV-1 RNAs.
• To characterize the functions of individual viral transcripts.
• To identify viral genes responsible for cell transformation.

Main Methods:

• Constructed a cDNA library from BPV-1 transformed mouse C127 cells using an Okayama and Berg plasmid.
• Isolated and sequenced 200 BPV-1 specific cDNA clones.
• Analyzed differential splicing patterns and open reading frames (ORFs).
• Utilized a vector with mammalian transcriptional regulatory elements for functional characterization.

Main Results:

• Identified differential splicing patterns in BPV-1 mRNA.
• Deduced the structure of potential viral proteins from ORFs.
• Discovered two distinct classes of cDNA clones capable of transforming mouse C127 cells.
• One class contained the E2 ORF, the other contained the E6 ORF.

Conclusions:

• BPV-1 E2 and E6 ORFs are crucial for cell transformation.
• The E2 and E6 viral functions act synergistically in vitro transformation.
• This study elucidates the molecular mechanisms of BPV-1 induced cell transformation.