The Experts below are selected from a list of 126 Experts worldwide ranked by ideXlab platform
Richard Schlegel - One of the best experts on this subject based on the ideXlab platform.
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dihydroartemisinin is cytotoxic to Papillomavirus expressing epithelial cells in vitro and in vivo
Cancer Research, 2005Co-Authors: Gary L Disbrow, Hang Yuan, Astrid Baege, Katie A Kierpiec, Jose A Centeno, Clare A Thibodeaux, Dan P Hartmann, Richard SchlegelAbstract:Nearly all cervical cancers are etiologically attributable to human Papillomavirus (HPV) infection and pharmaceutical treatments targeting HPV-infected cells would be of great medical benefit. Because many neoplastic cells (including cervical cancer cells) overexpress the transferrin receptor to increase their iron uptake, we hypothesized that iron-dependent, antimalarial drugs such as artemisinin might prove useful in treating HPV-infected or transformed cells. We tested three different artemisinin compounds and found that dihydroartemisinin (DHA) and artesunate displayed strong cytotoxic effects on HPV-immortalized and transformed cervical cells in vitro with little effect on normal cervical epithelial cells. DHA-induced cell death involved activation of the mitochondrial caspase pathway with resultant apoptosis. Apoptosis was p53 independent and was not the consequence of drug-induced reductions in viral oncogene expression. Due to its selective cytotoxicity, hydrophobicity, and known ability to penetrate epithelial surfaces, we postulated that DHA might be useful for the topical treatment of mucosal Papillomavirus lesions. To test this hypothesis, we applied DHA to the Oral mucosa of dogs that had been challenged with the Canine Oral Papillomavirus. Although applied only intermittently, DHA strongly inhibited viral-induced tumor formation. Interestingly, the DHA-treated, tumor-negative dogs developed antibodies against the viral L1 capsid protein, suggesting that DHA had inhibited tumor growth but not early rounds of Papillomavirus replication. These findings indicate that DHA and other artemisinin derivatives may be useful for the topical treatment of epithelial Papillomavirus lesions, including those that have progressed to the neoplastic state.
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Characterization of HPV16 L1 loop domains in the formation of a type-specific, conformational epitope
BMC Microbiology, 2004Co-Authors: Vanessa A Olcese, Richard Schlegel, Yan Chen, Hang YuanAbstract:Background Virus-like particles (VLPs) formed by the human Papillomavirus (HPV) L1 capsid protein are currently being tested in clinical trials as prophylactic vaccines against genital warts and cervical cancer. The efficacy of these vaccines is critically dependent upon L1 type-specific conformational epitopes. To investigate the molecular determinants of the HPV16 L1 conformational epitope recognized by monoclonal antibody 16A, we utilized a domain-swapping approach to generate a series of L1 proteins composed of a Canine Oral Papillomavirus (COPV) L1 backbone containing different regions of HPV16 L1. Results Gross domain swaps, which did not alter the ability of L1 to assemble into VLPs, demonstrated that the L1 N-terminus encodes at least a component of the 16A antigenic determinant. Finer epitope mapping, using GST-L1 fusion proteins, mapped the 16A epitope to the L1 variable regions I and possibly II within the N-terminus. Conclusions These results suggest that non-contiguous loop regions of L1 display critical components of a type-specific, conformational epitope.
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immunization with a pentameric l1 fusion protein protects against Papillomavirus infection
Journal of Virology, 2001Co-Authors: Hang Yuan, Patricia A Estes, Vanessa A Olcese, Robert L Garcea, Joseph T Newsome, Yan Chen, Richard SchlegelAbstract:The prophylactic Papillomavirus vaccines currently in clinical trials are composed of viral L1 capsid protein that is synthesized in eukaryotic expression systems and purified in the form of virus-like particles (VLPs). To evaluate whether VLPs are necessary for effective vaccination, we expressed the L1 protein as a glutathione S -transferase (GST) fusion protein in Escherichia coli and assayed its immunogenic activity in an established Canine Oral Papillomavirus (COPV) model that previously validated the efficacy of VLP vaccines. The GST-COPV L1 fusion protein formed pentamers, but these capsomere-like structures did not assemble into VLPs. Despite the lack of VLP formation, the GST-COPV L1 protein retained its native conformation as determined by reactivity with conformation-specific anti-COPV antibodies. Most importantly, the GST-COPV L1 pentamers completely protected dogs from high-dose viral infection of their Oral mucosa. L1 fusion proteins expressed in bacteria represent an economical alternative to VLPs as a human Papillomavirus vaccine.
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systemic immunization with Papillomavirus l1 protein completely prevents the development of viral mucosal papillomas
Proceedings of the National Academy of Sciences of the United States of America, 1995Co-Authors: Joann Suzich, Shin-je Ghim, Frances J Palmerhill, J K Tamura, J A Newsome, Wendy I. White, Alfred B. Jenson, J A Bell, Richard SchlegelAbstract:Abstract Infection of mucosal epithelium by Papillomaviruses is responsible for the induction of genital and Oral warts and plays a critical role in the development of human cervical and oropharyngeal cancer. We have employed a Canine model to develop a systemic vaccine that completely protects against experimentally induced Oral mucosal papillomas. The major capsid protein, L1, of Canine Oral Papillomavirus (COPV) was expressed in Sf9 insect cells in native conformation. L1 protein, which self-assembled into virus-like particles, was purified on CsCl gradients and injected intradermally into the foot pad of beagles. Vaccinated animals developed circulating antibodies against COPV and became completely resistant to experimental challenge with COPV. Successful immunization was strictly dependent upon native L1 protein conformation and L1 type. Partial protection was achieved with as little as 0.125 ng of L1 protein, and adjuvants appeared useful for prolonging the host immune response. Serum immunoglobulins passively transferred from COPV L1-immunized beagles to naive beagles conferred protection from experimental infection with COPV. Our results indicate the feasibility of developing a human vaccine to prevent mucosal papillomas, which can progress to malignancy.
Marc Van Ranst - One of the best experts on this subject based on the ideXlab platform.
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Isolation and cloning of the raccoon (Procyon lotor) Papillomavirus type 1 by using degenerate Papillomavirus-specific primers.
The Journal of general virology, 2005Co-Authors: Annabel Rector, John P Sundberg, Koenraad Van Doorslaer, Mads Bertelsen, Ian K Barker, Rolf-arne Olberg, Philippe Lemey, Marc Van RanstAbstract:Partial sequences of a novel Papillomavirus were amplified from a cutaneous lesion biopsy of a raccoon (Procyon lotor), by using PCR with degenerate Papillomavirus-specific primers. The Procyon lotor Papillomavirus type 1 (PlPV-1) DNA was amplified with long template PCR in two overlapping fragments, together encompassing the entire genome, and the complete PlPV-1 genomic sequence was determined. The PlPV-1 genome consists of 8170 bp, and contains the typical papillomaviral open reading frames, encoding five early proteins and two late capsid proteins. Besides the classical non-coding region (NCR1) between the end of L1 and the start of E6, PlPV-1 contains an additional non-coding region (NCR2) of 1065 bp between the early and late protein region, which has previously also been described for the Canine Oral Papillomavirus (COPV) and the Felis domesticus Papillomavirus (FdPV-1). Phylogenetic analysis places PlPV-1 together with COPV and FdPV-1 in a monophyletic branch which encompasses the Lambda Papillomavirus genus.
H Shirasawa - One of the best experts on this subject based on the ideXlab platform.
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detection of Canine Oral Papillomavirus dna in Canine Oral squamous cell carcinomas and p53 overexpressing skin papillomas of the dog using the polymerase chain reaction and non radioactive in situ hybridization
Veterinary Microbiology, 1998Co-Authors: J P Teifke, C V Lohr, H ShirasawaAbstract:Abstract Nineteen cutaneous and mucocutaneous papillomas, as well as 29 Oral and 25 non-Oral squamous cell carcinomas of dogs were analyzed immunohistologically for the presence of Papillomavirus (PV)-antigens. Canine Oral Papillomavirus (COPV)-DNA was detected in formalin-fixed, paraffin-embedded tissues by polymerase chain reaction (PCR) and non-radioactive in situ hybridization (ISH). Furthermore, the expression of the tumor suppressor protein p53 was investigated. PV-antigens were detectable in more than 50% of the Oral and cutaneous papillomas, while no PV-antigens could be demonstrated in venereal papillomas. One squamous cell carcinoma was PV-antigen positive. Only two cutaneous papillomas of the head showed a strong p53-specific immunostaining, while overexpressed p53 was detectable in approximately 35% of all squamous cell carcinomas. It was possible to amplify fragments of the E6, E7 and L1 gene by polymerase chain reaction (PCR) from five of eight Oral and from five of eight cutaneous papillomas as well as from three Oral squamous cell carcinomas. Nine of 10 papillomas showed a strong nucleus-associated hybridization signal typical for COPV-DNA. In three squamous cell carcinomas COPV-DNA was located in nests of the epithelial tumor cells surrounding `horn pearls' or disseminated in the carcinoma tissue. These observations support the view that COPV may also induce non-Oral papillomas in the dog and confirm the opinion that a progression of viral papillomas into carcinomas in dogs may occur.
Gary Ketner - One of the best experts on this subject based on the ideXlab platform.
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hpv16 l1 capsid protein expressed from viable adenovirus recombinants elicits neutralizing antibody in mice
Vaccine, 2007Co-Authors: Michael Berg, Richard B S Roden, Ratish Gambhira, Mark C Siracusa, Egbert Hoiczyk, Gary KetnerAbstract:Immunization against human Papillomavirus (HPV) infection promises to reduce the worldwide burden of cervical cancer. To evaluate the potential of live recombinant adenoviruses for induction of HPV infection-blocking immunity, we prepared viable adenovirus recombinants that express the HPV16 L1 gene from the adenovirus major late transcriptional unit. Adenovirus-produced HPV16 L1 assembles into virus-like particles (VLPs) in infected cells in culture. Purified HPV16 VLPs are recognized by HPV16 neutralizing antibodies and induce high neutralizing titers when injected intraperitoneally into mice. Canine Oral Papillomavirus VLPs derived from previously described recombinants also induce strong antibody responses in mice. These data support our suggestion that viable adenovirus recombinants will be able to induce protective immunity to Papillomavirus infection during replication in human vaccinees.
Hang Yuan - One of the best experts on this subject based on the ideXlab platform.
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dihydroartemisinin is cytotoxic to Papillomavirus expressing epithelial cells in vitro and in vivo
Cancer Research, 2005Co-Authors: Gary L Disbrow, Hang Yuan, Astrid Baege, Katie A Kierpiec, Jose A Centeno, Clare A Thibodeaux, Dan P Hartmann, Richard SchlegelAbstract:Nearly all cervical cancers are etiologically attributable to human Papillomavirus (HPV) infection and pharmaceutical treatments targeting HPV-infected cells would be of great medical benefit. Because many neoplastic cells (including cervical cancer cells) overexpress the transferrin receptor to increase their iron uptake, we hypothesized that iron-dependent, antimalarial drugs such as artemisinin might prove useful in treating HPV-infected or transformed cells. We tested three different artemisinin compounds and found that dihydroartemisinin (DHA) and artesunate displayed strong cytotoxic effects on HPV-immortalized and transformed cervical cells in vitro with little effect on normal cervical epithelial cells. DHA-induced cell death involved activation of the mitochondrial caspase pathway with resultant apoptosis. Apoptosis was p53 independent and was not the consequence of drug-induced reductions in viral oncogene expression. Due to its selective cytotoxicity, hydrophobicity, and known ability to penetrate epithelial surfaces, we postulated that DHA might be useful for the topical treatment of mucosal Papillomavirus lesions. To test this hypothesis, we applied DHA to the Oral mucosa of dogs that had been challenged with the Canine Oral Papillomavirus. Although applied only intermittently, DHA strongly inhibited viral-induced tumor formation. Interestingly, the DHA-treated, tumor-negative dogs developed antibodies against the viral L1 capsid protein, suggesting that DHA had inhibited tumor growth but not early rounds of Papillomavirus replication. These findings indicate that DHA and other artemisinin derivatives may be useful for the topical treatment of epithelial Papillomavirus lesions, including those that have progressed to the neoplastic state.
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Characterization of HPV16 L1 loop domains in the formation of a type-specific, conformational epitope
BMC Microbiology, 2004Co-Authors: Vanessa A Olcese, Richard Schlegel, Yan Chen, Hang YuanAbstract:Background Virus-like particles (VLPs) formed by the human Papillomavirus (HPV) L1 capsid protein are currently being tested in clinical trials as prophylactic vaccines against genital warts and cervical cancer. The efficacy of these vaccines is critically dependent upon L1 type-specific conformational epitopes. To investigate the molecular determinants of the HPV16 L1 conformational epitope recognized by monoclonal antibody 16A, we utilized a domain-swapping approach to generate a series of L1 proteins composed of a Canine Oral Papillomavirus (COPV) L1 backbone containing different regions of HPV16 L1. Results Gross domain swaps, which did not alter the ability of L1 to assemble into VLPs, demonstrated that the L1 N-terminus encodes at least a component of the 16A antigenic determinant. Finer epitope mapping, using GST-L1 fusion proteins, mapped the 16A epitope to the L1 variable regions I and possibly II within the N-terminus. Conclusions These results suggest that non-contiguous loop regions of L1 display critical components of a type-specific, conformational epitope.
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immunization with a pentameric l1 fusion protein protects against Papillomavirus infection
Journal of Virology, 2001Co-Authors: Hang Yuan, Patricia A Estes, Vanessa A Olcese, Robert L Garcea, Joseph T Newsome, Yan Chen, Richard SchlegelAbstract:The prophylactic Papillomavirus vaccines currently in clinical trials are composed of viral L1 capsid protein that is synthesized in eukaryotic expression systems and purified in the form of virus-like particles (VLPs). To evaluate whether VLPs are necessary for effective vaccination, we expressed the L1 protein as a glutathione S -transferase (GST) fusion protein in Escherichia coli and assayed its immunogenic activity in an established Canine Oral Papillomavirus (COPV) model that previously validated the efficacy of VLP vaccines. The GST-COPV L1 fusion protein formed pentamers, but these capsomere-like structures did not assemble into VLPs. Despite the lack of VLP formation, the GST-COPV L1 protein retained its native conformation as determined by reactivity with conformation-specific anti-COPV antibodies. Most importantly, the GST-COPV L1 pentamers completely protected dogs from high-dose viral infection of their Oral mucosa. L1 fusion proteins expressed in bacteria represent an economical alternative to VLPs as a human Papillomavirus vaccine.
