Cloning and characterization of an equine cutaneous papillomavirus.

This research article discusses the isolation, cloning, and characterisation of equine papillomaviruses (EqPV), a type of virus causing skin lesions in horses and ponies. The study also investigates to what extent EqPV shares genetic similarities with other related viruses and how it differs depending on the anatomic site of the papillomas.

Isolation and Cloning

• The researchers isolated EqPV from cases of cutaneous papillomatosis in several ponies and a horse.
• With the aid of the peroxidase-antiperoxidase technique, they were able to detect Group specific papillomavirus structural antigens in sections of the papillomas, a type of benign growth on the skin caused by the virus.
• Virions, the mature virus particles, were identified in the cell nuclei of the stratum granulosum and corneum, layers of the skin.
• These virions, purified from papilloma homogenates and measured at 55 nm in diameter, presented typical papillomavirus morphology, indicating the presence of EqPV.
• Genomes of two distinct isolates of the virus were cloned into pBR322, a kind of plasmid, providing more resources for studying the virus.

Characterization and Analysis

• The researchers generated a detailed restriction map of the viral genome. A restriction map helps in understanding the layout of different genes on a particular DNA molecule.
• Using subgenomic fragments of BPV-1, a bovine papillomavirus, as probes for Southern blot hybridizations, allowed for the organization of the EqPV genome to be established.
• Southern blot analysis allowed researchers to detect specific DNA sequences in DNA samples. The study revealed that EqPV shares more homology with the late region of the BPV-1 genome and the E2 region of the HPV-1 genome compared to other parts of the same viral DNAs, meaning they have common ancestors or similar evolutionary path.

Other Findings

• Utilizing EqPV DNA as a probe, researchers identified papillomavirus-specific sequences in papillomas from other anatomic sites.
• This newfound knowledge suggests that the genomes found in DNA from penile papillomas, a specific location of growth, have a distinct restriction pattern and only hybridized to the EqPV probe under nonstringent conditions.
• The findings suggest the potential for EqPVs to manifest differently or have different genetic structure depending on the location of the growth.