International collaborative proficiency study of Human Papillomavirus type 16 serology

Naturally developed HPV16 antibodies and risk of newly detected cervical HPV infection outcomes

Little is known about the protection conferred by antibodies from natural human papillomavirus (HPV) infection. Our objective was to evaluate the association between HPV16 seroreactivity and HPV16 redetection, newly detected HPV infections, and loss of HPV DNA detection during follow-up. We analyzed data from 2462 unvaccinated Brazilian women. HPV16 IgG and neutralizing antibodies at baseline were assessed by enzyme-linked immunosorbent assay (n = 1975) and by the pseudovirus-based papillomavirus neutralization assay (n = 487). HPV detection, genotyping, and viral load were assessed by PCR-based methods. The associations were analyzed by Cox proportional hazards models. We observed a positive association between HPV16 IgG seroreactivity and redetection of HPV16 infections. Age-adjusted hazard ratios (HR) with 95% confidence intervals (CI) ranged from 2.45 (1.04-5.74) to 5.10 (1.37-19.00). Positive associations were also observed between HPV16 IgG antibodies and (1) newly detected HPV infections by genotypes unrelated to HPV16 (age-adjusted HR [95% CI] = 1.32 [1.08-1.2]) and (2) loss of detection of HPV infections by genotypes unrelated to HPV16 (age-adjusted HR [95% CI] = 1.24 [1.03-1.50]). Naturally developed HPV16 antibodies do not prevent recurrent HPV infections. Overall HPV16 IgG and neutralizing antibodies seem to be serological markers for latent or past infections.

Human Papillomavirus Seroprevalence and Seroconversion Among Men Living With HIV: Cohort Study in South Africa

BACKGROUND

Men living with HIV (MLHIV) have a high burden of human papillomavirus (HPV)-related cancer. Understanding serological dynamics of HPV in men can guide decisions on introducing HPV vaccination and monitoring impact. We determined HPV seroprevalence and evaluated factors associated with HPV seroconversion among MLHIV in Johannesburg, South Africa.

METHODS

We enrolled 304 sexually active MLHIV 18 years and older and collected sociobehavioral data, blood samples (CD4 counts, HIV-1 plasma viral load, and HPV serology), and genital and anal swabs [HPV DNA and HPV viral load (VL)] at enrollment and 6-monthly for up to 18 months. Antibodies to 15 HPV types were measured using HPV pseudovirions. Generalized estimating equations were used to evaluate correlates of HPV seroconversion.

RESULTS

Median age at enrollment was 38 years (IQR: 22-59), 25% reported >1 sexual partner in the past 3 months, and 5% reported ever having sex with other men. Most participants (65%) were on antiretroviral therapy (ART), with median CD4 count of 445 cells/µL (IQR: 328-567). Seroprevalence for any HPV type was 66% (199/303). Baseline seropositivity for any bivalent (16/18), quadrivalent (6/11/16/18), and nonavalent (6/11/16/18/31/33/45/52/58) vaccine types was 19%, 37%, and 60%, respectively. At 18 months, type-specific seroconversion among 59 men whose genital samples were HPV DNA positive but seronegative for the same type at enrollment was 22% (13/59). Type-specific seroconversion was higher among men with detectable HIV plasma viral load (adjusted odds ratio = 2.78, 95% CI: 1.12 to 6.77) and high HPV VL (adjusted odds ratio = 3.32, 95% CI: 1.42 to 7.74).

CONCLUSIONS

Seropositivity and exposure to nonavalent HPV types were high among MLHIV. HPV vaccination of boys before they become sexually active could reduce the burden of HPV infection among this at-risk population.

Serum and cervicovaginal IgG immune responses against α7 and α9 HPV in non-vaccinated women at risk for cervical cancer: Implication for catch-up prophylactic HPV vaccination

BACKGROUND

Cervical cancer associated with high risk-human papillomavirus (HR-HPV) infection is becoming the one of the most common female cancer in many sub-Saharan African countries. First-generation immigrant African women living in Europe are at-risk for cervical cancer, in a context of social vulnerability, with frequent lack of cervical cancer screening and HPV vaccination.

OBJECTIVE

Our objective was to address immunologically the issue of catch-up prophylactic HPV vaccination in first-generation African immigrant women living in France.

METHODS

IgG immune responses and cross-reactivities to α7 (HPV-18, -45 and -68) and α9 (HPV-16, -31, -33, -35, -52 and -58) HPV types, including 7 HR-HPV targeted by the Gardasil-9® prophylactic vaccine, were evaluated in paired serum and cervicovaginal secretions (CVS) by HPV L1-virus-like particles-based ELISA. Genital HPV were detected by multiplex real time PCR (Seegene, Seoul, South Korea).

RESULTS

Fifty-one immigrant women (mean age, 41.7 years; 72.5% HIV-infected) were prospectively included. More than two-third (68.6%) of them carried genital HPV (group I) while 31.4% were negative (group II). The majority (90.2%) exhibited serum IgG to at least one α7/α9 HR-HPV. Serum HPV-specific IgG were more frequently detected in group I than group II (100% versus 68.7%; P = 0.002). The distribution of serum and genital HPV-specific IgG was similar, but mean number of IgG reactivities to α7/α9 HR-HPV was higher in serum than CVS (5.6 IgG per woman in serum versus 3.2 in CVS; P<0.001). Rates of IgG cross-reactivities against HPV different from detected cervicovaginal HPV were higher in serum and CVS in group I than group II. Finally, the majority of groups I and II women (68.6% and 68.7%, respectively) exhibited serum or cervicovaginal IgG to Gardasil-9® HR-HPV, with higher mean rates in group I than group II (6.1 Gardasil-9® HR-HPV per woman versus 1.4; P<0.01). One-third (31.2%) of group II women did not show any serum and genital HPV-specific IgG.

CONCLUSIONS

Around two-third of first-generation African immigrant women living in France showed frequent ongoing genital HPV infection and high rates of circulating and genital IgG to α7/α9 HPV, generally cross-reacting, avoiding the possibility of catch-up vaccination. Nevertheless, about one-third of women had no evidence of previous HPV infection, or showed only low levels of genital and circulating HR-HPV-specific IgG and could therefore be eligible for catch-up vaccination.

Seropositivity to Multiple Anogenital Human Papillomavirus (HPV) Types Is Associated With Current Anogenital HPV Infection, Abnormal Cytology, and Seropositivity for Nongenital HPVs

Background

Antibodies against human papillomaviruses (HPVs) are biomarkers for current or past infections. We assessed whether antibodies against multiple HPV types were determinants of current multiple anogenital HPV infections, abnormal cytology, and seropositivity for cutaneous HPVs.

Methods

A total of 1848 Slovenian women attended 2 rounds of cervical cancer screening 3 years apart and provided data on HPV antibodies and HPV DNA at both visits. Antibodies against 15 anogenital HPV types and 6 cutaneous HPVs were determined using pseudovirion-Luminex serology and anogenital HPV DNA using Linear Array. Antibodies to polyomaviruses were evaluated as a control. Women were grouped as either HPV seronegative or having antibodies to 1-2 HPV types or to ≥3 HPV types.

Results

Presence of antibodies to multiple anogenital HPV types at baseline was associated strongly with (i) presence of HPV DNA at the cervix (χ2 = 68.8; P < .0001), (ii) multiple types of HPV DNA at baseline (χ2 = 58.6; P < .0001), (iii) HPV DNA at follow-up (χ2 = 22.9; P < .0001), (iv) abnormal cytology (χ2 = 9.8; P = .0017), and (v) concomitant presence of antibodies to any of 6 nongenital HPV types (χ2 = 40.1; P < .0001). Presence of antibodies to ≥3 anogenital HPV types tended to persist over time.

Conclusions

Seropositivity against at least 3 anogenital HPV types is associated with current multiple anogenital HPV infections, abnormal cytology, and seropositivity to nongenital HPVs.

Long-term Antibody Response to Human Papillomavirus Vaccines: Up to 12 Years of Follow-up in the Finnish Maternity Cohort

Background

Most cervical cancers are caused by vaccine-preventable infections with human papillomaviruses (HPV). The HPV prophylactic vaccines Gardasil and Cervarix have been widely used for >10 years and are reported to induce high antibody levels. A head-to-head comparison of the antibody responses induced by the 2 vaccines has been performed only up to 5 years.

Methods

Among 3300 Finnish females aged 16-17 years who got 1 of the 2 HPV vaccines in phase 3 licensure trials, virtually all consented to registry-based long-term follow-up. Linkage with the Finnish Maternity Cohort found that they donated >2500 serum samples up to 12 years later. Sera of 337 (38.6%) Gardasil and 730 (30.3%) Cervarix vaccine recipients were retrieved from the Finnish Maternity Cohort biobank and type-specific anti-HPV antibody levels were determined using in-house multiplexed heparin-HPV pseudovirion Luminex assay.

Results

Anti-HPV-16 and anti-HPV-18 antibody levels remained stable and above natural infection-related antibody levels for up to 12 years for most vaccine recipients. The median antibody levels were higher among Cervarix recipients 7-12 years post vaccination (P < .0001).

Conclusions

The stability of vaccine-induced antibody levels is in accordance with the high long-term protection reported previously. The differences in antibody levels induced by the 2 vaccines imply that continued follow-up to identify possible breakthrough cases and estimation of the minimal protective levels of serum antibodies is a research priority.

Human Papillomavirus Serology Among Women Living With HIV: Type-Specific Seroprevalence, Seroconversion, and Risk of Cervical Reinfection

Background

Human papillomavirus (HPV) serodynamics following infection has never been evaluated prospectively among women living with HIV (WLHIV). We determined HPV seroprevalence, seroconversion, and cervical HPV-DNA acquisition among WLHIV.

Methods

Prospective study of 604 WLHIV in Johannesburg, South Africa aged 25-50 years. At baseline and 16 months (endline), HPV type-specific antibodies (HPV6/11/16/18/31/33/35/39/45/52/56/58/59/68/73) were measured using HPV-pseudovirions and cervical HPV-DNA genotypes using INNO-LiPA.

Results

Seroprevalence of any-HPV was 93.2% and simultaneous seropositivity for HPV types of the bivalent (HPV16/18), quadrivalent (HPV6/11/16/18), and nonavalent (HPV6/11/16/18/31/33/45/52/58) vaccines were 21.4%, 10.9%, and 2.8%. Among 219 women with cervical HPV-DNA, same-type seronegative and without high-grade cervical intraepithelial neoplasia at baseline, 51 (23.3%) had type-specific seroconversion at endline. Risk of type-specific seroconversion was higher among recent antiretroviral therapy users (ART ≤2 years vs ART naive: adjusted OR [aOR] = 2.39; 95% CI, 1.02-5.62), and lower among women with low CD4+ at endline (≤350 vs >350 cells/mm3: aOR = 0.51; 95% CI, 0.24-1.07). Risk of cervical HPV-DNA acquisition was lower in women seropositive for HPV18, 35, and 58 at baseline.

Conclusion

WLHIV have evidence of seroconversion in response to baseline HPV-DNA, dependent on CD4+ count and ART. Baseline HPV seropositivity confers limited protection against some HPV types.

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.

Screening for human papillomavirus-driven oropharyngeal cancer: Considerations for feasibility and strategies for research

The incidence and burden of human papillomavirus (HPV)‐driven oropharyngeal cancer is expected to increase for decades, thus motivating discussions regarding possibilities for screening. This article addresses issues related to the validity and timeliness of screening for HPV‐driven oropharyngeal cancer, and raises important questions, highlights deficits and confusion in the existing literature, and proposes needed steps in the research agenda.

Opportunities and challenges for human papillomavirus vaccination in cancer

The discovery of genotype 16 as the prototype oncogenic human papillomavirus (HPV) initiated a quarter century of laboratory and epidemiological studies that demonstrated their necessary, but not sufficient, aetiological role in cervical and several other anogenital and oropharyngeal cancers. Early virus-induced immune deviation can lead to persistent subclinical infection that brings the risk of progression to cancer. Effective secondary prevention of cervical cancer through cytological and/or HPV screening depends on regular and widespread use in the general population, but coverage is inadequate in low-resource settings. The discovery that the major capsid antigen L1 could self-assemble into empty virus-like particles (VLPs) that are both highly immunogenic and protective led to the licensure of several prophylactic VLP-based HPV vaccines for the prevention of cervical cancer. The implementation of vaccination programmes in adolescent females is underway in many countries, but their impact critically depends on the population coverage and is improved by herd immunity. This Review considers how our expanding knowledge of the virology and immunology of HPV infection can be exploited to improve vaccine technologies and delivery of such preventive strategies to maximize reductions in HPV-associated disease, including incorporation of an HPV vaccine covering oncogenic types within a standard multitarget paediatric vaccine.

First international collaborative study to evaluate rabies antibody detection method for use in monitoring the effectiveness of oral vaccination programmes in fox and raccoon dog in Europe

The most effective and sustainable method to control and eliminate rabies in wildlife is the oral rabies vaccination (ORV) of target species, namely foxes and raccoon dogs in Europe. According to WHO and OIE, the effectiveness of oral vaccination campaigns should be regularly assessed via disease surveillance and ORV antibody monitoring. Rabies antibodies are generally screened for in field animal cadavers, whose body fluids are often of poor quality. Therefore, the use of alternative methods such as the enzyme-linked immunosorbent assay (ELISA) has been proposed to improve reliability of serological results obtained on wildlife samples. We undertook an international collaborative study to determine if the commercial BioPro ELISA Rabies Ab kit is a reliable and reproducible tool for rabies serological testing. Our results reveal that the overall specificity evaluated on naive samples reached 96.7%, and the coefficients of concordance obtained for fox and raccoon dog samples were 97.2% and 97.5%, respectively. The overall agreement values obtained for the four marketed oral vaccines used in Europe were all equal to or greater than 95%. The coefficients of concordance obtained by laboratories ranged from 87.2% to 100%. The results of this collaborative study show good robustness and reproducibility of the BioPro ELISA Rabies Ab kit.

Human papillomavirus DNA positivity and seropositivity in rural Chinese men and women: a population-based cross-sectional study

Data on simultaneous analysis of human papillomavirus (HPV) DNA and serology and the correlations within a single general population are limited. Among 1603 men and 2187 women enrolled from rural China, serum antibodies against bacterially derived GST-L1 fusion proteins of HPV were assessed with multiplexed serology and HPV DNA was evaluated with PCR-based sequencing. Few subjects were dually positive to HPV DNA and serum antibodies for any HPV (6.6% of men and 3.1% of women). The proportion of men ever having been infected with any HPV (DNA and/or antibody positive) was higher than that of women (71.0% vs. 65.2%, P < 0.001). Type-specific association was observed for genital HPV infection and HPV seropositivity among women but not among men. A positive correlation between the number of lifetime sexual partners and positivity for oncogenic HPV DNA and/or antibodies was found in men but was absent in women. Among 762 couples, the presence of HPV DNA and/or antibodies in one partner was positively associated with the identical HPV type in the other partner. These findings may reflect a site-specific natural course of HPV infection and further understanding of the epidemiology of HPV.

Human Papillomavirus neutralizing and cross-reactive antibodies induced in HIV-positive subjects after vaccination with quadrivalent and bivalent HPV vaccines

Ninety-one HIV-infected individuals (61 men and 30 women) were randomized to vaccination either with quadrivalent (Gardasil™) or bivalent (Cervarix™) HPV vaccine. Neutralizing and specific HPV-binding serum antibodies were measured at baseline and 12 months after the first vaccine dose. Presence of neutralizing and binding antibodies had good agreement (average Kappa for HPV types 6, 11, 16, 18, 31, 33 and 45 was 0.65). At baseline, 88% of subjects had antibodies against at least one genital HPV. Following vaccination with Cervarix™, all subjects became seropositive for HPV16 and 18. After Gardasil™ vaccination, 96% of subjects seroconverted for HPV16 and 73% for HPV18. Levels of HPV16-specific antibodies were <1 international unit (IU) in 87% of study subjects before vaccination but >10IU in 85% of study subjects after vaccination. Antibodies against non-vaccine HPV types appeared after Gardasil™ vaccination for >50% of vaccinated females for HPV 31, 35 and 73 and for >50% of Cervarix™-vaccinated females for HPV 31, 33, 35, 45, 56 and 58. Cross-reactivity with non-genital HPV types was also detected. In conclusion, HIV-infected subjects responded to HPV vaccination with induction of neutralizing antibodies against both vaccine and non-vaccine types.

Identification and validation of immunogenic potential of India specific HPV-16 variant constructs: In-silico &in-vivo insight to vaccine development

Cervical cancer is one of the most common gynecological cancers in the world but in India, it is the top most cancer among women. Persistent infection with high-risk human papillomaviruses (HR-HPVs) is the most important risk factor. The sequence variation(s) in the most common HR-HPV i.e. HPV type 16 leads to altered biological functions with possible clinical significance in the different geographical locations. Sixteen major variants (V1-V16) in full length L1 gene of HPV-16 were identified following analysis of 250 prospectively collected cervical cancer tissue biopsies and their effect on immunogenicity was studied. The effect of these major variations on the epitopes were predicted by in silico methods and the immunogenicity of variants and respective reference DNA vaccine constructs were evaluated by administration of prepared DNA vaccine constructs in female BALB/c mice to evaluate antibody titer. In the present study, L500F (V16) variation showed a significant ~2.7 fold (p < 0.002) increase in antibody titer, whereas T379P (V8) showed ~0.4 fold (p < 0.328) decrease after final injection. These results showed a promising roadmap for the development of DNA based vaccine and for the generation of effective response, though there is a need to study more prevalent variants of HPV in the Indian population.

Long-term efficacy and safety of human papillomavirus vaccination

In this paper, we review the published evidence about the long-term efficacy of the available human papillomavirus (HPV) vaccines and their safety profile. Two prophylactic HPV vaccines - bivalent (bHPV) and quadrivalent (qHPV) - are now available, and vaccination programs are being widely implemented, primarily targeting adolescent girls. Efficacy has been widely demonstrated for both vaccines. Since the risk of HPV exposure potentially persists throughout a woman's sexual life, vaccine duration of protection is critical to overall effectiveness. Interpreting the results of long-term efficacy studies for the two HPV vaccines can be puzzling, due to the heterogeneity of studies, different methods used in the assessment of immunogenicity, histopathological and virological end points, and statistical power issues. Moreover, an immunologic correlate of protection has not yet been established, and it is unknown whether higher antibody levels will really result in a longer duration of protection. Disease prevention remains the most important measure of long-term duration of vaccine efficacy. To date, the longest follow-up of an HPV vaccine has been 9.4 years for the bHPV vaccine. Long-term follow-up for qHPV vaccine goes up to 8 years. The vaccine continues to be immunogenic and well tolerated up to 9 years following vaccination. All randomized controlled clinical trials of the bHPV and the qHPV vaccines provide evidence of an excellent safety profile. The most common complaint reported is pain in the injection site, which is self-limiting and spontaneously resolved. The incidence of systemic adverse events (AEs), serious AEs, and discontinuations due to a serious AE reported in clinical studies are similar between the two vaccines and their control groups. In particular, no increased risk of autoimmune disease has been shown among HPV-vaccinated subjects in long-term observation studies. As these are crucial topics in HPV vaccination, it is important to establish systems for continued monitoring of vaccine immunogenicity, efficacy, and safety over time.

Pre-vaccination seroprevalence of 15 human papillomavirus (HPV) types among women in the population-based Slovenian cervical screening program

OBJECTIVES

To estimate seroprevalence of 11 high-risk (hr) HPV types and four low-risk (lr) HPV types among 20-64 years old Slovenian women participating in the population-based cervical cancer screening program.

METHODS

Serum samples from 3259 women were tested for HPV type-specific antibodies with a multiplexed pseudovirion-based serological assay (PsV-Luminex).

RESULTS

Seropositivity for any of the 15 HPV types was 65.7%, any of the 11 hr-HPV types 59.2%, and any of the four lr-HPV types 33.1%. Antibodies against at least one of the four vaccine HPV types (HPV 6, 11, 16, 18) were detected in 40.8% women. Among hr-HPV types, seropositivity was highest for HPV 16 (25.2%) and among lr-HPV types for HPV 6 (19.1%). Age-specific HPV16 seropositivity was highest among 30-39 years old (29.6%) and decreased with increasing age to 14.0% among 60-64 years old.

CONCLUSION

The lifetime sexual exposure to genital HPV types is substantial, emphasising the need for HPV vaccination.

Pseudovirion-binding and neutralizing antibodies to cutaneous human papillomaviruses (HPV) correlated with the presence of HPV DNA in skin

Whereas the antibody response to the anogenital human papillomaviruses (HPVs) is known to be mainly type-specific, correlated with the presence of viral DNA and mainly directed to conformational epitopes of the virion, it is not known if this applies also to the antibody response to cutaneous HPVs. For 434 non-immunosuppressed patients with skin lesions (squamous cell carcinoma and basal cell carcinoma of the skin, actinic keratosis and benign skin lesions), we compared HPV DNA status with seroreactivity to HPV pseudovirions (PsV) and to GST-L1 fusion proteins from HPV types -5, -6, -15, -16, -32 and -38. Biopsies from the skin lesions were tested for the presence of HPV DNA using three different PCR methods, with typing by sequencing. Serum samples from subjects with HPV DNA-positive biopsies and randomly selected serum samples from subjects with HPV DNA-negative biopsies were also tested with neutralization assays with HPV5, -38 and -76 PsV. Agreement of the three serological methods varied from poor to moderate. Type-specific seroprevalences among patients positive for the same type of HPV DNA (sensitivity of serology) was improved with the PsV-based method (mean of 40 %, maximum 63 %) compared with the GST-L1 method (mean of 20 %, maximum of 25 %). Neutralization was the most sensitive assay for HPV38 (50 %). In summary, cutaneous HPVs also appear to induce a type-specific antibody response that correlates with the presence of HPV DNA and that can be detected with improved sensitivity using PsV-based serology.

Serum antibodies to human papillomavirus (HPV) pseudovirions correlate with natural infection for 13 genital HPV types

BACKGROUND

Serology for human papillomaviruses (HPV) types -16 and -18 is established as an important tool for studies of HPV vaccinology and epidemiology. However, as there are a large number of oncogenic genital types of HPV there is a need for development of high-throughput, validated HPV serological assays that can be used for more comprehensive seroepidemiological studies and for research on multivalent HPV vaccines.

OBJECTIVES

To develop a multiplexed pseudovirion-based serological assay (PsV-Luminex) encompassing 21 HPV types and validate the method by correlating the serology with the presence of type specific HPV DNA in cervical samples.

STUDY DESIGN

Cervical swabs from 3,291 unvaccinated women attending organized cervical screening in Slovenia were tested with 3 different HPV DNA detection methods and presence of HPV DNA compared to presence of serum antibodies to pseudovirions from 15 genital HPV types (HPV-6,-11,-16,-18,-31,-33,-35,-39,-45,-52,-56,-58,-59,-68,-73).

RESULTS

On average 51% of the HPV DNA positive women were seropositive for the same HPV type that was detected in the cervical specimen. We found a strong correlation with presence of HPV DNA and antibodies to the same HPV type for 13/15 genital HPV types (median OR = 5.7, CI 95% = 2.4-12.9). HPV-52 serology failed the validation and HPV-11 serology could not be validated because only a single woman was positive for HPV-11 DNA. The correlation between serology and HPV DNA status tended to be stronger among women infected with single HPV type (median OR=10.5, CI 95% = 2.4-48.4) than among women with multiple HPV infections (median OR = 4.6, CI 95% = 1.8-11.7).

CONCLUSIONS

A multiplexed HPV PsV-Luminex assay has been developed and validated to correlate with natural HPV infection for 13 HPV types, thus enabling more comprehensive studies in HPV epidemiology and vaccine research.

Evidence of immune memory 8.5 years following administration of a prophylactic human papillomavirus type 16 vaccine

BACKGROUND

The duration of protection conferred by prophylactic human papillomavirus (HPV) L1 virus-like particle vaccines is a critical determinant of their public health impact. A feature of vaccines that confer long-term immunity is their ability to induce immune memory.

OBJECTIVES

We evaluated antibody responses against HPV types 6, 11, 16 and 18 following administration of the quadrivalent HPV-6/11/16/18 vaccine to women who had previously received a monovalent HPV-16 vaccine.

STUDY DESIGN

As part of an extended follow-up study conducted between 2006 and 2009 in Seattle, Washington, we administered the quadrivalent HPV-6/11/16/18 vaccine to 52 women (19 vaccine and 33 placebo recipients) who had participated in a monovalent HPV-16 vaccine trial 8.5 years earlier. Serum samples were tested for anti-HPV antibodies using competitive Luminex immunoassay.

RESULTS

Following administration of the first dose of the quadrivalent HPV-6/11/16/18 vaccine, the anti-HPV-16 geometric mean titer among monovalent HPV-16 vaccine recipients (GMT=5024.0 milli-Merck units per milliliter [mMU/mL]; 95% confidence interval [CI]: 2710.1, 9313.6 mMU/mL) substantially exceeded that among the placebo recipients (GMT=136.1; 95% CI: 78.5, 235.8 mMU/mL; p<0.01) and their own highest anti-HPV-16 response observed during the original trial (GMT at month 7 of the original trial=1552.7 mMU/mL; 95% CI: 1072.6, 2247.7 mMU/mL; p<0.01).

CONCLUSIONS

The findings suggest that the administration of the three-dose regimen of the monovalent HPV-16 vaccine had produced memory lymphocytes, characterized by a heightened immune response following administration of the quadrivalent HPV-6/11/16/18 vaccine that effectively served as an antigen challenge.