Safety and immunogenicity trial in adult volunteers of a human papillomavirus 16 L1 virus-like particle vaccine

Understanding and learning from the success of prophylactic human papillomavirus vaccines

An estimated 5% of human cancers are caused by human papillomavirus (HPV) infections, and most of these cancers are of the cervix. Two prophylactic HPV vaccines that target the two most oncogenic virus types, HPV16 and HPV18, are now commercially available. In controlled clinical trials, the vaccines proved to be effective at preventing incident anogenital infection and the associated neoplastic disease that is induced by these virus types. Here, we highlight the specific aspects of HPV biology and vaccine composition that are likely to contribute to the efficacy of these vaccines, and we discuss how these particular features might or might not be relevant for the development of effective vaccines against other sexually transmitted viruses such as HIV and herpes simplex virus (HSV).

Human papillomavirus type 58 L1 virus-like particles purified by two-step chromatography elicit high levels of long-lasting neutralizing antibodies

Human papillomavirus (HPV) type 58 is a high-risk type of HPV frequently detected in cervical cancers, especially in Eastern Asia. There are still no commercially available vaccines against HPV 58 infection. High levels of long-lasting neutralizing antibodies are crucial for long-term protection against HPV infection. Here, we have developed a two-step chromatography strategy and have purified highly pure HPV L1 proteins, which form more homogenous and uniform VLPs than those purified by CsCl ultracentrifugation. Low-dosage immunization with HPV 58 L1 VLPs alone or co-administrated with HPV 16 and HPV 18 L1 VLPs is sufficient to induce high levels of long-lasting neutralizing antibodies in mice. Our results suggest that the highly immunogenic HPV 58 L1 VLPs are a good candidate for use in developing effective vaccines against HPV 58 infection.

Epithelial cell responses to infection with human papillomavirus

Human papillomavirus (HPV) infection of the genital tract is common in young sexually active individuals, the majority of whom clear the infection without overt clinical disease. Most of those who do develop benign lesions eventually mount an effective cell-mediated immune (CMI) response, and the lesions regress. Regression of anogenital warts is accompanied histologically by a CD4(+) T cell-dominated Th1 response; animal models support this and provide evidence that the response is modulated by antigen-specific CD4(+) T cell-dependent mechanisms. Failure to develop an effective CMI response to clear or control infection results in persistent infection and, in the case of the oncogenic HPVs, an increased probability of progression to high-grade intraepithelial neoplasia and invasive carcinoma. Effective evasion of innate immune recognition seems to be the hallmark of HPV infections. The viral infectious cycle is exclusively intraepithelial: there is no viremia and no virus-induced cytolysis or cell death, and viral replication and release are not associated with inflammation. HPV globally downregulates the innate immune signaling pathways in the infected keratinocyte. Proinflammatory cytokines, particularly the type I interferons, are not released, and the signals for Langerhans cell (LC) activation and migration, together with recruitment of stromal dendritic cells and macrophages, are either not present or inadequate. This immune ignorance results in chronic infections that persist over weeks and months. Progression to high-grade intraepithelial neoplasia with concomitant upregulation of the E6 and E7 oncoproteins is associated with further deregulation of immunologically relevant molecules, particularly chemotactic chemokines and their receptors, on keratinocytes and endothelial cells of the underlying microvasculature, limiting or preventing the ingress of cytotoxic effectors into the lesions. Recent evidence suggests that HPV infection of basal keratinocytes requires epithelial wounding followed by the reepithelization of wound healing. The wound exudate that results provides a mechanistic explanation for the protection offered by serum neutralizing antibody generated by HPV L1 virus-like particle (VLP) vaccines.

Human papillomavirus as a target for management, prevention and therapy

The discovery that human papillomavirus (HPV) is the necessary causal factor in cervical carcinogenesis has made it a target for prophylactic and therapeutic vaccines, as well as a diagnostic tool in cervical screening. Whilst prophylactic vaccination has proven very effective in terms of preventing cervical cancer precursor lesions, therapeutic strategies have presented far greater challenges. HPV testing has shown itself to be extremely valuable in the triage of low grade cytological abnormalities, test of cure following treatment of cervical intraepithelial neoplasia (CIN), and will, over the next 10 years, gradually replace cytology as the mainstay of primary cervical screening. In this review, the latest evidence supporting HPV as both a biomarker of risk for cervical cancer and a target for prophylactic and therapeutic vaccination is presented.

MF59 formulated with CpG ODN as a potent adjuvant of recombinant HSP65-MUC1 for inducing anti-MUC1+ tumor immunity in mice

MF59 is an oil-in-water emulsion adjuvant approved for influenza vaccines for human use in Europe. Due to its Th2 inducing properties, MF59 is seldom tested for cancer vaccines. In this study, MF59 formulated with a C-type CpG oligodeoxynucleotide (YW002) was tested for its Th1 adjuvant activity to induce immune responses to HSP65-MUC1, a recombinant fusion protein incorporating a mycobacterial heat shock protein (HSP65) and mucin 1, cell surface associated (MUC1) derived peptide. Combination of YW002 with MF59 (MF59-YW002) could confer a potent Th1 biasing property to the adjuvant, which enhanced the immunogenicity of HSP65-MUC1 to induce significantly higher levels of specific IgG2c, increased IFN-γ mRNA expression in splenocytes and the generation of antigen-specific cytotoxic T lymphocytes in mice. When prophylactically applied, MF59-YW002 adjuvant containing HSP65-MUC1 inhibited the growth of MUC1⁺ B16 melanoma and prolonged the survival of tumor-bearing mice. In contrast, adjuvant containing MF59 with HSP65-MUC1 in the absence of YW002, promoted the growth of MUC1⁺ B16 melanoma in mice. These results suggest that MF59 plus CpG oligodeoxynucleotide might be developed as an efficient adjuvant for tumor vaccines against melanoma, and possibly other tumors.

Age of recipient and number of doses differentially impact human B and T cell immune memory responses to HPV vaccination

Vaccination is one of the most effective medical interventions. However, optimization of existing as well as design of new vaccines is still mostly conducted empirically; a rational approach to vaccine design is largely prohibited by the lack of insight into the relevant mechanisms underlying immune-mediated protection. To delineate the impact of variables on immune memory formation following vaccination, we took advantage of a trial assessing the role of the age of the recipient and the number of administered doses of the quadrivalent HPV vaccine in a well-characterized longitudinal cohort of girls and young women. We found that age of the recipient and the number of doses administered differentially impact the development of B and T cell memory. Specifically, age of the recipient significantly impacted generation of HPV 18-specific B cell memory, while the number of vaccine doses displayed a significant effect on the development of HPV-specific T cell memory. Our data indicate that rational design of vaccines has to be tailored according to the desired induction of B and/or T cell memory.

Developments in virus-like particle-based vaccines for infectious diseases and cancer

Virus-like particles hold great promise for the development of effective and affordable vaccines. Indeed, virus-like particles are suitable for presentation and efficient delivery of linear as well as conformational antigens to antigen-presenting cells. This will ultimately result in optimal B-cell activation and cross-presentation with both MHC class I and II molecules to prime CD4(+) T-helper as well as CD8(+) cytotoxic T cells. This article provides an update on the development and use of virus-like particles as vaccine approaches for infectious diseases and cancer.

International collaborative proficiency study of Human Papillomavirus type 16 serology

We performed an international proficiency study of Human Papillomavirus (HPV) type 16 serology. A common methodology for serology based on virus-like particle (VLP) ELISA was used by 10 laboratories in 6 continents. The laboratories used the same VLP reference reagent, which was selected as the most stable, sensitive and specific VLP preparation out of VLPs donated from 5 different sources. A blinded proficiency panel consisting of 52 serum samples from women with PCR-verified HPV 16-infection, 11 control serum samples from virginal women and the WHO HPV 16 International Standard (IS) serum were distributed. The mean plus 3 standard deviations of the negative control serum samples was the most generally useful "cut-off" criterion for distinguishing positive and negative samples. Using sensitivity of at least 50% and a specificity of 100% as proficiency criteria, 6/10 laboratories were proficient. In conclusion, an international Standard Operating Procedure for HPV serology, an international reporting system in International Units (IU) and a common "cut-off" criterion have been evaluated in an international HPV serology proficiency study.

Light it up: highly efficient multigene delivery in mammalian cells

Multigene delivery and expression systems are emerging as key technologies for many applications in contemporary biology. We have developed new methods for multigene delivery and expression in eukaryotic hosts for a variety of applications, including production of protein complexes for structural biology and drug development, provision of multicomponent protein biologics, and cell-based assays. We implemented tandem recombineering to facilitate rapid generation of multicomponent gene expression constructs for efficient transformation of mammalian cells, resulting in homogenous cell populations. Analysis of multiple parameters in living cells may require co-expression of fluorescently tagged sensors simultaneously in a single cell, at defined and ideally controlled ratios. Our method enables such applications by overcoming currently limiting challenges. Here, we review recent multigene delivery and expression strategies and their exploitation in mammalian cells. We discuss applications in drug discovery assays, interaction studies, and biologics production, which may benefit in the future from our novel approach.

The first international standard for antibodies to HPV 16

Current HPV vaccines and vaccine candidates are based on recombinant virus capsid proteins, so called virus-like particles (VLPs). Standardisation of assays for HPV capsid antibody will assist with epidemiology studies and future vaccine development. A World Health Organization international collaborative study was undertaken to assess the suitability of a freeze-dried serum, obtained from women naturally infected with HPV 16 and reactive against HPV 16 only, to serve as the International Standard for antibodies to HPV 16 in immunoassays and pseudovirion neutralisation assays. Eleven laboratories from nine countries participated in the collaborative study in which the candidate (NIBSC code 05/134) was assayed alongside samples from both vaccinees and naturally infected individuals. 05/134 had titres which were comparable to those obtained with serum from a naturally infected individual. Overall the variation between laboratories is similar to that observed in the previous study for samples from naturally infected individuals although slightly wider for sera from vaccinees. 05/134 has been established by the WHO Expert Committee on Biological Standardization as the 1st International Standard for antibodies to HPV 16, human serum, with an assigned potency of 5IUper ampoule.

Identification of epitopes in Indian human papilloma virus 16 E6: a bioinformatics approach

HPV-16 is reported as the cause of cervical and other related carcinomas. The early expressed protein E6 in cancer cells is found to be the target for immune therapeutic methods. The sequence of HPV-16 E6 (Accession No: ABK32509) from NCBI databank has been taken for this study. Hydrophilicity, flexibility, accessibility, turns, exposed surface, polarity and antigenic propensity scales were used for the B cell epitope prediction. MHC Class I and Class II alleles for the accession were predicted by the MHCPred 2.0 Program. The epitope sequences were also found out. Computer-based prediction program results show, A0203 and DRB0101 lower IC50 than other alleles. The best peptide binding affinity was 21HLCTELQTT30 of A0203 allele. In DRB0101 allele the peptide found was 39YCKQQLLRR48. Different structural features of the protein have also been predicted including glycosylation, kinase C phosphorylation, casein kinase II phosphorylation and N-myristylation sites. These computational prediction programs show four glycosylation, five kinase C phosphorylation, two casein kinase II phosphorylation, zero N-myristylation sites and seven disulphide sites. Development and approval of new vaccines are the keys for control of cancer. Epitopes and other structural features of protein prediction could be the best source of information and can help in molecular and medical studies of viral infection and development of HPV associated cancer drugs.

Progress towards a universal influenza vaccine

Seasonal influenza is a common and highly transmissible disease, characterized by frequent and unpredictable mutations occurring in the viral envelope glycoproteins. Owing to this high variability, annual reformulation and immunization are required and still, the vaccine is not effective enough when there is an antigenic mismatch with circulating strains. A solution could come from the construction of a universal vaccine that would be based on highly conserved antigens and would be effective against many strains: some universal vaccine developers focus on the Matrix 2 protein, whereas others use additional conserved proteins, such as the nucleoprotein and Matrix 1, or even a range of peptides from these proteins and others to induce cross-strain immunity. This article aims to highlight recent significant advances in the development of a universal vaccine against influenza and focuses mainly on studies using the epitope-based approach that have also entered the clinical trial stage; it includes a brief summary of current vaccines against influenza as well as the ongoing efforts to develop a universal vaccine.

MF59™ as a vaccine adjuvant: a review of safety and immunogenicity

Approximately 70 years passed between the licensing of alum salts as vaccine adjuvants and that of MF59™ MF59, an oil-in-water emulsion, is currently licensed for use in the elderly as an adjuvant in seasonal influenza vaccines. Its mechanism of action is not fully understood, but enhancement of the interaction between the antigen and the dendritic cell seems to be involved. When used with seasonal influenza vaccines, an increase occurs in the hemagglutination inhibition antibody titers against some, but not all, seasonal vaccine influenza strains. The adjuvant effect is more pronounced when MF59 is combined with novel influenza antigens such as H9 and H5. The use of the adjuvant is associated with an increase in the frequency of local and systemic early post-vaccine adverse events (3-7 days), but no increase in adverse events was observed thereafter. Currently, MF59 is under evaluation as an adjuvant with other antigens such as pandemic influenza antigens and cytomegalovirus antigens.

Prophylactic vaccination against human papillomaviruses to prevent cervical cancer and its precursors

This is the protocol for a review and there is no abstract. The objectives are as follows: To evaluate the immunogenicity, clinical efficacy, and safety of prophylactic HPV vaccines in females. The assessment of clinical efficacy will address protection against HPV infection (for homologous and heterologous HPV types), against re-infection, against cervical cancer and its precursors (high-grade CIN (grade 2 or grade 3), adenocarcinoma in situ) in women previously not exposed to HPV infection (negative at enrolment for both HPV DNA and antibodies against the vaccine HPV types). We will assess clinical effectiveness by evaluating outcomes in all women, irrespective of the HPV DNA or serology status at enrolment. Evaluation by fine age and time since sexual debut categories is also planned.

Prevention of cancer by prophylactic human papillomavirus vaccines

Oncogenic human papillomaviruses (HPVs) are exclusively mucosal pathogens that are noncytopathic and the basal epithelial cells harboring and maintaining an infection do not produce either capsid antigen or virus. The efficacy of the licensed L1 virus-like particle (VLP) vaccines has encouraged development of several second generation vaccines aimed at expanding the coverage to all oncogenic HPV types and reducing barriers to global implementation. Currently there is no defined immune correlate of protection that can be used to determine if an individual patient is protected and for the evaluation of these second generation vaccines. Surprisingly, passive transfer of neutralizing serum antibody is protective in animal models. Recent studies suggest how neutralizing antibody mediates immunity against mucosal HPV and the possible impact of memory B cells.

In vivo mechanisms of vaccine-induced protection against HPV infection

Using a human papillomavirus (HPV) cervicovaginal murine challenge model, we microscopically examined the in vivo mechanisms of L1 virus-like particle (VLP) and L2 vaccine-induced inhibition of infection. In vivo HPV infection requires an initial association with the acellular basement membrane (BM) to induce conformational changes in the virion that permit its association with the keratinocyte cell surface. By passive transfer of immune serum, we determined that anti-L1 antibodies can interfere with infection at two stages. Similarly to active VLP immunization, transfer of high L1 antibody concentrations prevented BM binding. However, in the presence of low concentrations of anti-L1, virions associated with the BM, but to the epithelial cell surface was not detected. Regardless of the concentration, L2 vaccine-induced antibodies allow BM association but prevent association with the cell surface. Thus, we have revealed distinct mechanisms of vaccine-induced inhibition of virus infection in vivo.

E6 and E7 fusion immunoglobulin from human papilloma virus 16 induces dendritic cell maturation and antigen specific activation of T helper 1 response

Human papilloma virus (HPV) 16 causes cervical cancer. Induction of oncogenesis by HPV 16 is primarily dependent on the function of E6 and E7 proteins, which inactivate the function of p53 and pRB, respectively. Thus, blocking the activity of the E6 and E7 proteins from HPV 16 is critical to inhibiting oncogenesis during infection. We have expressed and purified soluble HPV 16 E6 and E7 fusion immunoglobulin (Ig), which were combined with the constant region of an Ig heavy chain, in a mammalian system. To assess whether soluble E6 and E7 fusion Igs induce effective cellular immune responses, immature dendritic cells (DCs) were treated with these fusion proteins. Soluble E6 and E7 fusion Igs effectively induced maturation of DCs. Furthermore, immunization with soluble E6 and E7 fusion Igs in mice resulted in antigen-specific activation of T helper 1 (Th1) cells. This is the first comprehensive study to show the molecular basis of how soluble HPV 16 E6 or E7 fusion Igs induces Th1 responses through the maturation of DCs. In addition, we show that DC therapy using soluble HPV E6 and E7 fusion Igs may be a valuable tool for controlling the progress of cervical cancer.

Monitoring of human papillomavirus vaccination

Persistent infection with oncogenic human papillomavirus (HPV) is a necessary causal factor in the development of cervical cancer. Moreover, HPV, predominately type 16 and to a lesser degree type 18, is linked causally to varying proportions of other anogenital cancers (vulva, vagina, penis, anus) as well as cancers elsewhere in the body (oropharynx, larynx, conjunctiva). HPV types 6 and 11 cause most of genital warts and recurrent respiratory papillomatosis. Effective prophylactic vaccines have been developed. In this review, we address briefly the immunological aspects of HPV infection and the results of HPV vaccination trials. Internationally standardized monitoring and evaluation of prophylactic HPV vaccination programmes will be essential for arriving at the most cost-effective strategies for cancer control.

HPV - immune response to infection and vaccination

HPV infection in the genital tract is common in young sexually active individuals, the majority of whom clear the infection without overt clinical disease. However most of those who develop benign lesions eventually mount an effective cell mediated immune (CMI) response and the lesions regress.

Failure to develop effective CMI to clear or control infection results in persistent infection and, in the case of the oncogenic HPVs, an increased probability of progression to CIN3 and invasive carcinoma. The prolonged duration of infection associated with HPV seems to be associated with effective evasion of innate immunity thus delaying the activation of adaptive immunity.

Natural infections in animals show that neutralising antibody to the virus coat protein L1 is protective suggesting that this would be an effective prophylactic vaccine strategy. The current prophylactic HPV VLP vaccines are delivered i.m. circumventing the intra-epithelial immune evasion strategies. These vaccines generate high levels of antibody and both serological and B cell memory as evidenced by persistence of antibody and robust recall responses. However there is no immune correlate - no antibody level that correlates with protection. Recent data on how HPV infects basal epithelial cells and how antibody can prevent this provides a mechanistic explanation for the effectiveness of HPV VLP vaccines.

Epidemiological study of anti-HPV16/18 seropositivity and subsequent risk of HPV16 and -18 infections

BACKGROUND

Infection with human papillomavirus (HPV) 16 or HPV18 elicits an antibody response, but whether the elicited antibodies protect women against subsequent infection by a homologous HPV type compared with seronegative women is unknown.

METHODS

Study participants were women aged 18-25 years at enrollment in the control group of the ongoing National Cancer Institute-sponsored, community-based, randomized HPV16/18 Costa Rica Vaccine Trial. At enrollment, 2813 participants were negative for cervical HPV16 DNA and 2950 for HPV18 DNA. Women were interviewed regarding sociodemographic data and medical and health history. Medical and pelvic examinations were conducted for all consenting sexually experienced women. Serum samples taken at enrollment were tested for total HPV16/18 antibodies with a polyclonal enzyme-linked immunosorbent assay, and cervical specimens were tested for type-specific HPV DNA over 4 years of follow-up. Using Poisson regression, we compared rate ratios of newly detected cervical HPV16 or HPV18 infection among homologous HPV-seropositive and HPV-seronegative women, adjusting for age, education, marital status, lifetime number of sexual partners, and smoking.

RESULTS

There were 231 newly detected HPV16 infections during 5886 person-years among HPV16-seronegative women compared with 12 newly detected HPV16 infections during 581 person-years among HPV16-seropositive women with the highest HPV16 sero-levels. There were 136 newly detected HPV18 infections during 6352 person-years among HPV18-seronegative women compared with six new infections detected during 675 person-years among HPV18 seropositives with the highest sero-levels. After controlling for risk factors associated with newly detected HPV infection, having high HPV16 antibody titer at enrollment was associated with a reduced risk of subsequent HPV16 infection (women in the highest tertile of HPV16 antibody titers, adjusted rate ratio = 0.50, 95% confidence interval = 0.26 to 0.86 vs HPV16-seronegative women). Similarly, having high HPV18 antibody titer at enrollment was associated with a reduced risk of subsequent HPV18 infection (women in the highest tertile of HPV18 antibody titers, adjusted rate ratio = 0.36, 95% confidence interval = 0.14 to 0.76 vs HPV18-seronegative women).

CONCLUSION

In this study population, having high antibody levels against HPV16 and HPV18 following natural infection was associated with reduced risk of subsequent HPV16 and HPV18 infections.

Guillain-Barré syndrome after Gardasil vaccination: data from Vaccine Adverse Event Reporting System 2006-2009

Using data from Vaccine Adverse Event Reporting System, we identified 69 reports of Guillain-Barré Syndrome (GBS) after Gardasil vaccination that occurred in the United States between 2006 and 2009. The onset of symptoms was within 6 weeks after vaccination in 70% of the patients in whom the date of vaccination was known. The estimated weekly reporting rate of post-Gardasil GBS within the first 6 weeks (6.6 per 10,000,000) was higher than that of the general population, and higher than post-Menactra and post-influenza vaccinations. Further prospective active surveillance for accurate ascertainment and identification of high-risk groups of GBS after Gardasil vaccination is warranted.

Virus-like particles as a vaccine delivery system: myths and facts

Vaccines against viral disease have traditionally relied on attenuated virus strains or inactivation of infectious virus. Subunit vaccines based on viral proteins expressed in heterologous systems have been effective for some pathogens, but have often suffered from poor immunogenicity due to incorrect protein folding or modification. In this chapter we focus on a specific class of viral subunit vaccine that mimics the overall structure of virus particles and thus preserves the native antigenic conformation of the immunogenic proteins. These virus-like particles (VLPs) have been produced for a wide range of taxonomically and structurally distinct viruses, and have unique advantages in terms of safety and immunogenicity over previous approaches. With new VLP vaccines for papillomavirus beginning to reach the market place we argue that this technology has now ‘come-of-age’ and must be considered a viable vaccine strategy.

Characterization of the HPV-specific memory B cell and systemic antibody responses in women receiving an unadjuvanted HPV16 L1 VLP vaccine

Human papillomavirus (HPV)-specific antibodies are proposed to be the correlate of protection afforded by HPV L1 virus-like particle (VLP) vaccines. Previous studies have characterized the systemic antibody response to immunization in terms of both the quantity and the ability to neutralize HPV. Here, we have adapted a generalized memory B cell ELISPOT to the HPV16 system and expanded the analysis of the systemic antibody response to include an avidity measurement of HPV L1 VLP-specific antibodies. We show the results of the memory B cell ELISPOT significantly correlated with IgG and neutralizing antibody titers, but not with the avidity measurement. This is the first comprehensive study to correlate a variety of humoral aspects potentially associated with protective immunity following vaccination with a HPV16 L1 VLP vaccine.

Cost-effectiveness analysis of a quadrivalent human papilloma virus vaccine in Mexico

BACKGROUND AND AIMS

Cervical cancer is one of the main causes of death in women in low- and middle-income countries. Despite technological and scientific advances that allow an early detection of precancerous lesions and curative treatment of cervical cancer, Mexico and other Latin American countries have only been able to obtain a small decrease in the mortality rates for this kind of cancer. How to implement and sustain effective public health strategies for cervical cancer prevention, such as increasing cytology-based screening program coverage and implementing HPV-DNA testing and vaccination, are important questions. The aim of this study is to perform a cost-effectiveness analysis of the introduction of a quadrivalent (HPV 6/11/16/18) HPV vaccine into the public health system and evaluate the epidemiological and economic benefits on prevention of cervical cancer in Mexico.

METHODS

A Markov model is used to simulate the natural history of HPV infection in a cohort of Mexican women to evaluate the cost-effectiveness of the cervical cancer screening strategy used in Mexico as well as the benefits of other potential strategies such as 1) vaccination only, 2) conventional cytology-based screening program only and 3) vaccination followed by screening. For the strategies that involve screening we have chosen screening intervals of 3 and 5 years. The model produces results that are reasonably close to the epidemiological data related to HPV and cervical cancer in Mexico.

RESULTS

The quadrivalent HPV vaccine could reduce the probability of persistent HPV-16/18 infection by at least 60%, which would result in a near-proportional reduction in HPV-16/18-associated invasive cervical cancer and CIN 3.

CONCLUSIONS

The strategy of using only vaccination ($45 USD for three doses) as a preventive measure was a very cost-effective strategy in Mexico ($68USD/LYS). The strategy of vaccination with traditional screening of Pap test every 3 years produced higher cost by a lower performance of cervical cytology in Mexico, at a cost of $15,935 USD per life-year. The cost-effectiveness of the vaccination strategy was highly sensitive to age of vaccination, duration of vaccine efficacy, and cost of vaccination. The Mexican model predicts that a quadrivalent HPV vaccine will reduce the incidence of high- and low-risk-associated cervical cancer. A program of vaccination as a preventive strategy is likely cost effective. The results of this study could be of great value in decision-making for the implementation of an HPV vaccine as a public health policy in Mexico provided that the cost of each dose will be, at most, $15 dollars (USD) dollars, combined with HPV testing, the new strategy of national secondary prevention program.

Prevalence of HPV infection among Greek women attending a gynecological outpatient clinic

Background

Human papillomavirus (HPV) infection is a causative factor for cervical cancer. Early detection of high risk HPV types might help to identify women at high risk of cervical cancer. The aim of the present study was to examine the HPV prevalence and distribution in cervical smears in a sample of Greek women attending a gynecological outpatient clinic and to explore the determinants of the infection.

Methods

A total of 225 women were studied. All women underwent a regular gynecological control. 35 HPV types were studied; 6, 11, 16, 18, 26, 31, 33, 35, 39, 40, 42, 43, 44, 45, 51, 52, 53, 54, 56, 58, 59, 61, 62, 66, 68, 70, 71, 72, 73, 81, 82, 83, 84, 85 and 89. Also, basic demographic information, sociodemographic characteristics and sexual behavior were recorded.

Results

HPV was detected in 22.7% of the study population. The percentage of the newly diagnosed women with HPV infection was 17.3%. HPV-16 was the most common type detected (5.3%) followed by HPV-53 (4.9%). 66.2% of the study participants had a Pap test during the last year without any abnormalities. HPV infection was related positively with alcohol consumption (OR: 2.19, 95% CI: 1.04-4.63, P = 0.04) and number of sexual partners (OR: 2.16, 95% CI: 1.44-3.25, P < 0.001), and negatively with age (OR: 0.93, 95% CI: 0.87-0.99, P = 0.03), and monthly income (OR: 0.63, 95% CI: 0.44-0.89, P = 0.01).

Conclusion

The prevalence of HPV in women attending an outpatient clinic is high. Number of sexual partners and alcohol consumption were the most significant risk factors for HPV infection, followed by young age and lower income.

A replication-incompetent Rift Valley fever vaccine: chimeric virus-like particles protect mice and rats against lethal challenge

Virus-like particles (VLPs) present viral antigens in a native conformation and are effectively recognized by the immune system and therefore are considered as suitable and safe vaccine candidates against many viral diseases. Here we demonstrate that chimeric VLPs containing Rift Valley fever virus (RVFV) glycoproteins G(N) and G(C), nucleoprotein N and the gag protein of Moloney murine leukemia virus represent an effective vaccine candidate against Rift Valley fever, a deadly disease in humans and livestock. Long-lasting humoral and cellular immune responses are demonstrated in a mouse model by the analysis of neutralizing antibody titers and cytokine secretion profiles. Vaccine efficacy studies were performed in mouse and rat lethal challenge models resulting in high protection rates. Taken together, these results demonstrate that replication-incompetent chimeric RVF VLPs are an efficient RVFV vaccine candidate.

Cervical cancer vaccine development

Cervical cancer is initiated by infection of cervical epithelium with human papillomavirus. Vaccines have been developed, incorporating papillomavirus viral capsids and alum based adjuvants. In extensive clinical trials these vaccines have been shown safe and effective in preventing infection with, and disease caused by, the papillomavirus genotypes they incorporate, in women not already infected. These vaccines have the potential to reduce the global burden of cervical cancer by up to 70%.

Papillomavirus and disease in humans and animals

Papillomavirus (PV) induces exophytic lesions (papillomas, warts) and flat lesions (flat warts, cervical intraepithelial neoplasia) in cutaneous and mucosal epithelia. The lesions are usually benign and generally regress without eliciting any serious clinical problems in a host but occasionally persist. Persistent lesions can be debilitating and can also provide a focus for malignant transformation to squamous cell carcinoma, particularly in the presence of environmental or genetic cofactors. This has been experimentally demonstrated in animals, particularly in cattle, where bovine PV (BPV)-induced papillomas progress to cancer of the upper gastrointestinal (GI) tract and the urinary bladder in animals exposed to bracken fern in the pasture, and in rabbits, where the progression of skin papillomas to squamous cell carcinoma depends on a particular variant of cottontail rabbit PV (CRPV) and on the major histocompatibility complex (MHC) class II haplotype of the animal. In this review, various aspects of the biology of BPV and CRPV are described and compared with those of human PV, including viral genome structure, regulation of transcription of the viral oncogenes, function of the viral oncoproteins, co-operation between virus and cofactors, virus latency, immunity and vaccination.

Virus-like particle vaccines and adjuvants: the HPV paradigm

Complex antigen structures currently represent the most-studied approach for prophylactic as well as therapeutic vaccines. Different types of complex vaccines, including virus-like particles and virosomes, have been developed depending on the nature of the viral pathogen they are trying to replicate (enveloped vs naked) or the modality to express antigenic epitopes (i.e., the binding of envelope protein on liposomic structures). The complex structure of these vaccines provides them with some adjuvanted properties, not uniformly present for all virus-like particle types. The further inclusion of specific adjuvants in vaccine preparations can modify the presentation modality of such particles to the immune system with a specific Th1 versus Th2 polarization efficacy. A paradigm of the relevance of these new adjuvants are the immunological results obtained with the inclusion of monophosphoryl lipid A adjuvant in the formulation of L1-based human papillomavirus-naked virus-like particles to reduce a Th1 cellular immunity impairment, peculiar for alum-derived adjuvants, along with the induction of highly enhanced humoral and memory B-cellular immunity.

[HPV immunization for the prevention of cervical cancer]

CONTEXT

Human Papillomaviruses (HPV) infect epithelial cells of the skin and mucosae. Mucosal high-risk HPV types (mainly HPV 16 and 18) are involved in the development of cervical cancer, one of the most common cancers in young women. HPV infection is usually asymptomatic and clears spontaneously, but 10 - 15 % of high-risk HPV infections are persistent and increase the risk of precancerous and cancerous lesions of the cervix. Two HPV vaccines have been licensed to provide protection against cervical cancer.

OBJECTIVES

To report the different aspects of HPV infection in order to improve the understanding of the particular problems of HPV vaccination and to review the most recent findings related to HPV vaccines, particularly regarding the protective efficacy of vaccines and the roles of adjuvants and immune response in protection.

METHODS

Articles were selected from the PubMed database (National Library of Medicine- National Institute of Health) with the following Keywords "HPV", "Prevention", "HPV vaccines", "Immune response", "Antibody". Abstracts of oral presentations from international meetings were also selected for the more recent findings. a critical analysis of the majority of papers published was undertaken and relevant information summarized.

RESULTS

Virus-like particle production by expressing the major protein of the HPV capsid was carried out in the early 90's, leading to the recent development of two HPV vaccines. These vaccines are now licensed in many countries and have been demonstrated to be highly immunogenic. In subjects that are non-infected at the time of vaccination, HPV vaccines are highly effective in preventing persistent HPV 16 - 18 infections (90 %) and precursors lesions of cervical cancer associated with these two HPV types (close to 100 %). Clinical trials have also confirmed that HPV vaccines are well tolerated by recipients.

CONCLUSIONS

The present paper is a detailed review published in French on HPV vaccines, their efficacy in the prevention of HPV infections and unresolved questions regarding the use of HPV vaccines. This report also includes biological and immunological information to improve the understanding of HPV vaccination.

Virus-like particle vaccine comprised of the HA, NA, and M1 proteins of an avian isolated H5N1 influenza virus induces protective immunity against homologous and heterologous strains in mice

Highly pathogenic avian influenza H5N1 virus represents a growing threat for an influenza pandemic. Development of effective vaccines for H5N1 is a priority for pandemic preparedness. Focusing on influenza virus-like particles (VLPs) has been suggested as a promising vaccine approach. Recent VLP vaccination efforts have been concentrated on the H5N1 strains isolated from humans. Because all confirmed cases of human H5N1 infection were directly transmitted from infected poultry, it is of interest to develop VLP vaccines comprised of antigenic proteins of avian H5N1 strains in order to compare their efficacy in fighting diverse H5N1 strains with vaccines developed using human isolates. In this study, we generated a VLP vaccine composed of the HA, NA, and M1 proteins of the avian H5N1 influenza virus isolate A/chicken/Hubei/489/2004, which seems to occupy a unique phylogenetic position; it belongs to neither clade 1 nor clade 2. Upon infection of Sf9 insect cells using recombinant baculoviruses, the co-expressed HA, NA, and M1 proteins self-assembled and released into the culture medium as VLPs. In a mouse model, purified VLPs elicited an effective antibody response and conferred complete protection against heterologous human H5N1 influenza virus, as well as a homologous avian H5N1 influenza virus isolate. Our work provides further evidence that vaccination with influenza VLPs may be a productive approach to achieve protection against diverse H5N1 strains.

Screening, prevention and treatment of cervical cancer -- a global and regional generalized cost-effectiveness analysis

The paper calculates regional generalized cost-effectiveness estimates of screening, prevention, treatment and combined interventions for cervical cancer. Using standardised WHO-CHOICE methodology, a cervical cancer model was employed to provide estimates of screening, vaccination and treatment effectiveness. Intervention effectiveness was determined via a population state-transition model (PopMod) that simulates the evolution of a sub-regional population accounting for births, deaths and disease epidemiology. Economic costs of procedures and treatment were estimated, including programme overhead and training costs. In regions characterized by high income, low mortality and high existing treatment coverage, the addition of any screening programme to the current high treatment levels is very cost-effective. However, based on projections of the future price per dose (representing the economic costs of the vaccination excluding monopolistic rents and vaccine development cost) vaccination is the most cost-effective intervention. In regions characterized by low income, low mortality and existing treatment coverage around 50%, expanding treatment with or without combining it with screening appears to be cost-effective or very cost-effective. Abandoning treatment in favour of screening in a no-treatment scenario would not be cost-effective. Vaccination is usually the most cost-effective intervention. Penta or tri-annual PAP smears appear to be cost-effective, though when combined with HPV-DNA testing they are not cost-effective. In regions characterized by low income, high mortality and low treatment levels, expanding treatment with or without adding screening would be very cost-effective. A one off vaccination plus expanding treatment was usually very cost-effective. One-off PAP or VIA screening at age 40 are more cost-effective than other interventions though less effective overall. From a cost-effectiveness perspective, consideration should be given to implementing vaccination (depending on cost per dose and longevity of efficacy) and screening programmes on a worldwide basis to reduce the burden of disease from cervical cancer. Treatment should also be increased where coverage is low.

Developing vaccines against minor capsid antigen L2 to prevent papillomavirus infection

A subset of human papillomavirus (HPV) genotypes is responsible for approximately 5% of all cancer deaths globally, and uterine cervical carcinoma accounts for the majority of these cases. The impact of HPV is greatest for women who do not have access to effective secondary preventive measures, and consequently over 80% of cervical cancer deaths worldwide occur in developing nations. The understanding that persistent infection by this 'oncogenic' subset of HPV genotypes is necessary for the development of cervical carcinoma has driven the development of preventive vaccines. Two preventive vaccines comprising recombinant HPV L1 virus-like particles (VLPs) have been licensed. However, the current cost of these vaccines precludes sustained global delivery, and they target only two of the approximately 15 known oncogenic HPV types, although approximately 70% of cervical cancer cases are attributed to these two types and there is evidence for some degree of cross-protection against other closely related types. A possible approach to broader immunity at lower cost is to consider vaccination against L2. L2 vaccines can be produced inexpensively and they also have the promise of conferring much broader cross-type protective immunity than that observed with L1 VLP immunization. However, L2 vaccine development lags behind L1 VLP vaccines and several technical hurdles remain.

Concatenated multitype L2 fusion proteins as candidate prophylactic pan-human papillomavirus vaccines

BACKGROUND

Vaccination with minor capsid protein L2 induces antibodies that cross-neutralize diverse papillomavirus types. However, neutralizing antibody titers against the papillomavirus type from which the L2 vaccine was derived are generally higher than the titers against heterologous types, which could limit effectiveness against heterologous types. We hypothesized that vaccination with concatenated multitype L2 fusion proteins derived from known cross-protective epitopes of several divergent human papillomavirus (HPV) types might enhance immunity across clinically relevant HPV genotypes.

METHODS

Antibody responses of mice (n = 120) and rabbits (n = 23) to vaccination with HPV-16 amino-terminal L2 polypeptides or multitype L2 fusion proteins, namely, 11-200 x 3 (HPV types 6, 16, 18), 11-88 x 5 (HPV types 1, 5, 6, 16, 18), or 17-36 x 22 (five cutaneous, two mucosal low-risk, and 15 oncogenic types), that were formulated alone or in GPI-0100, alum, or 1018 ISS adjuvants were compared with vaccination with L1 virus-like particles (VLPs), including Gardasil, a licensed quadrivalent HPV L1 vaccine, and a negative control. Mice were challenged with HPV-16 pseudovirions 4 months after vaccination. Statistical tests were two-sided.

RESULTS

The HPV-16 L2 polypeptides generated robust HPV-16-neutralizing antibody responses, albeit lower than those to HPV-16 L1 VLPs, and lower responses against other HPVs. In contrast, vaccination with the multitype L2 fusion proteins 11-200 x 3 and 11-88 x 5 induced high serum neutralizing antibody titers against all heterologous HPVs tested. 11-200 x 3 formulated in GPI-0100 adjuvant or alum with 1018 ISS protected mice against HPV-16 challenge (reduction in HPV-16 infection vs phosphate-buffered saline control, P < .001) 4 months after vaccination as well as HPV-16 L1 VLPs, but 11-200 x 3 alone or formulated with either alum or 1018 ISS was less effective (reduction in HPV-16 infection, P < .001).

CONCLUSION

Concatenated multitype L2 proteins in adjuvant have potential as pan-oncogenic HPV vaccines.

High-throughput two-step LNA real time PCR assay for the quantitative detection and genotyping of HPV prognostic-risk groups

BACKGROUND

Human papillomavirus (HPV) infection is a necessary event in the development of cervical carcinoma. High risk (HR) HPV genotypes, however, may progress differentially from low grade lesions to malignancy.

OBJECTIVES

The necessity to genotype and quantify HPV-DNA in cervical screening programs, in the follow up post-surgical treatments and in monitoring the effectiveness of HPV vaccination programs, requires access to economical, high-throughput and flexible molecular technologies.

STUDY DESIGN

A high-throughput two-step LNA real time PCR assay was developed consisting of real time PCR reactions with fluorescent Locked Nucleic Acid (LNA) probes. The first step permits classification into three prognostic-risk groups of nine HR HPV genotypes (16, 18, 31, 33, 35, 45, 52, 56 and 58) most frequently found associated with cervical lesions in Europe. The second step allows us to genotype/quantify the HPV-DNA only when clinical, epidemiological or prophylactic aims exist.

RESULTS

The specificity, repeatability, detection and quantitation limit, and linearity of the assay were evaluated and appear to be in agreement with guidelines for the validation of analytical procedures. The overall genotype concordance on cervical samples between our assay and INNOLiPA test was 94% (k 0.83) indicating good agreement.

CONCLUSIONS

The two-step PCR assay can give much information relative to the predictive value of different HR HPV types and can quantify the genotype-specific viral load. In particular, its ability to detect and quantify nine HR HPV genotypes can help provide more efficient and successful patient care and may be useful for the monitoring of the efficacy of HPV vaccines.

Human papillomavirus type 16 (HPV-16) virus-like particle L1-specific CD8+ cytotoxic T lymphocytes (CTLs) are equally effective as E7-specific CD8+ CTLs in killing autologous HPV-16-positive tumor cells in cervical cancer patients: implications for L1 dendritic cell-based therapeutic vaccines

Papillomavirus-like particles (VLPs) based on L1 capsid protein represent a promising prophylactic vaccine against human papillomavirus (HPV) infections. However, cell-mediated immune responses against this antigen are believed to be of limited therapeutic value in established HPV-infected cervical lesions and, for this reason, have not been intensively investigated in cervical cancer patients. In this study we analyzed and quantified by real-time PCR (RT-PCR) the RNA expression levels of E6, E7, and L1 genes in flash-frozen HPV-16 cervical carcinomas. In addition, the kinetics of expression of E6, E7, and L1 in HPV-16-infected primary cell lines established as long-term cultures in vitro was also evaluated at RNA and protein levels. Finally, in order to evaluate the therapeutic potential of L1-specific CD4(+) and CD8(+) T lymphocytes responses in cervical cancer patients, L1 VLP-loaded dendritic cells (DCs) were used to stimulate peripheral blood lymphocytes from cervical cancer patients and such responses were compared to those elicited by the E7 oncoprotein. We show that 22 of 22 (100%) flash-frozen cervical biopsy samples collected from HPV-16-positive cervical cancer patients harbor L1, in addition to E6 and E7 RNA, as detected by RT-PCR. E7 RNA copy number (mean, 176.2) was significantly higher in HPV-16-positive cervical cancers compared to the E6 RNA copy number (mean, 47.3) and the L1 copy number (mean, 58.3) (P < 0.0001 and P < 0.001, respectively). However, no significant differences in expression levels between E6 and L1 were found. Kinetic studies of E6, E7, and L1 RNA and protein expression levels in primary tumors showed a sharp reduction in L1 expression after multiple in vitro passages compared to E6 and E7. Autologous DCs pulsed with HPV-16 VLPs or recombinant full-length E7 elicited strong type 1 L1- and E7-specific responses in CD4(+) and CD8(+) T cells from cervical cancer patients. Importantly, L1 VLP-specific CD8(+) T lymphocytes expressed strong cytolytic activity against autologous tumor cells and were as effective as E7-specific cytotoxic T lymphocytes in lysing naturally HPV-16-infected autologous tumor cells. Taken together, these data demonstrate a consistent expression of L1 in primary cervical tumors and the possibility of inducing effective L1/tumor-specific CD4(+) and CD8(+) T-lymphocyte responses in patients harboring HPV-infected cervical cancer. These results may have important implications for the treatment of patients harboring established HPV-infected lesions with L1 VLPs or combined E7/L1 DC-based vaccinations.

Influenza vaccines based on virus-like particles

The simultaneous expression of structural proteins of virus can produce virus-like particles (VLPs) by a self-assembly process in a viral life cycle even in the absence of genomic material. Taking an advantage of structural and morphological similarities of VLPs to native virions, VLPs have been suggested as a promising platform for new viral vaccines. In the light of a pandemic threat, influenza VLPs have been recently developed as a new generation of non-egg based cell culture-derived vaccine candidates against influenza infection. Animals vaccinated with VLPs containing hemagglutinin (HA) or HA and neuraminidase (NA) were protected from morbidity and mortality resulting from lethal influenza infections. Influenza VLPs serve as an excellent model system of an enveloped virus for understanding the properties of VLPs in inducing protective immunity. In this review, we briefly describe the characteristics of influenza VLPs assembled with a lipid bilayer containing glycoproteins, and summarize the current progress on influenza VLPs as an alternative vaccine candidate against seasonal as well as pandemic influenza viruses. In addition, the protective immune correlates induced by vaccination with influenza VLPs are discussed.

Gene expression patterns induced by HPV-16 L1 virus-like particles in leukocytes from vaccine recipients

Human papillomavirus (HPV) virus-like particle (VLP) vaccines were recently licensed. Although neutralizing Ab titers are thought to be the main effectors of protection against infection, early predictors of long-term efficacy are not yet defined and a comprehensive understanding of innate and adaptive immune responses to vaccination is still lacking. Here, microarrays were used to compare the gene expression signature in HPV-16 L1 VLP-stimulated PBMCs from 17 vaccine and 4 placebo recipients before vaccination and 1 mo after receiving the second immunization. Vaccination with a monovalent HPV-16 L1 VLP vaccine was associated with modulation of genes involved in the inflammatory/defense response, cytokine, IFN, and cell cycle pathways in VLP-stimulated PBMCs. Additionally, there was up-regulation of probesets associated with cytotoxic (GZMB, TNFSF10) and regulatory (INDO, CTLA4) activities. The strongest correlations with neutralizing Ab titers were found for cyclin D2 (CCND2) and galectin (LGALS2). Twenty-two differentially expressed probesets were selected for confirmation by RT-PCR in an independent sample set. Agreement with microarray data was seen for more than two-thirds of these probesets. Up-regulation of immune/defense response genes by HPV-16 L1 VLP, in particular, IFN-induced genes, was observed in PBMCs collected before vaccination, with many of these genes being further induced following vaccination. In conclusion, we identified important innate and adaptive response-related genes induced by vaccination with HPV-16 L1 VLP. Further studies are needed to identify gene expression signatures of immunogenicity and long-term protection with potential utility in prediction of long-term HPV vaccination outcomes in clinical trials.

Immunotherapeutic polyoma and human papilloma virus-like particles

Polyomavirus and human papillomavirus (HPV) virus-like particles (VLPs) can be obtained by producing their major capsid protein VP1 (for polyomavirus) or L1 (for HPV) free from other viral genes in, for example, a baculovirus insect system, yeast, Escherichia coli or similar systems. Polyomavirus and HPV VLPs can immunize healthy individuals, and in some cases T-cell-deficient hosts, against primary infection with the corresponding virus. Chimeric VLPs from polyomaviruses or HPVs containing fusion proteins between the VP1/L1 or VP2/VP3/L2 minor capsid proteins and selected antigens can also be produced. These VLPs can then induce B- or T-cell immune responses and be used as preventive or therapeutic vaccines against cancers induced by the corresponding virus, or a cancer bearing the selected tumor antigen.

Human papillomavirus vaccine and cervical cancer prevention

Cervical cancer is one of the most common types of cancer in women worldwide, with the highest rates observed in underdeveloped countries. In the last decades, its incidence has decreased after the implementation of screening programs, mainly in developed countries. Infection with high-risk oncogenic HPV is associated with precancerous lesions and cervical cancer. Advances in the understanding of the role of HPV in the etiology of high-grade cervical lesions (CIN 2/3) and cervical cancer have led to the development, evaluation and recommendation of two prophylactic HPV vaccines. This review article provides a summary of the studies related with their development and efficacy.

Influenza virus-like particles as pandemic vaccines

There is an urgent need to develop novel approaches for vaccination against emerging pathogenic avian influenza viruses as a priority for pandemic preparedness. Influenza virus-like particles (VLPs) have been suggested and developed as a new generation of non-egg-based cell culture-derived vaccine candidates against influenza infection. Influenza VLPs are formed by a self-assembly process incorporating structural proteins into budding particles composed of the hemagglutinin (HA), neuraminidase (NA) and M1 proteins, and may include additional influenza proteins such as M2. Animals vaccinated with VLPs were protected from morbidity and mortality resulting from lethal influenza infections. The protective mechanism of influenza VLP vaccines was similar to that of the currently licensed influenza vaccines inducing neutralizing antibodies and hemagglutination inhibition activities. Current studies demonstrate that influenza VLP approaches can be a promising alternative approach to developing a vaccine for pandemic influenza viruses. The first human clinical trial of a recombinant pandemic-like H5N1 influenza VLP vaccine was initiated in July 2007 (Bright et al., unpublished).

Prophylactic HPV vaccines

Human papillomavirus (HPV) is one of the most common sexually transmitted diseases worldwide. Cervical and other anogenital cancers, cervical and anal intraepithelial neoplasia, genital warts, and recurrent respiratory papillomatosis are HPV associated diseases. Prophylactic HPV vaccines are composed of HPV L1 capsid protein that self-assemble into virus-like particles (VLPs) when expressed in recombinant systems. Two types of prophylactic vaccines are designed as a bivalent vaccine to protect against high-risk HPV types 16 and 18 and a quadrivalent vaccine designed to protect against HPV 16 and 18, and low-risk, genital wart-causing HPV 6 and 11. Proof-of-principle trials have suggested that intramuscular injections of VLPs result in strong adaptive immune responses that are capable of neutralizing subsequent natural infections. Recent research on the safety and efficacy of candidate prophylactic vaccines against HPV have shown very promising results with nearly 100% efficacy in preventing the development of persistent infections and cervical precancerous lesions in vaccinated individuals.

Immunobiology of human papillomavirus infection and vaccination - implications for second generation vaccines

Prophylactic human papillomavirus (HPV) L1 virus like particle (VLP) vaccines have been shown, in large clinical trials, to be very immunogenic, well-tolerated and highly efficacious against genital disease caused by the vaccine HPV types. However these vaccines, at the present, protect against only two of the 15 oncogenic genital HPV types, they are expensive, delivered by intramuscular injection and require a cold chain. The challenges are to develop cheap, thermo-stable vaccines that can be delivered by non-injectable methods that provide long term (decades) protection at mucosal surfaces to most, if not all, oncogenic HPV types that is as good as the current VLP vaccines. Current approaches include L1 capsomers, L2 protein and peptides, delivery via recombinant L1 bacterial and viral vectors and large-scale VLP production in plants. Rational design and successful development of such vaccines will be based on an understanding of the immune response, and particularly the 'cross talk' between the innate and adaptive responses. This will be central in the development of adjuvants and vaccine formulations that induce the response to provide effective protection.

Vaccination with HPV16 L2E6E7 fusion protein in GPI-0100 adjuvant elicits protective humoral and cell-mediated immunity

A vaccine comprising human papillomavirus type 16 (HPV16) L2, E6 and E7 in a single tandem fusion protein (termed TA-CIN) has the potential advantages of both broad cross-protection against HPV transmission through induction of L2 antibodies able to cross neutralize different HPV types and of therapy by stimulating T cell responses targeting HPV16 early proteins. However, patients vaccinated with TA-CIN alone develop weak HPV neutralizing antibody and E6/E7-specific T cell responses. Here we test TA-CIN formulated along with the adjuvant GPI-0100, a semi-synthetic quillaja saponin analog that was developed to promote both humoral and cellular immune responses. Subcutaneous administration to mice of TA-CIN (20 microg) with 50microg GPI-0100, three times at biweekly intervals, elicited high titer HPV16 neutralizing serum antibody, robust neutralizing titers for other HPV16-related types, including HPV31 and HPV58, and neutralized to a lesser extent other genital mucosatropic papillomaviruses like HPV18, HPV45, HPV6 and HPV11. Notably, vaccination with TA-CIN in GPI-0100 protected mice from cutaneous HPV16 challenge as effectively as HPV16 L1 VLP without adjuvant. Formulation of TA-CIN with GPI-0100 enhanced the production of E7-specific, interferon gamma producing CD8(+) T cell precursors by 20-fold. Vaccination with TA-CIN in GPI-0100 also completely prevented tumor growth after challenge with 5x10(4) HPV16-transformed TC-1 tumor cells, whereas vaccination with TA-CIN alone delayed tumor growth. Furthermore, three monthly vaccinations with 125 microg of TA-CIN and 1000 microg GPI-0100 were well tolerated by pigtail macaques and induced both HPV16 E6/E7-specific T cell responses and serum antibodies that neutralized all HPV types tested.

Evaluation of systemic and mucosal anti-HPV16 and anti-HPV18 antibody responses from vaccinated women

Ideal methods to monitor HPV neutralizing antibodies induced by vaccination have not been established yet. Here, we evaluated systemic and cervical antibody levels induced by HPV16/18 AS04-adjuvanted vaccine (GlaxoSmithKline Biologicals) using a secreted alkaline phosphatase neutralization assay (SEAP-NA) and enzyme-linked immunosorbent assay (ELISA). Serum and cervical secretions from 50 vaccinated women were used to assess (1) overall assay reproducibility; (2) inter-assay and inter-specimen correlation; (3) correlations between month 1 and month 12 titers. Strong correlations between SEAP-NA and ELISA were observed (serum anti-HPV16/18, rho=0.91/0.85; cervix anti-HPV16/18, rho=0.84/0.89). Systemic and cervical antibody measures also correlated well (rho range: 0.64-0.75); except at mid-cycle (rho range: 0.28-0.65). Correlations between antibody levels at 1 and 12 months following the start of vaccination were poor (rho range: 0.16-0.38). In conclusion, HPV16/18 VLP-based ELISA is a reliable and valid method to monitor anti-HPV16/18 neutralizing potential for the first year following vaccination; however, additional studies will be required to better define the effects of the time on cycle and patterns of antibody response over time following vaccination.