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

HPV-specific antibodies in female genital tract secretions captured via first-void urine retain their neutralizing capacity

Human papillomavirus (HPV) vaccines, primarily relying on neutralizing antibodies, have proven highly effective. Recently, HPV-specific antibodies have been detected in the female genital tract secretions captured by first-void urine (FVU), offering a minimally invasive diagnostic approach. In this study, we investigated whether HPV16-specific antibodies present in FVU samples retain their neutralizing capacity by using pseudovirion-based neutralization assays. Paired FVU and serum samples (vaccinated n = 25, unvaccinated n = 25, aged 18-25) were analyzed using two orthogonal pseudovirion-based neutralization assays, one using fluorescence microscopy and the other using luminescence-based spectrophotometry. Results were compared with HPV16-specific IgG concentrations and correlations between neutralizing antibodies in FVU and serum were explored. The study demonstrated the presence of neutralizing antibodies in FVU using both pseudovirion-based neutralization assays, with the luminescence-based assay showing higher sensitivity for FVU samples, while the fluorescence microscopy-based assay exhibited better specificity for serum and overall higher reproducibility. High Spearman correlation values were calculated between HPV16-IgG and HPV16-neutralizing antibodies for both protocols (rs: 0.54-0.94, p < .001). Significant Spearman correlations between FVU and serum concentrations were also established for all assays (rs: 0.44-0.91, p < .01). This study demonstrates the continued neutralizing ability of antibodies captured with FVU, supporting the hypothesis that HPV vaccination may reduce autoinoculation and transmission risk to the sexual partner. Although further protocol optimizations are warranted, these findings provide a foundation for future research and larger cohort studies that could have implications for the optimal design, evaluation, and implementation of HPV vaccination programs.

Assessing the reduction of viral infectivity in HPV16/18-positive women after one, two, and three doses of Gardasil-9 (RIFT): Study protocol

Human Papillomavirus (HPV) prophylactic vaccination has proven effective in preventing new infections, but it does not treat existing HPV infections or associated diseases. Hence, there is still an important reservoir of HPV in adults, as vaccination programs are mainly focused on young women. The primary objective of this non-randomized, open-label trial is to evaluate if a 3-dose regimen of Gardasil-9 in HPV16/18-positive women could reduce the infective capacity of their body fluids. We aim to assess if vaccine-induced antibodies could neutralize virions present in the mucosa, thus preventing the release of infective particles and HPV transmission to sexual partners. As our main endpoint, the E1^E4-HaCaT model will be used to assess the infectivity rate of cervical, anal and oral samples, obtained from women before and after vaccination. HPV DNA positivity, virion production, seroconversion, and the presence of antibodies in the exudates, will be evaluated to attribute infectivity reduction to vaccination. Our study will recruit two different cohorts (RIFT-HPV1 and RIFT-HPV2) of non-vaccinated adult women. RIFT-HPV1 will include subjects with an HPV16/18 positive cervical test and no apparent cervical lesions or cervical lesions eligible for conservative treatment. RIFT-HPV2 will include subjects with an HPV16/18 positive anal test and no apparent anal lesions or anal lesions eligible for conservative treatment, as well as women with an HPV16/18 positive cervical test and HPV-associated vulvar lesions. Subjects complying with inclusion criteria for both cohorts will be recruited to the main cohort, RIFT-HPV1. Three doses of Gardasil-9 will be administered intramuscularly at visit 1 (0 months), visit 2 (2 months) and visit 3 (6 months). Even though prophylactic HPV vaccines would not eliminate a pre-existing infection, our results will determine if HPV vaccination could be considered as a new complementary strategy to prevent HPV-associated diseases by reducing viral spread. Trial registration: https://clinicaltrials.gov/ct2/show/NCT05334706.

A synthetic notch (synNotch) system linking intratumoral immune-cancer cell communication to a synthetic blood biomarker assay

Introduction: Cellular immunotherapy has greatly improved cancer treatment in recent years. For instance, chimeric antigen receptor (CAR) T cell therapy has been proven highly effective in treating hematological malignancies, and many CAR cell designs are being explored for solid tumors. However, many questions remain why responses differ across patients and some tumor types are resistant. Improved and relatively inexpensive ways to monitor these cells could provide some answers. Clinically, blood tests are regularly used to monitor these therapies, but blood signals often do not reflect the activity of immune cells within the tumor(s). Here, using the synthetic Notch (synNotch) receptor that tethers antigen binding to customized transgene expression, we linked intratumoral immune-cancer cell communication to a simple secreted reporter blood test. Specifically, we engineered immune cells with a CD19-targeted synNotch receptor and demonstrated that binding to CD19 on cancer cells in vivo resulted in the production of secreted embryonic alkaline phosphatase (SEAP) at levels that are readily detected in the blood. Methods and Results: Jurkat T cells were engineered via sequential lentiviral transduction of two components: an anti-CD19 synNotch receptor and a synNotch response element encoding SEAP. Co-culture of engineered cells with CD19+, but not CD19-, Nalm6 cells, resulted in significantly elevated SEAP in media. Nod-scid-gamma (NSG) mice were subcutaneously injected with either CD19+ or CD19- Nalm6 cells. Intratumoral injection of engineered T cells (1x107) resulted in significantly elevated blood SEAP activity in mice bearing CD19+ tumors (n = 7), but not CD19- tumors (n = 5). Discussion: Our synNotch reporter system allows for the monitoring of antigen-dependent intratumoral immune-cancer cell interactions through a simple and convenient blood test. Continued development of this system for different target antigens of interest should provide a broadly applicable platform for improved monitoring of many cell-based immunotherapies during their initial development and clinical translation, ultimately improving our understanding of design considerations and patient-specific responses.

Long-term human papillomavirus vaccination effectiveness and immunity in Rwandan women living with and without HIV: a study protocol

INTRODUCTION

Prophylactic human papillomavirus (HPV) vaccines have been shown to be highly effective in protecting women against cervical infections, high-grade abnormalities and cancer caused by the targeted HPV types. However, the evidence for their effectiveness in women living with HIV (WLWH) is less clear.

METHODS

WLWH and HIV-negative women who likely did (birth cohorts 1996 and later) and WLWH and HIV(-) negative who likely did not (birth cohorts before 1996) receive HPV vaccination (n=3028; 757 participants for each of the four groups). Between groups, we will compare cervicovaginal, anal and oral prevalent and 6-12 month persistent HPV6/11/16/18 infections as measured using a modified AmpFire HPV genotyping assay that tests for 15 high-risk or intermediate-risk HPV genotypes, HPV6 and HPV11. We will also compare the HPV immune response in HPV-vaccinated WLWH to HPV-vaccinated HIV-negative women using an anti-HPV16 and anti-HPV18 ELISA. Vaccination status will be confirmed through national vaccination records.

ANALYSIS

We will calculate point prevalence and prevalence of 6-12 month persisting infections by individual HPV-type specific infections and groups of infections for each anatomic site and for each group of women. Results will be stratified by age at vaccination, age at enrolment and the number of doses (3 vs 2) as well as other factors possibly associated with HPV prevalence. Differences in endpoints between groups, overall and between subgroups, will be tested for statistical significance (p<0.05) using Fisher's exact or Pearson χ² test. Differences in geometric mean titres and seropositivity will be tested for statistical significance using the Mann-Whitney and Fisher's exact tests, respectively.

ETHICS AND DISSEMINATION

The study was approved by the Albert Einstein College of Medicine Institutional Review Board and the Rwanda National Ethics Committee. Results will be disseminated through publication in peer-reviewed journals.

HPV16 infection decreases vaccine-induced HPV16 antibody avidity: the CVT trial

The HPV vaccine has shown sustained efficacy and consistent stabilization of antibody levels, even after a single dose. We defined the HPV16-VLP antibody avidity patterns over 11 years among women who received one- or three doses of the bivalent HPV vaccine in the Costa Rica HPV Vaccine Trial. Absolute HPV16 avidity was lower in women who received one compared to three doses, although the patterns were similar (increased in years 2 and 3 and remained stable over the remaining 8 years). HPV16 avidity among women who were HPV16-seropositive women at HPV vaccination, a marker of natural immune response to HPV16 infection, was significantly lower than those of HPV16-seronegative women, a difference that was more pronounced among one-dose recipients. No differences in HPV16 avidity were observed by HPV18 serostatus at vaccination, confirming the specificity of the findings. Importantly, point estimates for vaccine efficacy against incident, six-month persistent HPV16 infections was similar between women who were HPV16 seronegative and seropositive at the time of initial HPV vaccination for both one-dose and three-dose participants. It is therefore likely that this lower avidity level is still sufficient to enable antibody-mediated protection. It is encouraging for long-term HPV-vaccine protection that HPV16 antibody avidity was maintained for over a decade, even after a single dose.

Design of a Phase III efficacy, immunogenicity, and safety study of 9-valent human papillomavirus vaccine in prevention of oral persistent infection in men

BACKGROUND

Seven high-risk human papillomavirus (HPV) types (16/18/31/33/45/52/58) covered by the 9-valent HPV (9vHPV) vaccine cause >90% of HPV-related head and neck cancers (HNCs). An ongoing clinical trial (NCT04199689) was designed to evaluate 9vHPV vaccine efficacy against HPV oral persistent infection, a surrogate endpoint for HPV-related HNCs.

METHODS

In this double-blind, placebo-controlled, international trial, men aged 20-45 years (N = 6000) are randomized 1:1 to receive 9vHPV vaccine or placebo on day 1, month 2, and month 6. The primary objective is to demonstrate whether 9vHPV vaccination reduces incidence of HPV16/18/31/33/45/52/58-related 6-month oral persistent infection. Incidence of HPV6/11-related 6-month oral persistent infection will be evaluated as a secondary endpoint. Oral rinse and gargle samples will be collected on day 1, month 7, month 12, and every 6 months thereafter for HPV detection by PCR. Primary analyses will be performed in per-protocol populations. Efficacy in this case-driven study will be analyzed upon accrual of ≥20 primary efficacy endpoint cases. Serum will be collected at day 1 and months 7, 12, 24, 36, and 42; anti-HPV antibody titers will be measured by competitive Luminex immunoassay. Data will be summarized as geometric mean titers and seropositivity rates. Injection-site and systemic adverse events (AEs) will be collected for 15 days post-any vaccination and serious AEs through 6 months after the last vaccination; deaths and vaccine-related serious AEs will be collected throughout the study.

DISCUSSION

This trial is expected to generate important data regarding the potential for 9vHPV vaccine to prevent HPV-related head and neck disease.

Increases in HPV-16/18 antibody avidity and HPV-specific memory B-cell response in mid-adult aged men post-dose three of the quadrivalent HPV vaccine

Strong quantitative and functional antibody responses to the quadrivalent human papillomavirus (HPV) vaccine were reported in mid-adult aged men, but there are limited data on the avidity of the antibody response and the memory B-cell response following vaccination. Although circulating antibodies induced by vaccination are believed to be the main mediators of protection against infection, evaluation of avidity of antibodies and memory B cell responses are critical for a better understanding of the vaccine immunogenicity mechanisms. Both the modified enzyme-linked immunosorbent assay (ELISA) and the enzyme-linked immunosorbent spot (ELISpot) assay are tools to measure the humoral and cellular immune responses post vaccination to characterize vaccine immunogenicity. The avidity of HPV-16 and HPV-18 specific IgG in the serum of mid-adult aged men (N = 126) who received three quadrivalent HPV vaccine doses was examined using a modified ELISA. HPV-16 memory B-cell responses were assessed via ELISpot at month 0 (prior to vaccination) and 1-month post-dose three of the vaccine (month 7). The quadrivalent vaccine induced an increase in HPV-16 and HPV-18 antibody avidity at month 7. HPV-18 avidity levels moderately correlated with anti-HPV-18 antibody titers, but no association was observed for HPV-16 antibody titers and avidity levels. The HPV-16-specific memory B-cell response was induced following three vaccine doses, however, no association with anti-HPV-16 antibody avidity was observed. Three doses of quadrivalent HPV vaccine increased antibody affinity maturation for HPV-16/18 and increased the frequency of anti-HPV-16 memory B-cells in mid-adult aged men.

Minicircles for a two-step blood biomarker and PET imaging early cancer detection strategy

Early cancer detection can dramatically increase treatment options and survival rates for patients, yet detection of early-stage tumors remains difficult. Here, we demonstrate a two-step strategy to detect and locate cancerous lesions by delivering tumor-activatable minicircle (MC) plasmids encoding a combination of blood-based and imaging reporter genes to tumor cells. We genetically engineered the MCs, under the control of the pan-tumor-specific Survivin promoter, to encode: 1) Gaussia Luciferase (GLuc), a secreted biomarker that can be easily assayed in blood samples; and 2) Herpes Simplex Virus Type 1 Thymidine Kinase mutant (HSV-1 sr39TK), a PET reporter gene that can be used for highly sensitive and quantitative imaging of the tumor location. We evaluated two methods of MC delivery, complexing the MCs with the chemical transfection reagent jetPEI or encapsulating the MCs in extracellular vesicles (EVs) derived from a human cervical cancer HeLa cell line. MCs delivered by EVs or jetPEI yielded significant expression of the reporter genes in cell culture versus MCs delivered without a transfection reagent. Secreted GLuc correlated with HSV-1 sr39TK expression with R² = 0.9676. MC complexation with jetPEI delivered a larger mass of MC for enhanced transfection, which was crucial for in vivo animal studies, where delivery of MCs via jetPEI resulted in GLuc and HSV-1 sr39TK expression at significantly higher levels than controls. To the best of our knowledge, this is the first report of the PET reporter gene HSV-1 sr39TK delivered via a tumor-activatable MC to tumor cells for an early cancer detection strategy. This work explores solutions to endogenous blood-based biomarker and molecular imaging limitations of early cancer detection strategies and elucidates the delivery capabilities and limitations of EVs.

A dose-reduction HPV vaccine immunobridging trial of two HPV vaccines among adolescent girls in Tanzania (the DoRIS trial) - Study protocol for a randomised controlled trial

BACKGROUND

Human papillomavirus (HPV) infection is the primary cause of cervical cancer. In 2018, the World Health Organization (WHO) Director General announced his commitment to eliminate cervical cancer, with HPV vaccination as a priority. However, the costs of setting up a multi-dose HPV vaccination programme remain a barrier to its introduction.

METHODS/DESIGN

We are conducting a randomised-controlled trial of reduced dose schedules of HPV vaccine in Tanzania to establish whether a single dose produces immune responses that will be effective in preventing cervical cancer. 930 girls aged 9-14 years in Mwanza, Tanzania, were randomised to one of 6 arms, comprising 3 different dose schedules of the 2-valent (Cervarix) and 9-valent (Gardasil-9) HPV vaccines: 3 doses; 2 doses given 6 months apart; or a single dose. All participants will be followed for 36 months; those in the 1 and 2 dose arms will be followed for 60 months. Trial outcomes focus on vaccine immune responses including HPV 16/18-specific antibody levels, antibody avidity, and memory B cell responses. Results will be immunobridged to historical cohorts of girls and young women in whom efficacy has been demonstrated.

DISCUSSION

This is the first randomised trial of the single dose HPV vaccine schedule in the target age group. The trial will allow us to examine the quality and durability of immune responses of reduced dose schedules in a population with high burden of malaria and other infections that may affect vaccine immune responses. Initial results (24 months) are expected to be published in early 2021.

Immune Response Following Quadrivalent Human Papillomavirus Vaccination in Women After Hematopoietic Allogeneic Stem Cell Transplant: A Nonrandomized Clinical Trial

Importance

Human papillomavirus (HPV) infection is found in about 40% of women who survive allogeneic hematopoietic stem cell transplant and can induce subsequent neoplasms.

Objective

To determine the safety and immunogenicity of the quadrivalent HPV vaccine (HPV-6, -11, -16, and -18) in clinically stable women post-allogeneic transplant compared with female healthy volunteers.

Interventions

Participants received the quadrivalent HPV vaccine in intramuscular injections on days 1 and 2 and then 6 months later.

Design, Setting, and Participants

This prospective, open-label phase-1 study was conducted in a government clinical research hospital and included clinically stable women posttransplant who were or were not receiving immunosuppressive therapy compared with healthy female volunteers age 18 to 50 years who were followed up or a year after first receiving quadrivalent HPV vaccination. The study was conducted from June 2, 2010, until July 19, 2016. After all of the results of the study assays were completed and available in early 2018, the analysis took place from February 2018 to May 2019.

Main Outcomes and Measures

Anti-HPV-6, -11, -16, and -18-specific antibody responses using L1 virus-like particle enzyme-linked immunosorbent assay were measured in serum before (day 1) and at months 7 and 12 postvaccination. Anti-HPV-16 and -18 neutralization titers were determined using a pseudovirion-based neutralization assay.

Results

Of 64 vaccinated women, 23 (35.9%) were receiving immunosuppressive therapy (median age, 34 years [range, 18-48 years]; median 1.2 years posttransplant), 21 (32.8%) were not receiving immunosuppression (median age, 32 years [range, 18-49 years]; median 2.5 years posttransplant), and 20 (31.3%) were healthy volunteers (median age, 32 years [range, 23-45 years]). After vaccine series completion, 18 of 23 patients receiving immunosuppression (78.3%), 20 of 21 not receiving immunosuppression (95.2%), and all 20 volunteers developed antibody responses to all quadrivalent HPV vaccine types (P = .04, comparing the 3 groups). Geometric mean antibody levels for each HPV type were higher at months 7 and 12 than at baseline in each group (all geometric mean ratios >1; P < .001) but not significantly different across groups. Antibody and neutralization titers for anti-HPV-16 and anti-HPV-18 correlated at month 7 (Spearman ρ = 0.92; P < .001 for both). Adverse events were mild and not different across groups.

Conclusions and Relevance

Treatment with the HPV vaccination was followed by strong, functionally active antibody responses against vaccine-related HPV types and no serious adverse events. These findings suggest that HPV vaccination may be safely administered to women posttransplant to potentially reduce HPV infection and related neoplasia.

Trial Registration

ClinicalTrials.gov Identifier: NCT01092195.

Comparison of a VLP-based and GST-L1-based multiplex immunoassay to detect vaccine-induced HPV-specific antibodies in first-void urine

Vaccine-induced human papillomavirus (HPV) antibodies originating from cervicovaginal secretions were recently shown to be detectable in first-void (FV) urine. This presents a novel opportunity for noninvasive sampling to monitor HPV antibody status in women participating in large epidemiological studies and HPV vaccine trials. With a view towards method optimization, this study compared the measurement of HPV antibodies in FV urine using a multiplex L1/L2 virus-like particles (VLP)-based ELISA (M4ELISA) with previously reported results using a glutathione S-transferase (GST)-L1-based immunoassay (GST-L1-MIA). We tested 53 paired FV urine and serum samples from 19- to 26-year-old healthy women, unvaccinated (n = 17) or vaccinated with either the bivalent or quadrivalent HPV-vaccine during adolescence (n = 36). HPV6/11/16/18 antibodies were measured using M4ELISA and compared with GST-L1-MIA results. Inter-assay and inter-specimen correlations were examined using the Spearman's rank test (rs). As expected, lower HPV antibody concentrations were found in FV urine than in serum. Vaccinated women had significantly higher HPV6/11/16/18 antibody levels in both FV urine and serum compared with those unvaccinated (M4ELISA; FV urine P = .0003; serum P ≤ .0001). HPV antibody levels in FV urine and serum showed a significant positive correlation (M4ELISA anti-HPV6/11/16/18, rs  = 0.85/0.86/0.91/0.79, P ≤ .001). Despite assay differences, there was moderate to good correlation between M4ELISA and GST-L1-MIA (FV urine anti-HPV6/11/16/18, rs  = 0.86/0.83/0.89/0.53, P ≤  .0001; serum anti-HPV6/11/16/18, rs  = 0.93/0.89/0.94/0.75, P ≤ .0001). FV urine HPV antibody detection is comparable with both assays, further supporting this noninvasive sampling method as a possible option for HPV vaccine assessment. Approaches to improve the sensitivity and larger studies are warranted to determine the feasibility of FV urine for vaccine-induced HPV antibody detection.

Evaluation of Durability of a Single Dose of the Bivalent HPV Vaccine: The CVT Trial

BACKGROUND

The authors investigated the durability of vaccine efficacy (VE) against human papillomavirus (HPV)16 or 18 infections and antibody response among nonrandomly assigned women who received a single dose of the bivalent HPV vaccine compared with women who received multiple doses and unvaccinated women.

METHODS

HPV infections were compared between HPV16 or 18-vaccinated women aged 18 to 25 years who received one (N = 112), two (N = 62), or three (N = 1365) doses, and age- and geography-matched unvaccinated women (N = 1783) in the long-term follow-up of the Costa Rica HPV Vaccine Trial. Cervical HPV infections were measured at two study visits, approximately 9 and 11 years after initial HPV vaccination, using National Cancer Institute next-generation sequencing TypeSeq1 assay. VE and 95% confidence intervals (CIs) were estimated. HPV16 or 18 antibody levels were measured in all one- and two-dose women, and a subset of three-dose women, using a virus-like particle-based enzyme-linked immunosorbent assay (n = 448).

RESULTS

Median follow-up for the HPV-vaccinated group was 11.3 years (interquartile range = 10.9-11.7 years) and did not vary by dose group. VE against prevalent HPV16 or 18 infection was 80.2% (95% CI = 70.7% to 87.0%) among three-dose, 83.8% (95% CI = 19.5% to 99.2%) among two-dose, and 82.1% (95% CI = 40.2% to 97.0%) among single-dose women. HPV16 or 18 antibody levels did not qualitatively decline between years four and 11 regardless of the number of doses given, although one-dose titers continue to be statistically significantly lower compared with two- and three-dose titers.

CONCLUSION

More than a decade after HPV vaccination, single-dose VE against HPV16 or 18 infection remained high and HPV16 or 18 antibodies remained stable. A single dose of bivalent HPV vaccine may induce sufficiently durable protection that obviates the need for more doses.

Non-invasive Assessment of Vaccine-Induced HPV Antibodies via First-Void Urine

The potential of first-void (FV) urine as a non-invasive method to monitor human papillomavirus (HPV) vaccination has been reported, mainly focusing on urine as a sample to assess HPV DNA. Besides HPV DNA, vaccine-induced HPV antibodies originating from cervicovaginal secretions were recently shown to be detectable in FV urine as well. This presents a novel opportunity for non-invasive sampling to monitor HPV antibody status in women participating in large epidemiological studies and HPV vaccine trials. The simultaneous assessment of both HPV infection and immunogenicity on a non-invasive, readily obtained sample is particularly attractive.

Infection and vaccine-induced HPV-specific antibodies in cervicovaginal secretions. A review of the literature

Background

Human papillomavirus (HPV) infects and propagates in the cervical mucosal epithelium. Hence, in addition to assessing systemic immunity, the accurate measurement of cervical immunity is important to evaluate local immune responses to HPV infection and vaccination. This review discusses studies that investigated the presence of infection and vaccine-induced HPV-specific antibodies in cervicovaginal secretions (CVS).

Methods

We searched the two main health sciences databases, PubMed and the ISI Web of Science, from the earliest dates available to March 2019. From the eligible publications, information was extracted regarding: (i) study design, (ii) the reported HPV-specific antibody concentrations in CVS (and the associated serum levels, when provided), (iii) the CVS collection method, and (iv) the immunoassays used.

Results

The systematic search and selection process yielded 44 articles. The evidence of HPV-specific antibodies in CVS after natural infection (26/44) and HPV vaccination (18/44) is discussed. Many studies indicate that HPV-specific antibody detection in CVS is variable but feasible with a variety of collection methods and immunoassays. Most CVS samples were collected by cervicovaginal washing or wicks, and antibody presence was mostly determined by VLP-based ELISAs. The moderate to strong correlation between vaccine-induced antibody levels in serum and in CVS indicates that HPV vaccines generate antibodies that transudate through the cervical mucosal epithelium.

Conclusion

Although HPV-specific antibodies have lower titres in CVS than in serum samples, studies have shown that their detection in CVS is feasible. Nevertheless, the high variability of published observations and the lack of a strictly uniform, well-validated method for the collection, isolation and quantification of antibodies indicates a need for specific methods to improve and standardize the detection of HPV-specific antibodies in CVS.

Oral and systemic HPV antibody kinetics post-vaccination among HIV-positive and HIV-negative men

Duration and functional aspects of the oral and systemic antibody responses following HPV vaccination in HIV-negative (HIV-) and HIV-positive (HIV+) men are not well characterized. Oral and systemic HPV-16 and HPV-18-specific antibody levels were evaluated over 18-months of follow-up, in HIV+ and HIV- men. Sera and oral gargles from 147 HIV- men, ages 27-45 and 75 HIV+ men, ages 22-61, who received 3-doses of quadrivalent HPV vaccine were tested for HPV-16 and HPV-18 antibodies at Day 1, Month 7 (1 month post-dose 3), and Month 18 (12 months post-dose 3) and HPV avidity (Day 1, and Month 7) using L1-VLP ELISA. All individuals seroconverted, regardless of HIV-status, following 3-doses of vaccine for HPV-16 and HPV-18. Serum HPV-16 and HPV-18 antibody geometric mean levels were >2-fold lower in HIV+ compared to HIV- men at Month 7 (HPV-16: 808.5 versus 2119.8 EU/mL, and HPV-18: 285.8 versus 611.6 EU/mL, p < 0.001) but not significantly different at Month 18 (HPV-16: 281.8 versus 359.7 EU/mL, p = 0.145, and HPV-18: 120.2 versus 93.4 EU/mL, p = 0.372). Post-vaccination, only oral HPV-16 antibody levels at Month 7 were significantly different between HIV+ and HIV- men (127.7 versus 177.1 EU/mg of IgG, p = 0.008). Among baseline HPV-seronegative men, circulating levels of HPV-16 and HPV-18 antibodies were up to >3 fold lower in HIV+ men, at Months 7 and 18. In contrast, levels of HPV-16 and HPV-18 antibodies after vaccination were not inferior in baseline HPV-seropositive, HIV+ men. HPV-16 and HPV-18 avidity was lower among HIV+ compared to HIV- men at Month 7 (HPV-16: 1.95 M versus 2.12 M, p = 0.027; HPV-18: 1.50 M versus 1.72 M, p < 0.001). Although differences in peak antibody levels were observed between HIV+ and HIV- men following 3 doses of vaccine, plateau antibody levels were overall comparable, and avidity was relatively high for both groups. These data indicate that the vaccine induced antibody affinity maturation in both HIV+ and HIV- men and will likely result in long-term protective immune responses.

A novel approach for assessment of prostate cancer aggressiveness using survivin-driven tumour-activatable minicircles

Early and accurate detection of cancer is essential to optimising patient outcomes. Of particular importance to prostate cancer is the ability to determine the aggressiveness of a primary tumour, which allows for effective management of patient care. In this work, we propose using gene vectors called tumour-activatable minicircles which deliver an exogenously encoded reporter gene into cancer cells, forcing them to produce a unique and sensitive biomarker. These minicircles express a blood reporter protein called secreted embryonic alkaline phosphatase mediated by the tumour-specific survivin promoter, which exhibits activity graded to prostate cancer aggressiveness. Together, these components underlie a detection system where levels of blood reporter are indicative of not only the presence, but also the metastatic potential of a tumour. Our goal was to assess the ability of tumour-activatable minicircles to detect and characterise primary prostate lesions. Our minicircles produced reporter levels related to survivin expression across a range of prostate cancer cell lines. When survivin-driven minicircles were administered intratumourally into mice, reporter levels in blood samples were significantly higher (p < 0.05) in mice carrying prostate tumours of high versus low-aggressiveness. Continued development of this gene-based system could provide clinicians with a powerful tool to evaluate prostate cancer aggressiveness using a sensitive and affordable blood assay.

Immunogenicity of HPV prophylactic vaccines: Serology assays and their use in HPV vaccine evaluation and development

When administered as standard three-dose schedules, the licensed HPV prophylactic vaccines have demonstrated extraordinary immunogenicity and efficacy. We summarize the immunogenicity of these licensed vaccines and the most commonly used serology assays, with a focus on key considerations for one-dose vaccine schedules. Although immune correlates of protection against infection are not entirely clear, both preclinical and clinical evidence point to neutralizing antibodies as the principal mechanism of protection. Thus, immunogenicity assessments in vaccine trials have focused on measurements of antibody responses to the vaccine. Non-inferiority of antibody responses after two doses of HPV vaccines separated by 6 months has been demonstrated and this evidence supported the recent WHO recommendations for two-dose vaccination schedules in both boys and girls 9-14 years of age. There is also some evidence suggesting that one dose of HPV vaccines may provide protection similar to the currently recommended two-dose regimens but robust data on efficacy and immunogenicity of one-dose vaccine schedules are lacking. In addition, immunogenicity has been assessed and reported using different methods, precluding direct comparison of results between different studies and vaccines. New head-to-head vaccine trials evaluating one-dose immunogenicity and efficacy have been initiated and an increase in the number of trials relying on immunobridging is anticipated. Therefore, standardized measurement and reporting of immunogenicity for the up to nine HPV types targeted by the current vaccines is now critical. Building on previous HPV serology assay standardization and harmonization efforts initiated by the WHO HPV LabNet in 2006, new secondary standards, critical reference reagents and testing guidelines will be generated as part of a new partnership to facilitate harmonization of the immunogenicity testing in new HPV vaccine trials.

Evaluation of HPV-16 and HPV-18 specific antibody measurements in saliva collected in oral rinses and merocel® sponges

BACKGROUND

Current Human papillomavirus (HPV) L1 VLP vaccines protect against HPV-16 and HPV-18-associated cancers, in females and males. Although correlates of protection have not been identified, HPV-specific antibodies at sites of infection are thought to be the main mechanism of protection afforded by vaccination. Oral sampling has gained increased attention as a potential alternative to serum in monitoring immunity to vaccination and understanding local immunity in oral cancers.

METHODS

Serum was collected via venipuncture, and saliva was collected via oral rinses and Merocel® sponges from healthy volunteers: 16 unvaccinated females, 6 females (ages 24-41) and 6 mid-adult aged males (ages 27-45) recipients of three doses of the HPV-16/18/6/11 vaccine (Gardasil®). Mid-adult male vaccine trial participants were compared to female participants. Samples were tested for anti-HPV-16 and anti-HPV-18 immunoglobulin G levels by an L1 virus-like particle-based enzyme-linked immunosorbent assay (ELISA).

RESULTS

All vaccinated participants had detectable serum anti-HPV-16 and anti-HPV-18 antibodies. Optimal standard concentration range and sample serial dilutions for oral rinses were determined. The standard curve was not affected by the type of solution examined. Reproducibility of HPV-16 and HPV-18 antibody titers in mouthwash (overall CV < 10%) or in Merocel® extraction buffer was robust (CV < 13%). Excellent assay linearity (R2 > 0.9) was observed for sera spiked controls in both solutions. HPV-16 and HPV-18 specific antibodies were detectable in saliva from vaccine recipients, both in mouthwash and in Merocel® sponges but levels were several logs lower than those in serum.

CONCLUSIONS

This study confirms the application of HPV-16 and HPV-18 ELISAs currently used in sero-epidemiological studies of immunogenicity of HPV vaccines for use with oral samples. Oral samples may be a useful resource for the detection of HPV-16 and HPV-18-specific antibodies in saliva following vaccination.

Characterization of Immunoglobulin A/G Responses During 3 Doses of the Human Papillomavirus-16/18 ASO4-Adjuvanted Vaccine

BACKGROUND

Individuals receiving the human papillomavirus (HPV) vaccine develop high levels of circulating neutralizing antibodies. However, data about antibody responses in the cervix are limited.

METHODS

This study was designed to describe the course of IgA/IgG responses in cervical secretions and in serum after intramuscular administration of the HPV16/18 AS04-adjuvant vaccine. An enzyme-linked immunosorbent assay for detection of IgA and IgG anti-HPV-VLP was developed for this purpose.

RESULTS

Immunoglobulin G seroconversion after the second dose was observed in 100% of the participants and remained 1 month after the third dose. Regarding IgG reactivity in cervical secretions, conversion was observed in 85% of women after the final dose. Immunoglobulin A seroconversion was observed in 76.7% of women after the third dose. Lower levels of IgA were detected in the cervical mucus (28.3%) and decreased to 23.3% after the last dose. Comparing local and systemic IgG responses, positivity in both serum and cervical samples was observed in 85%, whereas in 15% only, the serum was IgG antibody positive. A weak agreement between local and systemic IgA responses was observed. Only 18.3% of participants were local and systemic IgA positive, 58.4% were positive only in serum, 5% were positive only in the cervix, and 18.3% were both local and systemic IgA antibody negative.

CONCLUSIONS

After the third vaccination, there is a strong agreement between cervical and systemic IgG antibody responses and a weak agreement between cervical and systemic IgA antibody responses. The induction of IgA antibodies seems to be secondary to that of IgG antibodies in response to HPV intramuscular vaccination.

Human papillomavirus first and second generation vaccines-current status and future directions

It has been more than 10 years that the first prophylactic papillomavirus vaccine became available, although distribution has been mainly limited to the more affluent countries. The first two vaccines have been a great success, hundreds of millions of women and a much smaller number of men have been vaccinated ever since. In a few countries with high vaccination coverage, in particular Australia but also parts of Great Britain and others, clinical impact of vaccination programs is already visible and there are indications for herd immunity as well. Vaccine efficacy is higher than originally estimated and the vaccines have an excellent safety profile. Gardasil9 is a second generation HPV virus-like particle vaccine that was licensed in 2015 and there are more to come in the near future. Currently, burning questions in respect to HPV vaccination are the duration of protection - especially in regard to cross-protection - reduction of the three-dose regimen and its impact on cross-protection; and duration of response, as well as protection against oropharyngeal HPV infections. Furthermore, researchers are seeking to overcome limitations of the VLP vaccines, namely low thermal stability, cost, invasive administration, limited coverage of non-vaccine HPV types, and lack of therapeutic efficacy. In this review we summarize the current status of licensed VLP vaccines and address questions related to second and third generation HPV vaccines.

Seropositivity to non-vaccine incorporated genotypes induced by the bivalent and quadrivalent HPV vaccines: A systematic review and meta-analysis

BACKGROUND

Human papillomavirus vaccines have demonstrated remarkable efficacy against persistent infection and disease associated with vaccine-incorporated genotypes and a degree of efficacy against some genetically related, non-vaccine-incorporated genotypes. The vaccines differ in the extent of cross-protection against these non-vaccine genotypes. Data supporting the role for neutralizing antibodies as a correlate or surrogate of cross-protection are lacking, as is a robust assessment of the seroconversion rates against these non-vaccine genotypes.

METHODS

We performed a systematic review and meta-analysis of available data on vaccine-induced neutralizing antibody seropositivity to non-vaccine incorporated HPV genotypes.

RESULTS

Of 304 articles screened, 9 were included in the analysis representing ca. 700 individuals. The pooled estimate for seropositivity against HPV31 for the bivalent vaccine (86%; 95%CI 78-91%) was higher than that for the quadrivalent vaccine (61%; 39-79%; p=0.011). The pooled estimate for seropositivity against HPV45 for the bivalent vaccine (50%; 37-64%) was also higher than that for the quadrivalent vaccine (16%; 6-36%; p=0.007). Seropositivity against HPV33, HPV52 and HPV58 were similar between the vaccines. Mean seropositivity rates across non-vaccine genotypes were positively associated with the corresponding vaccine efficacy data reported from vaccine trials.

CONCLUSIONS

These data improve our understanding of vaccine-induced functional antibody specificity against non-vaccine incorporated genotypes and may help to parameterize vaccine-impact models and improve patient management in a post-vaccine setting.

The prevalence of HPV infections in HPV-vaccinated women from the general population

Currently, three prophylactic HPV vaccines are commercially available to prevent HPV 16/18 infection and associated lesions. The aim of the study was to assess markers of HPV infection in women/girls before vaccination and to ascertain the prevalence and spectrum of post-vaccination HPV types. Three hundred and thirty subjects of which 75 were virgins were enrolled. Before the first dose of the HPV vaccine and 1, 3 and 5 years after the completion of HPV vaccination, the samples for cytology, HPV detection and anti-HPV antibody response were taken. At enrolment, HPV DNA was detected in 38% of sexually active girls/women. At the first, second and third follow-up, HPV DNA was found in 40, 45, and 39% of them. The seroprevalence rates to HPV 6, 11, 16 and 18 in these subjects were 31, 21, 18 and 10%. On the follow-up significantly higher levels of antibodies to HPV 16/18 were found after application of divalent vaccine. Results of the study demonstrate high prevalence of HPV infection in young women. In a substantial number of women, HPV-specific antibodies as well as high-risk HPV types were detected. HPV-specific antibodies were also frequently found in non-sexually active girls. The acquisition of HPV after the onset of sexual life was very fast.

Development of a simple and quick immunochromatography method for detection of anti-HPV-16/-18 antibodies

Immunochromatography (IC) is widely used to detect target molecules in biological fluids. Since this method can be performed without a special technique or device, IC is a convenient way to assess the existence of antibodies or pathogens such as viruses and bacteria, simply and quickly. In this study, we established an IC method to detect serum antibodies against oncogenic human papillomavirus (HPV)-16 and HPV-18 L1 proteins using recombinant L1 proteins produced by silkworms as antigens. Infection of oncogenic HPVs is a major risk factor of cervical cancer, which is one of the most common cancers in women worldwide. We first measured blood sera of two groups by magnetic beads enzyme-linked immunosorbent assay (MB-ELISA). For the first group, sera were collected prospectively from young women who planned to receive HPV vaccination. The second group consisted of children under 20 years of age, non-vaccinated healthy women, vaccinated healthy women, dysplasia, cervical intraepithelial neoplasia III, and cervical cancer patients. We confirmed that standard vaccination doses significantly increased serum HPV antibody concentrations, and the level was sustained at least more than 30 months after vaccination. In contrast, an increase in antibody concentration was not observed in patients with precancerous cervical changes and cervical cancer. We next measured the samples in both groups using the IC method we originally developed, and found that the measurement values of IC highly correlated with those of MB-ELISA. The simple and quick IC method would be a useful tool for rapid monitoring of L1 specific antibody levels in a non-laboratory environment. With less than one drop of serum, our IC can easily detect serum HPV-16/-18 antibodies within 15 minutes, without the need for electronic devices or techniques.

HPV disease transmission protection and control

Human papillomaviruses (HPVs) represent a large collection of viral types associated with significant clinical disease of cutaneous and mucosal epithelium. HPV-associated cancers are found in anogenital and oral mucosa, and at various cutaneous sites. Papillomaviruses are highly species and tissue restricted, and these viruses display both mucosotropic, cutaneotropic or dual tropism for epithelial tissues. A subset of HPV types, predominantly mucosal, are also oncogenic and cancers with these HPV types account for more than 200,000 deaths world-wide. Host control of HPV infections requires both innate and adaptive immunity, but the viruses have developed strategies to escape immune detection. Viral proteins can disrupt both innate pathogen-sensing pathways and T-cell based recognition and subsequent destruction of infected tissues. Current treatments to manage HPV infections include mostly ablative strategies in which recurrences are common and only active disease is treated. Although much is known about the papillomavirus life cycle, viral protein functions, and immune responsiveness, we still lack knowledge in a number of key areas of PV biology including tissue tropism, site-specific cancer progression, codon usage profiles, and what are the best strategies to mount an effective immune response to the carcinogenic stages of PV disease. In this review, disease transmission, protection and control are discussed together with questions related to areas in PV biology that will continue to provide productive opportunities of discovery and to further our understanding of this diverse set of human viral pathogens.

Therapeutic Cancer Vaccines

Cancer is one of the major leading death causes of diseases. Prevention and treatment of cancer is an important way to decrease the incidence of tumorigenesis and prolong patients' lives. Subversive achievements on cancer immunotherapy have recently been paid much attention after many failures in basic and clinical researches. Based on deep analysis of genomics and proteomics of tumor antigens, a variety of cancer vaccines targeting tumor antigens have been tested in preclinical and human clinical trials. Many therapeutic cancer vaccines alone or combination with other conventional treatments for cancer obtained spectacular efficacy, indicating the tremendously potential application in clinic. With the illustration of underlying mechanisms of cancer immune regulation, valid, controllable, and persistent cancer vaccines will play important roles in cancer treatment, survival extension and relapse and cancer prevention. This chapter mainly summarizes the recent progresses and developments on cancer vaccine research and clinical application, thus exploring the existing obstacles in cancer vaccine research and promoting the efficacy of cancer vaccine.

Immunogenicity of next-generation HPV vaccines in non-human primates: Measles-vectored HPV vaccine versus Pichia pastoris recombinant protein vaccine

Human papillomavirus (HPV) infection is the most common sexually transmitted disease worldwide. HPVs are oncogenic small double-stranded DNA viruses that are the primary causal agent of cervical cancer and other types of cancers, including in the anus, oropharynx, vagina, vulva, and penis. Prophylactic vaccination against HPV is an attractive strategy for preventing cervical cancer and some other types of cancers. However, there are few safe and effective vaccines against HPV infections. Current first-generation commercial HPV vaccines are expensive to produce and deliver. The goal of this study was to develop an alternate potent HPV recombinant L1-based vaccines by producing HPV virus-like particles into a vaccine that is currently used worldwide. Live attenuated measles virus (MV) vaccines have a well-established safety and efficacy record, and recombinant MV (rMV) produced by reverse genetics may be useful for generating candidate HPV vaccines to meet the needs of the developing world. We studied in non-human primate rMV-vectored HPV vaccine in parallel with a classical alum adjuvant recombinant HPV16L1 and 18L1 protein vaccine produced in Pichia pastoris. A combined prime-boost approach using both vaccines was evaluated, as well as immune interference due to pre-existing immunity against the MV. The humoral immune response induced by the MV, Pichia-expressed vaccine, and their combination as priming and boosting approaches was found to elicit HPV16L1 and 18L1 specific total IgG and neutralizing antibody titres. Pre-existing antibodies against measles did not prevent the immune response against HPV16L1 and 18L1.

Human papillomavirus infection in the oral cavity of HIV patients is not reduced by initiating antiretroviral therapy

Objective:

The incidence of human papillomavirus (HPV)-related oral malignancies is increasing among HIV-infected populations, and the prevalence of oral warts has reportedly increased among HIV patients receiving antiretroviral therapy (ART). We explored whether ART initiation among treatment-naive HIV-positive adults is followed by a change in oral HPV infection or the occurrence of oral warts.

Design:

Prospective, observational study.

Methods:

HIV-1 infected, ART-naive adults initiating ART in a clinical trial were enrolled. End points included detection of HPV DNA in throat-washes, changes in CD4⁺ T-cell count and HIV RNA, and oral wart diagnosis.

Results:

Among 388 participants, 18% had at least one HPV genotype present before initiating ART, and 24% had at least one genotype present after 12–24 weeks of ART. Among those with undetectable oral HPV DNA before ART, median change in CD4⁺ count from study entry to 4 weeks after ART initiation was larger for those with detectable HPV DNA during follow-up than those without (P =  0.003). Both prevalence and incidence of oral warts were low (3% of participants having oral warts at study entry; 2.5% acquiring oral warts during 48 weeks of follow-up).

Conclusion:

These results suggest: effective immune control of HPV in the oral cavity of HIV-infected patients is not reconstituted by 24 weeks of ART; whereas ART initiation was not followed by an increase in oral warts, we observed an increase in oral HPV DNA detection after 12–24 weeks. The prevalence of HPV-associated oral malignancies may continue to increase in the modern ART era.

Human papillomavirus vaccination induces neutralising antibodies in oral mucosal fluids

Background:

Mucosal human papillomaviruses (HPV) are a major cause of cancers and papillomas of the anogenital and oropharyngeal tract. HPV-vaccination elicits neutralising antibodies in sera and cervicovaginal secretions and protects uninfected individuals from persistent anogenital infection and associated diseases caused by the vaccine-targeted HPV types. Whether immunisation can prevent oropharyngeal infection and diseases and whether neutralising antibodies represent the correlate of protection, is still unclear.

Methods:

We determined IgG and neutralising antibodies against low-risk HPV6 and high-risk HPV16/18 in sera and oral fluids from healthy females (n=20) before and after quadrivalent HPV-vaccination and compared the results with non-vaccinated controls.

Results:

HPV-vaccination induced type-specific antibodies in sera and oral fluids of the vaccinees. Importantly, the antibodies in oral fluids were capable of neutralising HPV pseudovirions in vitro, indicating protection from infection. The increased neutralising antibody levels against HPV16/18 in sera and oral fluids post-vaccination correlated significantly within an individual.

Conclusions:

We provide experimental proof that HPV-vaccination elicits neutralising antibodies to the vaccine-targeted types in oral fluids. Hence, immunisation may confer direct protection against type-specific HPV infection and associated diseases of the oropharyngeal tract. Measurement of antibodies in oral fluids represents a suitable tool to assess vaccine-induced protection within the mucosal milieu of the orophayrynx.

Functional assessment and structural basis of antibody binding to human papillomavirus capsid

Persistent high-risk human papillomavirus (HPV) infection is linked to cervical cancer. Two prophylactic virus-like particle (VLP)-based vaccines have been marketed globally for nearly a decade. Here, we review the HPV pseudovirion (PsV)-based assays for the functional assessment of the HPV neutralizing antibodies and the structural basis for these clinically relevant epitopes. The PsV-based neutralization assay was developed to evaluate the efficacy of neutralization antibodies in sera elicited by vaccination or natural infection or to assess the functional characteristics of monoclonal antibodies. Different antibody binding modes were observed when an antibody was complexed with virions, PsVs or VLPs. The neutralizing epitopes are localized on surface loops of the L1 capsid protein, at various locations on the capsomere. Different neutralization antibodies exert their neutralizing function via different mechanisms. Some antibodies neutralize the virions by inducing conformational changes in the viral capsid, which can result in concealing the binding site for a cellular receptor like 1A1D-2 against dengue virus, or inducing premature genome release like E18 against enterovirus 71. Higher-resolution details on the epitope composition of HPV neutralizing antibodies would shed light on the structural basis of the highly efficacious vaccines and aid the design of next generation vaccines. In-depth understanding of epitope composition would ensure the development of function-indicating assays for the comparability exercise to support process improvement or process scale up. Elucidation of the structural elements of the type-specific epitopes would enable rational design of cross-type neutralization via epitope re-engineering or epitope grafting in hybrid VLPs.

Relationship between Humoral Immune Responses against HPV16, HPV18, HPV31 and HPV45 in 12-15 Year Old Girls Receiving Cervarix® or Gardasil® Vaccine

Background

Human papillomavirus (HPV) vaccines confer protection against the oncogenic genotypes HPV16 and HPV18 through the generation of type-specific neutralizing antibodies raised against virus-like particles (VLP) representing these genotypes. The vaccines also confer a degree of cross-protection against HPV31 and HPV45, which are genetically-related to the vaccine types HPV16 and HPV18, respectively, although the mechanism is less certain. There are a number of humoral immune measures that have been examined in relation to the HPV vaccines, including VLP binding, pseudovirus neutralization and the enumeration of memory B cells. While the specificity of responses generated against the vaccine genotypes are fairly well studied, the relationship between these measures in relation to non-vaccine genotypes is less certain.

Methods

We carried out a comparative study of these immune measures against vaccine and non-vaccine genotypes using samples collected from 12–15 year old girls following immunization with three doses of either Cervarix^® or Gardasil^® HPV vaccine.

Results

The relationship between neutralizing and binding antibody titers and HPV-specific memory B cell levels for the vaccine genotypes, HPV16 and HPV18, were very good. The proportion of responders approached 100% for both vaccines while the magnitude of these responses induced by Cervarix^® were generally higher than those following Gardasil^® immunization. A similar pattern was found for the non-vaccine genotype HPV31, albeit at a lower magnitude compared to its genetically-related vaccine genotype, HPV16. However, both the enumeration of memory B cells and VLP binding responses against HPV45 were poorly related to its neutralizing antibody responses. Purified IgG derived from memory B cells demonstrated specificities similar to those found in the serum, including the capacity to neutralize HPV pseudoviruses.

Conclusions

These data suggest that pseudovirus neutralization should be used as the preferred humoral immune measure for studying HPV vaccine responses, particularly for non-vaccine genotypes.

Immunogenicity and safety of an E. coli-produced bivalent human papillomavirus (type 16 and 18) vaccine: A randomized controlled phase 2 clinical trial

BACKGROUND

This study aimed to investigate the dosage, immunogenicity and safety profile of a novel human papillomavirus (HPV) types 16 and 18 bivalent vaccine produced by E. coli.

METHODS

This randomized, double-blinded, controlled phase 2 trial enrolled women aged 18-25 years in China. Totally 1600 eligible participants were randomized to receive 90μg, 60μg, or 30μg of the recombinant HPV 16/18 bivalent vaccine or the control hepatitis B vaccine on a 0, 1 and 6 month schedule. The designated doses are the combined micrograms of HPV16 and 18 VLPs with dose ratio of 2:1. The immunogenicity of the vaccines was assessed by measuring anti-HPV 16 and 18 neutralizing antibodies and total IgG antibodies. Safety of the vaccine was assessed.

RESULTS

All but one of the seronegative participants who received 3 doses of the HPV vaccines seroconverted at month 7 for anti-HPV 16/18 neutralizing antibodies and IgG antibodies. For HPV 16, the geometric mean titers (GMTs) of the neutralizing antibodies were similar between the 60μg (GMT=10,548) and 90μg (GMT=12,505) HPV vaccine groups and were significantly higher than those in the 30μg (GMT=7596) group. For HPV 18, the GMTs of the neutralizing antibodies were similar among the 3 groups. The HPV vaccine was well tolerated. No vaccine-associated serious adverse events were identified.

CONCLUSION

The prokaryotic-expressed HPV vaccine is safe and immunogenic in women aged 18-25 years. The 60μg dosage formulation was selected for further investigation for efficacy.

CLINICAL TRIALS REGISTRATION

NCT01356823.

Primary endpoints for future prophylactic human papillomavirus vaccine trials: towards infection and immunobridging

Although available human papillomavirus (HPV) vaccines have high efficacy against incident infection and disease caused by HPV types that they specifically target, new vaccine trials continue to be needed. The goals of these trials could include change of vaccine dose or route of administration (or both), development of second-generation vaccines, and the regional manufacture of biosimilar vaccines. We summarise present thinking about primary endpoints for HPV vaccine trials as developed at an experts workshop convened by the International Agency for Research on Cancer and the US National Cancer Institute in September, 2013. Efficacy trials that have led to licensure for cervical cancer prevention have used the disease endpoint of cervical intraepithelial neoplasia grade 2 or worse (CIN2+). However, on the basis of experience from the trials and present knowledge of HPV infection, future efficacy trials for new vaccines can be safely streamlined by the use of persistent HPV infection, which occurs more frequently than CIN2+, and can be more reproducibly measured as a primary endpoint. Immunobridging trials can be sufficient to ascertain immunological non-inferiority for licensure for alternate dosing schedules, bridging to age 26 years or younger, and biosimilar vaccines, with post-licensure surveillance confirming effectiveness. These recommendations are intended to help stimulate continued vaccine development while ensuring appropriate assessment of safety and efficacy.

Detecting cancers through tumor-activatable minicircles that lead to a detectable blood biomarker

Earlier detection of cancers can dramatically improve the efficacy of available treatment strategies. However, despite decades of effort on blood-based biomarker cancer detection, many promising endogenous biomarkers have failed clinically because of intractable problems such as highly variable background expression from nonmalignant tissues and tumor heterogeneity. In this work we present a tumor-detection strategy based on systemic administration of tumor-activatable minicircles that use the pan-tumor-specific Survivin promoter to drive expression of a secretable reporter that is detectable in the blood nearly exclusively in tumor-bearing subjects. After systemic administration we demonstrate a robust ability to differentiate mice bearing human melanoma metastases from tumor-free subjects for up to 2 wk simply by measuring blood reporter levels. Cumulative change in reporter levels also identified tumor-bearing subjects, and a receiver operator-characteristic curve analysis highlighted this test's performance with an area of 0.918 ± 0.084. Lung tumor burden additionally correlated (r(2) = 0.714; P < 0.05) with cumulative reporter levels, indicating that determination of disease extent was possible. Continued development of our system could improve tumor detectability dramatically because of the temporally controlled, high reporter expression in tumors and nearly zero background from healthy tissues. Our strategy's highly modular nature also allows it to be iteratively optimized over time to improve the test's sensitivity and specificity. We envision this system could be used first in patients at high risk for tumor recurrence, followed by screening high-risk populations before tumor diagnosis, and, if proven safe and effective, eventually may have potential as a powerful cancer-screening tool for the general population.

A comparative study of two different assay kits for the detection of secreted alkaline phosphatase in HPV antibody neutralization assays

To assess immunogenicity and development of antibodies in the context of vaccination, it is critical to quantify titers of neutralizing antibodies. We have been employing the 293TT cell-based neutralization assay system to quantify anti-HPV neutralizing antibodies. In this system, human papillomavirus (HPV) pseudovirion (PsV) particles encapsidating secreted alkaline phosphatase (SEAP) gene are used to measure infection of 293TT cells in 72-hr cell-culture supernatants. SEAP has traditionally been measured by Great EscAPe™ SEAP Chemiluminescence Kit 2.0 (GE). To reduce the cost, and to potentially increase efficiency, we sought a cheaper kit with better detection capability. Performance characteristics of the newer chemiluminescence kit, ZiVa® Ultra SEAP Plus Assay (Ziva) and GE were compared using the 293TT system. Dose titration of HPV PsV 16 or 18 showed that signal-to-noise ratios at 48 and 72 hr post-infection were higher for ZiVa at nearly all doses. ZiVa was superior to GE as it was able to detect SEAP at 48 hr, as well as when lower numbers of 293TT cells were used. The ability of ZiVa to quantitate HPV-16 and -18 neutralizing antibody titers was tested using sera from Cervarix® immunized individuals. Spearman rank correlational analyses showed excellent correlations between the titers obtained with ZiVa and GE for anti-HPV16 (r = 0.9822, p < 0.0001) and anti-HPV18 (r = 0.9832, p < 0.0001) antibodies. We concluded that ZiVa is superior to GE in detecting SEAP, and the antibody titers in sera of vaccinated individuals were similar to those obtained with GE. Thus, Ziva is a suitable alternative to GE.

Pre-clinical immunogenicity of human papillomavirus alpha-7 and alpha-9 major capsid proteins

•

Comprehensive pre-clinical immunogenicity evaluation of HPV L1 major capsid protein.

•

Majority neutralizing antibody response was genotype-specific.

•

Reciprocal cross-neutralization between some Alpha-7 and Alpha-9 genotypes.

•

Tetravalent formulation (HPV16/18/39/58) induced broadly neutralizing antibodies.

•

These data improve our understanding of the antigenic diversity of the L1 protein.

Human papillomavirus (HPV) vaccines confer protection against the oncogenic genotypes HPV16 and HPV18 through the generation of type-specific neutralizing antibodies raised against the constituent virus-like particles (VLP) based upon the major capsid proteins (L1) of these genotypes. The vaccines also confer a degree of cross-protection against some genetically related types from the Alpha-9 (HPV16-like: HPV31, HPV33, HPV35, HPV52, HPV58) and Alpha-7 (HPV18-like: HPV39, HPV45, HPV59, HPV68) species groups. The mechanism of cross-protection is unclear but may involve antibodies capable of recognizing shared inter-genotype epitopes. The relationship(s) between the genetic and antigenic diversity of the L1 protein, particularly for non-vaccine genotypes, is poorly understood.

We carried out a comprehensive evaluation of the immunogenicity of L1 VLP derived from genotypes within the Alpha-7 and Alpha-9 species groups in New Zealand White rabbits and used L1L2 pseudoviruses as the target antigens in neutralization assays.

The majority antibody response against L1 VLP was type-specific, as expected, but several instances of robust cross-neutralization were nevertheless observed including between HPV33 and HPV58 within the Alpha-9 species and between HPV39, HPV59 and HPV68 in the Alpha-7 species. Immunization with an experimental tetravalent preparation comprising VLP based upon HPV16, HPV18, HPV39 and HPV58 was capable of generating neutralizing antibodies against all the Alpha-7 and Alpha-9 genotypes. Competition of HPV31 and HPV33 cross-neutralizing antibodies in the tetravalent sera confirmed that these antibodies originated from HPV16 and HPV58 VLP, respectively, and suggested that they represent minority specificities within the antibody repertoire generated by the immunizing antigen. These data improve our understanding of the antigenic diversity of the L1 protein per se and may inform the rational design of a next generation vaccine formulation based upon empirical data.

Durable antibody responses following one dose of the bivalent human papillomavirus L1 virus-like particle vaccine in the Costa Rica Vaccine Trial

The Costa Rica HPV16/18 Vaccine Trial (CVT) showed that four-year vaccine efficacy against 12-month HPV16/18 persistent infection was similarly high among women who received one, two, or the recommended three doses of the bivalent HPV16/18 L1 virus-like particle (VLP) vaccine. Live-attenuated viral vaccines, but not simple-subunit vaccines, usually induce durable lifelong antibody responses after a single dose. It is unclear whether noninfectious VLP vaccines behave more like live-virus or simple-subunit vaccines in this regard. To explore the likelihood that efficacy will persist longer term, we investigated the magnitude and durability of antibodies to this vaccine by measuring HPV16- and HPV18-specific antibodies by VLP-ELISA using serum from enrollment, vaccination, and annual visits through four years in four vaccinated groups; one-dose (n = 78), two-doses separated by one month (n = 140), two doses separated by six months (n = 52), and three scheduled doses (n = 120, randomly selected). We also tested enrollment sera from n = 113 HPV16- or HPV18 L1-seropositive women prevaccination, presumably from natural infection. At four years, 100% of women in all groups remained HPV16/18 seropositive; both HPV16/18 geometric mean titers (GMT) among the extended two-dose group were non-inferior to the three-dose group, and ELISA titers were highly correlated with neutralization titers in all groups. Compared with the natural infection group, HPV16/18 GMTs were, respectively, at least 24 and 14 times higher among the two-dose and 9 and 5 times higher among one-dose vaccinees. Antibody levels following one-dose remained stable from month 6 through month 48. Results raise the possibility that even a single dose of HPV VLPs will induce long-term protection.

Glutathione S-transferase L1 multiplex serology as a measure of cumulative infection with human papillomavirus

BACKGROUND

Several assays are used to measure type-specific serological responses to human papillomavirus (HPV), including the bead-based glutathione S-transferase (GST)-L1 multiplex serology assay and virus-like particle (VLP)-based ELISA. We evaluated the high-throughput GST-L1, which is increasingly used in epidemiologic research, as a measure of cumulative HPV infection and future immune protection among HPV-unvaccinated women.

METHODS

We tested enrollment sera from participants in the control arm of the Costa Rica Vaccine Trial (n = 488) for HPV16 and HPV18 using GST-L1, VLP-ELISA, and two assays that measure neutralizing antibodies (cLIA and SEAP-NA). With statistical adjustment for sampling, we compared GST-L1 serostatus to established HPV seropositivity correlates and incident cervical HPV infection using odds ratios. We further compared GST-L1 to VLP-ELISA using pair-wise agreement statistics and by defining alternate assay cutoffs.

RESULTS

Odds of HPV16 GST-L1 seropositivity increased with enrollment age (OR = 1.20 per year, 95%CI 1.03-1.40) and lifetime number of sexual partners (OR = 2.06 per partner, 95%CI 1.49-2.83), with similar results for HPV18. GST-L1 seropositivity did not indicate protection from incident infection over 4 years of follow-up (HPV16 adjusted OR = 1.72, 95%CI 0.95-3.13; HPV18 adjusted OR = 0.38, 95%CI 0.12-1.23). Seroprevalence by GST-L1 (HPV16 and HPV18, respectively) was 5.0% and 5.2%, compared to 19.4% and 23.8% by VLP-ELISA, giving positive agreement of 39.2% and 20.8%. Lowering GST-L1 seropositivity cutoffs improved GST-L1/VLP-ELISA positive agreement to 68.6% (HPV16) and 61.5% (HPV18).

CONCLUSIONS

Our data support GST-L1 as a marker of cumulative HPV infection, but not immune protection. At lower seropositivity cutoffs, GST-L1 better approximates VLP-ELISA.

Seroprevalence of 8 oncogenic human papillomavirus genotypes and acquired immunity against reinfection

BACKGROUND

Natural human papillomavirus (HPV) antibody titers have shown protection against subsequent HPV infection, but previous studies were restricted to few HPV genotypes. We examined the association of naturally occurring antibodies against 8 carcinogenic HPV types with subsequent infections.

METHODS

A total of 2302 women enrolled in the Atypical Squamous Cells of Undetermined Significance/Low-Grade Squamous Intraepithelial Lesion Triage Study provided blood samples at baseline. Serum samples were tested for antibodies against 8 carcinogenic HPV genotypes (16, 18, 31, 33, 35, 45, 52, and 58) using a multiplex serology assay. We analyzed the relationship between HPV antibodies and HPV infection during 2 years of follow-up among women negative for the specific HPV type at baseline.

RESULTS

Baseline seroprevalence for HPV16 L1 was associated with decreased risk of DNA positivity for HPV16 (odds ratio, 0.39 [95% confidence interval, .18-.86]) at ≥2 follow-up visits. We observed similar but nonsignificant decreased risks for HPV18 and 31. These findings were restricted to women reporting a new sex partner during follow-up. There was no association between baseline seroprevalence and detection of precancer during follow-up.

CONCLUSIONS

Seroprevalence conferred protection against subsequent HPV infection for HPV16 and indicated possible protection for 2 other genotypes, suggesting that this effect is common to several HPV genotypes.

Cross-neutralizing antibodies elicited by the Cervarix® human papillomavirus vaccine display a range of Alpha-9 inter-type specificities

•

We explored Cervarix^® HPV vaccine cross-reactive antibody specificity.

•

L1 VLP binding was a poor surrogate for L1L2 pseudovirus neutralization specificity.

•

Cross-neutralizing antibodies comprise a small proportion of total antibody.

•

Multiple, overlapping cross-neutralizing antibody specificities exist.

The highly efficacious human papillomavirus (HPV) vaccines contain virus-like particles (VLP) representing genotypes HPV16 and HPV18, which together account for approximately 70% of cervical cancer cases. Vaccine-type protection is thought to be mediated by high titer, type-specific neutralizing antibodies. The vaccines also confer a degree of cross-protection against some genetically-related types from the Alpha-9 (HPV16-like: HPV31, HPV33, HPV35, HPV52, HPV58) and Alpha-7 (HPV18-like: HPV39, HPV45, HPV59, HPV68) species groups. Cross-protection is coincident with the detection of low titer serum responses against non-vaccine types by vaccinees. Such antibodies may be the effectors of cross-protection or their detection may be useful as a correlate or surrogate.

This study evaluated whether cross-neutralization of HPV types from the Alpha-9 species group is mediated by antibodies with a predominantly type-restricted specificity for HPV16 that nevertheless exhibit low affinity interactions with non-vaccine types, or by antibody specificities that demonstrate similar recognition of vaccine and non-vaccine types but are present at very low levels.

Antibodies generated following Cervarix^® vaccination of 13–14 year old girls were evaluated by pseudovirus neutralization, VLP ELISA and by enrichment of target antigen specificity using VLP-immobilized beads. Two-dimensional hierarchical clustering of serology data demonstrated that the antibody specificity profile generated by VLP ELISA was both quantitatively and qualitatively different from the neutralizing antibody specificity profile. Target-specific antibody enrichment demonstrated that cross-neutralization of non-vaccine types was due to a minority of antibodies rather than by the weak interactions of a predominantly type-restricted HPV16 antibody specificity. Furthermore, cross-neutralization of non-vaccine types appeared to be mediated by multiple antibody specificities, recognizing single and multiple non-vaccine types, and whose specificities were not predictable from examination of the serum neutralizing antibody profile. These data contribute to our understanding of the antibody specificities elicited following HPV vaccination and have potential implications for vaccine-induced cross-protection.

Comparison of antibody responses to human papillomavirus vaccination as measured by three assays

BACKGROUND

Different assays, including the competitive Luminex immunoassay (cLIA), secreted alkaline phosphatase neutralization assay (SEAP-NA), and virus-like particle-based ELISA, are commonly used to measure antibody responses after human papillomavirus (HPV) vaccination. Direct assay comparisons aid interpretation of immunogenicity data evaluated by different assays.

METHODS

We compared cLIA to SEAP-NA and ELISA among 51 HPV16/18-vaccinated women enrolled in the Costa Rica Vaccine Trial. We tested replicate serum samples collected at months 0, 1, and 12 by HPV16/18 cLIA, SEAP-NA, and ELISA. For a subset (N = 10), we further tested month 6, 24 and 36 samples. We calculated seroprevalence estimates and Spearman rank correlation coefficients comparing cLIA to SEAP-NA and ELISA.

RESULTS

After one vaccine dose, seroprevalence by SEAP-NA and ELISA was 100% (both HPV16 and HPV18), and by cLIA was 96% (95% CI 87-100%) for HPV16 and 71% (95% CI 56-83%) for HPV18. Seroprevalence was 100% by all assays after three doses. Correlation between assays was high after one vaccine dose [cLIA/SEAP-NA ρ = 0.91 (HPV16) and ρ = 0.86 (HPV18); cLIA/ELISA ρ = 0.84 (HPV16) and ρ = 0.74 (HPV18); all p < 0.001] and remained high through month 36. Ratios of mean antibody levels to seropositivity cutoffs at month 36 were lower for cLIA than for SEAP-NA or ELISA, particularly for HPV18 (HPV18 ratio for cLIA 1.9, SEAP-NA 3.5, ELISA 3.4).

CONCLUSION

Though correlation between cLIA and SEAP-NA/ELISA is high and stable after vaccination, the assays differ in scale and sensitivity, with notable differences after one vaccine dose and for HPV18. Our results demonstrate that comparisons of antibody responses to HPV vaccination measured by different assays are approximate, and must consider biological and technical differences between assays.

Therapeutic cancer vaccines

Therapeutic cancer vaccines have the potential of being integrated in the therapy of numerous cancer types and stages. The wide spectrum of vaccine platforms and vaccine targets is reviewed along with the potential for development of vaccines to target cancer cell "stemness," the epithelial-to-mesenchymal transition (EMT) phenotype, and drug-resistant populations. Preclinical and recent clinical studies are now revealing how vaccines can optimally be used with other immune-based therapies such as checkpoint inhibitors, and so-called nonimmune-based therapeutics, radiation, hormonal therapy, and certain small molecule targeted therapies; it is now being revealed that many of these traditional therapies can lyse tumor cells in a manner as to further potentiate the host immune response, alter the phenotype of nonlysed tumor cells to render them more susceptible to T-cell lysis, and/or shift the balance of effector:regulatory cells in a manner to enhance vaccine efficacy. The importance of the tumor microenvironment, the appropriate patient population, and clinical trial endpoints is also discussed in the context of optimizing patient benefit from vaccine-mediated therapy.

Immunogenicity assessment of HPV16/18 vaccine using the glutathione S-transferase L1 multiplex serology assay

The glutathione S-transferase (GST)-L1 multiplex serology assay has favorable properties for use in clinical trials and epidemiologic studies, including low cost, high throughput capacity, and low serum volume requirement. Therefore, we evaluated the GST-L1 assay as a measure of HPV16/18 vaccine immunogenicity. Our study population included 65 women selected from the Costa Rica Vaccine Trial who received the bivalent HPV16/18 virus-like particle (VLP) vaccine at the recommended 0/1/6-month schedule. We tested replicate serum samples from months 0/1/12 (i.e., after 0/1/3 doses) by GST-L1 and 3 other commonly used serology assays, VLP-ELISA, SEAP-NA, and cLIA. We calculated the percentage of women seropositive by GST-L1 by time point and HPV type (14 HPV types), and compared GST-L1 to other assays using Spearman rank correlation coefficients. After 1 vaccine dose, seropositivity by GST-L1 was 40% each for HPV16 and HPV18, increasing to 100% and 98%, respectively, after 3 doses. Seropositivity after 3 doses ranged from 32% to 69% for HPV types 31/33/45, for which partial vaccine efficacy is reported, though increases also occurred for types with no evidence for cross-protection (e.g., HPV77). GST-L1 correlated best after 3 doses with VLP-ELISA (HPV16 and HPV18 each ρ = 0.72) and SEAP-NA (HPV16 ρ = 0.65, HPV18 ρ = 0.71) (all P < 0.001); correlation was lower with cLIA. The GST-L1 is suitable for evaluating HPV16/18 vaccine immunogenicity after 3 vaccine doses, although in contrast to other assays it may classify some samples as HPV16/18 seronegative. The assay's utility is limited for lower antibody levels such as after receipt of 1 dose.

Human papillomavirus vaccines--immune responses

Prophylactic human papillomavirus (HPV) virus-like particle (VLP) vaccines are highly effective. The available evidence suggests that neutralising antibody is the mechanism of protection. However, despite the robust humoral response elicited by VLP vaccines, there is no immune correlate, no minimum level of antibody, or any other immune parameter, that predicts protection against infection or disease. The durability of the antibody response and the importance of antibody isotype, affinity and avidity for vaccine effectiveness are discussed. Once infection and disease are established, then cellular immune responses are essential to kill infected cells. These are complex processes and understanding the local mucosal immune response is a prerequisite for the rational design of therapeutic HPV vaccines. This article forms part of a special supplement entitled "Comprehensive Control of HPV Infections and Related Diseases" Vaccine Volume 30, Supplement 5, 2012.

A randomized, observer-blinded immunogenicity trial of Cervarix(®) and Gardasil(®) Human Papillomavirus vaccines in 12-15 year old girls

Background

The current generation of Human Papillomavirus (HPV) vaccines, Cervarix® and Gardasil®, exhibit a high degree of efficacy in clinical trials against the two high-risk (HR) genotypes represented in the vaccines (HPV16 and HPV18). High levels of neutralizing antibodies are elicited against the vaccine types, consistent with preclinical data showing that neutralizing antibodies can mediate type-specific protection in the absence of other immune effectors. The vaccines also confer protection against some closely related non-vaccine HR HPV types, although the vaccines appear to differ in their degree of cross-protection. The mechanism of vaccine-induced cross-protection is unknown. This study sought to compare the breadth and magnitudes of neutralizing antibodies against non-vaccine types elicited by both vaccines and establish whether such antibodies could be detected in the genital secretions of vaccinated individuals.

Methods and Findings

Serum and genital samples were collected from 12–15 year old girls following vaccination with either Cervarix® (n = 96) or Gardasil® (n = 102) HPV vaccine. Serum-neutralizing antibody responses against non-vaccine HPV types were broader and of higher magnitude in the Cervarix®, compared to the Gardasil®, vaccinated individuals. Levels of neutralizing and binding antibodies in genital secretions were closely associated with those found in the serum (r = 0.869), with Cervarix® having a median 2.5 (inter-quartile range, 1.7–3.5) fold higher geometric mean HPV-specific IgG ratio in serum and genital samples than Gardasil® (p = 0.0047). There was a strong positive association between cross-neutralizing antibody seropositivity and available HPV vaccine trial efficacy data against non-vaccine types.

Conclusions

These data demonstrate for the first time that cross-neutralizing antibodies can be detected at the genital site of infection and support the possibility that cross-neutralizing antibodies play a role in the cross-protection against HPV infection and disease that has been reported for the current HPV vaccines.

Trial Registration

ClinicalTrials.gov NCT00956553

Cross-protective vaccine efficacy of the bivalent HPV vaccine against HPV31 is associated with humoral immune responses: results from the Costa Rica Vaccine Trial

BACKGROUND

We investigated the role of antibody responses as potential mechanism for the cross-protective vaccine-efficacies (VE) observed from randomized clinical trials of the HPV16/18 bivalent vaccine. Results HPV31 cases had lower HPV16 antibody levels than controls (OR 4th quartile compared with 1st quartile = 0.63; 95%CI: 0.36-1.08; p-trend = 0.03). HPV31 cases were also less likely to have detectable HPV31 neutralization, and HPV16 avidity than controls. No statistically significant differences by HPV18 antibody or HPV45 neutralization were observed among HPV45 cases and controls. Protection against HPV58 was not associated with any of the markers, confirming the specificity of our findings.

METHODS

Samples are from three-dose HPV vaccine recipients from the Costa Rica HPV16/18 vaccine trial. Women with a new HPV31, HPV45, or HPV58 infections over four years of follow-up were compared with randomly selected control women--with no new infection with HPV31/45/58--with respect to HPV16 and HPV18 antibody, HPV31, HPV45, and HPV58 neutralization, and HPV16 avidity.

CONCLUSIONS

High HPV16 levels and avidity, and the ability to neutralize HPV31 were associated with protection against newly detected HPV31 infections, suggesting that the partial VE demonstrated for HPV31 is likely to be mediated at least in part through antibodies induced by HPV16/18 vaccination.

Kinetic and HPV infection effects on cross-type neutralizing antibody and avidity responses induced by Cervarix(®)

BACKGROUND

We previously demonstrated that Cervarix(®) elicits antibody responses against vaccine-related types for which clinical efficacy was demonstrated (HPV-31 and -45). Here, we evaluated the kinetics of neutralization titers and avidity of Cervarix(®)-induced antibodies up to 36 months of follow-up in unexposed and HPV infected women.

METHODS

A subset of women who participated in the Cost Rica HPV-16/18 Vaccine Trial had pre- and post-vaccination sera tested for antibody responses to HPV-16, -18, -31, -45, and -58 using a pseudovirion-based neutralization assay, and HPV-16 antibody avidity using an HPV-16 L1 VLP (virus-like particle)-based ELISA developed in our laboratory.

RESULTS

In uninfected women, neutralizing antibody titers did not reach significance until after the 3rd dose for HPV-31 (month 12, p=0.009) and HPV-45 (month 12, p=0.003), but then persisted up to month 36 (HPV-31, p=0.01; HPV-45, p=0.002). Individuals infected with HPV-16 or HPV-31 at enrollment developed a significantly higher median antibody response to the corresponding HPV type after one dose, but there was not a difference between median titers after three doses compared to the HPV negative group. Median HPV-16 antibody avidity and titer increased over time up to month 12; however, the HPV-16 avidity did not correlate well with HPV-16 neutralizing antibody titers at each time point examined, except for month 6. The median avidity levels were higher in HPV-16 infected women at month 1 (p=0.04) and lower in HPV-16 infected women at month 12 (p=0.006) compared to the HPV negative women.

CONCLUSIONS

The persistence of cross-neutralization titers at month 36 suggests cross-reactive antibody responses are likely to persist long-term and are not influenced by infection status at enrollment. However, the weak correlation between avidity and neutralization titers emphasizes the need for examining avidity in efficacy studies to determine if high avidity antibodies play a critical role in protection against infection.

Detection of systemic and mucosal HPV-specific IgG and IgA antibodies in adolescent girls one and two years after HPV vaccination

The bivalent HPV16/18 vaccine induces high antibody concentrations in serum while data about antibody responses in the cervix are limited. In this study, we investigated pre- and post-vaccination antibody responses against seven high-risk HPV types by detection of IgG and IgA HPV-specific antibodies in cervical secretion samples (CVS) and serum. From an HPV vaccine monitoring study CVS and serum samples were available (pre-vaccination (n = 297), one year (n = 211) and two years (n = 141) post-dose-one vaccination) from girls aged 14-16 y. The girls were vaccinated with the bivalent HPV vaccine at months 0, 1 and 6. CVS was self-sampled using a tampon. Samples were tested for HPV-specific antibodies (HPV16/18/31/33/45/52/58) by a VLP-based multiplex immunoassay. Post-vaccination, IgG and IgA antibody levels for HPV16/18 were detectable in CVS and amounted to 2% and 1% of the IgG and IgA antibody levels observed in serum, respectively. The antibody levels remained constant between one and two years after vaccination. The correlation between CVS and serum was similar for IgG and IgA vaccine-derived antibody levels for HPV16 (rs = 0.58, rs = 0.54) and HPV18 (rs = 0.50, rs = 0.55). Vaccine-derived IgG antibody levels against cross-reactive HPV types in CVS and in serum were highest for HPV45. No IgA cross-reactive antibody responses could be detected in CVS. Post-vaccination, HPV16/18 IgG and IgA antibodies are not only detectable in serum but also in CVS. The correlation of HPV16/18 IgG antibody levels between serum and CVS suggests that vaccine induced HPV antibodies transudate and/or exudate from the systemic circulation to the cervical mucosa to provide protection against HPV infections.