Analysis of cervical HPV infections among unvaccinated young adult women to inform vaccine strategies in this age group: the Costa Rica HPV Vaccine Trial

INTRODUCTION

Human papillomavirus (HPV) vaccines protect against incident HPV infections, which cause cervical cancer.

OBJECTIVES

We estimated the prevalence and incidence of HPV infections in young adult women to understand the impact of an HPV vaccination programme in this population.

METHODS

We collected cervical specimens from 6322 unvaccinated women, aged 18-37 years, who participated in the Costa Rica Vaccine Trial and its long-term follow-up. Women were followed for (median) 4.8 years and had (median) 4.0 study visits. Cervical specimens were tested for the presence/absence of 25 HPV genotypes. For each age band, we estimated the percentage of women with 1+ prevalent or 1+ incident HPV infections using generalised estimating equations. We also estimated the prevalence and incidence of HPV as a function of time since first sexual intercourse (FSI).

RESULTS

The model estimated HPV incident infections peaked at 28.0% (95% CI 25.3% to 30.9%) at age 20 years then steadily declined to 11.8% (95% CI 7.6% to 17.8%) at age 37 years. Incident oncogenic HPV infections (HPV16/18/31/33/35/39/45/51/52/56/58/59) peaked and then declined from 20.3% (95% CI 17.9% to 22.9%) to 7.7% (95% CI 4.4% to 13.1%); HPV16/18 declined from 6.4% (95% CI 5.1% to 8.1%) to 1.1% (95% CI 0.33% to 3.6%) and HPV31/33/45/52/58 declined from 11.0% (95% CI 9.3% to 13.1%) to 4.5% (95% CI 2.2% to 8.9%) over the same ages. The percentage of women with 1+ incident HPV of any, oncogenic, non-oncogenic and vaccine-preventable (HPV16/18, HPV31/33/45, HPV31/33/45/52/58, and HPV6/11) types peaked <1 year after FSI and steadily declined with increasing time since FSI (p for trends <0.001). We observed similar patterns for model estimated HPV prevalences.

CONCLUSION

Young adult women may benefit from HPV vaccination if newly acquired vaccine-preventable oncogenic infections lead to cervical precancer and cancer. HPV vaccination targeting this population may provide additional opportunities for primary prevention.

TRIAL REGISTRATION NUMBER

NCT00128661.

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.

Risk Factors for Non-Human Papillomavirus (HPV) Type 16/18 Cervical Infections and Associated Lesions Among HPV DNA-Negative Women Vaccinated Against HPV-16/18 in the Costa Rica Vaccine Trial

BACKGROUND

Factors that lead human papillomavirus (HPV) infections to persist and progress to cancer are not fully understood. We evaluated co-factors for acquisition, persistence, and progression of non-HPV-16/18 infections among HPV-vaccinated women.

METHODS

We analyzed 2153 women aged 18-25 years randomized to the HPV-vaccine arm of the Costa Rica HPV Vaccine Trial. Women were HPV DNA negative for all types at baseline and followed for approximately 11 years. Generalized estimating equation methods were used to account for correlated observations. Time-dependent factors evaluated were age, sexual behavior, marital status, hormonally related factors, number of full-term pregnancies (FTPs), smoking behavior, and baseline body mass index.

RESULTS

A total of 1777 incident oncogenic non-HPV-16/18 infections were detected in 12 292 visits (average, 0.14 infections/visit). Age and sexual behavior-related variables were associated with oncogenic non-HPV-16/18 acquisition. Twenty-six percent of incident infections persisted for ≥1 year. None of the factors evaluated were statistically associated with persistence of oncogenic non-HPV-16/18 infections. Risk of progression to Cervical Intraepithelial Neoplasia grade 2 or worst (CIN2+) increased with increasing age (P for trend = .001), injectable contraceptive use (relative risk, 2.61 [95% confidence interval, 1.19-5.73] ever vs never), and increasing FTPs (P for trend = .034).

CONCLUSIONS

In a cohort of HPV-16/18-vaccinated women, age and sexual behavior variables are associated with acquisition of oncogenic non-HPV-16/18 infections; no notable factors are associated with persistence of acquired infections; and age, parity, and hormonally related exposures are associated with progression to CIN2+.

Durability of Cross-Protection by Different Schedules of the Bivalent HPV Vaccine: The CVT Trial

BACKGROUND

The Costa Rica HPV Vaccine Trial has documented cross-protection of the bivalent HPV vaccine against HPV31/33/45 up to 7 years after vaccination, even with one dose of the vaccine. However, the durability of such protection remains unknown. Here, we evaluate the efficacy of different schedules of the vaccine against HPV31/33/45 out to 11 years postvaccination, expanding to other nontargeted HPV types.

METHODS

We compared the rates of HPV infection in vaccinated women with the rates in a comparable cohort of unvaccinated women. We estimated the average vaccine efficacy (VEavg) against incident infections and tested for a change in VE over time.

RESULTS

Among 3-dose women, we observed statistically significant cross-protection against HPV31/33/45 (VEavg = 64.4%, 95% confidence interval [CI] = 57.7% to 70.0%). Additionally, we observed borderline, statistically significant cross-protection against HPV35 (VEavg = 23.2%, 95% CI = 0.3% to 40.8%) and HPV58 (VEavg = 21.2%, 95% CI = 4.2% to 35.3%). There was no decrease in VE over time (two-sided Ptrend > .05 for HPV31, -33, -35, -45, and -58). As a benchmark, VEavg against HPV16/18 was 82.0% (95% CI = 77.3% to 85.7%). Among 1-dose women, we observed comparable efficacy against HPV31/33/45 (VEavg = 54.4%, 95% CI = 21.0% to 73.7%). Acquisition of nonprotected HPV types was similar between vaccinated and unvaccinated women, indicating that the difference in HPV infection rates was not attributable to differential genital HPV exposure.

CONCLUSIONS

Substantial cross-protection afforded by the bivalent vaccine against HPV31/33/45, and to a lesser extent, HPV35 and HPV58, was sustained and remained stable after 11 years postvaccination, reinforcing the notion that the bivalent vaccine is an effective option for protection against HPV-associated cancers.

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.

Evaluation of TypeSeq, a Novel High-Throughput, Low-Cost, Next-Generation Sequencing-Based Assay for Detection of 51 Human Papillomavirus Genotypes

BACKGROUND

Human papillomaviruses (HPV) cause over 500 000 cervical cancers each year, most of which occur in low-resource settings. Human papillomavirus genotyping is important to study natural history and vaccine efficacy. We evaluated TypeSeq, a novel, next-generation, sequencing-based assay that detects 51 HPV genotypes, in 2 large international epidemiologic studies.

METHODS

TypeSeq was evaluated in 2804 cervical specimens from the Study to Understand Cervical Cancer Endpoints and Early Determinants (SUCCEED) and in 2357 specimens from the Costa Rica Vaccine Trial (CVT). Positive agreement and risks of precancer for individual genotypes were calculated for TypeSeq in comparison to Linear Array (SUCCEED). In CVT, positive agreement and vaccine efficacy were calculated for TypeSeq and SPF10-LiPA.

RESULTS

We observed high overall and positive agreement for most genotypes between TypeSeq and Linear Array in SUCCEED and SPF10-LiPA in CVT. There was no significant difference in risk of precancer between TypeSeq and Linear Array in SUCCEED or in estimates of vaccine efficacy between TypeSeq and SPF10-LiPA in CVT.

CONCLUSIONS

The agreement of TypeSeq with Linear Array and SPF10-LiPA, 2 well established standards for HPV genotyping, demonstrates its high accuracy. TypeSeq provides high-throughput, affordable HPV genotyping for world-wide studies of cervical precancer risk and of HPV vaccine efficacy.

Evidence for single-dose protection by the bivalent HPV vaccine-Review of the Costa Rica HPV vaccine trial and future research studies

The Costa Rica Vaccine Trial (CVT), a phase III randomized clinical trial, provided the initial data that one dose of the HPV vaccine could provide durable protection against HPV infection. Although the study design was to administer all participants three doses of HPV or control vaccine, 20% of women did not receive the three-dose regimens, mostly due to involuntary reasons unrelated to vaccination. In 2011, we reported that a single dose of the bivalent HPV vaccine could be as efficacious as three doses of the vaccine using the endpoint of persistent HPV infection accumulated over the first four years of the trial; findings independently confirmed in the GSK-sponsored PATRICIA trial. Antibody levels after one dose, although lower than levels elicited by three doses, were 9-times higher than levels elicited by natural infection. Importantly, levels remained essentially constant over at least seven years, suggesting that the observed protection provided by a single dose might be durable. Much work has been done to assure these non-randomized findings are valid. Yet, the group of recipients who received one dose of the bivalent HPV vaccine in the CVT and PATRICIA trials was small and not randomly selected nor blinded to the number of doses received. The next phase of research is to conduct a formal randomized, controlled trial to evaluate the protection afforded by a single dose of HPV vaccine. Complementary studies are in progress to bridge our findings to other populations, and to further document the long-term durability of antibody response following a single dose.

The Natural History of Oral Human Papillomavirus in Young Costa Rican Women

BACKGROUND

Oral human papillomavirus (HPV) infection and related oropharyngeal cancer are uncommon in lower-income countries, particularly compared to HPV-associated cervical cancer. However, little is known about the natural history of oral HPV in less-developed settings and how it compares to the natural history of cervical HPV.

METHODS

Three hundred fifty women aged 22 to 33 years from the Costa Rica Vaccine Trial provided exfoliated cells from the cervical and oral regions at 2 visits 2 years apart. Samples from both visits were tested for 25 characterized α HPV types by the SPF10 PCR-DNA enzyme immunoassay-LiPA25 version 1 system. Risk factors for oral HPV persistence were calculated utilizing generalized estimating equations with a logistic link.

RESULTS

Among the 82 women with characterized α oral HPV DNA detected at baseline, 14 persisted and were detected 2 years later (17.6%; 95% confidence interval [CI], 10.9-28.5%) and was similar to the persistence of α cervical HPV (40/223; 17.7%; 95% CI, 13.1-23.9%; P = 0.86). Acquisition of new α oral HPV type was low; incident infection (1.7%; 95% CI, 0.6-3.7%).

CONCLUSIONS

Oral HPV DNA is uncommon in young women in Latin America, and often appears to clear within a few years at similar rates to cervical HPV.

Quantitative Detection and Genotyping of Helicobacter pylori from Stool using Droplet Digital PCR Reveals Variation in Bacterial Loads that Correlates with cagA Virulence Gene Carriage

BACKGROUND

Epidemiologic studies of the carcinogenic stomach bacterium Helicobacter pylori have been limited by the lack of noninvasive detection and genotyping methods. We developed a new stool-based method for detection, quantification, and partial genotyping of H. pylori using droplet digital PCR (ddPCR), which allows for increased sensitivity and absolute quantification by PCR partitioning.

MATERIALS AND METHODS

Stool-based ddPCR assays for H. pylori 16S gene detection and cagA virulence gene typing were tested using a collection of 50 matched stool and serum samples from Costa Rican volunteers and 29 H. pylori stool antigen-tested stool samples collected at a US hospital.

RESULTS

The stool-based H. pylori 16S ddPCR assay had a sensitivity of 84% and 100% and a specificity of 100% and 71% compared to serology and stool antigen tests, respectively. The stool-based cagA genotyping assay detected cagA in 22 (88%) of 25 stools from CagA antibody-positive individuals and four (16%) of 25 stools from CagA antibody-negative individuals from Costa Rica. All 26 of these samples had a Western-type cagA allele. Presence of serum CagA antibodies was correlated with a significantly higher load of H. pylori in the stool.

CONCLUSIONS

The stool-based ddPCR assays are a sensitive, noninvasive method for detection, quantification, and partial genotyping of H. pylori. The quantitative nature of ddPCR-based H. pylori detection revealed significant variation in bacterial load among individuals that correlates with presence of the cagA virulence gene. These stool-based ddPCR assays will facilitate future population-based epidemiologic studies of this important human pathogen.

Rationale and design of a long term follow-up study of women who did and did not receive HPV 16/18 vaccination in Guanacaste, Costa Rica

The Costa Rica Vaccine Trial (CVT) was a randomized clinical trial conducted between 2004 and 2010, which randomized 7466 women aged 18 to 25 to receive the bivalent HPV-16/18 vaccine or control Hepatitis-A vaccine. Participants were followed for 4 years with cross-over vaccination at the study end. In 2010 the long term follow-up (LTFU) study was initiated to evaluate the 10-year impact of HPV-16/18 vaccination, determinants of the immune response, and HPV natural history in a vaccinated population. Herein, the rationale, design and methods of the LTFU study are described, which actively follows CVT participants in the HPV-arm 6 additional years at biennial intervals (3 additional study visits for 10 years of total follow-up), or more often if clinically indicated. According to the initial commitment, women in the Hepatitis-A arm were offered HPV vaccination at cross-over; they were followed 2 additional years and exited from the study. 92% of eligible CVT women accepted participation in LTFU. To provide underlying rates of HPV acquisition and cervical disease among unvaccinated women to compare with the HPV-arm during LTFU, a new unvaccinated control group (UCG) of women who are beyond the age generally recommended for routine vaccination was enrolled, and will be followed by cervical cancer screening over 6 years. To form the UCG, 5000 women were selected from a local census, of whom 2836 women (61% of eligible women) agreed to participate. Over 90% of participants complied with an interview, blood and cervical specimen collection. Evaluation of comparability between the original (Hepatitis-A arm of CVT) and new (UCG) control groups showed that women's characteristics, as well as their predicted future risk for cervical HPV acquisition, were similar, thus validating use of the UCG. LTFU is poised to comprehensively address many important questions related to long-term effects of prophylactic HPV vaccines.

Influence of feeding status, time of the day, and season on baseline adrenocorticotropic hormone and the response to thyrotropin releasing hormone-stimulation test in healthy horses

Equine pituitary pars intermedia function can be assessed by the measurement of baseline and thyrotropin releasing hormone (TRH)-induced concentrations of adrenocorticotropic hormone (ACTH); however, these measurements may be affected by the environment. Therefore, a prospective observational study evaluated the influence of feeding, time of the day, and season on baseline and TRH-induced concentrations of ACTH in healthy horses. Baseline ACTH was measured in 50 horses before and 2 h after feeding. Six research horses were subjected to a crossover study in which 6 TRH tests were performed in 2 different seasons, March-April (MA) and July-September (JS), at 2 different times of the day, 8 AM and 8 PM, and, under 2 different conditions relative to feeding status, fasted and 2 h after feeding. Differences between fasted and fed horses were found in baseline ACTH, 17.1 ± 1.8 versus 46.1 ± 7.6 pg/mL (P = 0.003) and TRH-stimulated ACTH: 124.1 ± 21.3 versus 192.6 ± 33.1 pg/mL (P = 0.029) at 10 min, and 40.1 ± 4.9 versus 73.2 ± 13.4 pg/mL (P = 0.018) at 30 min post TRH injection. No differences were found between tests performed at different times of the day. Basal ACTH concentrations were greater in JS than in MA, 17.1 ± 1.8 versus 11.9 ± 0.6 pg/mL (P = 0.006). A seasonal influence was also found in stimulated ACTH values, which were much greater in JS 122.7 ± 36.7 versus 31.2 ± 7.4 pg/mL, at 10 min (P = 0.03) and 39.0 ± 7.2 versus 19.8 ± 3.1 pg/mL, at 30 min (P = 0.03). In addition to season, feeding is a potential confounding factor when measuring baseline or stimulated ACTH in horses. In conclusion, feeding status should be standardized for the diagnosis of equine pituitary pars intermedia dysfunction.

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.

Evaluation of the FTA carrier device for human papillomavirus testing in developing countries

Liquid-based methods for the collection, transportation, and storage of cervical cells are cumbersome and expensive and involve laborious DNA extraction. An FTA cartridge is a solid carrier device, easier to handle and allowing simple DNA elution for human papillomavirus (HPV) testing. HPV-DNA results from cervical specimens collected in PreservCyt medium (Hologic, Inc.) and the indicating FTA elute cartridge were compared in an area where transportation and storage may affect the performance of the test. Cervical cells from 319 young adult women enrolled in the Costa Rica Vaccine Trial were collected by a nurse using a Cervex brush (Roberts), which was placed on the FTA cartridge and subsequently rinsed in 20 ml of PreservCyt medium. Two 0.5-ml PreservCyt aliquots were frozen for HPV-PCR testing; the FTA cartridges were kept at room temperature. HPV-DNA detection and typing was performed using SPF(10) PCR/DEIA (DNA enzyme immunoassay detection of amplimers)/LiPA(25) system. The percent agreement, agreement among positives, and kappas were estimated. Positivity was higher for FTA compared to PreservCyt specimens (54.5% versus 45.8%, P < 0.001). For oncogenic types, the overall agreement was 0.92, the agreement between positives was 0.74, and the kappa was 0.79. For individual HPV types, the overall agreement ranged from 0.97 to 1.00. We did not observe reduced cytology adequacy when specimen collection for cytology was preceded by FTA collection for HPV testing. HPV-DNA detection from FTA cartridges is broadly comparable to detection from PC medium. The higher HPV detection observed for FTA-collected specimens should be explored further. FTA cartridges could provide a simpler and more cost-effective method for cervical cell collection, storage, and transportation for HPV-DNA detection in research settings in developing countries.

Body mass interacts with fat quality to determine the postprandial lipoprotein response in healthy young adults

BACKGROUND AND AIMS

Postprandial lipemia predicts the evolution of cardiovascular disease. Obesity is associated with an increase in the magnitude of postprandial lipemia. Our objective was to evaluate the influence of body mass index (BMI) on the effects of acute ingestion of different types of fat on the postprandial lipemic response.

METHODS AND RESULTS

Twenty-one healthy men followed a 4-week baseline diet and then consumed three fat-loaded meals that included 1g fat/kg body wt (65%fat) according to a randomized crossover design. The compositions of the three meals were olive oil meal (22% saturated fatty acids (SFA), 38% monounsaturated fatty acids (MUFA), 4% polyunsaturated fatty acids (PUFA)); butter meal (35% SFA, 22% MUFA, 4% PUFA); walnuts meal (20% SFA, 24% MUFA, 16% PUFA, and 4% α-linolenic acid). Higher-weight (HW) subjects (BMI greater than the median 26.18 kg/m(2), n = 11) presented higher incremental area under the curve (iAUC) for triglycerides (TG), both in large- and small-TG rich lipoproteins (TRL) than lower-weight (LW) subjects (BMI<26.18 kg/m(2), n = 10) (p<0.05), and a similar trend for plasma TG (p = 0.084). Moreover, HW subjects presented higher concentrations for small TRL-cholesterol and small TRL-TG in different timepoints of the postprandial lipemia after the intake of enriched walnuts or butter meals compared with the olive oil-enriched meal (p < 0.05) No significant differences were observed between the three types of meals in the postprandial response of LW subjects.

CONCLUSION

HW subjects present a greater postprandial response than LW subjects, and they benefit from the consumption of monounsaturated fatty acids from olive oil, to lower their levels of TRL particles during the postprandial state.