Assessment of the serological relatedness of genital human papillomaviruses by hemagglutination inhibition

Screening and identification of B cell epitope within the major capsid protein L1 of HPV 52, using monoclonal antibodies

The L1 protein of Human papillomavirus (HPV), the main capsid protein, induces the formation of neutralizing antibodies. In this study, HPV52 L1 protein was induced to be expressed. Monoclonal antibody (mAb) 6A7 against L1 protein were screened by cell fusion techniques. Western Blot and immunofluorescence assay (IFA) demonstrated the specificity of the mAb. The L1 protein was truncated for prokaryotic expression (N1∼N7) and Dot-ELISA showed that 6A7 recognized N3 (aa 200-350). The immunodominant regions were truncated again for expression, with 6A7 recognizing N6 (aa 251-305). The N6 proteins were further truncated and then were constructed an four-segment eukaryotic expression vector. IFA showed that 6A7 could recognize amino acid 262-279. Amino acid 262-279 was selected to be truncated into short peptides P1 and P2. Finally, Peptide-ELISA and Dot-ELISA showed that the epitope regions of mAb 6A7 were amino acid 262-273. The mAbs with defined epitopes can lay the foundation for the analysis of antigenic epitope characteristics and promote the development of epitope peptide vaccines.

The HPV Induced Cancer Resource (THInCR): a Suite of Tools for Investigating HPV-Dependent Human Carcinogenesis

Human papillomaviruses (HPVs) are highly infectious and cause the most common sexually transmitted viral infections. They induce hyperproliferation of squamous epithelial tissue, often forming warts. Virally encoded proteins reprogram gene expression and cell growth to create an optimal environment for viral replication. In addition to their normal roles in infection, functional alterations induced by viral proteins establish conditions that frequently contribute to human carcinogenesis. In fact, ~5% of human cancers are caused by HPVs, with virtually all cervical squamous cell carcinomas (CESC) and an increasing number of head and neck squamous cell carcinomas (HNSC) attributed to HPV infection. The Cancer Genome Atlas (TCGA) molecularly characterized thousands of primary human cancer samples in many cancer types, including CESC and HNSC, and created a comprehensive atlas of genomic, epigenomic, and transcriptomic data. This publicly available genome-wide information provides an unprecedented opportunity to expand the knowledge of the role that HPV plays in human carcinogenesis. While many tools exist to mine these data, few, if any, focus on the comparison of HPV-positive cancers with their HPV-negative counterparts or adjacent normal control tissue. We have constructed a suite of web-based tools, The HPV Induced Cancer Resource (THInCR), to utilize TCGA data for research related to HPV-induced CESC and HNSC. These tools allow investigators to gain greater biological and medical insights by exploring the impacts of HPV on cellular gene expression (mRNA and microRNA), altered gene methylation, and associations with patient survival and immune landscape features. These tools are accessible at https://thincr.ca/. IMPORTANCE The suite of analytical tools of THInCR provides the opportunity to investigate the roles that candidate target genes identified in cell lines or other model systems contribute to in actual HPV-dependent human cancers and is based on large-scale TCGA data sets. Expression of target genes, including both mRNA and microRNA, can be correlated with HPV gene expression, epigenetic changes in DNA methylation, patient survival, and numerous immune features, like leukocyte infiltration, interferon gamma response, T cell response, etc. Data from these analyses may immediately provide evidence to validate in vitro observations, reveal insights into mechanisms of virus-mediated alterations in cell growth, behavior, gene expression, and innate and adaptive immunity and may help hypothesis generation for further investigations.

Incidence, Clearance, and Persistence of Anal Human Papillomavirus in Men Who Have Sex With Men Living With Human Immunodeficiency Virus: Implications for Human Papillomavirus Vaccination

BACKGROUND

Men who have sex with men living with human immunodeficiency virus have a high risk of anal cancer. We estimate the likely benefit of human papillomavirus (HPV) vaccination among participants of the Anal Cancer Examination study.

METHODS

Anal swabs were collected for the detection and genotyping of anal HPV DNA by linear array (Roche Diagnostics) in this 2-year multicenter prospective cohort. We calculated the proportion of men, stratified by age, without detectable vaccine type-specific DNA.

RESULTS

Overall, 255 men, with a median age of 50 years (interquartile range, 44-56 years) contributed 488.9 person-years of follow-up. After 2 years of follow-up, 149 (58%; 95% confidence interval [CI], 52-65) had at least 1 high-risk HPV (HRHPV), and 71 (28%, 95% CI, 22-34) had HPV types 16/18 detected. Assuming that DNA-negative men would receive vaccine protection, vaccination at baseline could potentially prevent HRHPV infection in 10.2% of men (95% CI, 6.8-14.6, 26 of 255) 2 years later from incident HRHPV covered by the bivalent and quadrivalent vaccine, and 29.4% of men (95% CI, 23.9-35.4, 75/255) from incident HRHPV covered by the nonavalent vaccine.

CONCLUSION

Though there is high prevalence of anal HPV in men who have sex with men living with human immunodeficiency virus, there was also a high incidence of HRHPV vaccine types in the 2-year follow-up, indicating potential for prevention if these men were not previously infected with HPV vaccine types and were vaccinated at their baseline visit.

Rational design of a triple-type human papillomavirus vaccine by compromising viral-type specificity

Sequence variability in surface-antigenic sites of pathogenic proteins is an important obstacle in vaccine development. Over 200 distinct genomic sequences have been identified for human papillomavirus (HPV), of which more than 18 are associated with cervical cancer. Here, based on the high structural similarity of L1 surface loops within a group of phylogenetically close HPV types, we design a triple-type chimera of HPV33/58/52 using loop swapping. The chimeric VLPs elicit neutralization titers comparable with a mix of the three wild-type VLPs both in mice and non-human primates. This engineered region of the chimeric protein recapitulates the conformational contours of the antigenic surfaces of the parental-type proteins, offering a basis for this high immunity. Our stratagem is equally successful in developing other triplet-type chimeras (HPV16/35/31, HPV56/66/53, HPV39/68/70, HPV18/45/59), paving the way for the development of an improved HPV prophylactic vaccine against all carcinogenic HPV strains. This technique may also be extrapolated to other microbes.

Antibody Competition Reveals Surface Location of HPV L2 Minor Capsid Protein Residues 17-36

The currently available nonavalent human papillomavirus (HPV) vaccine exploits the highly antigenic L1 major capsid protein to promote high-titer neutralizing antibodies, but is limited to the HPV types included in the vaccine since the responses are highly type-specific. The limited cross-protection offered by the L1 virus-like particle (VLP) vaccine warrants further investigation into cross-protective L2 epitopes. The L2 proteins are yet to be fully characterized as to their precise placement in the virion. Adding to the difficulties in localizing L2, studies have suggested that L2 epitopes are not well exposed on the surface of the mature capsid prior to cellular engagement. Using a series of competition assays between previously mapped anti-L1 monoclonal antibodies (mAbs) (H16.V5, H16.U4 and H16.7E) and novel anti-L2 mAbs, we probed the capsid surface for the location of an L2 epitope (aa17-36). The previously characterized L1 epitopes together with our competition data is consistent with a proposed L2 epitope within the canyons of pentavalent capsomers.

Epidemiology of cervical human papillomavirus (HPV) infection and squamous intraepithelial lesions (SIL) among a cohort of HIV-infected and uninfected Ghanaian women

Background

There is limited data in Ghana on the epidemiology of HPV and cervical neoplasia and their associations with HIV. This study aimed to compare among HIV-1 seropositive and HIV-seronegative Ghanaian women: (1) the prevalence, genotype distribution and risk factors associated with cervical HPV infection; and (2) the prevalence and risk factors associated with abnormal cervical cytology.

Methods

A comparative frequency-matched study was conducted in a systematic sample of women aged ≥18 years attending HIV and general outpatient clinics in Cape Coast Teaching Hospital, Ghana. Participants were interviewed and cervical samples collected for HPV genotyping (Seegene Anyplex-II HPV28) and cytological testing.

Results

Overall, 333 women were recruited, 163 HIV-1 seropositive and 170 HIV-seronegative women of mean age 43.8 years (SD ±9.4)) and 44.3 years (SD ±12.8), respectively. The prevalence of 14 high-risk (hr) HPV genotypes was higher among HIV-1 seropositive women (65.6% vs. 30.2%, P < 0.0001), as was proportion with multiple hr.-HPV infections (60.6% vs. 21.3%, P < 0.0001). HPV35 was the most prevalent hr.-HPV genotype in both groups (11.9% and 5.3%). The main factors associated with hr.-HPV infection were age for HIV-positive women and circumcision status of main sexual partner for both HIV-negative and positive women.

Abnormal cervical cytology prevalence was higher among HIV-1 seropositive women (any SIL: 14.1% vs. 1.2%, P < 0.0001; low-grade SIL [LSIL]: 4.9% vs. 0.6%, P = 0.02; high-grade SIL: 1.8% vs. 0%, P = 0.07). Among HIV-1 seropositive women, number of pregnancies and CD4+ cell count were associated with LSIL+ cytology. There was strong association between LSIL+ abnormalities and HPV35 (aOR = 4.7, 95%CI: 1.3–17.7, P = 0.02).

Conclusions

HIV-1 infected women bear significant burden of HPV infection and related disease. Prevention and screening programmes should be specifically deployed for this population in Ghana.

Electronic supplementary material

The online version of this article (10.1186/s12885-017-3682-x) contains supplementary material, which is available to authorized users.

Development of HPV Vaccines for HPV-associated Head and Neck Squamous Cell Carcinoma

High-risk genotypes of the human papillomavirus (HPV), particularly HPV type 16, are found in a distinct subset of head and neck squamous cell carcinomas (HNSCC). Thus, these HPV-associated HNSCC may be prevented or treated by vaccines designed to induce appropriate HPV virus-specific immune responses. Infection by HPV may be prevented by neutralizing antibodies specific for the viral capsid proteins. In clinical trials, vaccines comprised of HPV virus-like particles (VLPs) have shown great promise as prophylactic HPV vaccines. However, given that capsid proteins are not expressed at detectable levels by infected basal keratinocytes, vaccines with therapeutic potential must target other non-structural viral antigens. Two HPV oncogenic proteins, E6 and E7, are important in the induction and maintenance of cellular transformation and are co-expressed in the majority of HPV-containing carcinomas. Therefore, therapeutic vaccines targeting these proteins may have potential to control HPV-associated malignancies. Various candidate therapeutic HPV vaccines are currently being tested whereby E6 and/or E7 is administered in live vectors, in peptides or protein, in nucleic acid form, as components of chimeric VLPs, or in cell-based vaccines. Encouraging results from experimental vaccination systems in animal models have led to several prophylactic and therapeutic vaccine clinical trials. Should they fulfill their promise, these vaccines may prevent HPV infection or control its potentially life-threatening consequences in humans.

Quantitative and epitope-specific antigenicity analysis of the human papillomavirus 6 capsid protein in aqueous solution or when adsorbed on particulate adjuvants

Human papillomavirus (HPV) 6 is a human pathogen which causes genital warts. Recombinant virus-like particle (VLP) based antigens are the active components in prophylactic vaccines to elicit functional antibodies. The binding and functional characteristics of a panel of 15 murine monoclonal antibodies (mAbs) against HPV6 was quantitatively assessed. Elite conformational indicators, recognizing the conformational epitopes, are also elite viral neutralizers as demonstrated with their viral neutralization efficiency (5 mAbs with neutralization titer below 4ng/mL) in a pseudovirion (PsV)-based system. The functionality of a given mAb is closely related to the nature of the corresponding epitope, rather than the apparent binding affinity to antigen. The epitope-specific antigenicity assays can be used to assess the binding activity of PsV or VLP preparations to neutralizing mAbs. These mAb-based assays can be used for process monitoring and for product release and characterization to confirm the existence of functional epitopes in purified antigen preparations. Due to the particulate nature of the alum adjuvants, the vaccine antigen adsorbed on adjuvants was considered largely as "a black box" due to the difficulty in analysis and visualization. Here, a novel method with fluorescence-based high content imaging for visualization and quantitating the immunoreactivity of adjuvant-adsorbed VLPs with neutralizing mAbs was developed, in which antigen desorption was not needed. The facile and quantitative in situ antigenicity analysis was amendable for automation. The integrity of a given epitope or two non-overlapping epitopes on the recombinant VLPs in their adjuvanted form can be assessed in a quantitative manner for cross-lot or cross-product comparative analysis with minimal manipulation of samples.

A human monoclonal antibody against HPV16 recognizes an immunodominant and neutralizing epitope partially overlapping with that of H16.V5

The presence of neutralizing epitopes in human papillomavirus (HPV) L1 virus-like particles (VLPs) is the structural basis of prophylactic vaccines. An anti-HPV16 neutralizing monoclonal antibody (N-mAb) 26D1 was isolated from a memory B cell of a human vaccinee. The pre-binding of heparan sulfate to VLPs inhibited the binding of both N-mAbs to the antigen, indicating that the epitopes are critical for viral cell attachment/entry. Hybrid VLP binding with surface loop swapping between types indicated the essential roles of the DE and FG loops for both 26D1 (DEa in particular) and H16.V5 binding. Specifically, Tyr(135) and Val(141) on the DEa loop were shown to be critical residues for 26D1 binding via site-directed mutagenesis. Partially overlap between the epitopes between 26D1 and H16.V5 was shown using pairwise epitope mapping, and their binding difference is demonstrated to be predominantly in DE loop region. In addition, 26D1 epitope is immunodominant epitope recognized by both antibodies elicited by the authentic virus from infected individuals and polyclonal antibodies from vaccinees. Overall, a partially overlapping but distinct neutralizing epitope from that of H16.V5 was identified using a human N-mAb, shedding lights to the antibody arrays as part of human immune response to vaccination and infection.

HPV vaccination to prevent cervical cancer and other HPV-associated disease: from basic science to effective interventions

Identification of HPV infection as the etiologic agent of virtually all cases of cervical cancer, as well as a proportion of other epithelial cancers, has led to development of three FDA-approved multivalent prophylactic HPV vaccines composed of virus-like particles (VLPs). This essay describes the research and development that led to the VLP vaccines; discusses their safety, efficacy, and short-term effect on HPV-associated disease; and speculates that even a single dose of these vaccines, when given to adolescents, might be able to confer long-term protection. The HPV field exemplifies how long-term funding for basic research has lead to clinical interventions with the long-term potential to eradicate most cancers attributable to HPV infection. Although this essay is the result of my receiving the 2015 Harrington Prize for Innovation in Medicine from the Harrington Discovery Institute and the American Society for Clinical Investigation, this clinical advance has depended on the research of many investigators, development of commercial vaccines by the pharmaceutical companies, and participation of many patient volunteers in the clinical trials.

Durable immunity to oncogenic human papillomaviruses elicited by adjuvanted recombinant Adeno-associated virus-like particle immunogen displaying L2 17-36 epitopes

Vaccination with the minor capsid protein L2, notably the 17-36 neutralizing epitope, induces broadly protective antibodies, although the neutralizing titers attained in serum are substantially lower than for the licensed L1 VLP vaccines. Here we examine the impact of other less reactogenic adjuvants upon the induction of durable neutralizing serum antibody responses and protective immunity after vaccination with HPV16 and HPV31 L2 amino acids 17-36 inserted at positions 587 and 453 of VP3, respectively, for surface display on Adeno-Associated Virus 2-like particles [AAVLP (HPV16/31L2)]. Mice were vaccinated three times subcutaneously with AAVLP (HPV16/31L2) at two week intervals at several doses either alone or formulated with alum, alum and MPL, RIBI adjuvant or Cervarix. The use of adjuvant with AAVLP (HPV16/31L2) was necessary in mice for the induction of L2-specific neutralizing antibody and protection against vaginal challenge with HPV16. While use of alum was sufficient to elicit durable protection (>3 months after the final immunization), antibody titers were increased by addition of MPL and RIBI adjuvants. To determine the breadth of immunity, rabbits were immunized three times with AAVLP (HPV16/31L2) either alone, formulated with alum±MPL, or RIBI adjuvants, and after serum collection, the animals were concurrently challenged with HPV16/31/35/39/45/58/59 quasivirions or cottontail rabbit papillomavirus (CRPV) at 6 or 12 months post-immunization. Strong protection against all HPV types was observed at both 6 and 12 months post-immunization, including robust protection in rabbits receiving the vaccine without adjuvant. In summary, vaccination with AAVLP presenting HPV L2 17-36 epitopes at two sites on their surface induced cross-neutralizing serum antibody, immunity against HPV16 in the genital tract, and long-term protection against skin challenge with the 7 most common oncogenic HPV types when using a clinically relevant adjuvant.

Capsid display of a conserved human papillomavirus L2 peptide in the adenovirus 5 hexon protein: a candidate prophylactic hpv vaccine approach

Background

Infection by any one of 15 high risk human papillomavirus (hrHPV) types causes most invasive cervical cancers. Their oncogenic genome is encapsidated by L1 (major) and L2 (minor) coat proteins. Current HPV prophylactic vaccines are composed of L1 virus-like particles (VLP) that elicit type restricted immunity. An N-terminal region of L2 protein identified by neutralizing monoclonal antibodies comprises a protective epitope conserved among HPV types, but it is weakly immunogenic compared to L1 VLP. The major antigenic capsid protein of adenovirus type 5 (Ad5) is hexon which contains 9 hypervariable regions (HVRs) that form the immunodominant neutralizing epitopes. Insertion of weakly antigenic foreign B cell epitopes into these HVRs has shown promise in eliciting robust neutralizing antibody responses. Thus here we sought to generate a broadly protective prophylactic HPV vaccine candidate by inserting a conserved protective L2 epitope into the Ad5 hexon protein for VLP-like display.

Methods

Four recombinant adenoviruses were generated without significant compromise of viral replication by introduction of HPV16 amino acids L2 12–41 into Ad5 hexon, either by insertion into, or substitution of, either hexon HVR1 or HVR5.

Results

Vaccination of mice three times with each of these L2-recombinant adenoviruses induced similarly robust adenovirus-specific serum antibody but weak titers against L2. These L2-specific responses were enhanced by vaccination in the presence of alum and monophoryl lipid A adjuvant. Sera obtained after the third immunization exhibited low neutralizing antibody titers against HPV16 and HPV73. L2-recombinant adenovirus vaccination without adjuvant provided partial protection of mice against HPV16 challenge to either the vagina or skin. In contrast, vaccination with each L2-recombinant adenovirus formulated in adjuvant provided robust protection against vaginal challenge with HPV16, but not against HPV56.

Conclusion

We conclude that introduction of HPV16 L2 12–41 epitope into Ad5 hexon HVR1 or HVR5 is a feasible method of generating a protective HPV vaccine, but further optimization is required to strengthen the L2-specific response and broaden protection to the more diverse hrHPV.

Development of chimeric candidate vaccine against HPV18: a proof of concept

Human papillomaviruses (HPVs) are prerequisite for the development of cervical cancer, with HPV16 and HPV18 being the most prevalent. Despite the fact that two prophylactic vaccines against HPVs are in the market, wide-scale application of the vaccine in developing countries is a major problem as far as cost of the vaccine and lack of therapeutic efficacy are concerned. Hence, the aim of our study was to develop HPV18 L1E7 chimeric virus-like particles (CVLPs) vaccine candidate possessing both, prophylactic and therapeutic potential against HPV18-associated cervical cancer. In this study, we have developed a potential candidate vaccine against HPV18 involving HPV18 L1E7 CVLPs, which was expressed in E. coli and assembled in vitro. These CVLPs were able to induce a neutralizing antibody response as well as a cell-mediated immune response in mice.

Characteristics of memory B cells elicited by a highly efficacious HPV vaccine in subjects with no pre-existing immunity

Licensed human papillomavirus (HPV) vaccines provide near complete protection against the types of HPV that most commonly cause anogenital and oropharyngeal cancers (HPV 16 and 18) when administered to individuals naive to these types. These vaccines, like most other prophylactic vaccines, appear to protect by generating antibodies. However, almost nothing is known about the immunological memory that forms following HPV vaccination, which is required for long-term immunity. Here, we have identified and isolated HPV 16-specific memory B cells from female adolescents and young women who received the quadrivalent HPV vaccine in the absence of pre-existing immunity, using fluorescently conjugated HPV 16 pseudoviruses to label antigen receptors on the surface of memory B cells. Antibodies cloned and expressed from these singly sorted HPV 16-pseudovirus labeled memory B cells were predominantly IgG (>IgA>IgM), utilized diverse variable genes, and potently neutralized HPV 16 pseudoviruses in vitro despite possessing only average levels of somatic mutation. These findings suggest that the quadrivalent HPV vaccine provides an excellent model for studying the development of B cell memory; and, in the context of what is known about memory B cells elicited by influenza vaccination/infection, HIV-1 infection, or tetanus toxoid vaccination, indicates that extensive somatic hypermutation is not required to achieve potent vaccine-specific neutralizing antibody responses.

There is an urgent need to better understand how to reliably generate effective vaccines, particularly subunit vaccines, as certain pathogens are considered to pose too great of a safety risk to be developed as live, attenuated or killed vaccines (e.g., HIV-1). The human papillomavirus (HPV) vaccines are two of the most effective subunit vaccines ever developed and have continued to show protection against HPV associated disease up to and beyond five years post-vaccination. Moreover, the target population for these vaccines have essentially no pre-existing immunity to the HPV types covered by the vaccine; therefore, these vaccines provide an excellent model for studying the immunity elicited by a highly effective subunit vaccine. As the HPV vaccines, like most vaccines, protect by generating antibodies, we are interested in characterizing the memory B cells elicited by the HPV vaccine. Memory B cells help to sustain antibody levels over time by rapidly differentiating into antibody secreting cells upon pathogen re-exposure. Although previous studies have provided evidence that the HPV vaccines elicit memory B cells, they did not characterize these cells. Here, we have isolated HPV-specific memory B cells from adolescent females and women who received the quadrivalent HPV vaccine and have cloned antibodies from these cells. Importantly, we find that these antibodies potently inhibit HPV and that the memory B cells from which they derive exhibit hallmarks of long-lived memory B cells.

Phylogenetic considerations in designing a broadly protective multimeric L2 vaccine

While the oncogenic human papillomavirus (HPV) types with the greatest medical impact are clustered within the α9 and α7 species, a significant fraction of cervical cancers are caused by α5, α6, and α11 viruses. Benign genital warts are caused principally by the α10 viruses HPV6 and HPV11. In an effort to achieve broad protection against both cervical cancer- and genital wart-associated types, we produced at high levels in bacteria a multimeric protein (α11-88x8) fusing eight polypeptides corresponding to a protective domain comprising L2 residues ∼11 to 88 derived from HPV6 (α10), HPV16 (α9), HPV18 (α7), HPV31 (α9), HPV39 (α7), HPV51 (α5), HPV56 (α6), and HPV73 (α11) and a truncated derivative with the last three units deleted (α11-88x5). Mice were immunized three times with α11-88x8 or α11-88x5 adjuvanted with alum or the licensed HPV vaccines and challenged intravaginally with HPV6, HPV16, HPV26, HPV31, HPV33, HPV35, HPV45, HPV51, HPV56, HPV58, or HPV59 pseudovirions. The α11-88x5 and α11-88x8 vaccines induced similarly robust protection against each HPV type tested and indistinguishable HPV16-neutralizing antibody titers. Passive transfer of α11-88x8 antisera was protective. Further, rabbit antisera to α11-88x8 and α11-88x5 similarly neutralized native HPV18 virions. These findings suggest that immunologic competition between units is not a significant issue and that it is not necessary to include a unit of L2 derived from each species to achieve broader protection against diverse medically significant HPV types than is achieved with the licensed HPV vaccines.

Multivalent human papillomavirus l1 DNA vaccination utilizing electroporation

Objectives

Naked DNA vaccines can be manufactured simply and are stable at ambient temperature, but require improved delivery technologies to boost immunogenicity. Here we explore in vivo electroporation for multivalent codon-optimized human papillomavirus (HPV) L1 and L2 DNA vaccination.

Methods

Balb/c mice were vaccinated three times at two week intervals with a fusion protein comprising L2 residues ∼11−88 of 8 different HPV types (11−88×8) or its DNA expression vector, DNA constructs expressing L1 only or L1+L2 of a single HPV type, or as a mixture of several high-risk HPV types and administered utilizing electroporation, i.m. injection or gene gun. Serum was collected two weeks and 3 months after the last vaccination. Sera from immunized mice were tested for in-vitro neutralization titer, and protective efficacy upon passive transfer to naive mice and vaginal HPV challenge. Heterotypic interactions between L1 proteins of HPV6, HPV16 and HPV18 in 293TT cells were tested by co-precipitation using type-specific monoclonal antibodies.

Results

Electroporation with L2 multimer DNA did not elicit detectable antibody titer, whereas DNA expressing L1 or L1+L2 induced L1-specific, type-restricted neutralizing antibodies, with titers approaching those induced by Gardasil. Co-expression of L2 neither augmented L1-specific responses nor induced L2-specific antibodies. Delivery of HPV L1 DNA via in vivo electroporation produces a stronger antibody response compared to i.m. injection or i.d. ballistic delivery via gene gun. Reduced neutralizing antibody titers were observed for certain types when vaccinating with a mixture of L1 (or L1+L2) vectors of multiple HPV types, likely resulting from heterotypic L1 interactions observed in co-immunoprecipitation studies. High titers were restored by vaccinating with individual constructs at different sites, or partially recovered by co-expression of L2, such that durable protective antibody titers were achieved for each type.

Discussion

Multivalent vaccination via in vivo electroporation requires spatial separation of individual type L1 DNA vaccines.

Enterovirus type 71 neutralizing antibodies in the serum of macaque monkeys immunized with EV71 virus-like particles

Enterovirus type 71 (EV71) is a virulent form of enteroviruses causing hospitalizations for children less than three years of age. Currently there are no anti-viral therapies or vaccines available for EV71. Due to the high risk of poliomyelitis-like paralysis and fatal encephalitis, an effective vaccine to EV71 could potentially prevent virus-induced morbidity and mortality. In this study, we first tested a potential EV71 vaccine candidate based on virus-like particles (VLP). We vaccinated macaque monkeys to validate the immunogenicity of the VLP vaccine to EV71. We detected the VLP or EV71-specific antibodies, neutralization titers, ELISPOT, and T cell response to find their immune responses to EV71. When the VLP vaccine adjuvanted with alum was given to macaque monkeys, these monkeys developed both specific humoral and cellular immune responses to EV71. Despite lower neutralizing antibodies to EV71 were found in sera of VLP-immunized monkeys than monkeys vaccinated with inactivated EV71, VLP-based vaccine generated a memory immune response to EV71. Hence, VLP-based EV71 vaccine is a potential vaccine against EV71 infection.

Evolutionary ecology of human papillomavirus: trade-offs, coexistence, and origins of high-risk and low-risk types

BACKGROUND

We address the ecological and evolutionary dynamics of human papillomavirus (HPV) that lead to the dichotomy between high-risk (HR) and low-risk (LR) types. We hypothesize that HPV faces an evolutionary tradeoff between persistence and per-contact transmission probability. High virion production enhances transmissibility but also provokes an immune response leading to clearance and limited persistence. Alternatively, low virion production increases persistence at the cost of diminished transmission probability per sexual contact. We propose that LR HPV types use the former strategy and that HR types use the latter. Sexual behaviors in a host population determine the success of each strategy.

METHODS

We develop an evolutionary model of HPV epidemiology, which includes host sexual behavior, and we find evolutionarily stable strategies of HPV.

RESULTS

A slow turnover of sexual partners favors HR HPV, whereas high frequency of partner turnover selects for LR. When both sexual behaviors exist as subcultures in a population, disruptive selection can result in the coevolution and ecological coexistence of both HR and LR HPV types.

CONCLUSIONS

Our results indicate that the elimination of HR HPV through vaccines may alter the evolutionary trajectory of the remaining types and promote evolution of new HR HPV types.

Safety and immunogenicity of BPV-1 L1 virus-like particles in a dose-escalation vaccination trial in horses

REASONS FOR PERFORMING STUDY

Infection with bovine papillomaviruses types 1 and 2 (BPV-1, BPV-2) can lead to the development of therapy-resistant skin tumours termed sarcoids and possibly other skin diseases in equids. Although sarcoids seriously compromise the welfare of affected animals and cause considerable economic losses, no prophylactic vaccine is available to prevent this common disease. In several animal species and man, immunisation with papillomavirus-like particles (VLP) has been shown to protect efficiently from papillomaviral infection.

HYPOTHESIS

BPV-1 L1 VLPs may constitute a safe and highly immunogenic vaccine candidate for protection of horses against BPV-1/-2-induced disease.

METHODS

Three groups of 4 horses each received 50, 100 or 150 µg of BPV-1 L1 VLPs, respectively, on Days 0, 28 and 168. Three control horses received adjuvant only. Horses were monitored on a daily basis for one week after each immunisation and then in 2 week intervals. Sera were collected immediately before, 2 weeks after each vaccination and one and 2 years after the final boost and analysed by pseudovirion neutralisation assay.

RESULTS

None of the horses showed adverse reactions upon vaccination apart from mild and transient swelling in 2 individuals. Irrespective of the VLP dose, all VLP-immunised horses had developed a BPV-1-neutralising antibody titre of ≥ 1600 plaque forming units (pfu)/ml 2 weeks after the third vaccination. Eight of 10 trial horses still available for follow-up had neutralising antibody titres ≥ 1600 pfu/ml one year and ≥ 800 pfu/ml 2 years after the last immunisation.

CONCLUSION

Intramuscular BPV-1 L1 VLP vaccination in horses is safe and results in a long-lasting antibody response against BPV-1. Neutralisation titres were induced at levels that correlate with protection in experimental animals and man.

POTENTIAL RELEVANCE

BPV-1 L1 VLPs constitute a promising vaccine candidate for prevention of BPV-1/-2-induced disease in equids.

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.

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.

Vaccination with multimeric L2 fusion protein and L1 VLP or capsomeres to broaden protection against HPV infection

Immunization with L1 as pentavalent capsomeres or virus-like particles (VLPs) generates high and long-lived titers of neutralizing antibodies and protection primarily against the human papillomavirus (HPV) type from which the vaccine was derived. Conversely, vaccination with L2 minor capsid protein derived from multiple HPV types induces lower titer, but more broadly neutralizing and protective antibody responses. We combined the advantages of each protective antigen by immunization with titrated doses of multi-type L2 with either L1 capsomeres or VLP. We observed no significant interference between the L1 and L2 antibody response upon co-administration of L1 vaccines with multi-type L2 vaccines.

Cross-protective responses to human papillomavirus infection

Human papillomavirus (HPV) infections with oncogenic types account for approximately 500,000 deaths per year worldwide, predominantly in underdeveloped countries. The major cause of death is cervical cancer in women, but some additional cancers of the head and neck and anogenital sites also have an HPV etiology. Current virus-like particle-based vaccines are in clinical trials, and show very strong, long-lasting protection against vaccine-matched HPV types. These vaccines currently contain virus-like particles for the HPV types 6, 11, 16 and 18 (Gardasil®) and HPV16 and -18 (Cervarix®). Although type-specific neutralizing antibodies develop from immunizations with these virus-like particle vaccines, promising evidence for cross-protection against related but nonvaccine HPV types is emerging. Strategies to increase cross-protection to cover all oncogenic HPV types (currently approximately 20 types) are underway. These strategies include increasing the number of HPV types in the virus-like particle vaccine, and to the development of second-generation HPV vaccines that include the minor coat protein.

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%.

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.

Serological relationship between cutaneous human papillomavirus types 5, 8 and 92

Evidence of a possible association of cutaneous human papillomavirus (HPV) types, especially members of the genus Betapapillomavirus, and the development of non-melanoma skin cancer (NMSC) is accumulating. Vaccination with virus-like particles (VLPs) consisting of self-assembled L1, the major capsid protein, has been introduced to control anogenital HPV infection. This study examined the serological relationship between betapapillomavirus (beta-PV) types 5 and 8 and the new type HPV-92, which has recently been isolated from a basal cell carcinoma containing a high number of viral genomes. Following expression by recombinant baculoviruses, the L1 protein of HPV-92 self-assembled into VLPs that elicited high-titre antibodies after immunization, similar to VLPs from HPV-5 and -8. Haemagglutination inhibition (HAI) assays were used as a surrogate method for the detection of virion-neutralizing antibodies, which correlates with protection from infection. Antisera raised against HPV-5 and -8 VLPs displayed HAI activity not only against the homologous type, but also against heterologous HPV types 5, 8 and 92, whereas HAI activity of antisera against HPV-92 VLP was restricted to the homologous type. The results of neutralization assays using HPV-5 pseudovirions were consistent with those from HAI assays. Cross-neutralizing immune responses by VLP vaccination against heterologous HPV types may provide broader protection against the multiplicity of HPV types detected in NMSC. If a close link to HPV infection can be conclusively established, these results may provide a basis for further evaluation of VLPs of beta-PVs as candidates for a prophylactic skin-type HPV vaccine, aimed at reducing the incidence of NMSC.

Human papillomavirus infection and the primary and secondary prevention of cervical cancer

A wealth of evidence has led to the conclusion that virtually all cases of cervical cancer are attributable to persistent infection by a subset of human papillomavirus (HPV) types, especially HPV type 16 (HPV-16) and HPV-18. These HPV types also cause a proportion of other cancers, including vulvar, vaginal, anal, penile, and oropharyngeal cancers. Although cervical cancer screening, primarily with the Papanicolaou (Pap) smear, has reduced the incidence of this cancer in industrialized countries, cervical cancer remains the second most common cause of death from cancer in women worldwide, because the developing world has lacked the resources for widespread, high-quality screening. In addition to advances in Pap smear technology, the identification of HPV as the etiologic agent has produced 2 recent advances that may have a major impact on approaches to reduce the incidence of this disease. The first is the development of a preventive vaccine, the current versions of which appear to prevent close to 100% of persistent genital infection and disease caused by HPV-16 and HPV-18; future second-generation vaccines may be able to protect against oncogenic infections by a broader array of HPV types. The second is the incorporation of HPV testing into screening programs. In women aged >30 years, HPV testing can identify high-grade cervical intraepithelial neoplasia earlier than Pap smears with acceptable rates of specificity. These results, together with the high sensitivity of HPV testing, suggest that such testing could permit increased intervals for screening. An inexpensive HPV test in development, if successful, may be incorporated as part of an economically viable 'screen-and-treat' approach in the developing world. The manner in which vaccination and screening programs are integrated will need to be considered carefully so that they are efficient in reducing the overall incidence of cervical cancer.

Patterns of genotype distribution in multiple human papillomavirus infections

The relationship between severe-grade cervical lesions and clusters of human papillomavirus (HPV) genotypes in a taxonomic classification was surveyed in 232 women with previous abnormal cytology. HPV co-infections were clustered according to phylogenetic criteria. Multiple infections were detected in 22.0% of the entire sample. Clade A10 (represented by HPV-6 and HPV-11) appeared more frequently in multiple infections than clade A9, which was represented by five of the most common high-risk types, including HPV-16. Although HPV-16 was the most frequent genotype, it was not more prevalent in multiple infections. Abortion and two or more sexual partners were risk-factors associated with HPV co-infections. Severe cervical dysplasia was associated with co-infections with oncogenic types from different clades, with the association being significant for the high-risk clades A7 and A9.

Surface-exposed Amino Acid Residues of HPV16 L1 Protein Mediating Interaction with Cell Surface Heparan Sulfate

Efficient infection of cells by human papillomaviruses (HPVs) and pseudovirions requires primary interaction with cell surface proteoglycans with apparent preference for species carrying heparan sulfate (HS) side chains. To identify residues contributing to virus/cell interaction, we performed point mutational analysis of the HPV16 major capsid protein, L1, targeting surface-exposed amino acid residues. Replacement of lysine residues 278, 356, or 361 for alanine reduced cell binding and infectivity of pseudovirions. Various combinations of these amino acid exchanges further decreased cell attachment and infectivity with residual infectivity of less than 5% for the triple mutant, suggesting that these lysine residues cooperate in HS binding. Single, double, or triple exchanges for arginine did not impair infectivity, demonstrating that interaction is dependent on charge distribution rather than sequence-specific. The lysine residues are located within a pocket on the capsomere surface, which was previously proposed as the putative receptor binding site. Fab fragments of binding-neutralizing antibody H16.56E that recognize an epitope directly adjacent to lysine residues strongly reduced HS-mediated cell binding, further corroborating our findings. In contrast, mutation of basic surface residues located in the cleft between capsomeres outside this pocket did not significantly reduce interaction with HS or resulted in assembly-deficient proteins. Computer-simulated heparin docking suggested that all three lysine residues can form hydrogen bonds with 2-O-, 6-O-, and N-sulfate groups of a single HS molecule with a minimal saccharide domain length of eight monomer units. This prediction was experimentally confirmed in binding experiments using capsid protein, heparin molecules of defined length, and sulfate group modifications.

Type-specific and cross-reactive antibodies induced by human papillomavirus 31 L1/L2 virus-like particles

The aim of this study was to determine whether antibodies induced by human papillomavirus (HPV) type 31 L1/L2 virus-like particles (VLPs) could cross-react with VLPs of the closely related HPV-16 and distantly related HPV-11, and to investigate the potential role of the L2 protein in L1/L2 VLPs in inducing cross-neutralizing antibodies. Antisera were prepared from rabbits immunized with intact or denatured HPV-31 L1/L2 VLPs. Cross-reaction and cross-neutralization were analysed by Western blotting and ELISA, and by haemagglutination inhibition, respectively. Western blotting results showed that H31 L1/L2 (D) antiserum (antiserum from a rabbit immunized with denatured HPV-31 L1/L2 VLPs) could cross-react with the L1 protein of HPV-11 and -16. HPV-31 L1/L2 VLP antiserum showed strong cross-reaction with and cross-neutralization of HPV-16 VLPs, but this was significantly less with HPV-11 VLPs. In addition, the cross-neutralizing activity against HPV-16 L1/L2 VLPs was slightly higher than that against HPV-16 L1 VLPs, although the difference was not statistically significant. Epitope-blocking ELISA showed that mAb H16.V5 could partially inhibit the cross-reaction of HPV-31 L1/L2 VLP antiserum with HPV-16 L1/L2 VLPs. These results suggested that (i) H31 L1/L2 (D) antiserum could cross-react with L1 protein from both closely related and distantly related HPV types, but HPV-31 L1/L2 VLP antiserum could only cross-neutralize closely related HPV types, (ii) surface-exposed epitopes of the L2 protein in L1/L2 VLPs may induce only low titres of cross-neutralizing antibodies and (iii) certain epitopes that cross-reacted with HPV-31 L1/L2 VLP antiserum are located close to the epitopes recognized by mAb H16.V5. These findings may provide suggestions for the design of multivalent VLP vaccines.

Protection of rabbits against challenge with rabbit papillomaviruses by immunization with the N terminus of human papillomavirus type 16 minor capsid antigen L2

Current L1 virus-like particle (VLP) vaccines provide type-restricted protection against a small subset of the human papillomavirus (HPV) genotypes associated with cervical cancer, necessitating continued cytologic screening of vaccinees. Cervical cancer is most problematic in countries that lack the resources for screening or highly multivalent HPV VLP vaccines, suggesting the need for a low-cost, broadly protective vaccinogen. Here, N-terminal L2 polypeptides comprising residues 1 to 88 or 11 to 200 derived from HPV16, bovine papillomavirus type 1 (BPV1), or cottontail rabbit papillomavirus (CRPV) were produced in bacteria. Rabbits were immunized with these N-terminal L2 polypeptides and concurrently challenged with CRPV and rabbit oral papillomavirus (ROPV). Vaccination with either N-terminal L2 polypeptides of CRPV effectively protected rabbits from CRPV challenge but not from papillomas induced by cutaneous challenge with CRPV genomic DNA. Furthermore, papillomas induced by CRPV genomic DNA deficient for L2 expression grew at the same rate as those induced by wild-type CRPV genomic DNA, further suggesting that the L2 polypeptide vaccines lack therapeutic activity. Neutralizing serum antibody titers of >15 correlated with protection (P < 0.001), a finding consistent with neutralizing antibody-mediated protection. Surprisingly, a remarkable degree of protection against heterologous papillomavirus types was observed after vaccination with N-terminal L2 polypeptides. Notably, vaccination with HPV16 L2 11-200 protected against cutaneous and mucosal challenge with CRPV and ROPV, respectively, papillomaviruses that are evolutionarily divergent from HPV16. Further, vaccination with HPV16 L2 11-200 generates broadly cross-neutralizing serum antibody, suggesting the potential of L2 as a second-generation preventive HPV vaccine antigen.

Translational mini-review series on vaccines: Monitoring of human papillomavirus vaccination

Persistent infection with oncogenic human papillomavirus (HPV) is a necessary cause of cervical cancer. Moreover, HPV type 16 (and to a lesser degree HPV type 18) is linked with more rare cancers, namely cancer of the vulva, vagina, penis, anus, oropharynx and larynx. Effective prophylactic vaccines have been developed. In this review, we briefly address 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.

Prophylactic DNA immunization against multiple papillomavirus types

At least 15 different papillomavirus types are causatively associated with the development of tumors in humans. Since the middle of 2006 a protective, virus-like particle based vaccine against the tumor-related HPV types 16 and 18 is commercially available. We investigated the possibility of applying DNA vaccination to obtain protective antibody responses against multiple papillomavirus types. Our data indicate that low amounts of DNA were sufficient to induce neutralizing antibodies in mice although a DNA dose-dependency in respect to the L1-specific antibody titers was observed. Furthermore, we found that immune responses against different PV types could be induced by simultaneous DNA vaccination with a mixture of expression vectors encoding L1 proteins of different papillomavirus types. However, we observed that there was a strong interference when plasmids encoding different L1 genes were used together. HPV 16 responses were repressed by co-administration of HPV 11 and/or BPV 1 L1 expression constructs. Likewise, BPV 1 responses were repressed by co-administration of HPV 16 or HPV 11 L1 plasmids. This interference could be overcome by administration of the different constructs into different sites of the animals or by sequential immunization. Thus, our results suggest that the mode of repression was due to interference with L1 particle assembly and was not a consequence of immunodominance of certain L1 proteins.

Prévention des infections à papillomavirus et du zona : nouveaux vaccins

Two new vaccines have been recently licensed : a quadrivalent vaccine against Human papillomavirus infections (HPV) 6, 11, 16 and 18, recommended to children from 9 years old and to young adults under the age of 26 years, and a vaccine against herpes zoster for adults from 60 years old onwards. A bivalent vaccine against HPV 16 and 18 will be shortly available. HPV vaccines are composed of the L1 structural proteins of 2 or 4 HPV genotypes, produced by genetic engineering and self-assembled. These inert vaccines are devoid of genetic materials and mimic the viral particle (virus-like particle, VLP). They allow, as suggested by the 4.5 to 5 years follow-up, to prevent HPV infections and the onset of pre-cancerous lesions associated with genotypes contained within the vaccine. They represent a major overhang in the vaccinology field, and, as anti-hepatitis B vaccine, will probably be effective in cancer prevention. Their use must be associated with the continued detection of cervix cancer by smears and also with the prevention of other sexually transmitted diseases. The herpes zoster vaccine is a living attenuated vaccine produced from the OKA/Merck strain already used in the vaccine against varicella. Its safety is good among persons 50 years old and over and its efficiency on lowering herpes zoster incidence, on the burden of illness and on post-herpetic neuralgia has been demonstrated in persons over 60 years old.

Review of current knowledge on HPV vaccination: An Appendix to the European Guidelines for Quality Assurance in Cervical Cancer Screening

The recognition of a strong etiological relationship between infection with high-risk human papillomavirusses and cervical cancer has prompted research to develop and evaluate prophylactic and therapeutic vaccines. One prophylactic quadrivalent vaccine using L1 virus-like particles (VLP) of HPV 6, 11, 16 and 18 is available on the European market since the end of 2006 and it is expected that a second bivalent vaccine containing VLPs of HPV16 and HPV18 will become available in 2007. Each year, HPV16 and HPV18 cause approximately 43,000 cases of cervical cancer in the European continent. Results from the phase-IIb and III trials published thus far indicate that the L1 VLP HPV vaccine is safe and well-tolerated. It offers HPV-naive women a very high level of protection against HPV persistent infection and cervical intra-epithelial lesions associated with the types included in the vaccine. HPV vaccination should be offered to girls before onset of sexual activity. While prophylactic vaccination is likely to provide important future health gains, cervical screening will need to be continued for the whole generation of women that is already infected with the HPV types included in the vaccine. Phase IV studies are needed to demonstrate protection against cervical cancer and to verify duration of protection, occurrence of replacement by non-vaccine types and to define future policies for screening of vaccinated cohorts. The European Guidelines on Quality Assurance for Cervical Cancer Screening provides guidance for secondary prevention by detection and management of precursors lesions of the cervix. The purpose of the appendix on vaccination is to present current knowledge. Developing guidelines for future use of HPV vaccines in Europe, is the object of a new grant offered by the European Commission.

How will HPV vaccines affect cervical cancer?

Cancer of the uterine cervix is the second largest cause of cancer deaths in women, and its toll is greatest in populations that lack screening programmes to detect precursor lesions. Persistent infection with 'high risk' genotypes of human papillomavirus (HPV) is necessary, although not sufficient, to cause cervical carcinoma. Therefore, HPV vaccination provides an opportunity to profoundly affect cervical cancer incidence worldwide. A recently licensed HPV subunit vaccine protects women from a high proportion of precursor lesions of cervical carcinoma and most genital warts. Here we examine the ramifications and remaining questions that surround preventive HPV vaccines.

Preclinical model to test human papillomavirus virus (HPV) capsid vaccines in vivo using infectious HPV/cottontail rabbit papillomavirus chimeric papillomavirus particles

A human papillomavirus (HPV) vaccine consisting of virus-like particles (VLPs) was recently approved for human use. It is generally assumed that VLP vaccines protect by inducing type-specific neutralizing antibodies. Preclinical animal models cannot be used to test for protection against HPV infections due to species restriction. We developed a model using chimeric HPV capsid/cottontail rabbit papillomavirus (CRPV) genome particles to permit the direct testing of HPV VLP vaccines in rabbits. Animals vaccinated with CRPV, HPV type 16 (HPV-16), or HPV-11 VLPs were challenged with both homologous (CRPV capsid) and chimeric (HPV-16 capsid) particles. Strong type-specific protection was observed, demonstrating the potential application of this approach.

Cellular immune responses to HPV-18, -31, and -53 in healthy volunteers immunized with recombinant HPV-16 L1 virus-like particles

Human papillomavirus-like particles (HPV VLP) are candidate vaccines that have shown to be efficacious in reducing infection and inducing robust antiviral immunity. Neutralizing antibodies generated by vaccination are largely type-specific, but little is known about the type-specificity of cellular immune responses to VLP vaccination. To determine whether vaccination with HPV-16 L1VLP induces cellular immunity to heterologous HPV types (HPV-18, HPV-31, and HPV-53), we examined proliferative and cytokine responses in vaccine (n=11) and placebo (n=5) recipients. Increased proliferative and cytokine responses to heterologous types were observed postvaccination in some individuals. The proportion of women responding to heterologous types postvaccination (36%-55%) was lower than that observed in response to HPV-16 (73%). Response to HPV-16 VLP predicted response to other types. The strongest correlations in response were observed between HPV-16 and HPV-31, consistent with their phylogenetic relatedness. In summary, PBMC from HPV-16 VLP vaccine recipients can respond to L1VLP from heterologous HPV types, suggesting the presence of conserved T cell epitopes.

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 GSK3beta. We also present evidence that PV signaling is activated via the alpha6beta4 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.

Prophylactic human papillomavirus vaccines

Human papillomavirus (HPV) infection causes virtually all cases of cervical cancer, the second most common cause of death from cancer among women worldwide. This Review examines prophylactic HPV subunit vaccines based on the ability of the viral L1 capsid protein to form virus-like particles (VLPs) that induce high levels of neutralizing antibodies. Following preclinical research by laboratories in the nonprofit sector, Merck and GlaxoSmithKline are developing commercial versions of the vaccine. Both vaccines target HPV16 and HPV18, which account for approximately 70% of cervical cancer. The Merck vaccine also targets HPV6 and HPV11, which account for approximately 90% of external genital warts. The vaccines have an excellent safety profile, are highly immunogenic, and have conferred complete type-specific protection against persistent infection and associated lesions in fully vaccinated women. Unresolved issues include the most critical groups to vaccinate and when the vaccine's cost may be low enough for widespread implementation in the developing world, where 80% of cervical cancer occurs.