Expanded strain coverage for a highly successful public health tool: Prophylactic 9-valent human papillomavirus vaccine

Vaccine Hesitancy among European Parents-Psychological and Social Factors Influencing the Decision to Vaccinate against HPV: A Systematic Review and Meta-Analysis

BACKGROUND

Due to low adherence to HPV vaccination programs, the European region struggles with vaccination rates lower than 30% among the targeted population. The present report investigated various socio-demographic and psychological factors influencing European parents' hesitancy towards vaccinating their children.

METHODS

As of September 2023, four databases were searched. After applying inclusion criteria, all articles comparing psychological and socio-demographic factors in parents who vaccinate or do not vaccinate their children were included.

RESULTS

Twenty-five primary publications met the criteria, totaling 385,460 responders, of which 311,803 want to or have already vaccinated their child, and 73,555 do not wish to do so. Immigrant and employment status, religion, age of parents and the child's gender seemed to influence their decision to vaccinate their child. Previous experience with vaccines, perceived safety and efficacy and the mother's previous abnormal CCS results also impacted their decision. The caregivers' education, gender, civil status, number of children, family history of neoplasia or mother's CCS attendance did not influence their hesitancy to vaccine.

CONCLUSION

Multiple demographic, social, economic and psychological barriers involved in the parents' hesitancy to vaccinate their children against the HPV virus were highlighted. Specific at-risk categories that need to be targeted with information, education and vaccination campaigns were identified.

Recent Developments in Human Papillomavirus (HPV) Vaccinology

Human papillomavirus (HPV) is causally associated with 5% of cancers, including cancers of the cervix, penis, vulva, vagina, anus and oropharynx. The most carcinogenic HPV is HPV-16, which dominates the types causing cancer. There is also sufficient evidence that HPV types 18, 31, 33, 35, 39, 45, 51, 52, 56, 58 and 59 cause cervical cancer. The L1 protein, which, when assembled into virus-like particles, induces HPV-type-specific neutralising antibodies, forms the basis of all commercial HPV vaccines. There are six licensed prophylactic HPV vaccines: three bivalent, two quadrivalent and one nonavalent vaccine. The bivalent vaccines protect from HPV types 16 and 18, which are associated with more than 70% of cervical cancers. Prophylactic vaccination targets children before sexual debut, but there are now catch-up campaigns, which have also been shown to be beneficial in reducing HPV infection and disease. HPV vaccination of adults after treatment for cervical lesions or recurrent respiratory papillomatosis has impacted recurrence. Gender-neutral vaccination will improve herd immunity and prevent infection in men and women. HPV vaccines are immunogenic in people living with HIV, but more research is needed on the long-term impact of vaccination and to determine whether further boosters are required.

The Effects of Human Papillomavirus Infection and Vaccination on Cardiovascular Diseases, NHANES 2003-2016

BACKGROUND

Human papillomavirus (HPV) infection has been proposed to be an unconventional risk factor for cardiovascular diseases. We investigated the association between HPV infection and cardiovascular diseases among women with or without HPV vaccination.

METHODS

This cross-sectional study included 9,353 women aged between 20 to 59 years old who were tested for vaginal HPV DNA in the National Health and Nutrition Examination Survey (NHANES) 2003-2016. Cardiovascular diseases were defined as the presence of self-reported coronary heart diseases, heart attacks, angina pectoris, and stroke. The association between HPV and cardiovascular diseases was studied using logistic regression, with adjustment for the potential confounders.

RESULTS

A total of 40.8% of women were HPV DNA positive; 3.0% had cardiovascular diseases; and 9.0% of women received the HPV vaccine. The presence of vaginal HPV infection was associated with cardiovascular diseases (odd ratio [OR] = 1.66, 95% confidence interval [CI] 1.28-2.16), which remained significant (OR = 1.54, 95% CI 1.15-2.08) after adjustment for sociodemographic characteristics, lifestyle behaviors, medical history, family history of cardiovascular diseases, and antihypertensive drugs. The association was absent among those who were vaccinated against HPV (OR= 0.50, 95% CI 0.07-3.51) but present among those who were not (OR = 1.63, 95% CI 1.18-2.25).

CONCLUSIONS

There was an association between HPV infection and cardiovascular diseases. This association was not significant among women vaccinated against HPV. The effect of HPV vaccination on cardiovascular diseases requires further investigation.

Clinical Value of Serum miR-106a in the Diagnosis and Prognosis of Human Papillomavirus-Positive Cervical Cancer

INTRODUCTION

Cervical cancer (CC) is a prevailing malignant tumor in women, mainly caused by human papillomavirus (HPV) infection. This study investigated miR-106a expression in the serum of HPV-positive CC patients and estimated its value in diagnosis and prognosis.

METHODS

We enrolled 120 CC patients as study subjects, with another 80 healthy women as controls. Clinical baseline data and clinicopathological indexes including age, tumor size, differentiation degree, FIGO stage, lymph node metastasis, and squamous cell carcinoma antigen (SCC-Ag) were recorded. Serum miR-106a expression was measured using reverse transcription-quantitative polymerase chain reaction. Receiver operating characteristic curve was employed to estimate the efficacy of miR-106a in diagnosing CC or HPV-positive CC. Under a 5-year follow-up, patient survival was recorded, and the impact of miR-106a on overall survival rate was analyzed by the Kaplan-Meier method. The logistic regression model was used to analyze whether miR-106a was an independent prognostic factor for HPV infection in CC patients.

RESULTS

Serum miR-106a was upregulated in CC patients and the level >1.365 assisted the CC diagnosis. miR-106a expression in HPV-positive CC patients was elevated relative to HPV-negative CC patients, and serum miR-106a level >1.300 distinguishing HPV positive and HPV negative. HPV positivity was linked with tumor differentiation degree, FIGO stage, lymph node metastasis, and SCC-Ag in CC patients, but not with age and tumor size. High expression of miR-106a in HPV-positive CC patients increased the risk of poor prognosis, and miR-106a expression is an independent prognostic factor for HPV infection in CC patients.

CONCLUSION

High expression of miR-106a assists in the diagnosis of HPV-positive CC and predicts poor prognosis.

The Increasing Burden of Cancer Among Women and in Rural Areas: A Retrospective Population-Based Study

The retrospective study aimed to describe the epidemiological characteristics and trends of cancer in Anhui Province, China between 2010 and 2018. Cancer registry data were analyzed using the Joinpoint regression model to calculate trends in cancer incidence and mortality. Age-standardized incidence rate, calculated based on the world Segi's population (ASIRW) was higher in males (239.34 per 100 000) than in females (157.13 per 100 000), and higher in rural areas (203.98 per 100 000) compared to urban areas (189.93 per 100 000). The ASIRW for males decreased with an AAPC of -3.0%, while that of females showed an upward trend with an AAPC of 2.1%. At the same time, the ASIRW in urban areas decreased with an AAPC of -2.4%, whereas it remained relatively stable in rural areas. Among males, lung cancer was the most prevalent type of cancer, while breast cancer was the most frequent cancer among women. The age-standardized mortality rate according to the world Segi's population (ASMRW) was 115.32 per 100 000. The ASMRW was higher in males (156.70 per 100 000) than in females (75.51 per 100 000), and higher in rural areas (122.18 per 100 000) than urban areas (109.21 per 100 000). Lung cancer accounted for the majority of cancer-associated mortalities in the province. Attention needs to be focused on women and rural areas due to rapidly increasing incidence and mortality rates for cancer. Furthermore, an effective public health response is imperative, encompassing early screening, diagnosis, and treatment of prevalent cancers in high-risk populations and regions. It's crucial to promote healthy lifestyles among the public through health education.

Healthcare professionals’ views on access to vaccines in Nigeria: A cross sectional study

Vaccines are important public health interventions that are critical in preventing the spread of infectious diseases. Sustainable access to these products is therefore critical in articulating contextual policies and strategies. This study aimed at exploring the views of healthcare professionals regarding perceived challenges and strategies that influence access to vaccines in Nigeria. A cross sectional study was undertaken amongst healthcare practitioners that attended a conference targeted at improving access to vaccines. A questionnaire was used for data collection, and analysis was undertaken using Statistical Package for Social Sciences version 25. Questionnaires were administered to a total of 604 participants, response rate was 87.1%, with male participants (54.4%) being slightly better represented than females (45.6%). A tenth of the participants (10.6%) were educated up to doctorate degree level, and a considerable proportion of the participants (43.6%) worked in the government sector. Slightly above three quarters (78.3%) of the participants were of the view that lack of local production capacity was an obstacle preventing access to vaccines, whilst above two thirds of the respondents (70.5%) were of the opinion that the current funding for research and development towards vaccines was sub-optimal. A total of 70.1% of the sample disagreed that the current policy environment was favourable to development of vaccines, whilst more than half of the participants (56%) perceived a lack of support by philanthropists and relevant foundations, for vaccines development in Nigeria. A majority of the participants (73.7%) indicated that sustainable access to vaccines in Nigeria could be achieved by harnessing local research capacity. This study identified critical challenges limiting access to vaccines in Nigeria and can consequently underpin relevant policy and practice reforms that aim to improve access to this public health tool.

High Expression of Circular RNA-Mitochondrial tRNA Translation Optimization 1 Assists the Diagnosis of High-Risk Human Papillomavirus Infection in Cervical Cancer

OBJECTIVE

Persistence of high-risk human papillomavirus (HR-HPV) infection is a paramount determinant in cervical cancer (CC) development. Circular RNAs have the potential to be promising biomarkers for various cancers. This study explored circular RNA-mitochondrial tRNA translation optimization 1 (circMTO1) expression in the serum of CC patients and its clinical value in diagnosing CC and predicting HR-HPV infection.

MATERIALS AND METHODS

In total, 125 CC patients (including 78 cases with HR-HPV) were enrolled, with another 76 healthy people as controls. Serum circMTO1 and miR-199a expressions were detected by reverse transcription-quantitative polymerase chain reaction, and the diagnostic efficacy of circMTO1 for CC and HR-HPV infection was analyzed by the receiver operating characteristic curve. According to the median of serum circMTO1 expression, CC patients were assigned into circMTO1 low/high expression groups to analyze the correlation between circMTO1 and clinical parameters using the Fisher and χ 2 tests. Independent association of circMTO1 with HR-HPV infection in CC was evaluated via logistics multivariate regression analysis. Targeted relationship between miR-199a and circMTO1 was predicted by Starbase Web site and validated via dual-luciferase assay, with their correlation further assessed by Pearson analysis.

RESULTS

Serum circMTO1 was increased in CC patients and prominently elevated in HR-HPV-positive CC patients, with a level greater than 1.485 assisting CC diagnosis and a level greater than 2.480 assisting HR-HPV-positive diagnosis. The circMTO1 was interrelated to clinical stage, tumor differentiation, lymph node metastasis, invasion depth, and independently linked with HR-HPV infection in CC. Serum miR-199a was downregulated in HR-HPV-positive CC patients and inversely correlated with circMTO1.

CONCLUSIONS

Serum circMTO1 is upregulated in HR-HPV-positive CC patients and has a diagnostic value for HR-HPV infection in CC.

Gaps and Opportunities to Improve Prevention of Human Papillomavirus-Related Cancers

Human papillomavirus (HPV) infections cause more than 35,900 cancers annually in the United States. Although cervical cancer is the most prevalent HPV-related malignancy in women, the virus is also responsible for a significant percentage of anal, vaginal, and vulvar cancers. A comprehensive approach to mitigating cervical cancer includes HPV vaccination (primary prevention), screening and treatment of precancerous lesions (secondary prevention), and diagnosis and treatment of invasive cancer (tertiary prevention). Although a successful strategy, there are opportunities to innovate and increase access that can also be adapted to address the unique clinical care gaps that exist with the other anogenital cancers. The Society for Women's Health Research held a series of interdisciplinary meetings and events, during which expert researchers, clinicians, patient advocates, and health care policy leaders evaluated the current landscape of HPV-related cancers and their effects on women's health. This report summarizes the discussions of this working group and areas it identified in which to address gaps in primary and secondary prevention approaches to improve access and health outcomes for women with HPV-related anogenital cancers.

Structural characterization of a neutralizing mAb H16.001, a potent candidate for a common potency assay for various HPV16 VLPs

With more human papillomavirus (HPV) virus-like particle (VLP) vaccines to hit the market in future, a monoclonal antibody (mAb) with preferably comparable reactivity against vaccines from different expression systems and bioprocesses is urgently needed for the potency characterization. Among all mAbs against HPV16 collected, rabbit mAb H16.001 is potently neutralizing with the highest affinity, recognizes an immune-dominant epitope, and can comparably react with HPV16 vaccines from various sources. Cryo-electron microscopic (cryo-EM) structure demonstrated that 360 H16.001 Fabs could bind to HPV16 capsid in preferable binding manner without steric hindrance between neighboring Fabs, potentially supporting its identification for VLP structural integrity and utility in monitoring VLP structural probity. This structural analysis indicated that mAb H16.001 afforded unbiased potency characterization for various HPV16 vaccines and was potential for use in vaccine regulation practice. This study also showed a model process for selecting suitable mAbs for potency assays of other vaccines.

Twenty years of research on HPV vaccines based on genetically modified lactic acid bacteria: an overview on the gut-vagina axis

Most cervical cancer (CxCa) are related to persistent infection with high-risk human papillomavirus (HR-HPV) in the cervical mucosa, suggesting that an induction of mucosal cell-mediated immunity against HR-HPV oncoproteins can be a promising strategy to fight HPV-associated CxCa. From this perspective, many pre-clinical and clinical trials have proved the potential of lactic acid bacteria (LAB) genetically modified to deliver recombinant antigens to induce mucosal, humoral and cellular immunity in the host. Altogether, the outcomes of these studies suggest that there are several key factors to consider that may offer guidance on improvement protein yield and improving immune response. Overall, these findings showed that oral LAB-based mucosal HPV vaccines expressing inducible surface-anchored antigens display a higher potential to induce particularly specific systemic and mucosal cytotoxic cellular immune responses. In this review, we describe all LAB-based HPV vaccine investigations by reviewing databases from international studies between 2000 and 2020. Our aim is to promote the therapeutic HPV vaccines knowledge and to complete the gaps in this field to empower scientists worldwide to make proper decisions regarding the best strategies for the development of therapeutic HPV vaccines.

Vaccination in patients under monoclonal antibody treatment: an updated comprehensive review

INTRODUCTION

Monoclonal antibodies (mAbs) have become an increasing source of biological treatments. Clinicians should make an effort to update their knowledge on mechanisms of action, indications, and adverse events of these novel therapies. Most of them have immunosuppressive effects and, therefore, vaccination is indicated.

AREAS COVERED

vaccination of patients under mAbs therapies.

EXPERT OPINION

Recommendations on vaccination are still based on expert recommendations and have not been updated in recent years. Specific recommendations for each mAb have not been addressed in the current literature. The aim of this comprehensive review was to collect all the therapeutic mAbs approved up to 1 January 2020 and, based on previous recommendations and the pharmaceutical characteristics of each drug, to propose an updated guide with recommendations on vaccination. Influenza, sequential pneumococcal and Hepatitis B vaccination in patients with negative serology were the only consistent recommendations. Hepatitis A vaccination was proposed for mAbs with special hepatotoxic characteristics. Other vaccines are reviewed and discussed. Several non-immunosuppressive mAbs were detected and, therefore, vaccinations not recommended. We hope that this review can serve as a starting point for compiling updated vaccination recommendations and collecting all the therapeutic mAbs approved up to 2020.

Assessing sociodemographic differences in human papillomavirus vaccine impact studies in the United States: a systematic review using narrative synthesis

OBJECTIVES

Sociodemographic disparities in the incidence and mortality of human papillomavirus (HPV)-associated conditions have been well documented in the pre-HPV vaccine era. It is still unknown if the introduction of routine vaccination has been effective in reducing these prevaccine era inequalities. The purpose of this review was to determine the utilization of sociodemographic variables to assess for disparities in population-level HPV vaccine impact research and to evaluate the current evidence for disparities in the reduction of HPV-associated conditions after vaccine introduction in the United States (US).

STUDY DESIGN

A systematic review of the literature from January 2007 through March 2018 was carried out to identify studies evaluating the impact HPV vaccines have had on the rates of HPV infection, genital warts, and cervical dysplasia (cervical intraepithelial neoplasia grades 1+) in the US. An in-depth review was then performed to synthesize these data and to assess the way prior studies have reported and evaluated for potential disparities in the vaccine's impact within various racial, ethnic, and/or socio-economic subgroups of the population.

METHODS

Vaccine impact studies measure the change in the population-level burden of disease prelicensure versus postlicensure of the vaccine. We systematically searched PubMed/Medline and Embase, combining search terms related to the HPV vaccine, sentinel surveillance, and HPV-associated conditions. Eligible studies were those with population-level, postvaccine introduction data that were conducted in the US. Finally, a cited reference search was conducted for all included articles using the Web of Science platform that accesses three major citation indexes: Science Citation Index, Social Sciences Citation Index, and Arts and Humanities Citation Index. This allowed us to screen not only the articles that were cited by our final collection of studies but also the articles that used our selected studies as one of their references. The study protocol is registered in PROSPERO (#CRD42018107579).

RESULTS

Overall, 23 of the 4139 references retrieved assessed the population-level impact of HPV vaccines between January 1, 2007, and March 29, 2018. Among these, 13 (57%) reported sociodemographic data. Only two articles reported stratified results by sociodemographic factors, thereby allowing assessment for potential disparate impact. One of these studies described differences in the impact of the vaccine by race, ethnicity, and income.

CONCLUSION

Although approximately half of the studies that assessed the impact of the HPV vaccine measured sociodemographic characteristics, few presented results in a way that allowed for the identification of potential differences in impact between the relevant subgroups of the population. Determining to what extent, if any, vaccines are reducing known sociodemographic disparities is an important public health priority and an essential step in developing immunization strategies that are beneficial for all.

Ubiquitin-Regulated Cell Proliferation and Cancer

Ubiquitin ligases (E3) play a crucial role in the regulation of different cellular processes such as proliferation and differentiation via recognition, interaction, and ubiquitination of key cellular proteins in a spatial and temporal regulated manner. The type of ubiquitin chain formed determines the fate of the substrates. The ubiquitinated substrates can be degraded by the proteasome, display altered subcellular localization, or can suffer modifications on their interaction with functional protein complexes. Deregulation of E3 activities is frequently found in various human pathologies, including cancer. The illegitimated or accelerated degradation of oncosuppressive proteins or, inversely, the abnormally high accumulation of oncoproteins, contributes to cell proliferation and transformation. Anomalies in protein abundance may be related to mutations that alter the direct or indirect recognition of proteins by the E3 enzymes or alterations in the level of expression or activity of ubiquitin ligases. Through a few examples, we illustrate here the complexity and diversity of the molecular mechanisms related to protein ubiquitination involved in cell cycle regulation. We will discuss the role of ubiquitin-dependent degradation mediated by the proteasome, the role of non-proteolytic ubiquitination during cell cycle progression, and the consequences of this deregulation on cellular transformation. Finally, we will highlight the novel opportunities that arise from these studies for therapeutic intervention.

Exploring lay public and dental professional knowledge around HPV transmission via oral sex and oral cancer development

Background

Human papillomavirus (HPV) has been associated with certain types of oropharyngeal cancers and yet, the level of knowledge that dental professionals and the lay public have in terms of HPV transmission, oral sexual activities, and oral cancer development needs exploration. The aim of this study was to assess the knowledge held by practicing dental professionals as well as the lay public regarding Human Papillomavirus (HPV) transmission through oral sex and subsequent oropharyngeal cancer development.

Methods

Textual data were collected from a public forum with dental professionals in.

Vancouver, who discussed the HPV-oral sex-oral cancer triad, and from survey data gathered from 212 lay public participants (also in Vancouver) who answered a 13-item questionnaire on the perceived risks of oral sex in terms of HPV infection and oropharyngeal cancer development. The data were analyzed statistically by age group, gender, and sexual orientation using descriptive statistics, while an ANOVA test was used to compare variation in the responses to the survey (p-value = 0.05).

Results

The forum engaged 46 health care professionals, many of whom were aware of the potential risks for head and neck cancer development due to HPV infection, while also questioning “how to effectively talk about HPV with patients.” The survey revealed that 34.5% of the participants believed that oral sex is an activity with no or low risk for the transmission of HPV, while 84% of participants believed the same sexual practices were of low or no-risk for HIV (Human Immunodeficiency Virus) transmission. Most participants (82%) never discussed oral sexual activities with their physicians or dentists/dental hygienists.

Conclusions

The general public remains mostly unaware of the potential links between HPV infection and oropharyngeal cancer. Physicians and dental providers should discuss oral sexual practice with their patients to raise awareness.

The cost-effectiveness of controlling cervical cancer using a new 9-valent human papillomavirus vaccine among school-aged girls in Australia

INTRODUCTION

Cervical cancer imposes a substantial health burden worldwide including in Australia and is caused by persistent infection with one of 13 sexually transmitted high-risk human papillomavirus (HPV) types. The objective of this study was to assess the cost-effectiveness of adding a nonavalent new Gardasil-9® (9vHPV) vaccine to the national immunisation schedule in Australia across three different delivery strategies.

MATERIALS AND METHODS

The Papillomavirus Rapid Interface for Modelling and Economics (PRIME) model was used to examine the cost-effectiveness of 9vHPV vaccine introduction to prevent HPV infection. Academic literature and anecdotal evidence were included on the demographic variables, cervical cancer incidence and mortality, treatment costs, and vaccine delivery costs. The incremental cost-effectiveness ratios (ICERs) were measured per disability-adjusted life years (DALYs) averted, using the heuristic cost-effectiveness threshold defined by the World Health Organisation (WHO). Analyses and data from international agencies were used in scenario analysis from the health system and societal perspectives.

RESULTS

The 9vHPV vaccination was estimated to prevent 113 new cases of cervical cancer (discounted) during a 20-year period. From the health system and societal perspectives, the 9vHPV vaccination was very cost-effective in comparison with the status quo, with an ICER of A$47,008 and A$44,678 per DALY averted, respectively, using the heuristic cost-effectiveness threshold level. Considering delivery strategies, the ICERs per DALY averted were A$47,605, A$46,682, and A$46,738 for school, health facilities, and outreach-based vaccination programs from the health system perspective, wherein, from the societal perspective, the ICERs per DALY averted were A$46,378, A$43,729, A$43,930, respectively. All estimates of ICERs fell below the threshold level (A$73,267).

CONCLUSIONS

This cost-effectiveness evaluation suggests that the routine two-dose 9vHPV vaccination strategy of preadolescent girls against HPV is very cost-effective in Australia from both the health system and societal perspectives. If equally priced, the 9vHPV option is the most economically viable vaccine. Overall, this analysis seeks to contribute to an evidence-based recommendation about the new 9vHPV vaccination in the national immunisation program in Australia.

Oral immunization with bacteriophage MS2-L2 VLPs protects against oral and genital infection with multiple HPV types associated with head & neck cancers and cervical cancer

Human papillomaviruses (HPVs) are the most common sexually transmitted infections. HPVs are transmitted through anogenital sex or oral sex. Anogenital transmission/infection is associated with anogenital cancers and genital warts while oral transmission/infection is associated with head and neck cancers (HNCs) including recurrent respiratory papillomatosis. Current HPV vaccines protect against HPV types associated with ∼90% of cervical cancers and are expected to protect against a percentage of HNCs. However, only a few studies have assessed the efficacy of current vaccines against oral HPV infections. We had previously developed a mixed MS2-L2 candidate HPV vaccine based on bacteriophage MS2 virus-like particles (VLPs). The mixed MS2-L2 VLPs consisted of a mixture of two MS2-L2 VLPs displaying: i) a concatemer of L2 peptide (epitope 20-31) from HPV31 & L2 peptide (epitope 17-31) from HPV16 and ii) a consensus L2 peptide representing epitope 69-86. The mixed MS2-L2 VLPs neutralized/protected mice against six HPV types associated with ∼87% of cervical cancer. Here, we show that the mixed MS2-L2 VLPs can protect mice against additional HPV types; at the genital region, the VLPs protect against HPV53, 56, 11 and at the oral region, the VLPs protect against HPV16, 35, 39, 52, and 58. Thus, mixed MS2-L2 VLPs protect against eleven oncogenic HPV types associated with ∼95% of cervical cancer. The VLPs also have the potential to protect, orally, against the same oncogenic HPVs, associated with ∼99% of HNCs, including HPV11, which is associated with up to 32% of recurrent respiratory papillomatosis. Moreover, mixed MS2-L2 VLPs are thermostable at room temperature for up to 60 days after spray-freeze drying and they are protective against oral HPV infection.

Impact of naturally occurring variation in the human papillomavirus 52 capsid proteins on recognition by type-specific neutralising antibodies

We investigated the impact of naturally occurring variation within the major (L1) and minor (L2) capsid proteins on the antigenicity of human papillomavirus (HPV) type 52 (HPV52). L1L2 pseudoviruses (PsVs) representing HPV52 lineage and sublineage variants A1, A2, B1, B2, C and D were created and tested against serum from naturally infected individuals, preclinical antisera raised against HPV52 A1 and D virus-like particles (VLPs) and neutralising monoclonal antibodies (MAbs) raised against HPV52 A1 VLP. HPV52 lineage D PsV displayed a median 3.1 (inter-quartile range 2.0-5.6) fold lower sensitivity to antibodies elicited following natural infection with, where data were available, HPV52 lineage A. HPV52 lineage variation had a greater impact on neutralisation sensitivity to pre-clinical antisera and MAbs. Chimeric HPV52 A1 and D PsV were created which identified variant residues in the FG (Q281K) and HI (K354T, S357D) loops as being primarily responsible for the reported differential sensitivities. Homology models of the HPV52 L1 pentamer were generated which permitted mapping these residues to a small cluster on the outer rim of the surface exposed pentameric L1 protein. These data contribute to our understanding of HPV L1 variant antigenicity and may have implications for seroprevalence or vaccine immunity studies based upon HPV52 antigens.

Epitope clustering analysis for vaccine-induced human antibodies in relationship to a panel of murine monoclonal antibodies against HPV16 viral capsid

Human papillomavirus (HPV) type 16 is the most common type implicated as the etiological agent that causes cervical cancer. The marketed prophylactic vaccines against HPV infection are composed of virus-like particles (VLPs) assembled from the recombinant major capsid protein L1. Elicitation of functional and neutralizing antibodies by vaccination is the mode of action by which the vaccines prevent the viral infection. In this study, a panel of murine mAbs against HPV16 L1 were generated and comprehensively characterized with respect to their mapping to the epitope spectrum on the viral capsid. These mAbs were categorized into five epitope bins by two different methods based on the pairwise cross-inhibition and competition with human polyclonal antibodies. In addition, a preliminary demonstration of the spatial relationship of the epitopes recognized by these mAbs was performed using a cross-blocking assay with a well-characterized human mAb, 26D1. Interestingly, two mAbs recognizing different epitopes were found to act synergistically in the pseudovirion-based neutralization assay (PBNA). To facilitate cross-lab and cross-study comparison, the international standard (IS) serum 05/134 was used to calibrate the mAbs as well as the human serum samples from the HPV16/18 vaccine recipients. The neutralizing mAbs, particularly those that recognizing immunodominant epitopes, would be useful in developing epitope-specific assays for monitoring the vaccine production process and for serological assessment.