Viruses Genomes - BOVINE PAPILLOMAVIRUS

The definition of papilloma is a small benign epithelial tumor, such as a wart, consisting of an overgrowth of cells on a core of smooth connective tissue. They are found in a wide variety of vertebrate hosts and are highly species specific. Papillomaviruses are small, non-enveloped icosahedral particles ~52-55nm diameter.

Papillomaviruses have been investigated since the early 1930s when the first Papillomavirus was isolated from rabbits by Richard Shope in 1933. Study of papillomaviruses has been spurred on over the past decade by the development of an in vitro transformation assay as previously these viruses have not been successfully propagated in the laboratory. Bovine papillomavirus has served as a prototype papillomavirus for these studies and has provided the basis for most of our knowledge of papillomavirus molecular biology. More recently, the finding that specific human papillomaviruses are closely associated with certain human malignancies, most notably cervical and anogenital carcinomas, has further focused interest on these viruses.

Papillomavirus is widely distributed in cattle. Cattle are the main source and natural reservoir of infection by the virus but, halters, ropes, and instruments can serve as a potential source of infection. Not all animals carrying the virus will have warts. It can be transmitted from the inapparent carrier to the susceptible calf.

Bovine papillomavirus (BPV) induces papillomas of cutaneous or mucosal epithelia in cattle. The papillomas are benign tumours and generally regress, but occasionally persist and provide the focus for malignant transformation to squamous cell carcinoma, particularly in the presence of environmental cofactors. There are six bovine papillomaviruses associated with cutaneous fibropapillomas in cattle. BPV has also been inplicated in causing papillomas in the bovine upper digestive tract. In cattle infected with that virus and fed with bracken fern (which contains powerful carcinogens), papillomas become malignant and are accompanied by intestinal adenomas and adenocarcinomas.

The equine sarcoid, a locally aggressive, fibroblastic skin tumour, is the most common dermatological neoplasm reported in horses; there is no consistently effective therapy. It is widely accepted that bovine papillomavirus (BPV) types 1 and 2 are associated with the pathogenesis of sarcoid disease.

Commercial vaccines are available and these vaccines that prevent or cure BPV infection provide a model for the formulation of vaccines against human papillomavirus. Analysis of this complete genome sequence in conjunction with known transcriptional data for the virus provides a basis of determining the organization of the papillomavirus genome.

References:

http://bilbo.bio.purdue.edu/~baker/projects/papova/papilloma/bpv.html
http://www.positifs.org/c/c-54.htm
http://arjournals.annualreviews.org/doi/pdf/10.1146/annurev.ge.22.120188.001315
http://www.ces.purdue.edu/extmedia/VY/VY-58.html
http://www.medvet.umontreal.ca/pathologie_microbiologie/beluga/ehp_mars_02_c.htm
http://vir.sgmjournals.org/cgi/content/full/84/5/1055