Abstract
Papillomaviruses are epitheliotropic, nonenveloped, circular, double-stranded DNA viruses within the family Papillomaviridae that are associated with benign and malignant tumors in humans and animals. We report the complete genome sequence of canine papillomavirus type 10 identified from a pigmented plaque located on the head of a mixed-breed bloodhound.
GENOME ANNOUNCEMENT
Papillomaviruses (PVs) are epitheliotropic, nonenveloped, circular, double-stranded DNA viruses within the family Papillomaviridae that have been identified in many mammals and birds (1). They are most often associated with benign mucosal and cutaneous epithelial proliferations; however, certain PVs are associated with cancer. In humans, the low-risk human papillomaviruses (HPVs) are associated with benign mucosal and cutaneous tumors, whereas the high-risk HPVs are causally associated with certain anogenital cancers. Identification of the etiologic HPV within these cancers has led to the development of a vaccine to prevent cervical cancer in naïve patients (11).
Animal models of PV infection have been critical in elucidating many aspects of the PV life cycle, evolution, and pathogenesis. The canine model is an excellent system to study both cutaneous and mucosal PV infections. Studies on canine oral papillomavirus (CPV-1) were critical in elucidating the host immune response to PV infections (3, 5), HPV vaccine development (6, 8), and viral oncogenesis (2, 4, 7, 9). To date, the genome of nine CPVs has been fully sequenced (10). Several of these CPVs are associated with infection in immunocompromised dogs and even with development of metastatic squamous cell carcinoma (4).
This report describes the complete viral genome of a novel canine papillomavirus type, designated canine papillomavirus type 10 (CPV-10), identified from a pigmented plaque on the head of a mixed-breed bloodhound. Total viral DNA was isolated from this biopsy specimen by routine methods. PCR using degenerate consensus primers for the L1 gene was first used to amplify potential PV genome fragments. Sequencing results from this initial screen yielded a putatively novel PV DNA sequence. To further characterize this PV, the complete viral genome was generated using rolling circle amplification. The genome was then cloned into a pUC19 vector, and primer walking enabled sequencing of the entire viral genome from both directions. Analysis of the viral sequence was performed using ABI 3730xl DNA-analyzing instruments for capillary electrophoresis and fluorescent dye terminator detection. Vector NTI Advance 10 software (Invitrogen) was used to assemble the sequence contigs containing high-quality trace files. The results of the sequencing confirmed the presence of a novel CPV.
The complete viral genome for CPV-10 is 7,774 bp, and CPV-10 contains all of its open reading frames (ORFs) on the same coding strand of its circular, double-stranded genome. CPV-10 has seven ORFs, including the five early genes E1, E2, E4, E6, and E7 and the two late genes L1 and L2. The L1 gene is the most conserved gene within the genome and has been used for the identification and classification of new PVs. A new PV is recognized if the DNA sequence of the L1 ORF differs by more than 10% from all known PV types (1). CPV-10 is most closely related (73% homology) to CPV-8. This report will facilitate future investigations into the molecular pathogenesis of CPV infections.
Nucleotide sequence accession number.
The complete genome sequence of canine papillomavirus type 10 (CPV-10) is available in GenBank under accession no. NC_016075.1.
ACKNOWLEDGMENTS
This project was supported by the National Center for Research Resources and the Office of Research Infrastructure Programs (ORIP) of the National Institutes of Health through grants 1R01RR032315-01 (Georgetown University) and T32 RR07038 and the Center for Companion Animal Health, University of California, Davis, through grant CCAH2007-44-R.
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