Human Papillomavirus Virus-like Particles Research Articles

Chapter 13: Current findings from prophylactic HPV vaccine trials

Early data from randomized controlled trials consistently show that prophylactic human papillomavirus virus-like particle (HPV VLP) vaccines are effective in preventing infection and lesions caused by the targeted HPV type(s). Two vaccines, a bivalent HPV-16/18 VLP vaccine and a quadrivalent HPV-6/11/16/18 VLP vaccine, are currently undergoing evaluation in phase III trials with anticipation of receiving regulatory approval for use in immunization programs worldwide. Both vaccines have the potential to substantially reduce HPV-related morbidity and mortality. This review focuses on published data from clinical trials of these two vaccines.

Evaluation of antibodies induced by an HPV vaccine to cross-neutralize pseudovirions of vaccine-related HPV types

15008 Background: Human papillomavirus (HPV) is the causative agent of cervical cancer. The HPV types 6, 11, 16 and 18 quadrivalent L1 virus-like particle (VLP) vaccine has been shown to be highly efficacious in preventing HPV vaccine type-related disease. The HPV A7 species contains types 18, 45 and 59. The A9 species include types 16, 31, 33, 35, 52 and 58. The potential of the vaccine induced antibodies to cross-neutralize infection of pseudovirions (PsV) of HPV types within the A9 and A7 species was evaluated. Methods: Sera from quadrivalent, monovalent HPV 16, or monovalent HPV 18 vaccinees were evaluated. Sera were tested in a multiplexed competitive Luminex Immunoassay (cLIA) against vaccine types to demonstrate HPV type-specific seroconversion. A9 and A7 VLP type cross-reactive binding ability was assessed by a total IgG LIA. HPV L1 and L2 PsV containing secreted alkaline-phosphatase (SEAP) sequences were constructed using native HPV sequences for 16 and 31 and with mammalian codon-optimized sequences for 18 and 45. Demonstrated expression of SEAP was used as an indirect measure of PsV infection of 293TT cells. Results: All subjects seroconverted to high titers against the vaccine HPV types. Cross-reactive antibodies were generated. Quadrivalent vaccinee sera bound to HPV 31, 45, 52 and 58 VLPs. These total IgG titers were 1.5–2 logs lower than the titers to the vaccine types. PsV types 18 and 45 were neutralized using the 18 monovalent and the quadrivalent sera. At month 7, the PsV 18 neutralization titer was ∼1–1.5 logs less than that required for PsV 45 cross-neutralization. Neutralization studies using PsV of the A9 species are in progress. Conclusions: High titers of anti-HPV antibodies are elicited by vaccination with HPV VLP vaccines. These antibodies can prevent in vitro PsV infection of vaccine-HPV types. Cross-reactive, cross-neutralizing antibodies are generated, however at reduced titers compared to the vaccine-specific types. Antibody titers required for cross-protection against non-vaccine types are not known. [Table: see text]

Chapter 27: Research needs following initial licensure of virus-like particle HPV vaccines

Human papillomavirus virus-like particle (HPV VLP) HPV vaccines currently evaluated for licensing are likely to be available soon. Licensure will be based on evidence that the vaccine is well tolerated and provides near complete type-specific protection against HPV infections and their resulting lesions in the first few years after vaccination. Several important questions will remain to be answered after licensure to guide vaccine implementation and to permit the rational evaluation of vaccination in cancer prevention programs. These include the long-term safety and efficacy of vaccination, the optimal ages for vaccination, efficacy against HPV types not included in the vaccine and against existing infections, and efficacy in males. Modulators of vaccine efficacy (e.g., HIV infection) and immune mechanisms of long-term protection also remain to be defined. The real-world effectiveness of vaccination programs will need to be assessed. Issues related to the implementation of a vaccine that targets pre-adolescents and early adolescents and to the acceptability of a cancer vaccine targeted against a sexually transmitted infection will need to be understood before vaccination programs can be successful. It is hoped that continued improvements to the current HPV vaccines will lead to the introduction in future years of second generation vaccines that simplify delivery and/or expand its coverage. Finally, the natural history of HPV types not covered in the candidate vaccines will need to be carefully studied following vaccination. Public health authorities in various countries will play a pivotal role in determining if these questions are answered in a timely manner.

Papillomavirus virus-like particles activate the PI3-kinase pathway via alpha-6 beta-4 integrin upon binding

We have previously shown that human papillomavirus virus-like particles (VLPs) are able to activate the Ras/MAP kinase pathway. Ras can also elicit an anti-apoptotic signal via PI3-kinase so we investigated this further. Here we show that binding of VLPs from HPV types 6b, 18, 31, 35 and BPV1 results in activation of PI3-kinase. Activation was achieved by either L1 or L1/L2 VLPs and was dependent on both VLP–cell interaction and correct conformation of the virus particle. VLP-induced PI3-kinase activity resulted in efficient downstream signaling to Akt and consequent phosphorylation of FKHR and GSK3β. We also present evidence that PV signaling is activated via the α6β4 integrin. These data suggest that papillomaviruses use a common receptor that is able to signal through to Ras. Combined activation of the Ras/MAP kinase and PI3-kinase pathways may be beneficial for the virus by increasing cell numbers and producing an environment more conducive to infection.

Virus and virus-like particle-based immunogens for Alzheimer's disease induce antibody responses against amyloid-β without concomitant T cell responses

A vaccine targeting the amyloid-beta (Aβ) peptide is a promising potential immunotherapy for Alzheimer's disease patients. However, experience from a recent clinical trial of a candidate Aβ vaccine has suggested that it is important to develop techniques to induce high titer antibodies against Aβ associated with vaccine efficacy while reducing the T cell responses against Aβ that were potentially responsible for serious side effects. We have previously demonstrated that immunization with self- and foreign antigens arrayed in a repetitive fashion on the surface of virus-like particles (VLPs) induces high titer antibody responses at low doses and in the absence of potentially inflammatory adjuvants. In this study, we examined the antibody and T cell responses upon immunization with human papillomavirus VLP- and Qβ bacteriophage-based Aβ vaccines. Immunization with Aβ conjugated to VLPs or Qβ elicited anti-Aβ antibody responses at low doses and without the use of adjuvants. The flexibility of these virus-based display systems allowed us to link and induce antibodies against short Aβ-derived peptides from the amino- and carboxyl-termini of the peptide. Immunization of mice with Aβ peptide in combination with Freund's adjuvant elicited predominantly IgG2c antibodies and strong T cell proliferative responses against Aβ. In contrast, VLP-conjugated Aβ peptides elicited more balanced isotype responses, dominated by IgG1. Both VLP and Qβ-based Aβ vaccines induced weak or negligible T cell responses against Aβ. T cell responses were largely directed against linked viral epitopes. Taken together, virus-based vaccines that allow the presentation of Aβ in a repetitive dense array are new and potentially more effective vaccine candidates for Alzheimer's disease.

Human papillomavirus serology and the risk of esophageal and gastric cancers: Results from a cohort in a high‐risk region in China

Each year, esophageal and gastric cancers cause more than 900,000 deaths worldwide. Human papilloma virus (HPV), especially type 16, has been suggested to have a role in the etiology of esophageal cancer, however, the results of previous seroepidemiological studies have not been consistent. We conducted a large prospective study to examine the association between serum antibodies to HPV 16, HPV 18 and HPV 73 and subsequent development of esophageal squamous cell carcinoma (ESCC), gastric cardia adenocarcinoma (GCA), and gastric noncardia adenocarcinoma (GNCA) in a high-risk population for these cancers in Linxian, China. Case and control subjects for this study were selected from the 29,584 participants of the Linxian General Population Trial. Prediagnostic serum samples from 99 cases of ESCC, 100 cases of GCA, 70 cases of GNCA, and 381 age- and sex- matched controls were selected for this study. The presence of antibodies to HPV virus-like particles was determined by type-specific enzyme-linked immunosorbent assays. Fewer than 15% of ESCC, GCA, or GNCA cases were positive for each HPV type, and no significant associations were found. The adjusted odds ratios (ORs) and 95% confidence intervals (95% CIs) for HPV 16 seropositivity and ESCC, GCA, and GNCA risk were 1.6 (0.8-3.3), 1.3 (0.6-2.8) and 0.4 (0.1-1.6), respectively. The comparable ORs (95% CIs) for HPV 18 were 1.0 (0.4-2.2), 0.9 (0.4-2.1) and 1.5 (0.6-3.4). For HPV 73, these figures were 1.3 (0.6-2.5), 1.2 (0.6-2.3) and 0.9 (0.4-2.1). The results of this study do not support a major role for HPV 16, HPV 18 and HPV 73 in the etiology of esophageal and gastric cancers in Linxian, China.

Population-based enrolment of adolescents in a long-term follow-up trial of human papillomavirus vaccine efficacy

We evaluated a study setting for assessment of the long-term vaccine efficacy (VE) of human papillomavirus (HPV) virus-like-particle (VLP) vaccine against cervical carcinoma. A total of 22,412 16- to 17-year old adolescent women from seven cities in Finland were invited by letter to participate in a phase III study of a quadrivalent HPV (types 6, 11, 16, 18) VLP vaccine, between September 2002 and March 2003. A total of 30,947 18-year old women were invited to participate as unvaccinated controls. These women were asked about their willingness to participate in an HPV vaccination trial and to fill a health questionnaire. These three population-based cohorts of adolescent women, including women vaccinated with HPV vaccine or placebo vaccine and unvaccinated control women, are systematically followed over time. The study cohort database will be linked with the Finnish Cancer Registry using cervical carcinoma in situ (CIS) and invasive cervical carcinoma (ICC) as endpoints. Assuming that the cumulative incidence of CIS and ICC over 15 years is 0.45%, and that there is no loss to follow-up, and power of 80%, the determination of 70% total VE will require 3357 HPV vaccine recipients, 3357 placebo vaccine recipients, and 6714 unvaccinated controls. At the baseline, 2632 (12%) of the invited adolescents volunteered to the phase III vaccination trial, and 6790 (22%) responded to the questionnaire study. During a recruitment period of 10 months, 874 HPV vaccine recipients, 875 placebo recipients and 1919 unvaccinated controls were enrolled. Population-based enrollment of large cohorts of vaccinated and unvaccinated adolescents for passive registry-based follow-up with cervical carcinoma as the end-point is feasible and currently going on in Finland.

Prévention du cancer du col utérin : enjeux et perspectives de la vaccination antipapillomavirus

Cervical cancer remains a critical public health problem that is second only to breast cancer in overall disease burden for women throughout the world. In spite of the success of cervical cancer screening, Pap cytology screening is yet to be effectively implemented or has failed to reduce cervical cancer rates to an appreciable extent. Screening appears to benefit only a small fraction of women although a much larger percentage endures the inconvenience of the Pap test in order to avoid cervical cancer. The establishment of Human Papillomavirus (HPV) infection as the necessary cause of cervical precancers and cancers provides a tremendous opportunity for cervical cancer prevention through vaccination. HPV 16 and 18 which cause 70% of cervical cancers worldwide. Thus a prophylactic vaccine to prevent HPV related precancerous lesions and cancers would save lives, reduce the need for costly medical procedures and provide both women and communities throughout the world with substantial benefits. Based on the induction of neutralizing antibodies by non infectious Virus Like Particles (VLP) of L1 capside protein, prophylactic HPV vaccines have consistently induced high titter of neutralizing antibodies with minimal side effects and induce more than 90% protection from persistent HPV 16-18 infection and HPV 16 and 18 associated high-grade Cervical Intraepithelial Neoplasia (CIN) in proof of concept efficacy trials. HPV 16-18 vaccination will prevent HPV16-18 incident infection, and subsequently decrease in 90% the frequency of abnormal Pap attributable to these types and in about 50% overall abnormal Pap. HPV vaccination will reduce the number of women who require colposcopy, biopsy and cervical treatment for precancerous cervical lesions. The level of protection from death due to cervical cancer could exceed 95%. Three large phases prophylactic HPV VLP trials are now in progress and will form the basis for licensing of candidate vaccines in 2006. HPV vaccination targeting young female adolescents, aged 11 to 16 years, with a catch-up of those aged 17-25 years, would be a strategy to be addressed. Cervical cancer screening strategies, that will be cost-effective for the proper surveillance of women protected by HPV vaccination, are under analysis.

Role of DC‐SIGN in the activation of dendritic cells by HPV‐16 L1 virus‐like particle vaccine

Dendritic cell-specific intercellular adhesion molecule-grabbing non-integrin (DC-SIGN), a specific C-type lectin expressed on DC, binds and transmits different pathogens to susceptible cells. In the present study, we examined the role of DC-SIGN in the capture of human papillomavirus (HPV) pseudovirions and activation of DC. We demonstrate that HPV virus-like particles (VLP) bind to DC-SIGN expressed on transfected Raji cells and that antibodies against DC-SIGN block this interaction. DC take up VLP, which activate expression of costimulatory markers and cytokines/chemokines. Although our results indicate that DC-SIGN is not the major receptor for VLP in DC, this interaction contributes to the activation of DC surface antigens (HLA class I) and of various cytokines/chemokines, particularly TNF-alpha, IL-6, and RANTES. Induction of these markers in DC by VLP was significantly abrogated when binding to DC-SIGN was blocked by anti-DC-SIGN antibodies. These results suggest that DC-SIGN has a functional role in DC activation induced by HPV-16 L1-VLP, and thus highlight new aspects of DC interactions with HPV VLP.

Pharmaceutical and immunological evaluation of human papillomavirus viruslike particle as an antigen carrier

We report the preparation and the immunogenicity of a conjugate vaccine obtained by chemically conjugating a variant of the extracellular peptide fragment of influenza type A M2 protein to the human papillomavirus (HPV) viruslike particle (VLP). Conjugates comprised of approximately 4,000 copies of the antigenic peptide per VLP are obtained as the result of the reaction between a C-terminal cysteine residue on the peptide and the maleimide-activated HPV VLP. The resulting conjugates have an average particle size slightly larger than the carrier and present enhanced overall stability against chemical and thermal-induced denaturation. The M2-HPV VLP conjugates lost the binding affinity for anti-HPV conformational antibodies but retained reactivity to a M2-specific monoclonal antibody. The conjugate vaccine formulated with aluminum adjuvant and delivered in two doses of 30-ng peptide was found to be highly immunogenic and conferred good protection against lethal challenge of influenza virus in mice. These results suggest that HPV VLP can be used as a carrier for synthetic or small antigens for the development of subunit vaccines.

Prophylactic Human Papillomavirus Vaccine

Cervical cancer kills approximately 270,000 women every year worldwide, being the second most common cancer in women. Cervical cancer is largely preventable through effective massscreening programs. However, such programs are not feasible in developing countries, where approximately 80% of the almost 500,000 new cases of cervical cancer reported annually occur. Despite sufficient evidence for the excellent effectiveness of mass-screening programs in the prevention of cervical cancer, screening policies vary widely even among European countries [1]. Furthermore, the incidence of cervical cancer is increasing, particularly in younger women, due to the inability of the screening programs to tackle the rapidly increasing incidence of human papillomavirus (HPV) infections in adolescents [2]. The primary cause of cervical cancer is persistent high-risk HPV infection, which causes practically all such cases worldwide. Among the approximately 100 types of papillomaviruses characterized so far, approximately 40 types can infect the genital mucosa following sexual transmission. Of those, 16 are oncogenic or so-called high-risk HPV types. HPV-type distribution among women from different geographic populations varies, although HPV-16 is the most prevalent type worldwide [3]. Epidemiologic studies on the prevalence of HPV types in cervical cancer show that approximately 70% are related to HPV-16 and -18, and this is relatively consistent throughout the world [4]. The creation of HPV virus-like particle (VLP) vaccines has been an exceptionally rapid breakthrough. HPV VLPs were described in 1991, and Phase III HPV VLP vaccination efficacy trials have been underway since 1992.

Efficacy of Human Papillomavirus-16 Vaccine to Prevent Cervical Intraepithelial Neoplasia

Human papillomavirus (HPV) virus-like particle (VLP) vaccines have demonstrated effectiveness in preventing persistent HPV infections. Whether protection lasts longer than 18 months and, thus, impacts rates of cervical intraepithelial neoplasia (CIN) 2-3 has not yet been established. We present results from an HPV16 L1 VLP vaccine trial through 48 months. A total of 2,391 women, aged 16-23 years, participated in a randomized, double-blind, placebo-controlled trial. Either 40 mug HPV16 L1 VLP vaccine or placebo was given intramuscularly at day 1, month 2, and month 6. Genital samples for HPV16 DNA and Pap tests were obtained at day 1, month 7, and then 6-monthly through month 48. Colposcopy and cervical biopsies were performed if clinically indicated and at study exit. Serum HPV16 antibody titer was measured by radioimmunoassay. Among 750 placebo recipients in the per protocol population, 12 women developed HPV16-related CIN2-3 (6 CIN2 and 6 CIN3). Among 755 vaccine recipients, there were no cases (vaccine efficacy 100%, 95% confidence interval [CI] 65-100%). There were 111 cases of persistent HPV16 infection in placebo recipients and 7 cases in vaccine recipients (vaccine efficacy 94%, 95% CI 88-98%). After immunization, HPV16 serum antibody geometric mean titers peaked at month 7 (1,519 milli-Merck units [mMU]/mL), declined through month 18 (202 mMU/mL), and remained relatively stable between month 30 and month 48 (128-150 mMU/mL). The vaccine HPV16 L1 VLP provides high-level protection against persistent HPV16 infection and HPV16-related CIN2-3 for at least 3.5 years after immunization. Administration of L1 VLP vaccines targeting HPV16 is likely to reduce risk for cervical cancer. I.

Automation of a Multiplexed Competitive Luminex Immunoassay for Measuring Antibodies to Human Papillomavirus Types 6, 11, 16, and 18

Serum specimen pipetting is a labor-intensive process that can be a source of laboratory error, ergonomic stress, and a potential source of accidental exposure to infectious pathogens. Automated solutions for sample preparation reduce time spent on sample handling, minimize exposure to infectious pathogens, reduce laboratory error, reduce ergonomic stress, and save money. A fully automated method was developed for a custom-designed competitive Luminex immunoassay (cLIA) on a TECAN Genesis Workstation that measures antibodies to human papillomavirus (HPV) virus-like particles (VLPs). The automated program generated statistically similar data to assays performed manually. Overall, HPV 6, 11, 16, and 18 antibody titers obtained from samples prepared with the automated program were 3.2%, 6.6%, 3.6%, and 2.0% higher, respectively, than antibody titers from samples prepared manually. The agreement rates between methods for HPV positive and negative samples for HPV 6, 11, 16, and 18 were 100%, 96.8%, 98.4%, and 97.3%, respectively. An overview of the basic workflow of the automated HPV cLIA used to support our HPV vaccine Phase III clinical trials is described.

First-Generation Vaccines against Human Papillomavirus

There has been considerable progress in the development of a prophylactic human papillomavirus vaccine in the past 10 years, since the discovery of human papillomavirus virus-like particles. Licensure of the human papillomavirus vaccine is probably not far away. This would make it the first licensed vaccine against a common sexually transmitted infection. Although hepatitis B is a sexually transmitted infection for which there is an effective prophylactic vaccine, it is often not perceived as such by individuals taking the vaccine. Preclinical studies have already produced attractive vaccine candidates and recent clinical trials have yielded strikingly promising results. The candidate vaccines are generally well tolerated, induce high titers of serum antibodies to the human papillomavirus types and effectively prevent acquisition of infection and early clinical disease caused by common human papillomavirus types.

Stabilization of human papillomavirus virus-like particles by non-ionic surfactants

Human papillomavirus (HPV) virus-like-particles (VLPs) produced by recombinant expression systems are promising vaccine candidates for prevention of cervical cancers as well as genital warts. At high protein concentrations, HPV VLPs, comprised of the viral capsid protein L1 and expressed and purified from yeast, are protected against detectable aggregation during preparation and storage by high concentrations of NaCl. At low protein concentrations, however, high salt concentration alone does not fully protect HPV VLPs from aggregation. Moreover, the analytical analysis of HPV VLPs proved to be a challenge due to surface adsorption of HPV VLPs to storage containers and cuvettes. The introduction of non-ionic surfactants into HPV VLP aqueous solutions provides significantly enhanced stabilization of HPV VLPs against aggregation upon exposure to low salt and protein concentration, as well as protection against surface adsorption and aggregation due to heat stress and physical agitation. The mechanism of non-ionic surfactant stabilization of HPV VLPs was extensively studied using polysorbate 80 (PS80) as a representative non-ionic surfactant. The results suggest that PS80 stabilizes HPV VLPs mainly by competing with the VLPs for various container surfaces and air/water interfaces. No appreciable binding of PS80 to intact HPV VLPs was observed although PS80 does bind to the denatured HPV L1 protein. Even in the presence of stabilizing level of PS80, however, an ionic strength dependence of HPV VLP stabilization against aggregation is observed indicating optimization of both salt and non-ionic surfactant levels is required for effective stabilization of HPV VLPs in solution. © 2005 Wiley-Liss, Inc. and the American Pharmacists Association.

Human papillomavirus 16 virus-like particles use heparan sulfates to bind dendritic cells and colocalize with langerin in Langerhans cells

Langerhans cells (LC), the immature dendritic cells (DC) that reside in epithelial tissues are among the first immune cells to encounter human papillomavirus (HPV) and are not activated by HPV virus-like particles (VLPs) in contrast to DC. The notion that the differences in response to HPV VLPs between LC and DC are associated with different types of cell binding and intracellular trafficking has been addressed. Inhibition experiments with heparin and sodium chlorate showed that heparan sulfates are necessary for HPV 16 VLPs to bind to DC but not to LC. Electron microscopy analysis demonstrated a colocalization of HPV 16 VLPs and langerin, which is expressed only by LC. This colocalization was observed on the cell surface but also in cytoplasmic vesicles. As anti-langerin antibodies, HPV 16 VLPs were associated with a faster entry kinetics in LC, as reflected by the fact that VLPs were observed near the nuclear membrane of LC within 10 min whereas more than 60 min were needed in DC. However, no difference between LC and DC was observed for the endocytosis pathway. HPV 16 VLPs entered in both DC and LC by a clathrin-dependent-pathway and were then localized in large cytoplasmic vesicles resembling endosomes.

Papillomavirus virus‐like particles induce cytokines characteristic of innate immune responses in plasmacytoid dendritic cells

Human papillomavirus (HPV) virus-like particles (VLP) are being extensively tested as vaccines for the prevention of HPV-associated cervical cancer. Dendritic cells (DC) acquire and present antigens, initiating innate and adaptive immune responses. It has been shown previously that DC of the myeloid lineage are capable of generating adaptive immune responses to HPV VLP in vitro. However, the capacity of plasmacytoid DC (pDC) to acquire HPV VLP and the nature of the immune response generated have not been reported. In this study we found that freshly isolated as well as CpG-matured pDC bind papillomavirus VLP and that internalization occurs preferentially in the immature pDC. In contrast to myeloid DC, pDC did not undergo phenotypic maturation upon exposure to HPV16 VLP. However, HPV16 VLP induced pDC to secrete of IFN-alpha and IL-6, both cytokines that play a role in the generation of antibody responses, as well as TNFalpha and IL-8. Given that VLP do not contain viral nucleic acids, these results indicate that viral capsids alone may be capable of inducing cytokine production by pDC. Finally, CpG-activated pDC, but not pDC exposed to HPV16 VLP, activated lymphocytes to secrete IL-10 and low levels of IFN-gamma. Together these findings suggest a possible immunogenic effect of pDC in the setting of VLP vaccination.

Specific serologic response to genital human papillomavirus types in patients with vulvar precancerous and cancerous lesions

Antibodies to human papillomavirus are indicative for previous human papillomavirus exposure. Human papillomavirus antibody reactivities to vulvar precancerous lesions were reported poorly, and the role of human papillomavirus in some of these lesions is still unclear. In a direct enzyme-linked immunosorbent assay, serum samples from 126 healthy control subjects, 97 women with lichen sclerosus with or without squamous hyperplasia, 78 women with vulvar intraepithelial neoplasia, and 16 women with verrucous carcinoma were examined for immunoglobulin G and A antibodies to L1 virus-like particles of genital human papillomavirus types 6, 11, 16, 18, and 31, cutaneous human papillomavirus type 8, bovine papilloma virus, and cottontail rabbit papilloma virus. In lichen sclerosus/squamous hyperplasia with atypia immunoglobulin G and A, antibody positivity rates to high-risk human papillomavirus virus-like particle types 16, 18, and 31 were significantly higher than in the control group and the lichen sclerosus/squamous hyperplasia group without atypia. In patients with vulvar intraepithelial neoplasia I, increased immunoglobulin G antibody prevalences with both high-risk and low-risk human papillomavirus-virus-like particles were detected; whereas in patients with vulvar intraepithelial neoplasia II/III, this was observed only with the human papillomavirus types 16, 18, and 31. When only reactivities with 2 genital human papillomavirus types were compared, percentages of positives to only 1 of these 2 types ranged between 43% and 82%, with regard to all respective positives. Our data support the role of high-risk human papillomavirus types, mainly human papillomavirus-16, in the pathogenesis of different vulvar lesions with atypia. Serologically, there are no indications that lichen sclerosus/squamous hyperplasia without atypia is associated with human papillomavirus, but high-risk human papillomavirus in lichen sclerosus/squamous hyperplasia with atypia could play a role in carcinogenesis. High antibody specificity was clearly demonstrated among 5 genital, 1 cutaneous human, and 2 animal papillomavirus types.

Immune control of human papillomavirus (HPV) associated anogenital disease and potential for vaccination

This review discusses: (1) immune mechanisms relevant to the natural control of a human papillomavirus (HPV) infection; (2) viral strategies to evade or subvert immune attack; (3) the significance of immune escape as a feature of the evolution of invasive cancer; (4) vaccine strategies for prevention and/or therapy. HPV infection and associated malignancy can induce humoral and cellular immunity to capsid and oncogene viral proteins, but it is not always clear whether such responses are a consequence of the disease rather than the resolving factor(s). Prophylactic strategies are utilising virus-like particles (VLP) composed of the L1 viral capsid protein to induce neutralising antibodies, while therapeutic approaches are aimed at generating specific T cells targeted at the viral E6 and/or E7 oncogenes. Thus far, HPV VLP vaccines have proved clinically efficacious in the early clinical trials to prevent infection. Different types of therapeutic vaccines including peptide, protein, DNA or viral vector encoded have proved safe and immunogenic in patients, although there is often no correlation with clinical outcome. Understanding the equilibrium between viral and immunological factors will be important in providing the appropriate tools to evoke effective prophylactic and therapeutic immunity. It seems likely that combined prophylactic and therapeutic vaccine approaches could offer the best prospect for any significant reduction in death from cervical cancer worldwide.

Heterologous papillomavirus virus-like particles and human papillomavirus virus-like particle immune complexes activate human Langerhans cells

Chimeric human papillomavirus virus-like particles (HPV cVLP) are currently being explored as a therapeutic vaccination strategy against cervical cancer. HPV cVLP are being explored as a result of their interaction with and activation of dendritic cells, a potent antigen-presenting cell. However Langerhans cells, another type of antigen-presenting cell, can interact with HPV cVLP especially during mucosal routes of vaccine administration. Langerhans cells are not activated by HPV cVLP, utilize a different endocytosis mechanism than DC for HPV cVLP uptake, do not initiate an immune response toward HPV cVLP derived antigens, and are potentially immunosuppressive after interaction with HPV cVLP. Taken together, these findings indicate that the overall effectiveness of HPV cVLP as a therapeutic vaccine may be reduced. Bovine papillomavirus (BPV) VLP, cotton-tail rabbit papillomavirus (CRPV) VLP, and HPV VLP immune complexes (IC), which are taken up via similar endocytosis mechanisms in DC and LC, activate both cell types. DC and LC incubated with these VLP upregulate surface activation markers and increase secretion of IL-12 p70. The activated cells are then able to initiate an immune response against chimeric VLP-derived antigens. These data indicate that other therapeutic vaccination strategies based on using chimeric BPV VLP, chimeric CRPV VLP, or chimeric HPV VLP immune complexes may be more effective in generating an immune response against HPV-induced diseases such as cervical cancer.