Bovine papillomavirus

Bovine papillomavirus
Bovine papillomavirus type 1 (3D reconstruction)
Virus classification
Group:	Group I (dsDNA)
Order:	Unranked
Family:	Papillomaviridae
Genus:	Deltapapillomavirus Epsilonpapillomavirus Xipapillomavirus
Species:	BPV-1 BPV-2 BPV-3 BPV-4 BPV-5 BPV-6

Bovine papillomavirus (BPV) is a group of DNA viruses of the family Papillomaviridae that are common in cattle. Infection causes warts (papillomas and fibropapillomas) of the skin and alimentary tract, and more rarely cancers of the alimentary tract and urinary bladder. They are also thought to cause the skin tumour equine sarcoid in horses and donkeys.

Like other papillomaviruses, BPVs are small non-enveloped viruses with an icosahedral capsid around 50–60 nm in diameter. The capsid is formed of the L1 and L2 structural proteins, with the L1 C-terminus exposed.

All BPVs have a circular double-stranded DNA genome of 7.3–8.0 kb. The genetic organisation of those BPVs which have been sequenced is broadly similar to other papillomaviruses. The open reading frames (ORFs) are all located on one strand, and are divided into early and late regions. The early region encodes nonstructural proteins E1 to E7. There are three viral oncoproteins, E5, E6 and E7; BPVs of the Xipapillomavirus group lack E6. The late region encodes structural proteins L1 and L2. There is also a non-coding long control region (LCR).

Six types of BPV have been characterised, BPV-1 to BPV-6, which are divided into three broad subgroups.

A further thirteen putative BPVs have recently been identified; the novel viruses have yet to be assigned to subgroups.

BPV is highly prevalent, with around 50% of cattle being estimated to bear lesions in the UK. Cutaneous warts are most common in younger animals (under 2 years) and usually spontaneously regress due to the animal's immune response without significant scarring. The duration of infection is very variable (from one month to over a year) and recurrence is possible.

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