Erythroplasia of Queyrat is a carcinoma in situ that mainly occurs on the glans penis, the prepuce, or the urethral meatus of elderly males. Up to 30% progress to squamous cell carcinoma. The cause of erythroplasia of Queyrat is largely unknown. Human papillomavirus type 16 DNA has previously been detected only in very few distinctly characterized patients. We have investigated 12 paraffin-embedded biopsies from eight patients with penile erythroplasia of Queyrat and control biopsies of inflammatory penile lesions, of genital Bowen's disease, and of premalignant/malignant cervical or vulvar lesions by 10 different polymerase chain reaction protocols for the presence of cutaneous and genital/mucosal human papillomaviruses. Human papillomavirus typing was performed by sequencing (cloned) polymerase chain reaction products. Human papillomavirus DNA was detected in all erythroplasia of Queyrat patients and in none of the controls with inflammatory penile lesions. The rare cutaneous carcinogenic epidermodysplasia verruciformis-associated human papillomavirus type 8 was present in all erythroplasia of Queyrat patients and the genital high-risk human papillomavirus type 16 in seven of eight patients (88%). In addition to human papillomavirus type 8 and human papillomavirus type 16, four patients carried the genital carcinogenic human papillomavirus type 39 and/or type 51. All human papillomavirus type 8 sequences found in erythroplasia of Queyrat showed some polymorphism among each other and differed in specific nucleotide exchanges from the human papillomavirus type 8 reference sequence. Viral load determinations (human papillomavirus copies/beta-globin gene copies) by realtime polymerase chain reactions showed that the human papillomavirus type 16 levels in the erythroplasia of Queyrat biopsies were one to five orders of magnitude higher than the human papillomavirus type 8 levels. Human papillomavirus type 8 was not detected in cervical or vulvar precancerous and cancerous lesions and in Bowen's disease lesions that carried genital human papillomavirus types. The data suggest that in erythroplasia of Queyrat, in contrast to other genital neoplasias, a coinfection with human papillomavirus type 8 and carcinogenic genital human papillomavirus types occurs. The presence or absence of human papillomavirus type 8 might help to distinguish between penile erythroplasia of Queyrat and Bowen's diseases.

DNA of human papillomaviruses has frequently been detected in nonmelanoma skin cancers, raising the question of a possible causal contribution of these tumor viruses to skin carcinogenesis. Basal cell carcinomas are the most common nonmelanoma skin cancers; however, so far they are only poorly analyzed with regard to human papillomavirus infection. We searched for human papillomavirus-DNA in 69 biopsies from 61 immunocompetent basal cell carcinoma patients from two geographic locations in Europe using six different polymerase chain reaction primer systems. We could demonstrate human papillomavirus-DNA in 43.5% of the tested tumors. Human papillomavirus positivity did not seem to correlate with the duration of disease or patients' age. The vast majority of virus types in the biopsies belonged to the group of epidermodysplasia verruciformis-associated human papillomavirus. Of 31 sample pairs tested for human papillomavirus-DNA in tumors as well as in perilesional healthy skin, seven carried viral sequences in lesional and healthy skin and three only in the basal cell carcinoma. Six of the seven human papillomavirus-positive basal cell carcinoma/healthy skin pairs contained identical human papillomavirus types in tumors and histologically normal tissue. Forty basal cell carcinoma patients were additionally analyzed for IgG antibodies against virus-like particles of three representative epidermodysplasia verruciformis-human papillomavirus types: 8, 15, and 36. No statistically significant differences could be detected between human papillomavirus antibody prevalences of basal cell carcinoma patients and of dermatologically healthy individuals. Moreover, serologic findings did not correlate with the detection of specific human papillomavirus types in tumors. Our results seem to suggest that the occurrence of human papillomavirus-DNA in basal cell carcinoma does not reflect a major etiologic role of human papillomavirus in this cancer.

The E2 proteins of papillomaviruses (PV) bind to the coactivator CBP/p300 as do many other transcription factors, but the precise role of CBP/p300 in E2-specific functions is not yet understood. We show that the E2 protein of human PV type 8 (HPV8) directly binds to p300. Activation of HPV8 gene expression by low amounts of HPV8 E2 was stimulated up to sevenfold by coexpression of p300. The interaction between E2 and p300 may play a role in differentiation-dependent activation of PV gene expression, since we can show that the expression level of p300 increases during keratinocyte differentiation. Surprisingly, sequence-specific binding of E2 to its recognition sites within the regulatory region of HPV8 is not necessary for this cooperation, indicating that E2 can be recruited to the promoter via protein-protein interaction. HPV8 E2 binds via its N-terminal activation domain (AD), its C-terminal DNA binding domain (DBD), and its internal hinge region to p300 in vitro. Transient-transfection assays revealed that the AD is necessary and sufficient for cooperative activation with p300. However, we provide evidence that the interaction of the hinge and the DBD of HPV8 E2 with p300 may contribute. Our data suggest an important role of p300 in regulation of HPV8 gene expression and reveal a new mechanism by which E2 may be recruited to a promoter to activate transcription without sequence specific DNA binding.Papillomaviruses (PV) infect the basal cells of the skin or the mucosa, causing proliferative lesions like warts or dysplasias. PV require differentiating keratinocytes to replicate their DNA. The expression of the structural proteins is restricted to some of the most-differentiated keratinocytes. This cell tropism is due to the involvement of transcription factors specifically expressed in these cells. In addition to ubiquitously expressed and keratinocyte-specific cellular transcription factors, viral gene expression is also modulated by the viral E2 protein. The E2 protein binds via its carboxy (C)-terminal DNA binding domain (DBD) and dimerization domain to the 12-bp palindromic sequence ACCN 6 GGT mostly located within the regulatory region, also called the long control region or noncoding region (NCR) of the PV genome. In the case of bovine PV type 1 (BPV1), the long control region contains 12 E2 binding sites, which mediate a strong activation of several BPV1 promoters by E2 (48-50). Human PV (HPV) types infecting the genital mucosa contain four E2 binding sites in conserved positions. Here, only a moderate activation by E2 could be detected, and E2 repressed HPV gene expression in most cases. This repression is mediated by binding to two promoter-proximal E2 binding sites, as revealed by transient transfections of cervical carcinoma cell lines and immortalized skin keratinocytes (10,52,58,59). Repression of HPV gene expression by the E2 activator protein occurs when E2 binding sites are overlapping with the binding sites for cellular transcription factors necessary for promoter activity. In contrast to nat...

SummaryMolecular mimicry between viral antigens and host proteins was often suggested to be involved in induction of autoimmune diseases. In type 1 diabetes where pancreatic 13 cells are destroyed by autoimmune phenomena, a linear sequence homology between a major autoantigen, glutamate decarboxylase (GAD), and the 2C protein of coxsackie B4 was identified. In addition, a sequence homology between GAD and the mycobacterial heat shock protein 60 was described and the suggestions were made that molecular mimicry between GAD, coxsackievirus B4-2C protein, and/or heat shock protein 60 (hsp60) may be actively involved in an autoimmune reaction towards the pancreatic/g-cells. Our group was the first to isolate human monoclonal autoantibodies to GAD (MICA 1-6) from a patient with newly diagnosed type I diabetes. The MICA allowed a detailed characterization of the diabetes associated self-epitopes in GAD and represent a set of GAD autoantibodies present in sera from patients with type I diabetes. Using deletion mutants of GAD we demonstrated that the regions of GAD covering the homology sequences to coxsackievirus B4 and to the hsp60 were absolutely required for binding of the MICA to GAD. We now designed an antibody-based analysis to ask whether molecular mimicry between GAD and coxsackie B4-2C or hsp60 is relevant in type 1 diabetes. Since part of the MICA recognize conformational epitopes, they allow to test for conformational molecular mimicry in viruses that have been incriminated in the development of type I diabetes. Our data reveal no crossreactivity between the diabetes associated GAD epitopes defined by the MICA and hsp60, rubellavirus, cytomegalovirus, and coxsackie B1-B6 virus antigens. Neither coxsackie B4-specific antibodies in sera from normal individuals nor GAD-positive sera from patients with type 1 diabetes indicated a crossreactivity between coxsackie B4-2C and GAD. Although the regions in GAD homologous to coxsackie B4-2C and hsp60 represented parts of GAD indispensible for binding of diabetes associated autoantibodies they did not mediate a crossreactivity of autoantibodies between GAD and these two proteins. No evidence for molecular mimicry between GAD and a whole panel of foreign antigens was detected by autoantibodies in type 1 diabetes.

No abstract