ZIA BC 010579 (ZIA) | |||
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Title | Papillomavirus Virion Proteins and Vaccines | ||
Institution | NCI, Bethesda, MD | ||
Principal Investigator | Lowy, Douglas | NCI Program Director | N/A |
Cancer Activity | N/A | Division | CCR |
Funded Amount | $542,150 | Project Dates | 00/00/0000 - 00/00/0000 |
Fiscal Year | 2017 | Project Type | Intramural |
Research Topics w/ Percent Relevance | Cancer Types w/ Percent Relevance | ||
Cancer (100.0%) Digestive Diseases (10.0%) |
Anus (10.0%) Cervical Cancer (60.0%) Head and Neck (10.0%) Penis (10.0%) Vaginal (10.0%) |
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Research Type | |||
Exogenous Factors in the Origin and Cause of Cancer Vaccines |
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Abstract | |||
Papillomaviruses (PVs) infect the epithelia of animals and man, where they generally induce benign proliferation at the site of infection. In addition, persistent infection by some human papillomaviruses (HPV), especially HPV16, can induce malignant progression of human genital lesions and certain human papillomavirus (HPV) types. Our research is concerned with the biology of papillomavirus infection, elucidation of the PV life cycle, and development of vaccines and other strategies to inhibit HPV infection. We previously developed a simple and efficient strategy for generating high titers of infectious papillomavirus particles that transduce encapsidated marker plasmids, i.e. pseudovirions. We have exploited this technology in our basic virologic and translational research efforts, leading to development of the first cervicovaginal challenge model for HPVs. Using the mouse model, we determined that transient disruption of epithelial integrity is required for HPV infection, that the first step in the virus life cycle involves binding of the virus to the basement membrane, and that the virus transfers to target epithelial cells only after the L2 protein in the capsid has undergone an enzymatic cleavage while on the basement membrane. The cleavage of L2 is associated with a conformational change in the capsid, leading to exposure of highly conserved L2 cross-neutralization epitopes that lie C-terminal to the cleavage site. In a process that takes several hours, the virions transfer from the basement membrane to the surface of keratinocytes invading the site of trauma, and the virions are then internalized. The mouse model also enabled us to determine that antibodies induced by L1 VLP vaccines (which are now FDA-approved) and L2 vaccines (which we are developing as a more broadly cross type-neutralizing alternative) block in vivo infection by distinct mechanisms. At high concentrations, L1 VLP-induced antibodies block virion binding to the basement membrane, while at low concentrations, they permit basement membrane binding but prevent binding to target keratinocytes. Since the L2 cross-neutralization epitopes are cryptic, and are not exposed until after the virions have been bound to the basement membrane, L2 antibodies that broadly cross-neutralize HPV types do not interfere with initial basement membrane binding. Once the L2 epitopes are exposed, while the virions remain on the basement membrane, the L2 antibodies can bind to the virions, and abrogate the infectious process by preventing transfer of the virions to target keratinocytes. Both in the mouse model and in an analogous model developed for the rhesus macaque, infection is prevented by local application of carrageenan, which is an algal polysaccharide widely used in processed food and cosmetics and is the main gelling agent in some over-the-counter lubricants. Based on our data, clinical trials of carrageenan as a microbicide to prevent genital HPV infection in young women are underway. Using HPV pseudoviruses, we previously developed a high throughput in vitro HPV neutralization assay that has become the gold standard for the field. Based on the improved understanding of the in vivo infectious process and the mechanism by which L2 vaccines conferred protection, we developed a new in vitro neutralizing assay that is approximately three orders of magnitude more sensitive than the standard assay in detecting L2 neutralizing antibodies. The new assay should have considerable utility for determining the immunogenicity of candidate L2 vaccines and for clinical trials of L2 vaccines. Our development of a method to induce efficient HPV pseudovirus infection of the female genital tract after transient epithelial disruption with nonoxynol-9 (N-9) proved to be the key to our development of an effective intravaginal vaccination strategy. In patent pending studies, we found that intravaginal pseudovirus vaccination of N-9-treated mice induces strong systemic and mucosal T and B ce |