Viruses Genomes - COTTONTAIL RABBIT PAPILLOMAVIRUS

During the 1930's studies of the Cottontail rabbit papillomavirus provided the first animal model of a mammalian cancer caused by a virus. The discovery was by Richard Shope in 1933.

The Shope papillomavirus or Cottontail rabbit papillomavirus (CRPV) induces cutaneous papillomas (warts) in cottontail rabbits under natural conditions and in domestic rabbits under experimental conditions. Systemic regression of warts occurs in a variable proportion of rabbits as a consequence of a specific cell-mediated immune response. Persistent warts may progress into invasive carcinomas Progression into carcinomas is observed in approximately 25% of cottontail rabbits and in up to 75% of domestic rabbits with persistent warts.

CRPV has properties identical to the Papovirus family. Initially it was thought harmless however later it was discovered that its presence can lead to the development of malignant tumours. Ticks, mosquitoes and other insects seem to be involved in transmission demonstrated by the fact that papilloma occurs only on naked (fur free) parts of the rabbit. The tumours are generally devoid of the infectious virus however transmission occurs between rabbits.

CRPV infects and transforms the follicle cells leading to red swollen skin which can develop into horny warts. Left untreated 25% will become malignant. Metestases are prone to develop in the lungs and lymph nodes and in advanced stages in the liver and kidneys.

The only small-animal model of papillomavirus infection with long-term persistence and malignant progression of lesions is CRPV, therefore research and comparative studies into a possible vaccine against the human papillomavirus are underway. Results so far show that E6 gene vaccination protected rabbits against papilloma formation, suppressed papilloma growth, and stimulated papilloma regression to differing degrees depending on the vaccination strategy.

CRPV is responsible for the ancient belief that rabbits or hares could grow horns (Lepus cornutus in Latin) referenced in Tableau Encyclopedique et Methodique, 1789 and painted by Joris Hoefnagel in the late 1570's. Left untreated CRPV warts can grow into long horny shapes around the ears and chin.

References:
http://www.ratsteachmicro.com/2003_HCOE_PDFs/Papovavirus_Lecture_Outline__2005rev.pdf http://jvi.asm.org/cgi/content/full/74/22/10766 http://bilbo.bio.purdue.edu/~baker/projects/papova/crpv/crpv.html
http://ww2.lafayette.edu/~hollidac/jacksforreal.html