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Orlandi M, Mazzei M, Albanese F, Pazzini L, Mei M, Lazzarini G, Forzan M, Massaro M, Vascellari M, Abramo F. Clinical, histopathological, and molecular characterization of canine pigmented viral plaques. Vet Pathol 2023; 60:857-864. [PMID: 37644783 DOI: 10.1177/03009858231195762] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/31/2023]
Abstract
Canine pigmented viral plaques (PVPs) are proliferative epidermal lesions caused by canine papillomaviruses (CPVs). Although the lesions are benign, neoplastic transformation has been reported. Cases reported in the literature are few and mainly focused on genome sequencing. The aim of this study was to collect data on the epidemiology, clinicopathological features, and genotyping of PVPs. Fifty-five canine PVPs were retrospectively retrieved and histologically evaluated. Follow-up was available for 33 cases. The median age was 6.5 years and pugs were the most represented breed (25%). There were 4 clinical presentations: a single lesion (24%), multiple lesions (75%) in one (41%) or different sites (34%), and generalized lesions all over the body (24%). The abdomen and axillae were the most common sites. In single lesions, no recurrence was observed after conventional surgery, whereas different medical treatments reported for multiple lesions were not successful. Spontaneous regression was reported in 3 cases. Neoplasia in contiguity with PVPs was seen in 5 of 55 lesions (9%), and 1 dog was euthanized due to invasive squamous cell carcinoma (SCC). The most useful histopathological features for diagnosis were scalloped profile, epidermal spikes, hypergranulosis, and hyperpigmentation. L1 immunolabeling was present in 14 of 16 cases (87%). Sequencing revealed that 10 of 16 cases were associated with CPV-9 (71%), 2 cases were associated with CPV-4 (14%), and 2 cases were associated with CPV-8 (14%). In conclusion, this represents a large cohort study on canine PVPs reporting data on clinicopathological features, therapy, outcome, and the type of CPV involved for the first time in Italy.
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Affiliation(s)
| | - Maurizio Mazzei
- Department of Veterinary Sciences, University of Pisa, Pisa, Italy
| | | | - Luca Pazzini
- Private Veterinary Laboratory "MyLav," Passirana di Rho, Italy
| | - Martina Mei
- Department of Veterinary Sciences, University of Pisa, Pisa, Italy
| | - Giulia Lazzarini
- Department of Veterinary Sciences, University of Pisa, Pisa, Italy
| | - Mario Forzan
- Department of Veterinary Sciences, University of Pisa, Pisa, Italy
| | - Maria Massaro
- Private Veterinary Laboratory "MyLav," Passirana di Rho, Italy
| | - Marta Vascellari
- Istituto Zooprofilattico Sperimentale delle Venezie, Legnaro, Italy
| | - Francesca Abramo
- Department of Veterinary Sciences, University of Pisa, Pisa, Italy
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2
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Munday JS, Knight CG, Luff JA. Papillomaviral skin diseases of humans, dogs, cats and horses: A comparative review. Part 2: Pre-neoplastic and neoplastic diseases. Vet J 2022; 288:105898. [PMID: 36152994 DOI: 10.1016/j.tvjl.2022.105898] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Revised: 09/12/2022] [Accepted: 09/19/2022] [Indexed: 11/20/2022]
Abstract
Papillomaviruses (PVs) are well recognized to cause pre-neoplastic and neoplastic diseases in humans. Similarly, there is increasing evidence that PVs play a significant role in the development of pre-neoplastic and neoplastic diseases of the haired skin of dogs and cats, and the mucosa of horses. As the mechanisms by which PVs cause neoplasia are well studied in humans, it is valuable to compare the PV-induced neoplasms of humans with similar PV-associated neoplasms in the companion animal species. In the second part of this comparative review, the pre-neoplastic and neoplastic diseases thought to be caused by PVs in humans, dogs, cats, and horses are described. This includes PV-induced cutaneous plaques, cutaneous squamous cell carcinomas (SCCs) and mucosal SCCs within the four species. The review concludes with a discussion about the potential use of vaccines to prevent PV-induced diseases of dogs, cats, and horses.
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Affiliation(s)
- John S Munday
- Pathobiology, School of Veterinary Science, Massey University, Palmerston North, New Zealand.
| | - Cameron G Knight
- Department of Veterinary Clinical and Diagnostic Sciences, Faculty of Veterinary Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Jennifer A Luff
- Department of Population Health and Pathobiology, College of Veterinary Medicine, North Carolina State University, Raleigh, NC, USA
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3
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Reis JDR, Batista MVDA. New insights into Canis familiaris papillomaviruses genetics and biology: Is the genetic characterization of CPV types and their variants an important clinical issue? Genet Mol Biol 2022; 45:e20210388. [PMID: 36095300 PMCID: PMC9469487 DOI: 10.1590/1678-4685-gmb-2021-0388] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Accepted: 06/05/2022] [Indexed: 11/22/2022] Open
Abstract
Canis familiaris papillomavirus (CPV) is a member of the Papillomaviridae family and is found in dogs. After infection, the host can remain asymtomatic or develop benign ephitelial neoplasms such as papillomas and pigmented viral plaques, which can progress to cancer, in the form of squamous cell carcinoma (SCC). In humans, 227 types of human papillomavirus (HPV) have been described, with a well-established risk classification for cancer development. In addition, it is also known that variants of some high-risk HPV types may present different risks in respect of SCC development. In dogs, however, only a few types of CPV have been identified, despite the growing interest in this area, and knowledge on the genetic characterization of CPV variants is still scarce. Recent studies of CPV have shown that, as with HPV, benign neoplasia can develop into cancer, but it is believed that there are many more types and variants still to be described. Therefore, the aim of this study was to describe the genetics and biology of CPV, with the focus on what is known about lesions, geographic localization, virus types and variants.
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Affiliation(s)
- Jordana Dantas Rodrigues Reis
- Universidade Federal de Sergipe, Centro de Ciências Biológicas e da Saúde, Departamento de Biologia, Laboratório de Genética Molecular e Biotecnologia (GMBio), São Cristóvão, SE, Brazil
| | - Marcus Vinicius de Aragão Batista
- Universidade Federal de Sergipe, Centro de Ciências Biológicas e da Saúde, Departamento de Biologia, Laboratório de Genética Molecular e Biotecnologia (GMBio), São Cristóvão, SE, Brazil
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4
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Ayala-Díaz S, Jiménez-Lima R, Ramírez-Alcántara KM, Lizano M, Castro-Muñoz LJ, Reyes-Hernández DO, Arroyo-Ledezma J, Manzo-Merino J. Presence of Papillomavirus DNA sequences in the canine transmissible venereal tumor (CTVT). PeerJ 2019; 7:e7962. [PMID: 31667018 PMCID: PMC6816387 DOI: 10.7717/peerj.7962] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Accepted: 09/30/2019] [Indexed: 01/18/2023] Open
Abstract
Background The canine transmissible venereal tumor (CTVT) or Sticker’s sarcoma is a neoplastic disease affecting dogs. This disease is presented as a tumoral mass in the genital organs of both, male and female individuals. Up to date, there is no clear evidence indicating a viral agent as the causative mediator for CTVT development. Purpose The present work aims to analyze 21 samples from canines with CTVT for molecular identification of Papillomavirus DNA sequences. In addition, microbiological analysis, cytologic and histopathologic evaluations were also performed. Results All patients showed no biochemical and microbiological alterations. Molecular analysis demonstrated the viral DNA presence in the samples using different primer sets. The MY primers amplified a 450 bp band in seven out of 21 samples (33%). The PVF and Fap64 primer set, targeting the L1 sequence of Canine Papillomavirus (CPV), showed positivity in 16 out of 21 samples (76%). Conclusion These results support the possible causative association between CPV and CTVT; nevertheless, additional studies are required to uphold such statement. This work presents evidence indicating that a viral agent might be involved in the pathogenesis of CTVT and set the bases for a better understanding of the CTVT pathobiology.
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Affiliation(s)
- Sergio Ayala-Díaz
- Universidad del Mar, Puerto Escondido, Oaxaca, Mexico.,Programa de Maestría y Doctorado en Producción y Sanidad Animal, Universidad del Mar, Puerto Escondido, Oaxaca, Mexico
| | - Roberto Jiménez-Lima
- Clinical Research Division, Instituto Nacional de Cancerología, Mexico City, Mexico
| | - Katia M Ramírez-Alcántara
- Basic Research Division, Instituto Nacional de Cancerología, Mexico City, Mexico.,Programa de Posgrado en Ciencias Biológicas, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Marcela Lizano
- Basic Research Division, Instituto Nacional de Cancerología, Mexico City, Mexico.,Departamento de Medicina Genómica y Toxicología Ambiental, Instituto de Investigaciones Biomédicas, UNAM, Mexico City, Mexico
| | | | - Diego O Reyes-Hernández
- Basic Research Division, Instituto Nacional de Cancerología, Mexico City, Mexico.,Programa de Posgrado en Ciencias Médicas Odontológicas y de la Salud, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Jaime Arroyo-Ledezma
- Universidad del Mar, Puerto Escondido, Oaxaca, Mexico.,Asociación Esteriliza y Educa A.C., Puerto Escondido, Oaxaca, Mexico
| | - Joaquín Manzo-Merino
- Basic Research Division, Instituto Nacional de Cancerología, Mexico City, Mexico.,Cátedras CONACyT-Instituto Nacional de Cancerología, Mexico City, Mexico
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5
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Regalado Ibarra AM, Legendre L, Munday JS. Malignant Transformation of a Canine Papillomavirus Type 1-Induced Persistent Oral Papilloma in a 3-Year-Old Dog. J Vet Dent 2019; 35:79-95. [PMID: 29865982 DOI: 10.1177/0898756418774575] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
This case report describes a rare case of a persistent canine papillomavirus type 1 (CPV-1)-induced oral papilloma that underwent malignant transformation into an oral squamous cell carcinoma (OSCC) in a 3-year-old Labrador retriever cross. Initially, the patient had multiple and multifocal verrucous lesions populating the oral cavity exclusively. The papillomas persisted despite multiple surgical ablations, azithromycin, interferon α-2b, alternative medicines, and off-label drug use of an immunostimulant. After 1 year and 6 months, an aggressive lesion developed at the level of the left mandibular first molar (309) and progressed to a well-differentiated invasive OSCC. The presence of CPV-1 DNA in the OSCC, and the known oncogenic abilities of CPV-1, suggests that this virus might have played a significant role in the emergence of the OSCC that ultimately led to the patient's euthanasia due to poor quality of life. This is the first well-documented case where OSCC has developed from an oral papilloma caused by CPV-1 in which the presence of coinfection by another papillomavirus was excluded by multiple polymerase chain reaction tests using various primers.
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Affiliation(s)
| | - Loïc Legendre
- 1 West Coast Veterinary Dental Services, Vancouver, British Columbia, Canada
| | - John S Munday
- 2 Veterinary Pathology, Institute of Veterinary, Animal & Biomedical Sciences, Massey University, New Zealand
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6
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Luff J, Mader M, Rowland P, Britton M, Fass J, Yuan H. Viral genome integration of canine papillomavirus 16. PAPILLOMAVIRUS RESEARCH 2019; 7:88-96. [PMID: 30771493 PMCID: PMC6402295 DOI: 10.1016/j.pvr.2019.02.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Revised: 01/30/2019] [Accepted: 02/12/2019] [Indexed: 01/03/2023]
Abstract
Papillomaviruses infect humans and animals, most often causing benign proliferations on skin or mucosal surfaces. Rarely, these infections persist and progress to cancer. In humans, this transformation most often occurs with high-risk papillomaviruses, where viral integration is a critical event in carcinogenesis. The first aim of this study was to sequence the viral genome of canine papillomavirus (CPV) 16 from a pigmented viral plaque that progressed to metastatic squamous cell carcinoma in a dog. The second aim was to characterize multiple viral genomic deletions and translocations as well as host integration sites. The full viral genome was identified using a combination of PCR and high throughput sequencing. CPV16 is most closely related to chipapillomaviruses CPV4, CPV9, and CPV12 and we propose CPV16 be classified as a chipapillomavirus. Assembly of the full viral genome enabled identification of deletion of portions of the E1 and E2/E4 genes and two viral translocations within the squamous cell carcinoma. Genome walking was performed which identified four sites of viral integration into the host genome. This is the first description of integration of a canine papillomavirus into the host genome, raising the possibility that CPV16 may be a potential canine high-risk papillomavirus type.
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Affiliation(s)
- Jennifer Luff
- Department of Population Health and Pathobiology, North Carolina State University, Raleigh, North Carolina, USA.
| | - Michelle Mader
- Department of Population Health and Pathobiology, North Carolina State University, Raleigh, North Carolina, USA
| | | | - Monica Britton
- UC Davis Genome Center-Bioinformatics Core, University of California, Davis, CA, USA
| | - Joseph Fass
- UC Davis Genome Center-Bioinformatics Core, University of California, Davis, CA, USA
| | - Hang Yuan
- Department of Pathology, Georgetown University Medical Center, Washington, DC, USA
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7
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Brimer N, Drews CM, Vande Pol SB. Association of papillomavirus E6 proteins with either MAML1 or E6AP clusters E6 proteins by structure, function, and evolutionary relatedness. PLoS Pathog 2017; 13:e1006781. [PMID: 29281732 PMCID: PMC5760104 DOI: 10.1371/journal.ppat.1006781] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2017] [Revised: 01/09/2018] [Accepted: 11/29/2017] [Indexed: 01/11/2023] Open
Abstract
Papillomavirus E6 proteins bind to LXXLL peptide motifs displayed on targeted cellular proteins. Alpha genus HPV E6 proteins associate with the cellular ubiquitin ligase E6AP (UBE3A), by binding to an LXXLL peptide (ELTLQELLGEE) displayed by E6AP, thereby stimulating E6AP ubiquitin ligase activity. Beta, Gamma, and Delta genera E6 proteins bind a similar LXXLL peptide (WMSDLDDLLGS) on the cellular transcriptional co-activator MAML1 and thereby repress Notch signaling. We expressed 45 different animal and human E6 proteins from diverse papillomavirus genera to ascertain the overall preference of E6 proteins for E6AP or MAML1. E6 proteins from all HPV genera except Alpha preferentially interacted with MAML1 over E6AP. Among animal papillomaviruses, E6 proteins from certain ungulate (SsPV1 from pigs) and cetacean (porpoises and dolphins) hosts functionally resembled Alpha genus HPV by binding and targeting the degradation of E6AP. Beta genus HPV E6 proteins functionally clustered with Delta, Pi, Tau, Gamma, Chi, Mu, Lambda, Iota, Dyokappa, Rho, and Dyolambda E6 proteins to bind and repress MAML1. None of the tested E6 proteins physically and functionally interacted with both MAML1 and E6AP, indicating an evolutionary split. Further, interaction of an E6 protein was insufficient to activate degradation of E6AP, indicating that E6 proteins that target E6AP co-evolved to separately acquire both binding and triggering of ubiquitin ligase activation. E6 proteins with similar biological function clustered together in phylogenetic trees and shared structural features. This suggests that the divergence of E6 proteins from either MAML1 or E6AP binding preference is a major event in papillomavirus evolution.
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Affiliation(s)
- Nicole Brimer
- Department of Pathology, University of Virginia, Charlottesville, Virginia, United States of America
| | - Camille M. Drews
- Department of Pathology, University of Virginia, Charlottesville, Virginia, United States of America
| | - Scott B. Vande Pol
- Department of Pathology, University of Virginia, Charlottesville, Virginia, United States of America
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8
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Munday JS, Thomson NA, Luff JA. Papillomaviruses in dogs and cats. Vet J 2017; 225:23-31. [PMID: 28720294 DOI: 10.1016/j.tvjl.2017.04.018] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Revised: 04/27/2017] [Accepted: 04/30/2017] [Indexed: 12/22/2022]
Abstract
Papillomaviruses (PVs) cause disease in both dogs and cats. In dogs, PVs are thought to cause oral papillomatosis, cutaneous papillomas and canine viral pigmented plaques, whereas PVs have been rarely associated with the development of oral and cutaneous squamous cell carcinomas in this species. In cats, PVs are currently thought to cause oral papillomas, feline viral plaques, Bowenoid in situ carcinomas and feline sarcoids. Furthermore, there is increasing evidence that PVs may also be a cause of cutaneous squamous cell carcinomas and basal cell carcinomas in cats. These diseases are discussed in this review. Additionally, there is a brief overview of PV biology, including how these viruses cause disease. Diagnostic techniques and possible methods to prevent PV infection are also discussed.
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Affiliation(s)
- John S Munday
- Pathobiology, Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Palmerston North, New Zealand.
| | - Neroli A Thomson
- Pathobiology, Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Palmerston North, New Zealand
| | - Jennifer A Luff
- Department of Population Health and Pathobiology, College of Veterinary Medicine, North Carolina State University, Raleigh, NC, USA
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9
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Lange CE, Diallo A, Zewe C, Ferrer L. Novel canine papillomavirus type 18 found in pigmented plaques. PAPILLOMAVIRUS RESEARCH (AMSTERDAM, NETHERLANDS) 2016; 2:159-163. [PMID: 29074175 PMCID: PMC5886900 DOI: 10.1016/j.pvr.2016.08.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Revised: 08/29/2016] [Accepted: 08/30/2016] [Indexed: 01/04/2023]
Affiliation(s)
- Christian E Lange
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, Massachusetts, USA.
| | - Alos Diallo
- Immunology Division, Department of Microbiology and Immunobiology, Harvard Medical School, Boston, Massachusetts, USA
| | - Christine Zewe
- Cummings School of Veterinary Medicine, Tufts University, North Grafton, Massachusetts, USA
| | - Lluis Ferrer
- Cummings School of Veterinary Medicine, Tufts University, North Grafton, Massachusetts, USA
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10
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Gil da Costa RM, Peleteiro MC, Pires MA, DiMaio D. An Update on Canine, Feline and Bovine Papillomaviruses. Transbound Emerg Dis 2016; 64:1371-1379. [PMID: 27615361 DOI: 10.1111/tbed.12555] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2016] [Indexed: 12/14/2022]
Abstract
Over recent years, a growing number of papillomaviruses have been identified, which cause a wide range of lesions in domestic and wild animals. Papillomavirus-induced lesions may have a great impact on animal health, and some diseases observed in farm animals are associated with significant economic losses. This concise review brings together recent advancements on animal papillomavirus research, providing the scientific community and veterinary practitioners with an update on this rapidly evolving field. Among others, bovine, canine and feline papillomaviruses (BPV, CPV and FcaPV) are most extensively discussed, in view of the recent discovery of new viral types and their worldwide importance for animal health. Feline papillomaviruses 2 is an emerging, highly prevalent pathogen in domestic cats, associated with a subset of malignant skin lesions. Aspects related to cross-species infection by BPV and its environmental co-factors are also addressed. Animal papillomaviruses are also fascinating models for studying molecular and cell biology and have recently inspired some major breakthroughs. Overall, it is clear that additional, international and systematic efforts are needed to clarify which lesions are caused by which viral types and to develop experimental models for studying animal papillomavirus.
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Affiliation(s)
- R M Gil da Costa
- LEPABE, Chemical Engineering Department, Faculty of Engineering, University of Porto (FEUP), Porto, Portugal.,Molecular Oncology and Viral Pathology Group, CI-IPOP, Portuguese Institute of Oncology, Porto, Portugal
| | - M C Peleteiro
- Faculty of Veterinary Medicine, CIISA, University of Lisbon, Lisboa, Portugal
| | - M A Pires
- Veterinary Sciences Department, CECAV, University of Trás-os-Montes e Alto Douro (UTAD), Vila Real, Portugal
| | - D DiMaio
- Department of Genetics, Yale School of Medicine, New Haven, CT, USA.,Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, USA.,Department of Therapeutic Radiology, Yale School of Medicine, New Haven, CT, USA.,Yale Cancer Center, New Haven, CT, USA
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11
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Abstract
Papillomaviruses with the features of epitheliotropic, nonenveloped, circular, and double-stranded DNA belong to the family Papillomaviridae, which contributes to benign and malignant tumors in humans and animals. We report the whole-genome sequence of canine papillomavirus type 11 found at a pigmented plaque located on the skin of a mixed-breed bloodhound.
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12
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Dunowska M, Munday JS, Laurie RE, Hills SFK. Genomic characterisation of Felis catus papillomavirus 4, a novel papillomavirus detected in the oral cavity of a domestic cat. Virus Genes 2013; 48:111-9. [DOI: 10.1007/s11262-013-1002-3] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2013] [Accepted: 10/18/2013] [Indexed: 11/28/2022]
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13
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Rector A, Van Ranst M. Animal papillomaviruses. Virology 2013; 445:213-23. [PMID: 23711385 DOI: 10.1016/j.virol.2013.05.007] [Citation(s) in RCA: 156] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2013] [Revised: 04/29/2013] [Accepted: 05/03/2013] [Indexed: 11/26/2022]
Abstract
We provide an overview of the host range, taxonomic classification and genomic diversity of animal papillomaviruses. The complete genomes of 112 non-human papillomavirus types, recovered from 54 different host species, are currently available in GenBank. The recent characterizations of reptilian papillomaviruses extend the host range of the Papillomaviridae to include all amniotes. Although the genetically diverse papillomaviruses have a highly conserved genomic lay-out, deviations from this prototypic genome organization are observed in several animal papillomaviruses, and only the core ORFs E1, E2, L2 and L1 are present in all characterized papillomavirus genomes. The discovery of papilloma-polyoma hybrids BPCV1 and BPCV2, containing a papillomaviral late region but an early region encoding typical polyomaviral nonstructural proteins, and the detection of recombination breakpoints between the early and late coding regions of cetacean papillomaviruses, could indicate that early and late gene cassettes of papillomaviruses are relatively independent entities that can be interchanged by recombination.
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Affiliation(s)
- Annabel Rector
- Laboratory of Clinical and Epidemiological Virology, Rega Institute for Medical Research, University of Leuven, Minderbroedersstraat 10, 3000 Leuven, Belgium.
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