New types of human papillomaviruses and intracytoplasmic inclusion bodies: a classification of inclusion warts according to clinical features, histology and associated HPV types

Eosinophilic homogeneous intracytoplasmic inclusion bodies: Unique viral cytopathic changes associated with epidermodysplasia verruciformis and human papillomavirus type 49

Epidermodysplasia verruciformis (EDV) is a rare genodermatosis that predisposes affected individuals to persistent infection with certain types of human papillomavirus (HPV), particularly those that belong to the genus beta-HPV, including HPV-5 and HPV-8, which carry high oncogenic potential. There are three main HPV-related viral cytopathic changes in cutaneous verrucae in terms of intracytoplasmic inclusion bodies (ICBs), namely, granular, filamentous, and homogeneous type ICBs. To date, only HPV-4, HPV-60, and HPV-65 have been found in association with homogeneous ICBs. We report a unique case of HPV-49-associated EDV in a 41-year-old woman with common variable immunodeficiency, mycosis fungoides, and multiple cutaneous malignancies, including squamous cell carcinoma and Merkel cell carcinoma who presented with multiple pink papules and hyperpigmented macules on the left upper extremity. One of the skin lesions histopathologically revealed keratinocytic nuclear enlargement with abundant blue-gray cytoplasm, accompanied by hypergranulosis, characteristic of EDV, along with peculiar bright eosinophilic and homogeneous ICBs. To the best of our knowledge, this is the first reported case of EDV with detection of HPV-49 by genotyping, which features eosinophilic homogeneous ICBs, like those seen in the setting of HPV-4, HPV-60, or HPV-65 infection.

Determination of Causative Human Papillomavirus Type in Tissue Specimens of Common Warts Based on Estimated Viral Loads

Background: Assessment of human papillomavirus (HPV) type-specific viral load (VL) is a valid tool for determining the etiology of HPV-related skin tumors, especially when more than one HPV type is detected within one lesion.

Methods: The causative HPV type was determined in 185 fresh-frozen tissue specimens of histologically confirmed common warts (CWs) collected from 121 immunocompetent patients. All tissues were tested using the type-specific quantitative real-time polymerase chain reactions (PCR) for the most common wart-associated Alpha-PV (HPV2/27/57) and Mu-PV types (HPV1/63/204). The presence of 23 additional low-risk HPVs was evaluated using a conventional wide-spectrum PCR.

Results: HPV DNA was detected in 176/185 (95.1%) CWs and multiple HPV types in 71/185 (38.4%) lesions. Using the VL approach and a robust cutoff of one viral copy/cell established in this study, HPV2/27/57 were determined as causative agents in 41/53 (77.3%) and 53/71 (74.7%) CWs with single and multiple HPVs, respectively.

Conclusions: CWs are mostly etiologically associated with HPV2/27/57 and only rarely with HPV1. In the majority of CWs containing multiple HPVs, a single HPV type was present in high concentration, indicating etiological association. No significant differences in VLs of lesion-causing HPV types in CWs containing single or multiple HPVs were found.

Viral warts (Human Papilloma Virus) as a potential risk for breast cancer among younger females

INTRODUCTION

There have been several reports on the role of human papillomavirus (HPV) in the etiology of breast cancer. To our knowledge, this is first study to use disease-disease association data-mining approach to analyzing viral warts and breast cancer to be conducted in Taiwanese population.

MATERIALS AND METHODS

We analyzed the Taiwan's National Health Insurance database (NHIDM data comprising of 23 million patient data) to examine the association between viral warts and female breast carcinoma. The patients were categorized into three groups: breast cancer only, viral warts only, and those with both breast cancer and viral warts. The Cox proportion hazard regression analysis was used to measure the effect of HPV on the time to breast cancer diagnosis. Multivariable analyzes and stratified analyzes using hazard ratios (HRs) were presented with 95% confidence intervals (CIs) after adjusting for age, and CCI.

RESULT

Among 807,578 HPV population, we identified 6014 breast cancer cases. The HPV group was associated with a significantly higher risk of developing breast cancer (HR, 1.18; 95% CI, 1.15-1.21; p< 0.001) compared with the non-HPV group. HPV patients with age group 18-39 was slightly higher risk of breast cancer occurrence (HR, 1.07; 95% CI, 1.01-1.13; p<.05). The risk of breast cancer in 10-year incidence was 7% higher for females less than 40 years and 23% for over 40 year's patients when compared with non-HPV patients of the same age group.

CONCLUSION

Our study indicates that women who develop viral warts are at a significantly higher risk of developing breast cancer than women who have not diagnosed with viral warts. Thus, the presence of viral warts is a potential risk to breast cancer. Therefore, we suggest patients diagnosed with viral warts may get early screening for breast cancer.

The Human Papillomavirus and Its Role in Plantar Warts: A Comprehensive Review of Diagnosis and Management

Viral warts or verruca pedis (plantar warts) are common skin conditions seen in both children and adults. Human papilloma virus (HPV), a DNA virus, is responsible for plantar verrucae. It needs an epidermal abrasion and a transiently impaired immune system to inoculate a keratinocyte. These entities are a therapeutic conundrum for many practitioners. This article discusses HPV infiltration and its subtypes involved in plantar warts; the evaluation of patients with plantar warts; and subsequent treatment options, such as laser, Candida albicans immunotherapy, topical therapy such as phytotherapy, and surgical excision.

Human Papillomaviruses; Epithelial Tropisms, and the Development of Neoplasia

Papillomaviruses have evolved over many millions of years to propagate themselves at specific epithelial niches in a range of different host species. This has led to the great diversity of papillomaviruses that now exist, and to the appearance of distinct strategies for epithelial persistence. Many papillomaviruses minimise the risk of immune clearance by causing chronic asymptomatic infections, accompanied by long-term virion-production with only limited viral gene expression. Such lesions are typical of those caused by Beta HPV types in the general population, with viral activity being suppressed by host immunity. A second strategy requires the evolution of sophisticated immune evasion mechanisms, and allows some HPV types to cause prominent and persistent papillomas, even in immune competent individuals. Some Alphapapillomavirus types have evolved this strategy, including those that cause genital warts in young adults or common warts in children. These strategies reflect broad differences in virus protein function as well as differences in patterns of viral gene expression, with genotype-specific associations underlying the recent introduction of DNA testing, and also the introduction of vaccines to protect against cervical cancer. Interestingly, it appears that cellular environment and the site of infection affect viral pathogenicity by modulating viral gene expression. With the high-risk HPV gene products, changes in E6 and E7 expression are thought to account for the development of neoplasias at the endocervix, the anal and cervical transformation zones, and the tonsilar crypts and other oropharyngeal sites. A detailed analysis of site-specific patterns of gene expression and gene function is now prompted.

The E4 protein; structure, function and patterns of expression

The papillomavirus E4 open reading frame (ORF) is contained within the E2 ORF, with the primary E4 gene-product (E1^E4) being translated from a spliced mRNA that includes the E1 initiation codon and adjacent sequences. E4 is located centrally within the E2 gene, in a region that encodes the E2 protein's flexible hinge domain. Although a number of minor E4 transcripts have been reported, it is the product of the abundant E1^E4 mRNA that has been most extensively analysed. During the papillomavirus life cycle, the E1^E4 gene products generally become detectable at the onset of vegetative viral genome amplification as the late stages of infection begin. E4 contributes to genome amplification success and virus synthesis, with its high level of expression suggesting additional roles in virus release and/or transmission. In general, E4 is easily visualised in biopsy material by immunostaining, and can be detected in lesions caused by diverse papillomavirus types, including those of dogs, rabbits and cattle as well as humans. The E4 protein can serve as a biomarker of active virus infection, and in the case of high-risk human types also disease severity. In some cutaneous lesions, E4 can be expressed at higher levels than the virion coat proteins, and can account for as much as 30% of total lesional protein content. The E4 proteins of the Beta, Gamma and Mu HPV types assemble into distinctive cytoplasmic, and sometimes nuclear, inclusion granules. In general, the E4 proteins are expressed before L2 and L1, with their structure and function being modified, first by kinases as the infected cell progresses through the S and G2 cell cycle phases, but also by proteases as the cell exits the cell cycle and undergoes true terminal differentiation. The kinases that regulate E4 also affect other viral proteins simultaneously, and include protein kinase A, Cyclin-dependent kinase, members of the MAP Kinase family and protein kinase C. For HPV16 E1^E4, these kinases regulate one of the E1^E4 proteins main functions, the association with the cellular keratin network, and eventually also its cleavage by the protease calpain which allows assembly into amyloid-like fibres and reorganisation of the keratin network. Although the E4 proteins of different HPV types appear divergent at the level of their primary amino acid sequence, they share a recognisable modular organisation and pattern of expression, which may underlie conserved functions and regulation. Assembly into higher-order multimers and suppression of cell proliferation are common to all E4 proteins examined. Although not yet formally demonstrated, a role in virus release and transmission remains a likely function for E4.

Human papillomavirus type 8 interferes with a novel C/EBPβ-mediated mechanism of keratinocyte CCL20 chemokine expression and Langerhans cell migration

Infection with genus beta human papillomaviruses (HPV) is implicated in the development of non-melanoma skin cancer. This was first evidenced for HPV5 and 8 in patients with epidermodysplasia verruciformis (EV), a genetic skin disease. So far, it has been unknown how these viruses overcome cutaneous immune control allowing their persistence in lesional epidermis of these patients. Here we demonstrate that Langerhans cells, essential for skin immunosurveillance, are strongly reduced in HPV8-positive lesional epidermis from EV patients. Interestingly, the same lesions were largely devoid of the important Langerhans cells chemoattractant protein CCL20. Applying bioinformatic tools, chromatin immunoprecipitation assays and functional studies we identified the differentiation-associated transcription factor CCAAT/enhancer binding protein β (C/EBPβ) as a critical regulator of CCL20 gene expression in normal human keratinocytes. The physiological relevance of this finding is supported by our in vivo studies showing that the expression patterns of CCL20 and nuclear C/EBPβ converge spatially in the most differentiated layers of human epidermis. Our analyses further identified C/EBPβ as a novel target of the HPV8 E7 oncoprotein, which co-localizes with C/EBPβ in the nucleus, co-precipitates with it and interferes with its binding to the CCL20 promoter in vivo. As a consequence, the HPV8 E7 but not E6 oncoprotein suppressed C/EBPβ-inducible and constitutive CCL20 gene expression as well as Langerhans cell migration. In conclusion, our study unraveled a novel molecular mechanism central to cutaneous host defense. Interference of the HPV8 E7 oncoprotein with this regulatory pathway allows the virus to disrupt the immune barrier, a major prerequisite for its epithelial persistence and procarcinogenic activity.

Evaluation of a novel broad-spectrum PCR-multiplex genotyping assay for identification of cutaneous wart-associated human papillomavirus types

A large number of human papillomavirus (HPV) types, distributed over five papillomavirus genera, are detectable in the skin. HPV types belonging to the alpha, gamma, and mu genera have been detected in cutaneous warts. A state-of-the-art HPV genotyping assay for these cutaneous wart-associated HPV types does not exist although warts constitute a highly prevalent skin condition, especially in children (33%) and organ transplant recipients (45%). Cutaneous warts are again the focus of attention as their clinical relevance rises with the increasing number of chronically immunosuppressed patients. The objective of this study was to develop and evaluate a DNA-based genotyping system for all known cutaneous wart-related HPV types using PCR and Luminex xMAP technology. The broad-spectrum PCR amplified DNA of all known wart-associated HPV types from the genera alpha (HPVs 2, 3, 7, 10, 27, 28, 29, 40, 43, 57, 77, 91, and 94), gamma (HPVs 4, 65, 95, 48, 50, 60, and 88), mu (HPVs 1 and 63), and nu (HPV41). The probes were evaluated using plasmid HPV DNA and a panel of 45 previously characterized cutaneous wart biopsy specimens showing high specificity. HPV was also identified in 96% of 100 swabs from nongenital cutaneous warts. HPV types 1, 2, 27, and 57 were the most prevalent HPV types detected in 89% of the swabs. In conclusion, this Luminex-based genotyping system identifies all known cutaneous wart HPV types including phylogenetically related types, is highly HPV type specific, and is suitable for large-scale epidemiological studies.

High viral load of human wart-associated papillomaviruses (PV) but not beta-PV in cutaneous warts independent of immunosuppression

BACKGROUND

A broad spectrum of human papillomaviruses (HPV) has been detected in warts from immunocompetent patients and a much more diverse range from immunosuppressed organ transplant recipients (OTR).

OBJECTIVES

To determine the HPV types in warts from OTR, we assessed present infections of mucosal (alpha-PV), wart-associated (alpha-, micro- and nu-PV) and cutaneous HPV types (beta-/gamma-PV) in immunocompetent patients and OTR. Patients/methods Forty-one warts from 29 immunocompetent patients (non-OTR) and 53 warts from 33 OTR were analysed for DNA of human alpha-, beta-, gamma-, micro- and nu-PV. For frequent types viral load was determined by quantitative real-time PCR.

RESULTS

Compared with non-OTR prevalence of cutaneous HPV (79% vs. 49%, P < 0.01) and the number of multiple infections (62% vs. 17%, P < 0.0001) were significantly increased. The mean viral load of the wart-associated HPV was more than 10(5)-fold higher compared with human beta-PV in both cohorts.

CONCLUSIONS

The high load of wart-associated HPV suggests an active role of these viruses rather than cutaneous types in warts independent of immunosuppression; however, the substantial fraction of warts with low HPV genome copies remains to be explained.

[HPV-associated cutaneous lesions]

More than 100 HPV genotypes are presently distinguished by comparing the DNA sequence of the L1 ORF of each HPV. Two important aspects of the nature of this group of heterogeneous viruses are the way in which specific HPV genotypes are associated with distinct clinical and histological morphologies and the way specific HPV genotypes affect distinct anatomical sites. The former is best evidenced by the HPV type specific cytopathic or cytopathogenic effect (CPE), whereas the latter is suggested by the marked preference of each HPV genotype for specific tissues and sites. Recent studies have also suggested that specific HPV genotypes may target epithelial stem cells at specific anatomical sites. HPV type-specific CPE is the central schema when we analyze and understand the HPV-associated diseases. The concept was suggested by the characterization of distinct HPVs from different types of warts: HPV 2/27/57 from common warts, HPV 3/10/28 from flat warts, HPV 6/11 from condyloma acuminatum, and HPV 5/8 from lesions of epidermodysplasia verruciformis (EV). In this paper, I summarize recent advances in HPV study field, especially on HPV-associated cutaneous lesions. These include inclusion warts, HPV-associated epidermoid cysts, HPV type specific activation of melanogenesis, a double infection with HPV 1 and HPV 63 within a single cell, primary target cells and life cycle of the virus, and the identification of novel genes that are associated EV. The HPV-associated cutaneous lesions thus pose important problems to be resolved in virology and human pathology.

Epidermodysplasia verruciformis-associated and genital-mucosal high-risk human papillomavirus DNA are prevalent in nevus sebaceus of Jadassohn

BACKGROUND

The hamartoma nevus sebaceus (NS) presents at birth or early childhood as a yellowish plaque characterized histologically by variable acanthosis, papillomatosis, sebaceus hyperplasia, and proliferations of adnexal structures. Clinically apparent human papillomavirus (HPV) infection is also recognized by acanthosis and papillomatosis.

OBJECTIVE

We sought to determine the prevalence and physical state of HPV DNA in NS.

METHODS

DNA was retrieved from 44 formalin-fixed, paraffin-embedded samples of NS (22 with secondary tumors [eg, trichoblastoma, verruca, syringocystadenoma papilliferum] and two epidermal nevi [EN]). Nested polymerase chain reaction with multiple degenerate consensus and type-specific primers and direct sequencing of polymerase chain reaction products was performed. For selected cases, in situ hybridization using probes specific for HPV 5 and 8 and for high-risk genital-mucosal HPV types was performed.

RESULTS

HPV DNA was detected in 82% of NS and both EN, and consisted of genital-mucosal HPV types in 52% (HPV 6, 16, and 33) and a diverse variety of epidermodysplasia verruciformis-associated HPV types in 61%, including well-known epidermodysplasia verruciformis HPV types (5, 8, 15, 20, 22, 24, 36, 37, 38, and 80) and putatively novel epidermodysplasia verruciformis HPV types (DL285, DL287, DL436, and alb-1, -2, -3, -5, -6, -7, -8, -10, -11, -12, and -13). HPV coinfection was frequent, found in 48% (two HPV genotypes in 35% and 3 in 13%). Of NS and EN, 42% had HPV genotypes associated with cancer (ie, HPV 5, 8, 16, 20, 33, and 38); the two most commonly identified HPV types where HPV 16 (39%) and HPV 38 (18%). No differences were detected comparing frequency of HPV DNA detected with respect to age or presence of a secondary tumor. Histologically, all NS and EN showed HPV-associated cytopathic effects (ie, perinuclear halos, altered keratohyaline granules). By in situ hybridization, 64% (18/28) were positive, showing a low-intensity, punctate nuclear signal in epidermal and adnexal keratinocytes, indicating viral integration and low viral genome copy number.

LIMITATIONS

Absence of adjacent, uninvolved normal-appearing skin control samples.

CONCLUSION

HPV DNA is prevalent in NS, and HPV 16, the most frequently detected genotype, appears to be integrated into the host genome. Whether HPV represents a commensal infection caused by localized cutaneous predisposition, or is an essential factor in the pathogenesis of NS is unknown. The high frequency of oncogenic HPV types implicates maternal transmission of HPV and infection of an ectodermal stem cell leading to an epigenetic mosaic and altered skin development manifested along Blaschko's lines.

Human papillomavirus-associated plantar epidermoid cyst related to epidermoid metaplasia of the eccrine duct epithelium: a combined histological, immunohistochemical, DNA-DNA in situ hybridization and three-dimensional reconstruction analysis

BACKGROUND

We recently proposed that certain palmoplantar epidermoid cysts may be related to eccrine ducts and that human papillomavirus (HPV) 60 may play a role in their pathomechanism. However, the origin of palmoplantar epidermoid cysts is still controversial.

OBJECTIVES

To examine the contribution of eccrine ducts and HPV 60 in the development of epidermoid cysts.

METHODS

Five epidermoid cysts and four ridged warts that had developed on the soles of a patient were studied histologically, immunohistochemically and by DNA-DNA in situ hybridization. Using serial sections obtained from its entire body, a three-dimensional reconstruction (3DR) analysis was performed on the smallest cyst to analyse the relationship between the epidermoid cyst, eccrine duct and the overlying epidermis.

RESULTS

Histological and DNA-DNA in situ hybridization analyses demonstrated both homogeneous intracytoplasmic inclusion bodies pathognomonic for HPV 60 infection and HPV 60 DNA sequences not only in all of the epidermoid cysts and ridged warts but also in the acrosyringeal portion of an eccrine duct, with the dermal portion of which the smallest cyst had been revealed to connect by 3DR analysis. However, immunohistochemical analyses using antibodies against human carcinoembryonic antigen (CEA), involucrin and several cytokeratins (CKs) revealed that the immunoreactivity of the cyst was not identical to that of the eccrine dermal duct but was identical to that of suprabasal layers of the epidermis.

CONCLUSIONS

It was clearly demonstrated that an HPV 60-associated epidermoid cyst with immunoreactivities for CEA, involucrin and CKs which were identical to those of the epidermis connected with the eccrine dermal duct, supporting the idea that certain palmoplantar epidermoid cysts may develop following the epidermoid metaplasia of eccrine ducts with HPV 60 infection.

Eccrine-centred distribution of human papillomavirus 63 infection in the epidermis of the plantar skin

BACKGROUND

The primary target cell of human papillomaviruses (HPVs) is an unsettled issue. Recent studies have suggested that the hair follicle is an important candidate as the reservoir of certain HPV types. However, little is known about the cells which serve as the target or the reservoir of HPVs in nonhairy palmoplantar skin.

OBJECTIVES

To investigate whether the eccrine sweat gland, the only skin appendage in nonhairy palmoplantar skin, also serves as the target or the reservoir of HPVs.

METHODS

HPV 63-induced warts were employed in this study, because the virus induces tiny warty lesions of a punctuate appearance in the plantar skin and shows peculiar intracytoplasmic inclusion bodies as a diagnostic histopathological marker of infection: this seemed to provide a useful model for the present study. Serial sections were obtained from the entire body of each biopsy specimen and were investigated histologically, immunohistochemically and using DNA-DNA in situ hybridization (ISH) for the histological localization of HPV 63 infection.

RESULTS

On microscopy, HPV 63 histopathological changes were seen closely associated with eccrine ducts. Using ISH, HPV 63 DNA was detected not only in keratinocytes resident around acrosyringia but also in the uppermost portion of the eccrine dermal duct. A few keratinocytes harbouring HPV 63 DNA were also identified in acrosyringeal areas in the normal plantar skin adjacent to the wart lesions.

CONCLUSIONS

On the basis of our results, it seems likely that HPV 63 targets keratinocytes resident in or around the eccrine ducts in the plantar skin. The results may also suggest that not only hair follicles but also eccrine ducts serve as reservoirs for certain HPV types, including HPV 63, especially in the nonhairy plantar skin.

Life cycle heterogeneity in animal models of human papillomavirus-associated disease

Animal papillomaviruses are widely used as models to study papillomavirus infection in humans despite differences in genome organization and tissue tropism. Here, we have investigated the extent to which animal models of papillomavirus infection resemble human disease by comparing the life cycles of 10 different papillomavirus types. Three phases in the life cycles of all viruses were apparent using antibodies that distinguish between early events, the onset of viral genome amplification, and the expression of capsid proteins. The initiation of these phases follows a highly ordered pattern that appears important for the production of virus particles. The viruses examined included canine oral papillomavirus, rabbit oral papillomavirus (ROPV), cottontail rabbit papillomavirus (CRPV), bovine papillomavirus type 1, and human papillomavirus types 1, 2, 11, and 16. Each papillomavirus type showed a distinctive gene expression pattern that could be explained in part by differences in tissue tropism, transmission route, and persistence. As the timing of life cycle events affects the accessibility of viral antigens to the immune system, the ideal model system should resemble human mucosal infection if vaccine design is to be effective. Of the model systems examined here, only ROPV had a tissue tropism and a life cycle organization that resembled those of the human mucosal types. ROPV appears most appropriate for studies of the life cycles of mucosal papillomavirus types and for the development of prophylactic vaccines. The persistence of abortive infections caused by CRPV offers advantages for the development of therapeutic vaccines.

Protean manifestations of human papillomavirus type 60 infection on the extremities

BACKGROUND

Human papillomavirus type 60 (HPV-60) induces a ridged wart or an epidermal cyst on the sole of the foot, exhibiting identical pathological changes, with a single refractile eosinophilic intracytoplasmic inclusion body in infected cells. However, there is no information on the role of HPV-60 in the development of cutaneous lesions on other anatomical sites.

OBJECTIVES

To perform the clinicopathological analysis of various cutaneous lesions of a patient in relation to HPV genotype.

PATIENT

A 50-year-old male patient developed multiple papules, plaques and nodules on his hand, arm and legs.

RESULTS

Clinicopathologically, the lesions were classified into three categories. A common wart on the finger showed papillomatosis and acanthosis characterized by numerous keratohyalin granules. Plane warts on the arm showed perinuclear vacuolization of the cells in the upper Malpighian layer. On the other hand, a pigmented papillomatous nodule on the finger, and the other lesions on the hands and legs exhibited similar histological features with a unique cytoplasmic eosinophilic inclusion body. All the three categorized lesions were equally positive for HPV capsid antigen by immunohistochemistry. By blot hybridization analysis for HPV sequences, it was revealed that a common wart on the finger and plane warts on the arm harboured HPV-27 and HPV-3, respectively, while all the other lesions harboured HPV-60. The histological localization of each viral DNA was confirmed in the corresponding lesions by in situ hybridization.

CONCLUSIONS

HPV-60 is able to induce papular and nodular lesions on the extremities.

Synthesis of viral DNA and late capsid protein L1 in parabasal spinous cell layers of naturally occurring benign warts infected with human papillomavirus type 1

We investigated human papillomavirus type 1 (HPV1)-specific transcription, viral DNA replication, and viral protein expression in naturally occurring benign tumors by in situ hybridization, 5-bromodeoxyuridine (BrdU) incorporation, and immunohistochemistry and obtained results different from other HPV-infected benign tumors characterized so far. Moderate amounts of transcripts with a putative coding potential for E6/E7, E1, and E2 were demonstrated from the first subrabasal cell layer throughout the stratum spinosum and granulosum. In addition very large amounts of E4 and L1 transcripts were present in the same epithelial layers. This finding was substantiated by the demonstration of L1 and E4 protein already in the bottom-most spinous cell layer. Furthermore massive amplification of the viral DNA as measured by BrdU incorporation and different methods of in situ hybridization took place in the lowest 5 to 10 suprabasal cell layers. These findings are in contrast to the assumption that late gene expression and viral DNA synthesis are restricted to the more differentiated cell layers of the epithelium and point to differences in the regulation of the vegetative life cycle between different papillomavirus types.

Pigmented viral warts: a clinical and histopathological study including human papillomavirus typing

Although clinical, histological and viral correlations have recently been established among pigmented warts, homogeneous intracytoplasmic inclusion bodies and related types of human papillomavirus (HPV) (HPV 65, 4 and 60), the causes of the pigmentation remain unknown. In this study, comparative histological and histochemical analyses were performed with 53 pigmented (34 HPV 65-induced, 12 HPV 4-induced and seven HPV 60-induced) and 73 non-pigmented warts (27 HPV 2-induced, 23 HPV 1-induced, 12 HPV 63-induced, six unknown HPV-type induced and five HPV 60 induced) to clarify the causes of the pigmentation. Electron microscopy was also used to examine the pigmented warts. Many melanin blockade melanocytes were identified in all of the pigmented warts with Masson-Fontana staining and electron microscopy, and increased melanin in keratinocytes was also noted in 22 pigmented warts, suggesting that the dispersion of melanin granules in the dendrites of the melanin blockade melanocytes and the increased melanin granules in keratinocytes are the primary contributors to the pigmentation of the warts. The homogeneous intracytoplasmic inclusion bodies might also play a part in the darkening of the warts, as only the cases which had the inclusion bodies as well as the melanin blockade melanocytes were clinically pigmented. Although melanin blockade melanocytes were seen in a few cases of HPV 1- and HPV 2-induced warts in which the homogeneous inclusion bodies were not observed, the warts were not clinically pigmented. Melanin blockade melanocytes were not seen in any of the HPV 63-induced non-pigmented warts. In conclusion, the pigmented warts were associated with one of the related types of HPV (HPV 65, 4 and 60), and the pigmentation of the lesions is thus thought to be caused primarily by melanin blockade melanocytes. The homogeneous intracytoplasmic inclusion bodies might also play a part in the darkening of the lesions. This is the first report dealing with the pigmentary disorder associated with specific types of HPV.

Characterization of events during the late stages of HPV16 infection in vivo using high-affinity synthetic Fabs to E4

HPV late gene expression is initiated as an infected basal cell migrates through the differentiating layers of the epidermis, resulting in the onset of vegetative viral DNA replication and the expression of viral late proteins. We have used a large synthetic immunoglobulin library displayed on phage (diversity 6.5 x 10(10) phage) to isolate three Fabs (TVG405, 406, and 407) which recognize distinct epitopes on the E4 late protein of HPV16. A C-terminal monoclonal (TVG404) was generated by hybridoma technology, and N-terminal polyclonal antiserum was prepared by peptide immunization (alpha N-term). The most potent antibody (TVG405) had an affinity for E4 of approximately 1.0 nM. All antibodies recognized the protein in paraffin-embedded archival material, allowing us to map events in the late stages of virus infection. Expression of E4 in vivo does not coincide with synthesis of the major virus coat protein L1, but precedes it by 1 or 2 cell layers in premalignant lesions caused by HPV16 and by up to 20 cell layers in HPV63-induced warts. In higher grade lesions associated with HPV16, E4 is produced in the absence of L1. By contrast, vegetative viral DNA replication and E4 expression correlate exactly and in some lesions begin as the infected epithelial cell leaves the basal layer. Differentiation markers such as filaggrin, loricrin, and certain keratins are not detectable in E4-positive cells, and nuclear degeneration is delayed. HPV16 E4 has a filamentous distribution in the lower epithelial layers, but associates with solitary perinuclear structures in more differentiated cells. Antibodies to the N-terminus of the protein stained these structures poorly. Our findings are compatible with a role for the HPV16 E4 protein in vegetative DNA replication or in modifying the phenotype of the infected cell to favor virus synthesis or virus release. The Fabs will be of value in the evaluation of model systems for mimicking HPV infection in vitro.

Multiple pigmented cutaneous papules associated with a novel canine papillomavirus in an immunosuppressed dog

Cutaneous papillomavirus infection was diagnosed in a 6-year-old female Boxer dog that was under long-term corticosteroid therapy for atopic dermatitis. Multiple black, rounded papules were present on the ventral skin. Spontaneous regression occurred within 3 weeks after cessation of corticosteroids. Histologically, the lesions consisted of well-demarcated cup-shaped foci of epidermal endophytic hyperplasia with marked parakeratosis. In the upper stratum spinosum and in the stratum granulosum, solitary or small collections of enlarged keratinocytes were observed with basophilic intranuclear inclusion bodies and a single eosinophilic fibrillar cytoplasmic inclusion. Ultrastructurally, viruslike particles (40-45 nm in diameter) were observed within the nucleus, free or aggregated in crystalline arrays. Undulating fibrillar material, thought to be a modified keratin protein, was observed in the cytoplasmic inclusion. Immunohistochemistry, restriction enzyme analysis, and molecular hybridization experiments indicated that these distinctive clinical, histologic, and cytologic features were associated with a novel canine papillomavirus.