Canis Familiaris Papillomavirus Type 26: A Novel Papillomavirus of Dogs and the First Canine Papillomavirus within the Omegapapillomavirus Genus.

Domestic dogs are currently recognized as being infected by 25 different canine papillomavirus (CPV) types classified into three genera. A short sequence from a novel CPV type was amplified, along with CPV1, from a papilloma (wart) from the mouth of a dog. The entire 7499 bp genome was amplified, and CPV26 contained putative coding regions that were predicted to produce four early proteins and two late ones. The ORF L1 showed less than 62% similarity for all previously sequenced CPV types but over 69% similarity to multiple Omegapapillomavirus types from a variety of Caniform species including the giant panda, Weddel seal, and polar bear. Phylogenetic analysis confirmed CPV26 clusters within the Omegapapillomavirus genus. Specific primers were used to investigate the presence of CPV26 DNA within a series of 37 canine proliferative lesions. CPV26 DNA was amplified from one lesion, a cutaneous papilloma that also contained CPV6. This is the first time a PV type within the Omegapapillomavirus genus has been detected in a non-domestic species and this provides evidence that the omegapapillomaviruses infected a common ancestor of, and then co-evolved with, the Caniform species. Whether CPV26 causes disease is uncertain, but the absence of an E7 protein may suggest low pathogenicity.

Heterochromatin protein 1 expression is reduced in human thyroid malignancy.

Owing to the loss of heterochromatin integrity that occurs during thyroid tumorigenesis, the expression of Heterochromatin Protein 1 isoforms HP1α and HP1ß was assessed by immunohistochemistry in 189 thyroid tumors and non-neoplastic tissues. Expression of HP1ß was significantly decreased in all thyroid lesions, except in follicular adenomas, when compared with matched adjacent normal tissue. This loss of HP1ß expression may in part be caused by microRNA dysregulation. An example is miR-205, a microRNA that is abundantly upregulated in thyroid carcinomas and shown to reduce the expression of HP1ß. In contrast to HP1ß, HP1α expression was only reduced in metastatic carcinomas and poorly differentiated lesions. These results suggest the reduction of HP1ß followed by a decrease in HP1α contributes to the pathogenesis of thyroid carcinomas, and their loss is a potential marker of thyroid malignancy and metastatic potential, respectively.