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

Clearance of anal and penile HPV 6, 11, 16, and 18 DNA and antibodies among adolescent men who have sex with men (HYPER): An observational cohort study

Background

Clearance of human papillomavirus (HPV) among adolescent men who have sex with men (MSM) is not well studied. This study aimed to evaluate the clearance of HPV DNA and antibodies among adolescent MSM.

Methods

In our cohort study, we enrolled adolescent MSM in Melbourne between October 2010 and September 2013. At baseline, 3, 6, and 12 months, anal and penile swabs for HPV DNA and serum for HPV antibodies against genotypes 6, 11, 16, and 18, were collected. Definite clearance was defined as HPV DNA (same site) /antibodies for the same genotype undetected following a positive HPV DNA /antibodies test at baseline or month 3. Possible clearance was defined as HPV DNA (same site) /antibodies for the same genotype undetected at month 12 following a positive HPV DNA/antibodies test at month 6. Overall clearance was defined as either definite or possible clearance. The agreement between HPV DNA clearance and antibodies clearance was calculated.

Results

A total of 183 MSM were included (median age: 19 years, interquartile [IQR]: 18 to 20). At the anus, overall clearance rate was 21.6 (95 % confidence interval[CI]: 7.9 to 47.0), 44.8 (19.3 to 88.3), 51.9 (20.9 to 106.9) and 33.7 (7.0 to 98.5) per 1000 person months (PM) for HPV 6, 11, 16 and 18. At the penis, overall clearance rate was 64.5 (13.3 to 188.5), 71.3 (14.7 to 208.2), 96.5 (31.3 to 225.3) and 333.3 (8.4 to 1857.2) per 1000 PM for HPV 6, 11, 16 and 18. For antibodies, overall clearance rate was 22.2 (9.6 to 43.7), 18.8 (3.9 to 55.0), 10.8 (0.3 to 60.1) and 19.0 (2.3 to 68.8) per 1000 PM. Agreement between anal/penile HPV DNA clearance and antibodies clearance was low: kappa = -0.18 (95 % CI: -0.28 to 0.08)/-0.13 (-0.24 to -0.02), 0.04 (-0.29 to 0.36)/0.22 (-0.32 to 0.76), -0.10 (-0.27 to 0.08)/-0.14 (-0.37 to 0.10) and -0.14 (-0.28 to 0.01)/-0.14 (-0.33 to 0.06) for HPV 6, 11, 16 and 18, respectively.

Conclusion

Clearance rates of HPV DNA were low and varied by genotypes and anatomical sites among adolescent MSM. Antibodies against HPV were stable during the study period.

Association of naturally acquired type-specific HPV antibodies and subsequent HPV re-detection: systematic review and meta-analysis

BACKGROUND

Understanding the role of naturally acquired (i.e., infection-induced) human papillomavirus (HPV) antibodies against reinfection is important given the high incidence of this sexually transmitted infection. However, the protective effect of naturally acquired antibodies in terms of the level of protection, duration, and differential effect by sex remains incompletely understood. We conducted a systematic review and a meta-analysis to (1) strengthen the evidence on the association between HPV antibodies acquired through past infection and subsequent type-specific HPV detection, (2) investigate the potential influence of type-specific HPV antibody levels, and (3) assess differential effects by HIV status.

METHODS

We searched Embase and Medline databases to identify studies which prospectively assessed the risk of type-specific HPV detection by baseline homologous HPV serostatus among unvaccinated individuals. Random-effect models were used to pool the measures of association of naturally acquired HPV antibodies against subsequent incident detection and persistent HPV positivity. Sources of heterogeneity for each type were assessed through subgroup analyses stratified by sex, anatomical site of infection, male sexual orientation, age group, and length of follow-up period. Evidence of a dose-response relationship of the association between levels of baseline HPV antibodies and type-specific HPV detection was assessed. Finally, we pooled estimates from publications reporting associations between HPV serostatus and type-specific HPV detection by baseline HIV status.

RESULTS

We identified 26 publications (16 independent studies, with 62,363 participants) reporting associations between baseline HPV serostatus and incident HPV detection, mainly for HPV-16 and HPV-18, the most detected HPV type. We found evidence of protective effects of baseline HPV seropositivity and subsequent detection of HPV DNA (0.70, 95% CI 0.61-0.80, NE = 11) and persistent HPV positivity (0.65, 95% CI 0.42-1.01, NE = 5) mainly for HPV-16 among females, but not among males, nor for HPV-18. Estimates from 8 studies suggested a negative dose-response relationship between HPV antibody level and subsequent detection among females. Finally, we did not observe any differential effect by baseline HIV status due to the limited number of studies available.

CONCLUSION

We did not find evidence that naturally acquired HPV antibodies protect against subsequent HPV positivity in males and provide only modest protection among females for HPV-16. One potential limitation to the interpretation of these findings is potential misclassification biases due to different causes.

Comparison of HPV neutralizing and IgG antibodies in unvaccinated female adolescents

Aims: To analyze the consistency between HPV neutralizing antibodies and specific total IgG antibodies in unvaccinated females. Materials & methods: Serum samples from 978 unvaccinated Chinese females aged 9-26 years were measured for antibodies against HPV-16 and HPV-18 using simultaneous pseudovirus-based neutralization assay and ELISA. Results: There was a moderate level of consistency between HPV neutralizing antibodies and specific IgG in females aged 18-26 years (Cohen's κ coefficient for HPV-16 and HPV-18: 0.52 and 0.38) and poor consistency in those aged 9-17 years (Cohen's κ coefficient <0.05). However, Cohen's κ coefficient remained almost unchanged in sensitivity analysis when the IgG antibody cut-off value was raised. Conclusion: HPV neutralizing antibodies are a more specific indicator for the evaluation of HPV natural humoral immunity.

Outcomes of HPV type-specific serostatus do not associate with oral or genital HPV-carriage in non-vaccinated women followed for three years

BACKGROUND

The role of human papillomavirus (HPV) antibodies acquired through natural infection and their role in protection for subsequent cervical or oral HPV-carriage remains unclear.

METHODS

A total of 267 women, with a 36-months follow-up, from the Finnish Family HPV (FFHPV) study were evaluated to shed more light on persistent HPV-specific antibodies to genital or oral HPV-carriage, clearance or persistence during the three years follow-up. The type-specific seroprevalence for HPV genotypes 6, 11, 16, 18 and 45 in these women was assessed in relation to the detection of the same genotype or any HPV in their oral and genital samples. The following HPV serological outcomes where detected: being always seronegative, seroconversion or persistent seropositivity.

RESULTS

Genital HPV16 infections were most prevalent at the end of the follow-up (24- and 36-month visit) among women who tested always seronegative for HPV16. No such associations between serology and HPV detection were established for the other HPV genotypes in the genital or oral samples. The development of long-term type-specific HPV 6,11,16,18 and 45 persistence (≥ 24 months) or clearance of the genital or oral infections was not different among the women with high HPV genotype specific antibody levels and those testing always HPV-seronegative.

CONCLUSION

No significant role was disclosed for the acquired natural high-level- or persistent HPV antibodies as determinants of the genital or oral HPV infection outcomes in these young, non-vaccinated women.

Evaluation Frequency of Human Papillomavirus and Its Related Genotypes in Women of the General Population Living in 11 Provinces of Iran

Introduction

Persistent infection with one of the most high-risk genotypes of human papillomavirus causes all cases of cervical cancer and a significant proportion of other genital cancers. The HPV virus, unlike any other infection that leads to cancer, is transmitted only through sexual intercourse and is less affected by the general changes and development in lifestyle and medical standards, so only vaccination and screening can prevent the HPV virus and cancers caused by it. Therefore, determining the prevalence and distribution of HPV genotypes are of utmost importance in screening strategies regarding cervical cancer and vaccination decisions against HPV that vary based on the geographical and cultural characteristics of the study area. As a result, this study aimed to determine the frequency of human papillomavirus and the distribution of this virus's genotypes in the general population of women living in 11 provinces of Iran.

Materials and Methods

This study is a community-based survey study. Sampling was done by the cluster sampling method. Women aged 15–59 years old from the general population living in 11 provinces of Iran were included in the study after considering the inclusion and exclusion criteria. Data were collected using a questionnaire and vaginal examination. The study was performed on 2562 vaginal specimens that were referred to the laboratory of the present study. HPV genome was detected by the nested MY-GP method and papillomavirus genotyping was performed using the PCR multiplex method to identify 19 papillomavirus genotypes.

Results

The general prevalence of HPV in the 11 provinces was obtained at 2.4% (108 out of 2562 people). The highest prevalence of the virus was in the age group of 25–34 years. The prevalence of HPV was statistically significant among different provinces. Hormozgan province with 22 cases (5.9%) had the highest and Isfahan province with 6 cases (2.2%) had the lowest incidence of HPV. The prevalence of high-risk HPV and medium-risk HPV is 3%, and the prevalence of low-risk HPV was estimated to be 2.1% of the total female population. Also, the highest prevalence was related to genotype 16.

Conclusion

According to the high prevalence of the HPV virus in young age groups in Iran, it is necessary to pay attention to screening programs to reduce the incidence of cervical cancer.

HPV vaccination among seropositive, DNA negative cohorts: a systematic review & meta-analysis

Objective

Vaccine efficacy among previously exposed, but currently uninfected women, i.e., those who have serological evidence of a prior human papillomavirus (HPV) infection without corresponding detectable HPV DNA, remains incompletely defined. This meta-analysis assessed the serotype-specific efficacy of prophylactic HPV vaccination against HPV16/18 persistent infection (PI) and cervical intraepithelial neoplasia (CIN) among seropositive, DNA negative (SPDN) women enrolled to randomized controlled trials (RCTs) of HPV L1-based vaccines.

Methods

Searches were conducted on 08/16/20 on MEDLINE, Embase, Scopus and CENTRAL. RCTs of L1-based prophylactic bivalent or quadrivalent HPV vaccines, reporting serotype-specific clinical efficacy endpoints in the HPV16/18 seropositive, DNA-negative populations were included. Relative risks (RRs) of 6-month PI (6mPI), 12-month PI (12mPI), CIN1+ and CIN2+ were pooled using a random-effects model.

Results

A total of 1,727 citations were reviewed. 8 studies, with a total of 9,569 SPDN participants, met all eligibility criteria. The RR of 6mPI (RR=0.22; 95% confidence interval [CI]=0.08–0.61; p=0.018), 12mPI (RR=0.20; 95% CI=0.05–0.80; p=0.035), CIN1+ (RR=0.13; 95% CI=0.05–0.30; p=0.003) and CIN2+ (RR=0.15; 95% CI=0.04–0.59; p=0.022) was significantly reduced in the vaccinated compared to the unvaccinated group.

Conclusion

Our findings suggest high serotype-specific efficacy for HPV vaccination among cohorts of women with evidence of prior HPV16/18 infections, including 87% efficacy (95% CI=70%–95%; p=0.003) against HPV16/18 cervical dysplasia. HPV vaccination is highly effective among uninfected women, regardless of prior exposure history.

Trial Registration

PROSPERO Identifier: CRD42020206888

Longitudinal assessment of nonavalent vaccine HPV types in a sample of sexually active African American women from ten U.S. Cities

BACKGROUND

Chronic infection with high-risk human papillomavirus is a necessary cause for cervical carcinogenesis. This study examined prevalence of nonavalent vaccine preventable HPV types over four months among sexually active women in the United States.

METHODS

This sub-study obtained meta-data for 80 of the 1,365 women (18-25 years), enrolled in the BRAVO study, a randomized, open-label trial of home screening and treatment of asymptomatic bacterial vaginosis at high-risk for sexually transmitted infections conducted between 2008 and 2013. Participants were randomized to treatment or standard-of-care, and followed every 2-months for 12 months. Stored vaginal swabs from the first three visits were tested for the nine vaccine preventable HPV types using quantitative PCR. Prevalence and associated 95% confidence intervals for the HPV types were assessed using R (version 3.6.1).

RESULTS

The average age of the participants was 21.5 (SD ± 2.11) years, with 60% having ever been pregnant and all were African-American. Majority (71%) reported ≥ two sex partners in the prior year with 89% having unprotected vaginal sex and 45% having a new sex partner in the prior year. About 30% had ≥ one of the nine nonavalent vaccine HPV types at all three time points over a period of four months, 15% at two of any three visits, 19% at one of the three visits and 36% were negative for all nine vaccine HPV types at all time points. The most frequently detected HPV vaccine types were 52, 58, 16, and 18. The prevalence of any vaccine HPV types, and high-risk HPV types was 63.8% and 58.8%, respectively.

CONCLUSIONS

Our findings suggest that HPV vaccination which is currently recommended for all unvaccinated persons through age 26 years, is likely to be more beneficial than previously thought as nonavalent HPV vaccine was not available during the time these data were collected.

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.

Development and validation of a multiplex immunoassay for the simultaneous quantification of type-specific IgG antibodies to E6/E7 oncoproteins of HPV16 and HPV18

More than 170 types of human papilloma viruses (HPV) exist with many causing proliferative diseases linked to malignancy in indications such as cervical cancer and head and neck squamous cell carcinoma. Characterization of antibody levels toward HPV serology is challenging due to complex biology of oncoproteins, pre-existing titers to multiple HPV types, cross-reactivity, and low affinity, polyclonal responses. Using multiplex technology from MSD, we have developed an assay that simultaneously characterizes antibodies against E6 and E7 oncoproteins of HPV16 and 18, the primary drivers of HPV-associated oncogenesis. We fusion tagged our E6 and E7 proteins with MBP via two-step purification, spot-printed an optimized concentration of protein into wells of MSD 96-well plates, and assayed various cynomolgus monkey, human and HPV+ cervical cancer patient serum to validate the assay. The dynamic range of the assay covered 4-orders of magnitude and antibodies were detected in serum at a dilution up to 100,000-fold. The assay was very precise (n = 5 assay runs) with median CV of human serum samples ~ 5.3% and inter-run variability of 11.4%. The multiplex serology method has strong cross-reactivity between E6 oncoproteins from human serum samples as HPV18 E6 antigens neutralized 5 of 6 serum samples as strongly as HPV16 E6. Moderate concordance (Spearman’s Rank = 0.775) was found between antibody responses against HPV16 E7 in the multiplex assay compared to standard ELISA serology methods. These results demonstrate the development of a high-throughput, multi-plex assay that requires lower sample quantity input with greater dynamic range to detect type-specific anti-HPV concentrations to E6 and E7 oncoproteins of HPV16 and 18.

Risk of newly detected infections and cervical abnormalities in adult women seropositive or seronegative for naturally acquired HPV-16/18 antibodies

BACKGROUND

Infections with human papillomavirus (HPV) types 16 and 18 account for ~70% of invasive cervical cancers but the degree of protection from naturally acquired anti-HPV antibodies is uncertain. We examined the risk of HPV infections as defined by HPV DNA detection and cervical abnormalities among women >25 years in the Human Papilloma VIrus Vaccine Immunogenicity ANd Efficacy trial's (VIVIANE, NCT00294047) control arm.

METHODS

Serum anti-HPV-16/18 antibodies were determined at baseline and every 12 months in baseline DNA-negative women (N = 2687 for HPV-16 and 2705 for HPV-18) by enzyme-linked immunosorbent assay (ELISA) from blood samples. HPV infections were identified by polymerase chain reaction (PCR) every 6-months, and cervical abnormalities were confirmed by cytology every 12 months. Data were collected over a 7-year period. The association between the risk of type-specific infection and cervical abnormalities and serostatus was assessed using Cox proportional hazard models.

RESULTS

Risk of newly detected HPV-16-associated 6-month persistent infections (PI) (hazard ratio [HR] = 0.56 [95%CI:0.32; 0.99]) and atypical squamous cells of undetermined significance (ASC-US+) (HR = 0.28 [0.12; 0.67]) were significantly lower in baseline seropositive vs baseline seronegative women. HPV-16-associated incident infections (HR = 0.81 [0.56; 1.16]) and 12-month PI (HR = 0.53 [0.24; 1.16]) showed the same trend. A similar trend of lower risk was observed in HPV-18-seropositive vs -seronegative women (HR = 0.95 [0.59; 1.51] for IIs, HR = 0.43 [0.16; 1.13] for 6-month PIs, HR = 0.31 [0.07; 1.36] for 12-month PIs, and HR = 0.61 [0.23; 1.61] for ASC-US+).

CONCLUSIONS

Naturally acquired anti-HPV-16 antibodies were associated with a decreased risk of subsequent infection and cervical abnormalities in women >25 years. This possible protection was lower than that previously reported in 15- to 25-year-old women.

Mucosal and cutaneous Human Papillomavirus seroprevalence among adults in the prevaccine era in Germany - Results from a nationwide population-based survey

BACKGROUND

Human Papillomavirus (HPV) vaccination of girls was introduced in Germany in 2007. However, data on the distribution of vaccine-relevant HPV types in the general population in Germany in the prevaccine era are limited.

METHODS

Serum samples collected during the German National Health Interview and Examination Survey 1998 (GNHIES98), a nationally representative study including men and women aged 18-79 years, were tested for antibodies to 19 mucosal and cutaneous HPV types. Multivariable regression models were developed to identify associations between demographic and behavioral characteristics and HPV seropositivity.

RESULTS

Of the 6517 serum samples tested, almost a quarter was seropositive for at least one of the nine HPV vaccine types with no clear age-pattern. HPV-6 and HPV-59 were the most common mucosal types, while HPV-1 and HPV-4 were the most common cutaneous HPV types. Factors independently associated with HPV-16 seroprevalence were seropositive to other sexually transmitted infections and lifetime number of sex partners, as well as urbanity (only among females).

CONCLUSIONS

Prevalence of naturally acquired antibodies to HPV types which can be prevented by vaccination is high in both sexes and all age groups. These data can serve as baseline estimates to evaluate the population-level impact of the current vaccination strategy.

An Examination of HPV16 Natural Immunity in Men Who Have Sex with Men (MSM) in the HPV in Men (HIM) Study

Background: Evidence suggests that natural antibodies developed after HPV16 infection may protect some women but not men against subsequent HPV16 reacquisition. Less is known whether antibodies developed following HPV16 infection are protective among men who have sex with men (MSM).Methods: Four hundred seventy-five MSM from the Human Papillomavirus Infection in Men (HIM) study were tested for serum antibodies to HPV16 L1 using enzyme-linked immunosorbent assays, and for anal and genital HPV16 DNA using PCR consensus primer system (PGMY 09/11). Adjusted Cox regression was used to evaluate whether baseline HPV16 seropositivity impacts subsequent genital or anal HPV16 DNA.Results: The risk of subsequent genital HPV16 [aHR = 1.05, 95% confidence interval (CI) = 0.66-1.68] and anal HPV16 infections among MSM (aHR = 2.34, 95% CI = 0.92-5.98) was similar or nonsignificantly higher in HPV16-seropositive than HPV16-seronegative MSM. The risk of genital HPV16 was also similar between HPV16-seronegative and HPV16-seropositive MSM in the highest tertile of HPV16 antibody levels and when restricting to those with new sex partners during follow-up (P > 0.20). Among the 118 MSM who were HPV16 seropositive, 90% remained HPV16 seropositive up to 4 years later. When tested together, MSM with the highest antibody titers (top tertile) had similar levels to females (mean = 130.3 vs. 134.5 EU/mL, P = 0.84).Conclusions: Despite years of HPV16 seropositivity persistence and antibody titers comparable with females, this study suggested no evidence of HPV16 natural antibodies protecting against subsequent genital or anal HPV16 infection in MSM.Impact: This could help partially explain the high incidence of genital and anal HPV16 infection and related anal cancer seen in middle-aged and older MSM. Cancer Epidemiol Biomarkers Prev; 27(4); 496-502. ©2018 AACR.

Smoking and subsequent human papillomavirus infection: a mediation analysis

PURPOSE

Smoking is an established risk factor for a human papillomavirus (HPV) infection advancing to cervical precancer and cancer, but its role earlier in the natural history is less clear. Smoking is inversely associated with possessing HPV antibodies from a past infection suggesting that smoking may influence acquiring subsequent infections.

METHODS

In a cohort of 1976 U.S. women, we evaluate whether reduced antibodies to HPV-16 is a mechanism for smoking's role on acquiring a subsequent HPV-16 infection, through the analytic technique of causal mediation analysis. We posit a causal model and estimate two counterfactually defined effects: a smoking impaired antibody-mediated indirect effect and a nonmediated direct effect representing all other potential mechanisms of smoking.

RESULTS

Compared to never smokers, current smokers had increased odds of HPV-16 infection by the antibody-mediated indirect effect (odds ratio [OR] = 1.29; 95% confidence interval [CI]: 1.11, 1.73); the estimated direct effect was very imprecise (OR = 0.57; 95% CI, 0.26-1.13). We observed a stronger estimated indirect effect among women who smoked at least half a pack of cigarettes daily (OR = 1.61, 95% CI, 1.27-2.15) than among women who smoked less than that threshold (OR = 1.09; 95% CI, 0.94-1.44).

CONCLUSIONS

This is the first study to directly test the mechanism underlying smoking as an HPV cofactor. The results support current smoking as a risk factor earlier in the natural history of HPV and are consistent with the hypothesis that smoking increases the risk of a subsequent infection by reducing immunity.

Epidemiological investigation of the relationship between common lower genital tract infections and high-risk human papillomavirus infections among women in Beijing, China

BACKGROUND

The incidence of lower genital tract infections in China has been increasing in recent years. The link between high-risk human papillomavirus (HR-HPV) and other sexually transmitted diseases (STDs) remains unclear.

METHODS

From March to October 2014, gynecological examinations and questionnaires were conducted on 1218 married women. Cervical secretions and vaginal swab specimens were tested for Chlamydia trachomatis (CT), Neisseria gonorrhoeae (NG), Ureaplasma urealyticum (UU), yeast, clue cells and HR-HPV.

RESULTS

Laboratory results were available for 1195 of 1218 married women. HR-HPV was detected in 7.0% of participants. Forty-seven percent of women had lower genital tract infections (LGTIs). UU was the most common infection (35.5%), followed by bacterial vaginosis (BV) (10.5%), yeast infection (3.7%), CT (2.2%), and Trichomonas vaginalis (1.7%). BV was associated with an increased risk of HR- HPV (P < 0.0001; odds ratio, 3.0 [95% CI, 1.7-5.4]). There was a strong correlation between abnormal cervical cytology and HR-HPV infection (P < 0.0001).

CONCLUSIONS

The prevalence of LGTIs in Beijing is at a high level. It is clinically important to screen for the simultaneous presence of pathogens that cause co-infections with HR-HPV.

Bias Due to Correlation Between Times-at-Risk for Infection in Epidemiologic Studies Measuring Biological Interactions Between Sexually Transmitted Infections: A Case Study Using Human Papillomavirus Type Interactions

The clustering of human papillomavirus (HPV) infections in some individuals is often interpreted as the result of common risk factors rather than biological interactions between different types of HPV. The intraindividual correlation between times-at-risk for all HPV infections is not generally considered in the analysis of epidemiologic studies. We used a deterministic transmission model to simulate cross-sectional and prospective epidemiologic studies measuring associations between 2 HPV types. When we assumed no interactions, the model predicted that studies would estimate odds ratios and incidence rate ratios greater than 1 between HPV types even after complete adjustment for sexual behavior. We demonstrated that this residual association is due to correlation between the times-at-risk for different HPV types, where individuals become concurrently at risk for all of their partners' HPV types when they enter a partnership and are not at risk when they are single. This correlation can be controlled in prospective studies by restricting analyses to susceptible individuals with an infected sexual partner. The bias in the measured associations was largest in low-sexual-activity populations, cross-sectional studies, and studies which evaluated infection with a first HPV type as the exposure. These results suggest that current epidemiologic evidence does not preclude the existence of competitive biological interactions between HPV types.

Impact of Serum Antibodies to HPV Serotypes 6, 11, 16, and 18 to Risks of Subsequent Genital HPV Infections in Men: The HIM Study

Naturally induced serum antibodies against human papillomavirus (HPV) may affect risks of subsequent incident genital infections by HPV 6, 11, 16, or 18 in men. In this study, we examined the hypothesis by following 4,123 healthy men every 6 months (median follow-up time, 4.1 years). HPV antibodies were measured at baseline using a virus-like particle-based ELISA assay. Genital HPV genotypes were detected using Roche Linear Array. Incidence proportions and 6-month persistence proportions were calculated at 6-month intervals. Kaplan-Meier curves and Cox models were used to assess genotype-specific cumulative incidence and HRs, respectively. HPV 6, 11, 16, and 18 seroprevalence was 8.1%, 13.9%, 12.7%, and 10.8%, respectively. Significantly higher rates of incident infections were observed for HPV 16 among baseline-seropositive men [adjusted HR, 1.37; 95% confidence interval (CI), 1.01-1.86], with similar but nonsignificant HRs for 6-month persistent infections. Risk of persistent HPV 18 infection was significantly lower among seropositive men in the unadjusted model (HR, 0.22; 95% CI, 0.06-0.91), but not in the adjusted model (HR, 0.19; 95% CI, 0.03-1.37). Incident and 6-month persistent infections for HPV 6 and 11 did not differ by baseline serostatus. Baseline serostatus among men was not associated with a reduction in subsequent incident genital HPV 6, 11, and 16 infections. However, protection against persistent HPV18 infections was observed in unadjusted models. Our research suggests a need of further studies to examine the potentially protective effects of naturally induced HPV18 antibodies in men. Cancer Res; 76(20); 6066-75. ©2016 AACR.

Re-detection vs. new acquisition of high-risk human papillomavirus in mid-adult women

To understand high-risk (hr) human papillomavirus (HPV) epidemiology in mid-adulthood, we assessed whether associations between incident detection of hrHPV DNA and recent sexual behavior differed according to whether or not there was serologic evidence of prior infection. From 2011 to 2012, we enrolled 409 women aged 30-50 years into a 6-month longitudinal study. We collected health and sexual behavior histories, enrollment sera for HPV antibody testing, and monthly self-collected vaginal swabs for HPV DNA genotyping. Generalized estimating equations logistic regression identified risk factors for type-specific incident hrHPV DNA, stratified by type-specific hrHPV serostatus at enrollment. Population attributable risks of hrHPV due to prior and recent exposure were estimated. When type-specific hrHPV serology was negative, recent sexual risk behavior was positively associated with incident hrHPV DNA (odds ratio in women reporting ≥3 recent sexual risk behaviors [e.g., new or multiple partners] vs. no recent sexual activity = 9.8, 95% CI: 2.4-40.6). No associations with recent sexual behavior were observed with positive type-specific hrHPV serology. Thirty percent of incident hrHPV DNA detection was attributable to prior infection (with positive serology) and 40% was attributable to recent sexual risk behavior (with negative serology). The proportion of incident hrHPV DNA detection attributable to recent sexual risk behavior decreased with increasing age. Among women with serologic evidence of prior infection, re-detection of the same hrHPV type is likely due to reactivation or intermittent detection of persistent infection. Without serologic evidence of prior infection, new detection is likely due to new acquisition or to intermittent detection of persisting infection.

The Role of Chlamydia trachomatis in High-Risk Human Papillomavirus Persistence Among Female Sex Workers in Nairobi, Kenya

BACKGROUND

Little is known about risk factors for persistent high-risk human papillomavirus (hrHPV) infection in low-income settings, and prior research has not quantified the relative duration of hrHPV infections stratified by risk factors. We compared the duration of hrHPV infection among female sex workers (FSWs) by exposure to sexually transmitted infections (STIs), using a highly sensitive biomarker assay.

METHODS

From 2009 to 2011, 350 FSWs enrolled in this longitudinal study. Every 3 months, sociodemographic and sexual behavior data were collected via questionnaire, and APTIMA assays were used to detect the rRNA of Chlamydia trachomatis (CT), Neisseria gonorrhea, Trichomonas vaginalis, Mycoplasma genitalium, and messenger RNA of the E6/E7 oncoproteins expressed by hrHPV. Among 173 FSW who were infected with hrHPV during the observation period, accelerated failure time models estimated time ratios (TRs) for duration of hrHPV infection, comparing FSW infected with STIs at baseline to STI-uninfected FSWs.

RESULTS

Median follow-up time was 26.2 months (interquartile range, 18.8-27.5 months). The median duration of hrHPV infection among all FSWs was 9.3 months (95% confidence interval [CI], 9.3-11.5). The duration of hrHPV infection among FSW infected with CT at baseline was greater than that among FSWs who were uninfected (adjusted TR, 1.7; 95% CI, 1.2-2.6). Among FSWs who were coinfected with hrHPV and CT at baseline, the adjusted TR was 3.4 (95% CI, 2.5-5.4) compared with FSWs infected with hrHPV only. No other STI was associated with hrHPV duration.

CONCLUSIONS

Recent or concurrent CT infection was associated with prolonged hrHPV infection among a cohort of Nairobi FSWs. Management of CT could reduce risk for hrHPV persistence.

National- and state-level impact and cost-effectiveness of nonavalent HPV vaccination in the United States

Every year in the United States more than 12,000 women are diagnosed with cervical cancer, a disease principally caused by human papillomavirus (HPV). Bivalent and quadrivalent HPV vaccines protect against 66% of HPV-associated cervical cancers, and a new nonavalent vaccine protects against an additional 15% of cervical cancers. However, vaccination policy varies across states, and migration between states interdependently dilutes state-specific vaccination policies. To quantify the economic and epidemiological impacts of switching to the nonavalent vaccine both for individual states and for the nation as a whole, we developed a model of HPV transmission and cervical cancer incidence that incorporates state-specific demographic dynamics, sexual behavior, and migratory patterns. At the national level, the nonavalent vaccine was shown to be cost-effective compared with the bivalent and quadrivalent vaccines at any coverage despite the greater per-dose cost of the new vaccine. Furthermore, the nonavalent vaccine remains cost-effective with up to an additional 40% coverage of the adolescent population, representing 80% of girls and 62% of boys. We find that expansion of coverage would have the greatest health impact in states with the lowest coverage because of the decreasing marginal returns of herd immunity. Our results show that if policies promoting nonavalent vaccine implementation and expansion of coverage are coordinated across multiple states, all states benefit both in health and in economic terms.

Natural Acquired Immunity Against Subsequent Genital Human Papillomavirus Infection: A Systematic Review and Meta-analysis

BACKGROUND

Studies have been mixed on whether naturally acquired human papillomavirus (HPV) antibodies may protect against subsequent HPV infection. We performed a systematic review and meta-analysis to assess whether naturally acquired HPV antibodies protect against subsequent genital HPV infection (ie, natural immunity).

METHODS

We searched the MEDLINE and EMBASE databases for studies examining natural HPV immunity against subsequent genital type-specific HPV infection in female and male subjects. We used random-effects models to derive pooled relative risk (RR) estimates for each HPV type.

RESULTS

We identified 14 eligible studies that included >24,000 individuals from 18 countries that examined HPV natural immunity. We observed significant protection against subsequent infection in female subjects with HPV-16 (pooled RR, 0.65; 95% confidence interval, .50-.80) and HPV-18 (0.70; .43-.98) but not in male subjects (HPV-16: 1.22; .67-1.77 [P= .05 (test for heterogeneity)]; HPV-18: 1.50; .46-2.55; [P= .15]). We also observed type-specific protection against subsequent infection for a combined measure of HPV-6/11/31/33/35/45/52/58 in female subjects (pooled RR, 0.75; 95% confidence interval, .57-.92). Natural immunity was also evident in female subjects when analyses were restricted to studies that used neutralizing assays, used HPV persistence as an outcome, or reported adjusted analyses (each P< .05).

CONCLUSIONS

HPV antibodies acquired through natural infection provide modest protection against subsequent cervical HPV infection in female subjects.

Epidemiology of Human Papillomavirus-Positive Head and Neck Squamous Cell Carcinoma

Human papillomavirus (HPV) is now established as the principal cause of an increase in incidence of a subset of head and neck squamous cell cancers (HNCs) in numerous geographic regions around the world. Further study of the epidemiology of HPV-positive HNC will be critical to the development and implementation of public health interventions to reverse these global incidence trends. Here, recent data are reviewed to provide insight into several topics, including incidence trends and projections for HPV-positive HNC; the worldwide HPV-attributable fraction; sex disparities in cancer risk; the epidemiology of oral HPV infection; the latency period between infection and cancer; the potential impact of prophylactic HPV vaccination; and prospects for secondary prevention through screening for oral HPV infection or seroreactivity to viral antigens. The identification of a single necessary cause for any cancer provides a rare and perhaps extraordinary opportunity for cancer prevention.

Prophylactic HPV vaccination: past, present, and future

Human papillomavirus (HPV) is the necessary cause of cervical cancer, the fourth most common cancer and cause of cancer-related death in females worldwide. HPV also causes anal, vaginal, vulvar, penile, and oropharyngeal cancer. Prophylactic HPV vaccines based on recombinantly expressed virus-like particles have been developed. Two first-generation, U.S. Food and Drug Administration (FDA)-approved vaccines prevent infections and disease caused by HPV16 and HPV18, the two HPV genotypes that cause approximately 70% of cervical cancer, and one of these vaccines also prevents HPV6 and HPV11, the two HPV genotypes that cause 90% of genital warts. A next-generation vaccine, recently approved by the U.S. FDA, targets HPV16, HPV18, and five additional HPV genotypes that together causes approximately 90% of cervical cancer as well as HPV6 and HPV11. In clinical trials, these vaccines have shown high levels of efficacy against disease and infections caused by the targeted HPV genotypes in adolescent females and males and older females. Data indicate population effectiveness, and therefore cost effectiveness, is highest in HPV-naive young females prior to becoming sexually active. Countries that implemented HPV vaccination before 2010 have already experienced decreases in population prevalence of targeted HPV genotypes and related anogenital diseases in women and via herd protection in heterosexual men. Importantly, after more than 100 million doses given worldwide, HPV vaccination has demonstrated an excellent safety profile. With demonstrated efficacy, cost-effectiveness, and safety, universal HPV vaccination of all young, adolescent women, and with available resources at least high-risk groups of men, should be a global health priority. Failure to do so will result in millions of women dying from avertable cervical cancers, especially in low- and middle-income countries, and many thousands of women and men dying from other HPV-related cancers.

Naturally Occurring Capsid Protein Variants of Human Papillomavirus Genotype 31 Represent a Single L1 Serotype

We investigated naturally occurring variation within the major (L1) and minor (L2) capsid proteins of oncogenic human papillomavirus (HPV) genotype 31 (HPV31) to determine the impact on capsid antigenicity. L1L2 pseudoviruses (PsVs) representing the three HPV31 variant lineages, variant lineages A, B, and C, exhibited comparable particle-to-infectivity ratios and morphologies. Lineage-specific L1L2 PsVs demonstrated subtle differences in susceptibility to neutralization by antibodies elicited following vaccination or preclinical L1 virus-like particle (VLP) immunization or by monoclonal antibodies; however, these differences were generally of a low magnitude. These data indicate that the diagnostic lineage-specific single nucleotide polymorphisms within the HPV31 capsid genes have a limited effect on L1 antibody-mediated neutralization and that the three HPV31 variant lineages belong to a single L1 serotype. These data contribute to our understanding of HPV L1 variant antigenicity.

IMPORTANCE

The virus coat (capsid) of the human papillomavirus contains major (L1) and minor (L2) capsid proteins. These proteins facilitate host cell attachment and viral infectivity and are the targets for antibodies which interfere with these events. In this study, we investigated the impact of naturally occurring variation within these proteins upon susceptibility to viral neutralization by antibodies induced by L1 VLP immunization. We demonstrate that HPV31 L1 and L2 variants exhibit similar susceptibility to antibody-mediated neutralization and that for the purposes of L1 VLP-based vaccines, these variant lineages represent a single serotype.

NHANES 2009-2012 Findings: Association of Sexual Behaviors with Higher Prevalence of Oral Oncogenic Human Papillomavirus Infections in U.S. Men

The incidence of human papillomavirus (HPV)-positive oropharyngeal cancers is higher and increasing more rapidly among men than women in the United States for unknown reasons. We compared the epidemiology of oral oncogenic HPV infection between men and women ages 14 to 69 years (N = 9,480) within the U.S. National Health and Nutritional Examination Surveys (NHANES) 2009-2012. HPV presence was detected in oral DNA by PCR. Analyses were stratified by gender and used NHANES sample weights. Oral oncogenic HPV prevalence was higher among men than women (6.6% vs. 1.5%, P < 0.001), corresponding to 7.07 million men versus 1.54 million women with prevalent infection at any point in time during 2009-2012. Prevalence increased significantly with age, current smoking, and lifetime number of sexual partners for both genders (adjusted Ptrend < 0.02). However, men had more partners than women (mean = 18 vs. 7, P < 0.001). Although oncogenic HPV prevalence was similar for men and women with 0 to 1 lifetime partners, the male-female difference in prevalence significantly increased with number of lifetime partners (adjusted prevalence differences for none, 1, 2-5, 6-10, 11-20, and 20+ partners = 1.0%, 0.5%, 3.0%, 5.7%, 4.6%, and 9.3%, respectively). Importantly, the per-sexual partner increase in prevalence was significantly stronger among men than among women (adjusted synergy index = 3.3; 95% confidence interval, 1.1-9.7), and this increase plateaued at 25 lifetime partners among men versus 10 partners among women. Our data suggest that the higher burden of oral oncogenic HPV infections and HPV-positive oropharyngeal cancers among men than women arises in part from higher number of lifetime sexual partners and stronger associations with sexual behaviors among men.

The role of acquired immunity in the spread of human papillomavirus (HPV): explorations with a microsimulation model

Background

Knowledge of the natural history of human papillomavirus (HPV), in particular the role of immunity, is crucial in estimating the (cost-) effectiveness of HPV vaccination and cervical cancer screening strategies, because naturally acquired immunity after clearing an infection may already protect part of the risk population against new HPV infections.

Methods

We used STDSIM, an established stochastic microsimulation model, quantified to the Netherlands. We explored different assumptions regarding the natural history of HPV-16 and HPV-18, and estimated the transmission probabilities and durations of acquired immunity necessary to reproduce age-specific prevalence.

Results

A model without acquired immunity cannot reproduce the age-specific patterns of HPV. Also, it is necessary to assume a high degree of individual variation in the duration of infection and acquired immunity. According to the model estimates, on average 20% of women are immune for HPV-16 and 15% for HPV-18. After an HPV-16 infection, 50% are immune for less than 1 year, whereas 20% exceed 30 years. For HPV-18, up to 12% of the individuals are immune for less than 1 year, and about 50% over 30 years. Almost half of all women will never acquire HPV-16 or HPV-18.

Conclusions

Acquired immunity likely plays a major role in HPV epidemiology, but its duration shows substantial variation. Combined with the lifetime risk, this explains to a large extent why many women will never develop cervical cancer.

A longitudinal study of human papillomavirus 16 L1, e6, and e7 seropositivity and oral human papillomavirus 16 infection

BACKGROUND

Individuals with human papillomavirus (HPV) infections can develop IgG antibodies to HPV proteins including the L1 capsid and E6 and E7 oncoproteins. Evidence on whether L1 antibodies reduce the risk of cervical HPV infection is mixed, but this has not been explored for oral HPV infections. Antibodies to HPV16's E6 oncoprotein have been detected in some oropharyngeal cancer cases years before cancer diagnosis, but it is unknown if these antibodies are associated with oral HPV16 DNA.

METHODS

Enzyme-linked immunosorbent assays tested for serum antibodies to HPV16's L1 capsid in 463 HIV-infected and 293 HIV-uninfected adults, and for antibodies to recombinantly expressed E6 and E7 oncoproteins to HPV16 in 195 HIV-infected and 69 HIV-uninfected cancer-free participants at baseline. Oral rinse samples were collected semiannually for up to 3 years and tested for HPV DNA using PGMY 09/11 primers. Adjusted Poisson, logistic, and Wei-Lin-Weissfeld regression models were used.

RESULTS

Human papillomavirus 16 L1 seroreactivity did not reduce the subsequent risk of incident oral HPV16 infection in unadjusted (hazard ratio, 1.4; 95% confidence interval, 0.59-3.3) or adjusted (adjusted hazard ratio = 1.1; 95% confidence interval, 0.41-3.0) analysis. Antibodies to HPV16 E6 and E7 oncoproteins were detected in 7.6% and 3.4% of participants, respectively, but they were not associated with baseline oral HPV16 DNA prevalence or oral HPV16 persistence (each P > 0.40).

CONCLUSIONS

Naturally acquired HPV16 L1 antibodies did not reduce the risk of subsequent oral HPV16 infection. Human papillomavirus 16 E6 and E7 seropositivity was not a marker for oral HPV16 infection in this population without HPV-related cancer.

The age distribution of type-specific high-risk human papillomavirus incidence in two population-based screening trials

BACKGROUND

Age- and type-specific high-risk human papillomavirus (hrHPV) incidence estimates in screen-eligible women are relevant from a public health perspective because they provide an indication of the effect of vaccination on the occurrence of screen-positives in HPV-based screening. However, limited data from women over 25 years of age are available.

METHODS

In 24,105 hrHPV-negative women participating in Dutch (Population-Based Screening Study Amsterdam: POBASCAM) and Italian (New Technologies for Cervical Cancer: NTCC) population-based randomized controlled screening trials the age- and type-specific distribution of incident hrHPV infections detected at the next screening round was assessed. HPV types were grouped into vaccine (bivalent: HPV16/18; polyvalent HPV16/18/31/33/45/52/58) and nonvaccine types.

RESULTS

The incidence of screen-detected hrHPV among women ages 29 to 56 years was 2.54% (95% confidence interval, 2.30-2.78) in POBASCAM and 2.77% (2.36-3.19) in NTCC. In both studies, the incidence of bivalent, polyvalent, and nonpolyvalent infections decreased with age (P < 0.0001). Among women with incident infection(s), vaccine-type positivity changed quadratically with age, in particular for the polyvalent vaccine (P values: POBASCAM: bivalent 0.264, polyvalent 0.038; NTCC bivalent 0.039, polyvalent 0.005). However, more than 20% and 50% of women with incident hrHPV were positive for bivalent and polyvalent vaccine types, respectively, in all ages in both studies.

CONCLUSIONS

We observed decreasing age trends of hrHPV vaccine and nonvaccine type incidences and age-related differences in the vaccine-type positivity among women with incident infections. Most importantly, hrHPV infections continued to be detected in all ages and the contribution of vaccine types remained substantial.

IMPACT

Our results indicate a considerable reduction of new hrHPV infections in vaccinated cohorts, ensuing revision of screening guidelines.

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.