The pagetoid variant of urothelial carcinoma in situ of urinary bladder in a cow

A case of urothelial carcinoma in situ of urinary bladder is reported in a 10-year-old cow naturally grazing on bracken-infested land. The cow suffered from enzootic hematuria for more than 5 years. The presence of bovine papillomavirus type 2 (BPV-2) DNA sequences was detected by polymerase chain reaction. The carcinoma in situ was characterized by the presence of anaplastic cells with amphophilic cytoplasm and pleomorphic nuclei containing granular, irregularly dispersed chromatin. Focal areas within the tumor contained large isolated and/or clustered cells. These cells had pale acidophilic cytoplasm, large nuclei with single or multiple nucleoli, and well-defined borders resembling Paget's cells. Immunohistochemically, all malignant cells were negative for vimentin and S-100 and positive for cytokeratins. In addition, normal and neoplastic cells expressed fragile histidine triad (FHIT) protein; surprisingly, some pagetoid cells did not. FHIT, the tumor suppressor gene at 3p14.2, encodes a protein of 147 amino acids (16.8 kd) with diadenosine triphosphate hydrolase activity and is a common target of deletions in human cancers of epithelial origin. Antibody to laminin detected a continuous epithelial basement membrane, thus clearly showing that neoplastic changes were limited to urothelial cells without invading stromal tissue. To our knowledge, this is the first report of an unusual pattern of spread of urothelial carcinoma in situ in a cow.

Production of infectious bovine papillomavirus from cloned viral DNA by using an organotypic raft/xenograft technique

Bovine papillomavirus type 1 (BPV-1) induces fibropapillomas in its natural host and can transform fibroblasts in culture. The viral genome is maintained as an episome within fibroblasts, which has allowed extensive genetic analyses of the viral functions required for DNA replication, gene expression, and transformation. Much less is known about BPV-1 gene expression and replication in bovine epithelial cells because the study of the complete viral life cycle requires an experimental system capable of generating a fully differentiated stratified bovine epithelium. Using a combination of organotypic raft cultures and xenografts on nude mice, we have developed a system in which BPV-1 can replicate and produce infectious viral particles. Organotypic cultures were established with bovine keratinocytes plated on a collagen raft containing BPV-1-transformed fibroblasts. These keratinocytes were infected with virus particles isolated from a bovine wart or were transfected with cloned BPV-1 DNA. Several days after the rafts were lifted to the air interface, they were grafted on nude mice. After 6-8 weeks, large xenografts were produced that exhibited a hyperplastic and hyperkeratotic epithelium overlying a large dermal fibroma. These lesions were strikingly similar to a fibropapilloma caused by BPV-1 in the natural host. Amplified viral DNA and capsid antigens were detected in the suprabasal cells of the epithelium. Moreover, infectious virus particles could be isolated from these lesions and quantitated by a focus formation assay on mouse cells in culture. Interestingly, analysis of grafts produced with infected and uninfected fibroblasts indicated that the fibroma component was not required for productive infection or morphological changes characteristic of papillomavirus-infected epithelium. This system will be a powerful tool for the genetic analysis of the roles of the viral gene products in the complete viral life cycle.

Bovine papillomavirus transmission and chromosomal aberrations: an experimental model

Enzootic haematuria and urinary bladder cancer in cattle are associated with feeding on bracken fern and bovine papillomavirus (BPV) infection. An increased rate of chromosomal aberrations in peripheral blood lymphocytes from chronically affected haematuric cows raised in bracken fern pastures has been reported, suggesting the presence of BPV in the peripheral blood of afflicted animals. The purpose of the present investigation was to examine the role of peripheral blood as a potential BPV-transmitting agent and search for clastogenic effects in experimentally infected animals kept on a bracken fern-free diet. Healthy cows were inoculated with blood samples of haematuric animals every two weeks for 18 months. Recipient cows, their offspring, donor animals and a control group were kept on a bracken fern-free diet throughout the experiment. Clinical and molecular analyses for detection of BPV infection were carried out periodically in all groups. Short-term lymphocyte cultures were performed to assess chromosomal aberration levels. The donor cows, the recipient cows and their offspring presented increased levels of chromosomal aberrations. BPV-2 DNA was identified by Southern blotting, PCR and cycle-sequencing of PCR products in peripheral blood of donor and recipient animals and in the progeny of recipient animals. Data support both the concept that BPV can be transmitted through blood and the hypothesis that infection with the virus causes the clastogenic alterations observed in the present experimental model. The presence of BPV-2 DNA and chromosomal alterations in peripheral blood of offspring at the moment of birth is evidence for vertical transmission of BPV.

Screening for bovine papillomavirus in peripheral blood cells of donkeys with and without sarcoids

Papillomaviral DNA has been identified in peripheral blood cells of both cattle and humans with and without associated disease and it has been suggested that such cells may act as sites of viral latency. In order to investigate the possibility of latent papillomaviral infection in the aetiopathogenesis of the equine sarcoid, peripheral blood derived DNA samples from 20 healthy and 34 sarcoid-affected donkeys were subject to polymerase chain reaction (PCR) using papillomaviral specific primers. Analysis of blood derived DNA samples failed to demonstrate the presence of papillomaviral DNA in any animal. Screening of 37 matched sarcoid derived DNA samples confirmed the presence of BPV in 34 diseased donkeys. This study supports the hypothesis of BPV as an aetiological agent in the equine sarcoid and suggests that latent virus in circulating peripheral blood cells does not play a role in the pathogenesis and epidemiology of the equine sarcoid.

Sequence close to the N-terminus of L2 protein is displayed on the surface of bovine papillomavirus type 1 virions

The bovine papillomavirus type 1 (BPV1) L2 protein purified from Escherichia coli was used as an antigen to produce monoclonal antibodies (MAbs). A total of 26 individual clones which recognized the BPV1 L2 protein were obtained. Using infectious BPV1 virus particles, 3 of the MAbs were found to interact with BPV1 virus particles. Binding of the MAbs to BPV1 was confirmed by immunoelectron microscopy. A set of 92 13-mer peptides overlapping by 8 amino acids spanning the entire BPV1 L2 protein was synthesized on a membrane and used to map the epitopes recognized by these antibodies. Seventeen linear epitopes were identified. Our results revealed that a sequence toward the N-terminus of the L2 protein (aa 61-123) is displayed on the virus surface, while the remaining L2 sequences are hidden inside the virus capsid. Although the polyclonal antisera raised against BPV1 L2 neutralized the BPV1 virus, we failed to detect any neutralizing activity for the 3 L2-specific monoclonal antibodies which bound to the BPV1 particles. This suggests that extra binding sites may be needed for neutralization. This study prompted us to propose a model about how L1 and L2 proteins may interact during infectious papillomavirus assembly.

Bovine papillomavirus type 4 DNA isolated from a skin lesion in a steer

A lesion on the head of a steer, defined histologically as an epithelial papilloma, yielded DNA which did not hybridise with any of the bovine papillomavirus DNAs usually associated with the formation of skin lesions. DNA from the lesion did hybridise with DNA from bovine papillomavirus 4, even under stringent conditions, and contained a sequence that could be amplified by polymerase chain reaction with primers specific for that virus. Bovine papillomavirus 4 had previously been isolated only from lesions of the upper alimentary canal.

Bovine cutaneous papillomas associated with bovine papillomavirus type 5

Squamous papillomas obtained from bovine facial skin yielded viral DNA indistinguishable from that of bovine papillomavirus type 5. It was separated from recognised bovine papillomaviruses by its restriction endonuclease pattern and hybridization tests with DNA.

[Morphologic and molecular biologic studies of the etiology of equine sarcoid]

From 932 equine skin lesions 421 were diagnosed as sarcoids (about 45%). The most common locations were the ventral body regions, head, neck and sites of thin skin. Most often the fibroblastic type, less frequently the mixed type and most infrequent the verrucous type of sarcoid were diagnosed. Detection of BPV-DNA was performed by polymerase chain reaction (PCR) using an oligonucleotide primer pair located in the E5-open reading frame. DNA of BPV 1 and BPV 2 could be differentiated by digestion with restriction endonucleases. In 97 out of 108 sarcoids BPV-DNA was detected by PCR. Most samples showed a BPV 1 specific pattern in restriction enzyme analysis. Nonradioactive in situ hybridization was carried out on 20 sarcoids. The hybridization signal was associated with the nuclei of fibroblast-like tumor cells, predominantly at the dermo-epidermal junction. In epidermal cells, BPV-DNA could not be detected. This study confirms the opinion that sarcoids are the result of a nonproductive infection in an alien, nonpermissive host with BPV.

Genomic sequences of bovine papillomaviruses in formalin-fixed sarcoids from Australian horses revealed by polymerase chain reaction

Seventy six formalin-fixed paraffin-embedded sarcoids from 62 Australian horses, collected over a ten year period, were examined for the presence of genomic sequences from bovine papillomavirus 1 and 2 (BPV1, BPV2) with the polymerase chain reaction (PCR). Sequences that could be amplified by primers specific for BPV1 and BPV2 were present in 56 of the 76 sarcoids (73%). A restriction site present in BPV1 and absent from BPV2 was detected in 28 of 34 amplified products that were treated with endonuclease.

Latent papillomavirus infection in cattle

During a long term experiment designed to identify the contribution of bovine papillomavirus type 4 (BPV-4), environmental mutagens and immunosuppressants to the development of carcinomas of the upper alimentary tract of cattle, there was evidence of latent papillomavirus infection. Papillomatosis-free animals, when immunosuppressed either by feeding bracken fern or by azathioprine treatment, developed skin warts containing either BPV-1 or BPV-2. Skin warts appeared also in an immunocompetent animal at sites of damaged skin. It was concluded that the animals harboured latent papillomavirus which was reactivated by immunosuppression and/or physical trauma, causing skin warts. Papillomavirus DNA was also detected in lymphocytes of both experimental and control animals, suggesting that one of the sites of latency may be the circulating lymphocyte.

Differentiation-specific expression from the bovine papillomavirus type 1 P2443 and late promoters

The papillomavirus life cycle is tightly linked with keratinocyte differentiation in squamous epithelia. Vegetative viral DNA replication begins in the spinous layer, while synthesis of capsid proteins and virus maturation is restricted to the most differentiated or granular layer of the epithelium. In this study, in situ hybridization of bovine fibropapillomas was used to demonstrate that the activity of two promoters of bovine papillomavirus type 1 (BPV-1) is regulated in a differentiation-specific manner. In situ hybridization with a late promoter (PL)-specific oligonucleotide probe suggested that PL is dramatically upregulated in the granular layer of the fibropapilloma. Northern (RNA) blot analysis of RNA from BPV-1-infected fibropapillomas indicated that the three major BPV-1 late-region mRNAs were transcribed from PL. These RNAs include the previously described L1 (major capsid) mRNA as well as two larger mRNAs. The two larger mRNAs were characterized and shown to contain the L2 (minor capsid protein) open reading frame as well as the L1 open reading frame. In contrast to PL, the P2443 promoter was maximally active in basal keratinocytes and the fibroma. The major mRNA transcribed from P2443 is the putative E5 oncoprotein mRNA which is spliced between nucleotides 2505 and 3225. No signal was detected above the basal layer with use of a probe specific for this mRNA. The E5 oncoprotein has previously been localized by immunoperoxidase staining to the granular cell layer as well as the basal cell layer of the fibropapilloma (S. Burnett, N. Jareborg, and D. DiMaio, Proc. Natl. Acad. Sci. USA 89:5665-5669, 1992). These data suggest that E5 proteins in the basal cell and granular cell layers are not translated from the same mRNA.

A study from south India on the association between the papilloma virus and carcinoma of the penis

Specimens from 39 cases of squamous cell carcinoma of the penis were treated for the papilloma virus using the bovine papilloma virus antibody and the peroxidase-antiperoxidase technique. All 39 cases showed a viral antigen situated intranuclearly, intracytoplasmically or both intranuclearly and intracytoplasmically. No correlation could be seen between the presence of viral antigen and age of patient, duration of lesion, cell morphology and histological grade. The adjacent mucosa and skin were used as controls and showed no viral antigen. The inflammatory infiltrate was dense and predominantly "T" lymphocyte in type.

Search for bovine papilloma virus DNA in bovine ocular squamous cell carcinomas (BOSCC) and BOSCC-derived cell lines

Although the cause of bovine ocular squamous cell carcinoma (BOSCC) is attributed to viruses in addition to cofactors (eg, UV light), to our knowledge, the final causative agent has not been described. Bovine papilloma virus (BPV)-like particles were detected in approximately 33% of various putative precursor lesions of BOSCC. In contrast, it was reported that, using BPV-specific antibodies, it was not possible to detect viral antigens in BOSCC. Fourteen established BOSCC and 9 BOSCC-derived cell lines were examined for BPV DNA. Probes of all 6 known BPV types were used in various hybridization assays. Neither Southern blot analysis, under high and low stringency conditions, nor in situ hybridization resulted in detection of BPV DNA. Papilloma viruses were not observed in electron microscopic studies. Results exclude direct association between BOSCC and BPV types 1 to 6, or as yet unknown closely related BPV types. However, BPV may contribute to induction of precursor lesions or events leading to carcinogenic transformation, without being relevant for maintenance of the tumor.

Tumorigenic transformation of murine keratinocytes by the E5 genes of bovine papillomavirus type 1 and human papillomavirus type 16

To examine the biological properties of the bovine papillomavirus type 1 (BPV) and human papillomavirus type 16 (HPV16) E5 genes, each was cloned separately into a retroviral expression vector and helper-free recombinant viruses were generated in packaging cell lines. The BPV E5 retroviruses efficiently caused morphologic and tumorigenic transformation of cultured lines of murine fibroblasts, whereas the HPV16 E5 viruses were inactive in these assays. In contrast, infection of the p117 established line of murine epidermal keratinocytes with either the BPV or the HPV16 E5 retrovirus resulted in the generation of tumorigenic cells. Pam212 murine keratinocytes were also transformed to tumorigenicity by the HPV16 E5 gene but not by the gene carrying a frameshift mutation. These results establish that the HPV16 E5 gene is a transforming gene in cells related to its normal host epithelial cells.

Structures of bovine and human papillomaviruses. Analysis by cryoelectron microscopy and three-dimensional image reconstruction

The structures of bovine papillomavirus type 1 (BPV-1) and human papillomavirus type 1 (HPV-1) were determined at 2.5 nm resolution by cryoelectron microscopy and three dimensional image reconstruction techniques. As expected, the reconstructions showed that both viruses consist of a T = 7 icosahedral capsid (approximately 60 nm in diameter) which surrounds a nucleohistone core. The capsid morphologies of the two viruses are nearly indistinguishable. Each capsid consists of a shell layer (approximately 2 nm thick) of nearly continuous density from which capsomers project radially to a maximum height of approximately 5.8 nm. The five-coordinate (pentavalent) and six-coordinate (hexavalent) capsomers both exhibit distinct five-fold axial symmetry as was observed for SV40 and polyoma viruses. Thus, both genera (papilloma and polyoma) of the papovavirus family have now been shown to have the characteristic "all-pentamer" capsid construction. BPV-1 and HPV-1 capsomers consist of a thick (8.6 nm diameter) trunk that broadens distally to form a regular five-pointed, star-shaped head, and proximally to create the shell layer where capsomers associate. A cylindrical channel (approximately 2.8 nm diameter) extends along the axis of each capsomer from the interior of the virus to a point approximately half way to the capsomer surface. Computationally sectioned views of individual capsomers displayed at decreasing radii show that each of the five capsomer subunits (in both pentavalent and hexavalent capsomers) makes a pronounced (30 degrees) left-handed twist just above the outer surface of the capsid shell. Similar views of the reconstructions also clarify the morphology of intercapsomer contacts. For example, they show how hexavalent capsomers coordinate six neighboring capsomers despite the fact that they contain only five subunits. The system of intercapsomer contacts is indistinguishable in BPV-1 and HPV-1, but quite different from that reported for polyoma virus capsids assembled in vitro from the major capsid protein, VP1 (D. M. Salunke, D. L. D. Caspar, and R. L. Garcea. 1989. Biophys. J. 56:887-900). Thus, because both polyoma and papilloma viruses have all-pentamer capsids, it appears that intracapsomer subunit-subunit interactions which stabilize pentameric capsomers are better preserved evolutionarily than those involved in capsomer-capsomer contacts.

Characterization of BPV-like DNA in equine sarcoids

The DNA from equine sarcoid samples from New York State and Switzerland was isolated and probed with bovine papillomavirus type 1 (BPV-1) to determine if BPV genomes were present. Twelve of 13 sarcoids from New York State and 17/20 sarcoids from Switzerland contained DNA that hybridized to the BPV-1 probe. Restriction enzyme analysis of the positive samples demonstrated restriction fragment profiles characteristic of BPV-1 in 22 sarcoids and restriction fragment profiles characteristic of bovine papillomavirus type 2 (BPV-2) in 7 sarcoids. In addition, three tissues histologically diagnosed as pyogranulomatous dermatitis, fibropapilloma, and fibrosarcoma contained BPV-like DNA. Tissues with BPV-1-like and BPV-2-like DNA contained an average of 285.7 (21 to 808) and 125.8 (2 to 762) BPV-like genomes per cell, respectively. Minor differences in the restriction fragment profiles of the BPV-like DNA and evidence for partial BPV-like genomes were found in some sarcoids. BPV-like DNA was not detected in lymphocyte DNA from sarcoid-affected horses. These results confirm previous observations and support the hypothesis that bovine papillomavirus, or a very similar virus, is linked to the cause of equine sarcoid.

Infectious papillomavirus in the vapor of warts treated with carbon dioxide laser or electrocoagulation: detection and protection

Papillomavirus DNA has been reported recently in the vapor (smoke plume) derived from warts treated with carbon dioxide laser; this raises concerns for operator safety. We therefore have studied a group of human and bovine warts to define further the potential risk of wart therapy and to test whether a surgical mask could reduce exposure. Half of each wart was treated with carbon dioxide laser and the other half with electrocoagulation. The vapor produced by each form of therapy was collected with a dry filter vacuum apparatus and analyzed for the presence of papillomavirus. Vapor from human plantar warts was analyzed for the presence of human papillomavirus DNA, because there is no infectivity assay for human papillomavirus. Of plantar warts treated, five of eight laser-derived vapors and four of seven electrocoagulation-derived vapors were positive for human papillomavirus DNA. Greater amounts of papillomavirus DNA were usually recovered in the laser vapor than in the electrocoagulation vapor from the same wart. Bioassay readily detected infectious bovine papillomavirus in the vapor from bovine warts treated with either modality; more virus was present in laser-derived material. A surgical mask was found capable of removing virtually all laser- or electrocoagulation-derived virus, strongly suggesting that such masks can protect operators from potential inhalation exposure to papillomavirus.

Characterization of bovine papillomavirus type 1-transformed clones which show distinct transformed phenotypes

Seventeen independent cell clones were isolated from C127 cells transformed by bovine papillomavirus type 1 (BPV-1). Transformants showed differing degrees of expression of the transformed phenotype as monitored by saturation density, doubling time, growth in medium with a low serum concentration and colony-forming efficiency in soft agar. The degree of expression of the transformed phenotype did not correlate with either the BPV-1 copy number or levels of BPV-1-specific RNA in the transformed cell clones. A characteristic transformed cell clone, T1c, showed the lowest degree of expression of the transformed phenotype but contained the highest copy number of BPV-1 DNA and the highest level of BPV-1-specific mRNA. When we analysed different transformants by two-dimensional gel electrophoresis, we found that a set of six proteins changed quantitatively. Changes in the expression of these proteins were most consistent in clones expressing the greatest number of parameters of transformation, e.g. clone T4a. These data indicate that changes in the expression of cellular genes may correlate with the degree of expression of the transformed phenotype.

Papillomavirus in the vapor of carbon dioxide laser-treated verrucae

Vapor produced by the carbon dioxide laser during the vaporization of papillomavirus-infected verrucae was analyzed for viral DNA content. Two models were used for evaluation: an in vitro cutaneous bovine fibropapilloma and an in vivo human verruca model. Four bovine fibropapillomas were exposed to various laser parameters with power densities of 38,200 to 130 W/cm2 and energy fluences of 3820 to 130 J/cm2. The generated vapor was collected in a chamber in line with a vacuum system. Hybridization with bovine papillomavirus DNA probes revealed intact bovine papillomavirus DNA for all power densities and energy fluences used. The laser vapor from seven patients undergoing carbon dioxide laser therapy for plantar or mosaic verrucae was also collected. Laser parameter settings were similar to those usually chosen for clinical tissue vaporization. Intact human papillomavirus DNA was present in the vapor from two of seven patients. These studies indicate that intact viral DNA is liberated into the air with the vapor of laser-treated verrucae. It would be prudent for all practitioners who use the laser in treating patients with viral infections or conditions associated with viruses to practice extreme care and safety throughout the laser procedure.

Enzyme-linked immunosorbent assay for the detection of bovine papillomavirus

An enzyme-linked immunosorbent assay has been developed to detect and quantitate bovine papillomavirus in partially purified and in purified viral preparations, using rabbit antiserum against group-specific papillomavirus structural antigens and alkaline phosphatase-labeled affinity purified goat antibody to rabbit immunoglobulin G. Viral detection correlated well with negative-stain electron microscopy of the various preparations and peroxidase-antiperoxidase staining of paraffin sections of the original fibropapillomas. The technique is rapidly done and will detect minute amounts of viral protein (1 ng/ml).

Alimentary fibropapilloma in cattle: a spontaneous tumor, nonpermissive for papillomavirus replication

Fibropapillomatosis of the upper alimentary canal of cattle is described. The tumors, found in the esophagus, esophageal groove, and rumen, showed involvement of the subepithelial fibroblasts as well as of the squamous epithelial layer. Although the fibropapilloma cells harbored multiple episomal copies of the genome of bovine papillomavirus type 2 (BPV-2) easily detected by hybridization techniques, no mature virus could be isolated from these lesions or seen by electron microscopy, and no viral antigen could be detected by immunohistochemical methods. It would appear, therefore, that within the limitations of the techniques employed the alimentary canal epithelium and the underlying fibroblasts, while allowing BPV-2 DNA replication, are nonpermissive for the expression of the viral vegetative functions and that transformation of the epithelial cells, like transformation of fibroblasts, can take place in the absence of infectious viral progeny.