PAPOVAVIRIDAE PETER H. RUSSELL, BVSc, PhD, FRCPath, MRCVS Department of Pathology and Infectious Diseases, The Royal Veterinary College, Royal College Street, London NW1 OTU. Web siteWeb site

LEARNING OBJECTIVES Students should be able to: Understand the different ways in which these viruses cause transformation of epithelial cells; Appreciate that while most viruses are species specific there is evidence that bovine virus 2 may have a role in equine sarcoids; In cattle different viruses are associated with specific sites e.g teat or alimentary tract; but even more importantly some can become malignant by the interaction of other co-factors.e.g. bracken, sunlight; There is promising experimental evidence that vaccination using gene products will be successful.

This heterogeneous family of icosahedral double stranded DNA viruses [45-55nm, 72 capsomeres] originally included papillomaviruses, polyomaviruses and vacuolating agents. Only the papilloma viruses are of veterinary importance. The DNA is unusual in that it has a circular configuration and, lying independant of chromosone DNA, is described as episomal.

General properties

Transformation There are several ways by which papillomaviruses transform epithtelial cells, but they all are initiated via the early genes E5, E6, or E7.[1].1

EQUINE PAPILLOMAVIRUSES

EQUINE SARCOIDS

BOVINE PAPILLOMAVIRUSES

(cont.)

BOVINE PAPILLOMAVIRUSES (cont.)

CANINE PAPILLOMAVIRUS

RABBIT PAPILLOMAVIRUS

Further reading 1. Campo MS [1992] Cell transformation by animal papillomaviruses. J gen Virol Hayward MLR [1993].Filiform viral squamous papillomas in sheep. Vet.Rec Campo MS et al [1993] Prohylactic and therapeutic vaccination against a mucosal papillomavirus J gen Virol