No excess risk of cervical carcinoma among women seropositive for both HPV16 and HPV6/11

The cervical microbiota of Hispanics living in Puerto Rico is nonoptimal regardless of HPV status

The cervicovaginal microbiota is influenced by host physiology, immunology, lifestyle, and ethnicity. We hypothesized that there would be differences in the cervicovaginal microbiota among pregnant, nonpregnant, and menopausal women living in Puerto Rico (PR) with and without human papillomavirus (HPV) infection and cervical cancer. We specifically wanted to determine if the microbiota is associated with variations in cervical cytology. A total of 294 women, including reproductive-age nonpregnant (N = 196), pregnant (N = 37), and menopausal (N = 61) women, were enrolled. The cervicovaginal bacteria were characterized by 16S rRNA amplicon sequencing, the HPV was genotyped with SPF10-LiPA, and cervical cytology was quantified. High-risk HPV (HR-HPV, 67.3%) was prevalent, including genotypes not covered by the 9vt HPV vaccine. Cervical lesions (34%) were also common. The cervical microbiota was dominated by Lactobacillus iners. Pregnant women in the second and third trimesters exhibited a decrease in diversity and abundance of microbes associated with bacterial vaginosis. Women in menopause had greater alpha diversity, a greater proportion of facultative and strictly anaerobic bacteria, and higher cervicovaginal pH than premenopausal women. Cervical lesions were associated with greater alpha diversity. However, no significant associations between the microbiota and HPV infection (HR or LR-HPV types) were found. The cervicovaginal microbiota of women living in Puerto Rican were either dominated by L. iners or diverse microbial communities regardless of a woman's physiological stage. We postulate that the microbiota and the high prevalence of HR-HPV increase the risk of cervical lesions among women living in PR. IMPORTANCE In the enclosed manuscript, we provide the first in-depth characterization of the cervicovaginal microbiota of Hispanic women living in Puerto Rico (PR), using a 16S rRNA approach, and include women of different physiological stages. Surprisingly we found that high-risk HPV was ubiquitous with a prevalence of 67.3%, including types not covered by the 9vt HPV vaccine. We also found highly diverse microbial communities across women groups-with a reduction in pregnant women, but dominated by nonoptimal Lactobacillus iners. Additionally, we found vaginosis-associated bacteria as Dialister spp., Gardnerella spp., Clostridium, or Prevotella among most women. We believe this is a relevant and timely article expanding knowledge on the cervicovaginal microbiome of PR women, where we postulate that these highly diverse communities are conducive to cervical disease.

Relative distribution of HPV genotypes in histological cervical samples and associated grade lesion in a women population over the last 16 years in Burgundy, France

Human papillomavirus is a predominant sexually transmitted viral pathogen. Our objective was to analyze the relative distribution of genotypes over time and to determine the genotypes associated with adverse clinical lesions. The study was based on data from adult women with cytological abnormalities from whom histological samples were obtained from 2005 to 2021. HPV genotyping was performed using PCR and INNO-LiPA assay (Fujirebio). Among the 1,017 HPV-positive biopsies, 732 (72%) were infected with a single HPV genotype and 285 (28%) were infected with several HPV genotypes. Most of the infections involved the high-risk genotypes 16, 31, and 52. Throughout the study period, HPV 16 was the most encountered genotype (541, 53.2%), while HPV 18 was rather under-represented (46, 4.5%), especially in invasive cervical carcinoma. HVP52 (165, 16.2%) was detected mainly from 2008 to 2014, and its distribution reached 19.7% in 2011. Such epidemiological data underlines the possibility of an emergence of a high-risk genotype. The most detected low-risk HPV in combination with high-risk HPV was HPV 54 in 6.5% of samples. Monoinfection by HPV 16 led statistically more often to severe lesions than multi-infection involving HPV 16 (p < 0.001), while for HPV 52, 31 or 33, multi-infections were significantly associated with severe lesions (p < 0.001 for each of these three genotypes). HPV 16 was involved in 55.2% of high-grade lesions and in situ carcinoma and 76.3% of invasive carcinomas. In severe lesions, HPV 16 participation was predominant, whereas diverse genotypes were seen in low-grade lesions. Importantly, we observed that high-risk genotypes, for example HPV 52, can emerge for a few years then decrease even without vaccine pressure.

Quantifying the Effects of Medical Examination and Possible Risk Factors against the Incidence of Cervical Cancer in a Low Human Papillomavirus Vaccination Coverage: An Ecological Study in Japan

Cervical cancer (CC) is one of the most common gynecological malignancies in females, mainly caused by human papillomavirus (HPV). In countries with lower HPV vaccine coverage, such as Japan, medical examination may play a key role in decreasing CC incidence. This study aimed to quantify the effect of medical examination on cervical cancer (CC) incidence in Japan, considering the effects of possible risk factors. By collecting Japan's Prefectural data on CC incidence (2013-2017), incidence of sexually transmitted diseases (STDs; Chlamydia, Herpes, Condyloma, and Gonorrhea; 1993-2012), screening and detailed examination rate against CC (2013-2016), smoking rate (2001-2013), economic status (disposable income and economic surplus; 2014-2015), and education status (2015), we analyzed associations among them using Pearson's correlation coefficients. Additionally, assuming that the incidence of STDs reflects the frequency of risky sexual behavior at the co-infection point with HPV, we constructed generalized linear models to predict CC incidence, taking a 5-20-year time-lag between incidences of STDs and the CC incidence. Against CC incidence, Chlamydia in females and Gonorrhea in males with a 15-year time-lag showed positive associations, while Condyloma in both genders with a 15-year time-lag, screening rate, economic status, and smoking rate showed negative associations. An increase in screening test rate by 10% was estimated to decrease CC incidence by 9.6%. This means that screening tests decrease CC incidence effectively, but not drastically, suggesting the need for additional countermeasures for CC prevention.

Human papillomavirus co-infection and survival in oral and oropharyngeal squamous cell carcinoma: A study in 235 Brazilian patients

OBJECTIVES

While unknown for oropharyngeal squamous cell carcinoma (OPSCC) and oral squamous cell carcinoma (OSCC), some studies assessing cervical carcinoma have shown that human papillomavirus (HPV) co-infection can be associated with its prognosis.

METHODS

Through in situ hybridization (HPV and Epstein-Barr virus [EBV] probes) and immunohistochemistry (p16^INK4a, cyclin D1, p53, and Ki-67 antibodies), 126 OPSCC and 109 OSCC samples were assessed.

RESULTS

All patients were EBV-negative. OPSCC (25%) showed a significant association with HPV compared to OSCC (11%). Almost all HPV-associated cases were p16^INK4a-positive. Regarding OPSCC and OSCC, 23 and 7 cases were positive for high-risk HPV (HRHPV) only, 6 and 3 cases for low-risk HPV (LRHPV) only, and 3 and 2 cases for HRHPV/LRHPV, respectively. HPV-associated carcinomas showed a significantly higher proliferative index than HPV-unassociated carcinomas. Both carcinomas showed a similar overall survival rate, which was not affected by the HPV status. However, when comparing HPV-associated subgroups, patients with HRHPV/LRHPV-associated carcinomas showed worse survival.

CONCLUSION

LRHPV-associated and HRHPV/LRHPV-associated cases can also be detected when assessing OSCC and OPSCC. Further studies, especially in populations with a high prevalence of HPV-associated OPSCC, are necessary to understand the clinicopathological behavior of these neoplasm subgroups.

Potential Effects of Human Papillomavirus Type Substitution, Superinfection Exclusion and Latency on the Efficacy of the Current L1 Prophylactic Vaccines

There are >200 different types of human papilloma virus (HPV) of which >51 infect genital epithelium, with ~14 of these classed as high-risk being more commonly associated with cervical cancer. During development of the disease, high-risk types have an increased tendency to develop a truncated non-replicative life cycle, whereas low-risk, non-cancer-associated HPV types are either asymptomatic or cause benign lesions completing their full replicative life cycle. HPVs can also be present as non-replicative so-called “latent” infections and they can also show superinfection exclusion, where cells with pre-existing infections with one type cannot be infected with a different HPV type. Thus, the HPV repertoire and replication status present in an individual can form a complex dynamic meta-community which changes with respect to both time and exposure to different HPV types. In light of these considerations, it is not clear how current prophylactic HPV vaccines will affect this system and the potential for iatrogenic outcomes is discussed in light of recent outcome data.

Distinct geographic clustering of oncogenic human papillomaviruses multiple infections in cervical cancers: Results from a worldwide cross-sectional study

Coinfections by multiple Human Papillomaviruses (HPVs) are observed in approximately 6-8% of invasive cervical cancer (ICC) cases worldwide. But neither the presence of persistent HPVs coinfections nor their etiological role in the development of ICC is well understood. Cervical HPVs coinfections have been observed randomly, mostly in women with preneoplastic lesions, and only few studies have globally analyzed ICC cases. Here we explored the HPVs multiple infection patterns in a large worldwide sample of cross-sectional ICC cases. Paraffin-embedded ICC biopsy samples were tested using stringent HPV genotyping. Logistic regression models were used to identify the most likely pairwise HPV types in multiple infections. Multivariate analysis was applied to detect significant HPV coinfection patterns beyond pairwise HPVs comparison. Among 8780 HPV DNA-positive ICC cases worldwide, 6.7% (N = 587) contained multiple HPVs. Pairwise analysis revealed that HPV16|74, HPV31|33, HPV31|44, HPV33|44 and HPV45|70 pairs were significantly more frequently found together in multiple infections compared to any other HPV type combination, which supports the occasional role of Alpha-10 LR-HPVs in cervical cancers. In contrast, HPV16|31, HPV16|45, HPV16|51 and HPV18|HPV45 pairs were significantly less frequently found together than with any other HPV pair combination. Multivariate analysis sustained the results and revealed for the first time a distinct coinfection pattern in African ICCs stemming from the clustering of oncogenic HPV51/35/18/52 coinfections in African women. We suggest that the differential geographic HPVs coinfections clustering observed might be compatible with a specific modulation of the natural history/oncogenic potential of particular HPVs multiple infections and warrant monitoring for post-vaccinated.

Cervicovaginal Fungi and Bacteria Associated With Cervical Intraepithelial Neoplasia and High-Risk Human Papillomavirus Infections in a Hispanic Population

The human cervicovaginal microbiota resides at an interface between the host and the environment and may affect susceptibility to disease. Puerto Rican women have high human papillomavirus (HPV) infection and cervical cancer rates. We hypothesized that the population structure of the cervicovaginal bacterial and fungal biota changed with cervical squamous intraepithelial lesions and HPV infections. DNA was extracted from cervix, introitus, and anal sites of 62 patients attending high-risk San Juan clinics. The 16S rRNA V4 region and ITS-2 fungal regions were amplified and sequenced using Illumina technology. HPV genotyping was determined by reverse hybridization with the HPV SPF10-LiPA25 kit. HPV prevalence was 84% of which ∼44% subjects were infected with high-risk HPV, ∼35% were co-infected with as many as 9 HPV types and ∼5% were infected with exclusively low-risk HPV types. HPV diversity did not change with cervical dysplasia. Cervical bacteria were more diverse in patients with CIN3 pre-cancerous lesions. We found enrichment of Atopobium vaginae and Gardnerella vaginalis in patients with CIN3 lesions. We found no significant bacterial biomarkers associated with HPV infections. Fungal diversity was significantly higher in cervical samples with high-risk HPV and introitus samples of patients with Atypical Squamous Cells of Undetermined Significance (ASCUS). Fungal biomarker signatures for vagina and cervix include Sporidiobolaceae and Sacharomyces for ASCUS, and Malassezia for high-risk HPV infections. Our combined data suggests that specific cervicovaginal bacterial and fungal populations are related to the host epithelial microenvironment, and could play roles in cervical dysplasia.

Do Infection Patterns of Human Papillomavirus Affect the Cytologic Detection of High-Grade Cervical Lesions on Papanicolaou Tests?

Context.—

Persistent infection with high-risk human papillomavirus (hrHPV) is the major cause of cervical cancer. The effect of HPV infection patterns on cytologic detection of cervical lesions is unknown.

Objective.—

To determine the effect of HPV infection patterns on the sensitivity of cytologic detection of high-grade cervical lesions.

Design.—

Papanicolaou tests from 257 women with biopsy-confirmed, high-grade squamous intraepithelial lesions were analyzed with respect to HPV infection patterns.

Results.—

Among 257 biopsy-confirmed, high-grade squamous intraepithelial lesion cases, the preceding cytology showed 20 cases (8%) were benign; 166 cases (65%) were low-grade cervical lesions, including atypical squamous cell of undetermined significance and low-grade squamous intraepithelial lesions; and 71 cases (28%) were high-grade cervical lesions, including atypical squamous cells cannot rule out high-grade squamous intraepithelial lesion (atypical squamous cell–high), atypical glandular cells, and high-grade squamous intraepithelial lesions. In 236 cases tested for HPV, those exhibiting low-grade cervical lesions on cytology were often associated with coinfections of mixed hrHPV genotypes (31 of 40; 78%) or non-16/18 hrHPV (75/103; 73%), compared with single-genotype infections of HPV-16 (33 of 62; 53%) or HPV-18 (2 of 6; 33%) (P = .001). In contrast, high-grade cervical lesion cytomorphology tended to associate with the single-genotype infection of HPV-16 (20 of 62; 32%) or HPV-18 (3 of 6; 50%), compared with non-16/18 hrHPV (25 of 103; 24%) or multigenotype infection (8 of 40; 20%) (P = .01).

Conclusions.—

Our findings suggest that multigenotypic or non-16/18 hrHPV infections often produce deceptive lower-grade cytomorphology, which could result in underdiagnosis and delay of treatment. The HPV infection patterns may offer unrecognized benefit beyond HPV genotyping and should be considered during clinical risk evaluation of women with lower-grade cytology.

HPV genotypes co-infections associated with cervical carcinoma: Special focus on phylogenetically related and non-vaccine targeted genotypes

HPV is the major causative agent for cervical cancer. Study on the risk of cervical cancer associated with different hr-HPV genotypes would be useful for disease management and new vaccine strategy. With limited reports available, the present study aimed to investigate the pattern of HPV genotypes coinfections and risk of cervical carcinoma associated with them in Indian population. 15 HPV genotypes were detected by E6/E7 multiplex nested type-specific PCR in the HPV-positive cervical samples of 172 cervical cancer cases and 174 subjects with normal cytology. Association between the genotypes and cervical cancer was estimated by calculating the Odds ratio and 95% confidence interval. Risk of cervical carcinoma was associated with multiple genotypes excluding HPV16 (OR:5.87; 95% CI-1.28-26-29; p = .02), multiple genotypes excluding HPV18 (OR = 2.5; 95% CI = 1.09–6.05; p = .03), multiple genotypes of α9 species(OR = 5.3 95% CI = 1.14–24.03; p = .007), and multiple genotypes of α7 species (OR = 2.5; 95% CI = .49–13.45; p = .2). Genotypes not targeted by quadrivalent vaccine types (OR = 2.94 95% CI = 1.48–5.80; p = .001) conferred 2.94 fold higher risk of cervical carcinoma. Cases those coinfected with phylogenetically related genotypes (OR = 2.29; 95% CI(.69–7.59) p = .17) were at 2.9 fold higher risk of invasive cervical carcinoma than those infected with other genotypes although it is not statistically significant. Whereas phylogenetically unrelated genotypes coinfection is negatively associated with cervical carcinoma (OR = .44 95% CI (.244-.8) p = .007) and it is statistically significant.Genotypes not targeted by 9-valent vaccines (OR = .40; 95% CI = .19-.85; p = .017) associated with lesser risk of cervical carcinoma as compared to other genotypes. Subjects infected with any HPV genotype/genotypes excluding HPV16 in association with HPV 18 (OR = 4.1; 95% CI = 1.81–9.25 P = < .001) were at 4.1 fold higher risk of developing invasive cervical carcinoma.In conclusion, the risk of development of cervical cancer is genotype specific and might be associated with type-specific interactions between the genotypes in multiple infections.

High prevalence of co-infection between human papillomavirus (HPV) 51 and 52 in Mexican population

Background

Human papillomavirus (HPV) is associated with the genesis of cervical carcinoma. The co-infection among HPV genotypes is frequent, but the clinical significance is controversial; in Mexico, the prevalence and pattern of co-infection differ depending on the geographic area of study. We analyzed the mono- and co-infection prevalence of multiple HPV genotypes, as well as preferential interactions among them in a Mexico City sample population.

Methods

This study was designed as a retrospective cohort study. Cervical cytology samples from 1163 women and 166 urethral scraping samples of men were analyzed between 2010 and 2012. The detection of HPV infection was performed using the hybrid capture and the genotyping was by PCR (HPV 6, 11, 16, 18, 30, 31, 33, 35, 45, 51, and 52).

Results

36% of women were HPV-positive and the most prevalent genotypes were HPV 51, 52, 16, and 33 (42, 38, 37, and 34%, respectively). The prevalence of co-infection was higher (75.37%) than mono-infection in women HPV positives. All genotypes were co-infected with HPV 16, but the co-infection with 51–52 genotypes was the most frequent combination in all cases.

Conclusion

The co-infection was very common; each HPV genotype showed different preferences for co-infection with other genotypes, HPV 51–52 co-infection was the most frequent. The HPV 16, 33, 51 and 52 were the most prevalent and are a public health concern to the Mexican population.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-017-3519-7) contains supplementary material, which is available to authorized users.

Multiple Human Papilloma Virus Infections and Their Impact on the Development of High-Risk Cervical Lesions

OBJECTIVE

Individuals are often infected with multiple genotypes of human papillomavirus (HPV) simultaneously, but the role these infections play in the development of cervical disease is not well established. This study aimed to determine the association of multiple HPV infections with high-risk cervical lesions (hrCLs).

STUDY DESIGN

HPV genotyping was performed on 798 SurePath specimens collected between December 1, 2009, and April 30, 2011. The cases were classified as hrCL (n = 90) or non-hrCL (n = 708) based on cytology diagnoses. The association between hrCL and HPV infection patterns was analyzed.

RESULTS

Multiple HPV infections were frequently encountered (38.2%) in the cohort. Increased frequency of hrCLs was associated with a single high-risk HPV (hrHPV) infection. An additive or synergistic effect was not observed for hrCL in multiple HPV infections. The hrCL rates appeared to decrease in various patterns of multiple HPV infections, but the reduction was not statistically significant.

CONCLUSIONS

Multiple HPV infections are common with no additive or synergistic effect on the development of hrCL. Conversely, reduced hrCL rates were observed in various patterns of multiple HPV infections compared to their single-genotype infection counterparts, suggestive of possible intergenotypic competition or more effective immune response triggered by multiple infections. Further studies in larger cohorts are needed.

Interactions Between High- and Low-Risk HPV Types Reduce the Risk of Squamous Cervical Cancer

BACKGROUND

The clinical significance of co-infections with high-risk (HR) and low-risk (LR) human papillomavirus (HPV) in the etiology of cervical cancer is debated, as prospective evidence on this issue is limited. However, the question is of increasing relevance in relation to HPV-based cancer prevention.

METHODS

In two population-based nested case-control studies among women participating in cervical screening with baseline normal smears, we collected 4659 smears from women who later developed cancer in situ (CIS; n = 524) or squamous cervical cancer (SCC; n = 378) and individually matched control subjects who remained free of disease during study follow-up. The median follow-up until diagnosis was 6.4 to 7.8 years. All smears were tested for HPV. We used conditional logistic regression models with two-way interaction terms to estimate relative risks (RRs) for CIS and SCC, respectively. All statistical tests were two-sided.

RESULTS

Compared with women who were infected with HRHPV only, women who were also infected with LRHPV had a lower risk for SCC (RR = 0.2, 95% confidence interval [CI] = 0.04 to 0.99, P = .049). This interaction was not shown for CIS (RR = 1.1, 95% CI = 0.4 to 3.6). Women who were positive for both HRHPV and LRHPV had, on average, a 4.8 year longer time to diagnosis of SCC than women who were positive for HRHPV only (P = .006). Results were highly robust in sensitivity analyses.

CONCLUSION

Co-infection with LRHPV is associated with a lower risk of future invasive disease and longer time to diagnosis than infection with HRHPV alone. We propose that co-infection with LRHPV interferes with the rate of progression to invasive cervical cancer.

Concurrence of multiple human papillomavirus infections in a large US population-based cohort

We examined the concurrence of multiple human papillomavirus (HPV) infections in 47,617 women who underwent cervical screening in New Mexico between December 2007 and April 2009 using the LINEAR ARRAY HPV Genotyping Test (Roche Diagnostics, Indianapolis, Indiana), which detects 37 different types of HPV. Our primary goal was to examine the distributions of multiple HPV types with a special interest in negative interactions, which could signal the possibility of type replacement associated with a common niche if some HPV types were prevented by vaccination. Multiple infections were found to be more common than expected under independence, but this could largely be accounted for by a woman-specific latent heterogeneity parameter which was found to be dependent on age and cytological grade. While multiple infections were more common in young women and in those with abnormal cytology, greater heterogeneity was seen in older women and in those with normal cytology, possibly reflecting greater variability in exposure due to current or past HPV exposure or due to heterogeneity in related HPV reactivation or in immune responses to HPV infection or persistence. A negative interaction was found between HPV 16 and several other HPV types for women with abnormal cytology but not for those with normal cytology, suggesting that type replacement in women vaccinated against HPV 16 is unlikely to be an issue for the general population.

Multiple human papillomavirus infection with or without type 16 and risk of cervical intraepithelial neoplasia among women with cervical cytological abnormalities

PURPOSE

To evaluate the impact of multiple human papillomavirus (HPV) infections on the risk of cervical intraepithelial neoplasia grade 3 or worse (CIN3+) in subjects with cervical cytological abnormalities.

METHODS

A cross-sectional study of 3,842 women attending a colposcopy service was carried out. Genotyping of 18 high-risk, seven low-risk, and two undefined-risk HPVs was carried out by the INNO-LiPA genotyping system.

RESULTS

The final colposcopic/pathological diagnoses were as follows: 1,933 (50.3 %) subjects were negative; 1,041 (27.1 %) CIN1; 280 (7.3 %) CIN2; 520 (13.5 %) CIN3; and 68 (1.8 %) invasive cervical cancer. The prevalence of HPV infection was 75.8 % (2,911/3,842), whereas multiple HPVs were detected in 34.5 % of HPV-positive subjects (2,255/3,842). The adjusted risks of CIN3+ in the group with multiple compared to the group with single infection were 2.31 (95 % CI = 1.54-3.47), among HPV16-positive women, and 3.25 (95 % CI = 2.29-4.61, p = 0.21 compared with HPV16-positive subjects), in HPV16-negative subjects. Out of a total of 1,285 subjects with mild lesions, followed up for a median of 16.1 months (interquartile range = 8.9-36.8), the rate of progression to CIN2-3 was 0.6 % (5/541) among subjects negative or with low-risk HPVs, 1.7 % (8/463) among those with single high-risk HPV, and 5 % (14/281, p < 0.001 compared with HPV-negative/low-risk HPV and p = 0.038 compared with single high-risk HPV) among those with multiple high-risk HPVs.

CONCLUSIONS

Among women with cervical cytological abnormalities, infection by multiple high-risk HPVs increased the risk of CIN3+ in both HPV16-positive and HPV16-negative subjects. These findings suggest a potential synergistic interaction between high-risk HPVs, favoring the progression of CIN lesions.

Coxsackievirus B1 is associated with induction of β-cell autoimmunity that portends type 1 diabetes

The rapidly increasing incidence of type 1 diabetes implies that environmental factors are involved in the pathogenesis. Enteroviruses are among the suspected environmental triggers of the disease, and the interest in exploring the possibilities to develop vaccines against these viruses has increased. Our objective was to identify enterovirus serotypes that could be involved in the initiation of the disease process by screening neutralizing antibodies against 41 different enterovirus types in a unique longitudinal sample series from a large prospective birth-cohort study. The study participants comprised 183 case children testing persistently positive for at least two diabetes-predictive autoantibodies and 366 autoantibody-negative matched control children. Coxsackievirus B1 was associated with an increased risk of β-cell autoimmunity. This risk was strongest when infection occurred a few months before autoantibodies appeared and was attenuated by the presence of maternal antibodies against the virus. Two other coxsackieviruses, B3 and B6, were associated with a reduced risk, with an interaction pattern, suggesting immunological cross-protection against coxsackievirus B1. These results support previous observations suggesting that the group B coxsackieviruses are associated with the risk of type 1 diabetes. The clustering of the risk and protective viruses to this narrow phylogenetic lineage supports the biological plausibility of this phenomenon.

Replication interference between human papillomavirus types 16 and 18 mediated by heterologous E1 helicases

Background

Co-infection of multiple genotypes of human papillomavirus (HPV) is commonly observed among women with abnormal cervical cytology, but how different HPVs interact with each other in the same cell is not clearly understood. A previous study using cultured keratinocytes revealed that genome replication of one HPV type is inhibited by co-existence of the genome of another HPV type, suggesting that replication interference occurs between different HPV types when co-infected; however, molecular mechanisms underlying inter-type replication interference have not been fully explored.

Methods

Replication interference between two most prevalent HPV types, HPV16 and HPV18, was examined in HPV-negative C33A cervical carcinoma cells co-transfected with genomes of HPV16 and HPV18 together with expression plasmids for E1/E2 of both types. Levels of HPV16/18 genome replication were measured by quantitative real-time PCR. Physical interaction between HPV16/18 E1s was assessed by co-immunoprecipitation assays in the cell lysates.

Results

The replication of HPV16 and HPV18 genomes was suppressed by co-expression of E1/E2 of heterologous types. The interference was mediated by the heterologous E1, but not E2. The oligomerization domain of HPV16 E1 was essential for HPV18 replication inhibition, whereas the helicase domain was dispensable. HPV16 E1 co-precipitated with HPV18 E1 in the cell lysates, and an HPV16 E1 mutant Y379A, which bound to HPV18 E1 less efficiently, failed to inhibit HPV18 replication.

Conclusions

Co-infection of a single cell with both HPV16 and HPV18 results in replication interference between them, and physical interaction between the heterologous E1s is responsible for the interference. Heterooligomers composed of HPV16/18 E1s may lack the ability to support HPV genome replication.

Potential impact of combined high- and low-risk human papillomavirus infection on the progression of cervical intraepithelial neoplasia 2

AIM

Few studies have examined the effect of combined low-risk human papillomavirus (LR-HPV) and high-risk human papillomavirus (HR-HPV) infection on the progression of cervical intraepithelial neoplasia (CIN)2 to CIN3. This multi-institutional prospective cohort study investigated the risk of progression of CIN2 with various combinations of HR-HPV and LR-HPV infection.

METHODS

Between January 2007 and May 2008, 122 women with CIN2 (aged 20-50 years) from 24 hospitals throughout Japan were enrolled in the study. Ninety-three women were analyzed after a 2-year follow-up with cytology, colposcopy, HR-HPV testing and HPV genotyping. Colposcopy-directed biopsy was performed at entry and the end of this study, or when disease progression was suspected.

RESULTS

Among 93 women with CIN2, 87 (93.5%) had HR-HPV infection. Among these 87 cases, 24 (27.6%) progressed to CIN3 and 49 (56.3%) regressed. None of the six women with CIN2 without HR-HPV infection progressed. The progression rate was significantly lower in women with combined HR-HPV and LR-HPV infection (3/28, 10.7%) than in those with HR-HPV infection only (21/59, 35.6%; P = 0.016). Multivariate analyses showed that CIN2 progression in women with HR-HPV infection was negatively associated with LR-HPV co-infection (hazard ratio = 0.152; 95% confidence interval [CI] = 0.042-0.553). CIN2 regression was positively associated with LR-HPV co-infection (odds ratio = 4.553; 95% CI = 1.378-15.039).

CONCLUSION

The risk of CIN2 progression is low in women with combined infection of HR-HPV and LR-HPV. The finding may be useful for management of women diagnosed with CIN2.

Nordic biological specimen bank cohorts as basis for studies of cancer causes and control: quality control tools for study cohorts with more than two million sample donors and 130,000 prospective cancers

The Nordic countries have a long tradition of large-scale biobanking and comprehensive, population-based health data registries linkable on unique personal identifiers, enabling follow-up studies spanning many decades. Joint Nordic biobank-based studies provide unique opportunities for longitudinal molecular epidemiological research. The Nordic Biological Specimen Banks working group on Cancer Causes and Control (NBSBCCC) has worked out very precise quality assurance principles for handling of the samples, based on the tradition in biobank culture. The aim of this paper is to demonstrate how high standards of quality assurance can also be developed for the data related to the subjects and samples in the biobanks. Some of the practices adopted from the strong Nordic cohort study experience evidently improve quality of nested case-control studies nested in biobank cohorts. The data quality requirements for the standardised incidence ratio calculation offer a good way to check and improve accuracy of person identifiers and completeness of follow-up for vital status, which are crucial in case-control studies for picking up right controls for the cases. The nested case-control design applying incidence-density sampling is recommended as an optimal design for most biobank-based studies. It is demonstrated how some types of biobanks have a period immediately after sampling, when the cancer risk is not comparable with the cancer risk in the base population, and how many of the biobanks never represent the normal average population of the region. The estimates on the population-representativeness of the biobanks assist in interpretation of generalisability of results of the studies based on these samples, and the systematic tabulations of numbers of cancer cases will serve in study power estimations. The well over 130,000 prospective cancer cases registered among subjects in the NBSBCCC biobank cohorts have already offered unique possibilities for tens of strong studies, but for rare exposure-outcome combinations predictions on future numbers of cases improve the chance to select the right moment when the study will have accurate statistical power.

Population fraction of cervical neoplasia attributable to high-risk human papillomaviruses

AIMS

The efficacy of human papillomavirus (HPV) type 16 and 18 vaccines against cervical intraepithelial neoplasia grade II (CIN2+) has been verified, but the active follow-up of studies with invasive cervical cancer or cervical intraepithelial neoplasia grade III (CIN3) as primary end points are ethically not possible. Furthermore, ongoing registry-based passive follow-up studies with invasive cervical cancer as the end point will take time.

MATERIALS & METHODS

To evaluate the feasibility of CIN3 as a surrogate end point, we compared high-risk (hr) HPV-associated relative risk and population attributable fraction (PAF) of CIN3 and/or squamous cell carcinoma (SCC) estimated in a large serological case-cohort HPV study. Our case-cohort comprised 83 SCC and 389 CIN3 cases and a subcohort of 7862 out of 230,998 Finnish women, who at baseline were under 32 years of age and had undergone a minimum of two pregnancies within 5 years during 1983-1997.

RESULTS

PAFs of the case-cohort, approach-based, serologically defined and misclassification-corrected HPV16 and hrHPV (HPV types 16, 18, 31 and 33) exposures in the SCC samples were 61% (95% CI: 18-85) and 73% (95% CI: 13-93), respectively. Considerably lower HPV16 and hrHPV PAF estimates in CIN3 of 6% (95% CI: -19-35) and 36% (95% CI: -5-65), respectively, were obtained. A meta-analysis-derived, PCR-based, hrHPV-associated relative risk estimate of 20.3 in CIN2/3+ yielded a PAF estimate for hrHPV in CIN2/3+ of 86% (90% CI: 63-95) in our study population. The former, hrHPV serology-based CIN3 PAF estimates were biased owing to low sensitivity of HPV16 and/or HPV16/18/31/33 serology, most notably in cervical cancer precursor lesions, but the latter estimate overlapped with our hrHPV serology-based cervical cancer PAF estimate.

CONCLUSION

CIN3 may be a valid surrogate efficacy end point for HPV vaccination studies, but the associated causality of multiple hrHPV exposures needs to be unambigously defined.

Prospective study of human papillomavirus (HPV) types, HPV persistence, and risk of squamous cell carcinoma of the cervix

BACKGROUND

The link between squamous cell cervical carcinoma and human papillomavirus (HPV) 16/18 is well established, but the magnitude of the risk association is uncertain and the importance of other high-risk HPV (HRHPV) types is unclear.

METHODS

In two prospective nested case-control series among women participating in cytologic screening in Sweden, we collected 2,772 cervical smears from 515 women with cancer in situ (CIS), 315 with invasive squamous cell carcinoma (SCC), and individually matched controls. All smears were tested for HPV with PCR assays, and the median follow-up until diagnosis was 5 to 7 years. Conditional logistic regression was used to estimate relative risks (RR) and 95% confidence intervals (95% CI).

RESULTS

The presence of HPV16/18 in the first smear was associated with 8.5-fold (95% CI, 5.3-13.7) and 18.6-fold (95% CI, 9.0-38.9) increased risks of CIS and SCC, respectively, compared with women negative for HPV. Infection with other HRHPV types in the first smear was also associated with significantly increased risks for both CIS and SCC. Persistence of HPV16 infection conferred a RR of 18.5 (95% CI, 6.5-52.9) for CIS and 19.5 (95% CI, 4.7-81.7) for SCC. The HPV16/18 attributable risk proportion was estimated at 30% to 50% for CIS, and 41% to 47% for SCC. Other HRHPV types also conferred significant proportions.

CONCLUSIONS

Our large population-based study provides quantification of risks for different HPV types and prospective evidence that non-16/18 HRHPV types increase the risk for future cervical cancer.

IMPACT

This study gives further insights into cervical cancer risk stratification with implications for HPV-based prevention strategies.

Multiple human papilloma virus types in cervical infections: competition or synergy?

Coinfection with multiple human papilloma virus (HPV) types is common in cervical HPV infection. To evaluate if infections with different HPV types occur independently, we examined 3558 women above 15 years of age suspected of cervical HPV infection. Among them, 1842 (52%) women were HPV negative and 1716 (48%) were HPV positive as analysed by a PCR-based commercial microarray assay for mucosal types. Of the HPV-positive samples, 824 (48%) had single infections, while 892 (52%) had multiple infections. Observed numbers of concurrent HPV types differed from expected numbers under the assumption of independence between infections by the various HPV types. Significant positive associations were observed for 16 pairs of HPV types in statistical analysis accounting for mass significance. Significant negative associations were also found, i.e. women with HPV-16 infection had 0.4 times the odds of having HPV-51 compared with women not infected with HPV-16. HPV-16 was the only type with odds ratios <1 for all pairwise combinations. While our findings of statistically significant coexistence do not prove biological dependence among HPV types, they do suggest that infections with some HPV types may depend on the existence of certain other HPV types. Any interaction between coexisting HPV types could either decrease or increase the efficacy of current HPV vaccines that offer mainly type-specific protection, depending on whether the types vaccinated against compete with other HPV types or not.

Baseline assessment of prevalence and geographical distribution of HPV types in Chile using self-collected vaginal samples

BACKGROUND

Chile has broad variations in weather, economics and population from the far desert north (Region 1) to the cold, icy south (Region 12). A home-based self-collected vaginal sampling was nested in the 2003 Chilean population-based health survey in order to explore the possibility of a type-specific geographical variation for human papillomavirus

METHODS

The population was a national probability sample of people 17 years of age and over. Consenting women provided self-collected cervicovaginal swabs in universal collection media (UCM). DNA was extracted and typed to 37 HPV genotypes using PGMY consensus PCR and line blot assay. Weighted prevalence rates and adjusted OR were calculated.

RESULTS

Of the 1,883 women participating in the health survey, 1,219 (64.7%) provided a cervicovaginal sample and in 1,110 (56.2% of participants and 66.5% of those eligible) the samples were adequate for analysis. Refusal rate was 16.9%. HPV prevalence was 29.2% (15.1% high-risk HPV and 14.1% low-risk HPV). Predominant high-risk types were HPV 16, 52, 51, 56 and 58. Predominant low-risk HPVs were HPV 84, CP6108, 62, 53 and 61. High-risk and low-risk HPV rates were inversely correlated between the regions. High-risk HPV prevalence was highest among the youngest women, whereas low-risk HPV increased slightly with age.

CONCLUSION

Self-obtained vaginal sampling is adequate for monitoring HPV in the community, for identifying high-risk areas, and for surveying the long term impact of interventions.

Modelling the population-level impact of vaccination on the transmission of human papillomavirus type 16 in Australia

BACKGROUND

Vaccines are now available to prevent the development of cervical cancer from genital human papillomavirus (HPV) infection. The decision to vaccinate depends on a vaccine's cost-effectiveness. A rigorous cost-effectiveness model for vaccinated individuals is presented in a companion paper; this paper investigates the additional benefits the community might receive from herd immunity.

METHODS

A mathematical model was developed to estimate the impact of a prophylactic vaccine on transmission of HPV type 16 in Australia. The model was used to estimate the expected reduction in HPV incidence and prevalence as a result of vaccination, the time required to achieve these reductions, and the coverage required for elimination. The modelled population was stratified according to age, gender, level of sexual activity and HPV infection status using a differential equation formulation. Clinical trials show that the vaccine is highly effective at preventing persistent infection and pre-cancerous lesions. These trials do not, however, provide conclusive evidence that infection is prevented altogether. The possible modes of vaccine action were investigated to see how vaccination might change the conclusions.

RESULTS

The model predicts that vaccination of 80% of 12-year-old girls will eventually reduce HPV 16 prevalence by 60-100% in vaccinated and 7-31% in unvaccinated females. If 80% of boys are also vaccinated, reductions will be 74-100% in vaccinated and 86-96% in unvaccinated females. A campaign covering only 12-year-old girls would require 5-7 years to achieve 50% of the eventual reduction. With a catch-up campaign covering 13-26-year-olds, this delay would be reduced to only 2 years. Unrealistically high coverage in both sexes would be required to eliminate HPV 16 from the population. Under pessimistic assumptions about the duration of vaccine-conferred immunity, HPV 16 incidence is predicted to rise in some older age groups.

CONCLUSIONS

Mass vaccination with a highly effective vaccine against HPV 16 has the potential to substantially reduce the incidence and prevalence of infection. Catch-up vaccination offers the potential to substantially reduce the delay before the benefits of vaccination are observed. A booster vaccination might be required to prevent an increase in incidence of infection in women over 25 years of age.

Nordic biological specimen banks as basis for studies of cancer causes and control--more than 2 million sample donors, 25 million person years and 100,000 prospective cancers

The Nordic countries have a long tradition of large-scale biobanking and comprehensive, population-based health data registries linkable on unique personal identifiers, enabling follow-up studies spanning many decades. Joint Nordic biobank-based studies provide unique opportunities for longitudinal molecular epidemiological research. The purpose of the present paper is to describe the possibilities for such joint studies, by describing some of the major Nordic biobank cohorts with a standardised calculation of the cancer incidence in these cohorts. Altogether two million donors have since 1966 donated more than four million biological samples, stored at -20 degrees C to -135 degrees C, to 17 biobank cohorts in Finland, Iceland, Norway and Sweden. As a result of joint database handling principles, the accuracy of personal identifiers and completeness of follow-up for vital status in all participating biobanks was improved. Thereafter, the cancer incidence was determined using follow-up through the national cancer registries. Biobanks based on random samples of population typically showed slightly lower cancer incidence rates than the general population, presumably due to better participation rates among health-conscious subjects. On the other hand, biobanks including samples for viral screening or clinical testing showed 1.5 to 2.1 fold increased incidence of cancer. This excess was very high immediately after sampling, but for some cancer sites remained elevated for years after clinical sampling. So far, more than 100 000 malignant neoplasms have occurred after sample donation, and the annual increase of the cancer cases in these cohorts is about 10 000. The estimates on the population-representativity of the biobanks will assist in interpretation of generalizability of results of future studies based on these samples, and the systematic tabulations of numbers of cancer cases will serve in study power estimations. The present paper summarizes optimal study designs of biobank-based studies of cancer.

Seroprevalence of human papillomaviruses and Chlamydia trachomatis and cervical cancer risk: nested case-control study

A nested case-control study of invasive and in situ cervical cancer was performed within a community-based cohort of 13,595 Taiwanese women assembled in 1991, with a follow-up period of 9 years. Baseline serum or plasma samples were analysed for antibodies against human papillomavirus (HPV) types 6, 16 and 18 and Chlamydia trachomatis. In total, 114 cases (42 incident cases identified during follow-up and 72 prevalent cases identified at baseline) and 519 matched controls were included in the study. HPV-16 seropositivity was strongly associated with cervical cancer (OR=6.33; 95% CI 3.45-11.62). Overall, C. trachomatis was not associated with cervical cancer, but was associated with cervical cancer in analyses restricted to incident cases of cancer (OR=2.94; 95% CI 1.17-7.42) or to cases in which serum samples were analysed (OR=3.13; 95% CI 1.16-8.47). An antagonistic interaction between HPV-6 and -16 was found in a multiplicative model. These results suggest that different HPV types might interfere in cervical carcinogenesis and that C. trachomatis is associated with cervical cancer in prospective studies, and support the notion that HPV-16 seropositivity is strongly associated with cervical cancer.

Cost-effectiveness analyses of human papillomavirus vaccination

With a human papillomavirus (HPV) vaccine soon to become available for widespread use, several studies have modelled the cost-effectiveness of vaccination. These pioneer studies are likely to be influential on the design of further analyses, and we have therefore summarised and critically reviewed the strengths and limitations of their methods and assumptions. Despite a lack of transparency in some key elements, the most influential assumptions were identified as relating to vaccine effectiveness, cervical screening, and model design. Although the studies suggest that the introduction of an HPV vaccine could be cost effective compared with current practice in the USA, there is still substantial uncertainty around key variables, and model validation seems insufficient. The desirability of vaccinating boys in addition to girls has been explored in only one study. Further refinements to model design and epidemiological variables of (type-specific) HPV disease progression, and expansions on the options for vaccine use, are required for policy making.

Strategies for the introduction of human papillomavirus vaccination: modelling the optimum age- and sex-specific pattern of vaccination in Finland

Phase III trials have demonstrated the efficacy of human papillomavirus (HPV) vaccines in preventing transient and persistent high-risk (hr) HPV infection and precancerous lesions. A mathematical model of HPV type 16 infection and progression to cervical cancer, parameterised to represent the infection in Finland, was used to explore the optimal age at vaccination and pattern of vaccine introduction. In the long term, the annual proportion of cervical cancer cases prevented is much higher when early adolescents are targeted. Vaccinating against hr HPV generates greater long-term benefits if vaccine is delivered before the age at first sexual intercourse. However, vaccinating 12 year olds delays the predicted decrease in cervical cancer, compared to vaccinating older adolescents or young adults. Vaccinating males as well as females has more impact on the proportion of cases prevented when vaccinating at younger ages. Implementing catch-up vaccination at the start of a vaccination programme would increase the speed with which a decrease in HPV and cervical cancer incidence is observed.

Vaccines for cervical cancer

The review focuses on current and future prevention of invasive cervical cancer (ICC), the second most common cancer among women worldwide. Implementation of population-based cytological screening programmes, using the 'Pap' smear to detect pre-cancerous lesions in the cervix, has resulted in substantial declines in mortality and morbidity from ICC in North America and some European countries. However, cases of, and deaths from, ICC continue to occur. Primary prevention of infection with high-risk human papillomavirus (HPV) types, the central causal factor of ICC, could further reduce incidence of and mortality from ICC. This is particularly the case in developing countries, which bear 80% of the burden of ICC, and where effective Pap screening programmes are extremely difficult to implement. Very promising results from several trials of synthetic HPV type-specific monovalent (HPV 16) and bivalent (HPV 16 and 18) vaccines have recently been published, showing high efficacy against type-specific persistent HPV infection and development of type-specific pre-cancerous lesions. Large-scale phase III trials of a number of such vaccine candidates are currently underway, and there is real hope that an effective vaccine capable of protecting against infection with HPV types 16 and 18 (which together account for approximately 70% of cervical cancer cases worldwide), and thereby of preventing development of a very significant proportion of cases of ICC, could be available within the next 2 years.

Seroprevalence atlas of infections with oncogenic and non-oncogenic human papillomaviruses in Finland in the 1980s and 1990s

Vaccines against high-risk (hr) human papillomaviruses (HPVs) causing cervical cancer may soon be licensed. Thus, nature of HPV epidemics needs to be studied now. Random sampling for studies on HPV epidemiology was done from all 230,998 women belonging to the population-based Finnish Maternity Cohort and having a minimum of 2 pregnancies between 1983 and 1994. First pregnancy serum specimens were retrieved for 7,805 subjects, and were analyzed for antibodies to HPV6/11, 16 and 18 with standard ELISAs. HPV16 seroprevalence almost doubled from the 1980s to the 1990s, and the epidemic spread to new areas in 23-31 year olds, i.e. the bulk of pregnant female population in the southwest part of the country. The HPV16 epidemic in the 14-22 year olds in 1983-1988 (1961-1974 birth cohorts) and in the 23-31 year olds in 1989-1994 (1958-1971 birth cohorts) overlapped with strong clustering of HPV16 and HPV18 infections in the latter (odds ratio 8.0, 95% confidence interval 6.6-9.7). Similar clustering of HPV16 and HPV6/11 infections was not found. The epidemic and the clustering may be due to high transmission probability of the hrHPV types and increase in sexual activity of the index birth cohorts.

IgG antibodies to HPV16, 52, 58 and 6 L1-capsids and spontaneous regression of cervical intraepithelial neoplasia

To identify the predictive markers for spontaneous regression of cervical intraepithelial neoplasia (CIN), we examined whether IgG antibody responses to common human papillomavirus (HPV) L1-capsids correlate with CIN regression. In a cohort study, a total of 116 Japanese women with CIN grade I/II were tested for cervical HPV DNA and serum IgG antibodies to HPV16/52/58/6 L1-capsids. Our data suggest that baseline IgG reactivities to HPV L1-capsids do not serve as a predictive marker of CIN regression, in contrast to histological CIN grades and HPV DNA status.

Prophylactic human papillomavirus vaccines: the beginning of the end of cervical cancer

Persistent infection with one of the oncogenic human papillomavirus (HPV) types is a necessity for the development of cervical cancer. By HPV vaccination, cervical cancer could become a very rare disease. Two types of HPV vaccines can be distinguished: (i) therapeutic vaccines which induce cellular immunity targeted against epithelial cells infected with HPV and (ii) prophylactic vaccines inducing virus-neutralizing antibodies protecting against new but not against established infections. At present, several vaccines have been developed and tested in clinical trials. The vaccines are generally well tolerated and highly immunogenic. The current clinical data indicate that prophylactic vaccines are very effective against new persistent infections and the development of cervical intraepithelial lesions. The protection is type specific. However, the follow-up of the vaccination trials is still short. The effect of HPV vaccines on future cancer incidence will only be known after decades of follow-up. This article will address the status of recently terminated phase II and currently running phase III trials with prophylactic HPV vaccines.

Evidence for the coexistence of two genital HPV types within the same host cell in vitro

Studies on the presence of human papillomavirus (HPV) DNA in cervical samples show that 10% or more of all clinical lesions contain at least two different HPV types. We have investigated if multiple HPV types can exist in the same cell and interact with one another or if they merely exist in the same tissue. Combinations of genital HPV genomes were electroporated into primary keratinocytes. Southern analyses of the electroporated cultures indicate that while a subset of high-risk HPV types can be stably maintained and replicate episomally in the same cell, interactions between types do occur, often to the detriment of one or both viruses in question. These studies provide insight into the interactions that may occur between HPV types in naturally occurring lesions.

Joint effects of different human papillomaviruses and Chlamydia trachomatis infections on risk of squamous cell carcinoma of the cervix uteri

This case-control study based in Nordic serum banks evaluated the joint effects of infections with genital human papillomavirus (HPV) types, and Chlamydia trachomatis in the aetiology of cervical squamous cell carcinoma. Through a linkage with the cancer registries, 144 cases were identified and 420 controls matched to them. Exposure to past infections was defined by the presence of specific IgG antibodies. The odds ratio (OR) for the second-order interaction of HPV16, HPV6/11 and C. trachomatis was small (1.0) compared to the expected multiplicative OR, 57, and the additive OR, 11. The interactions were not materially different among HPV16 DNA-positive squamous cell carcinomas. When HPV16 was replaced with HPV18/33 in the analysis of second-order interactions with HPV6/11 and C. trachomatis, there was no evidence of interaction, the joint effect being close to the expected additive OR. Possible explanations for the observed antagonism include misclassification, selection bias or a true biological phenomenon with HPV6/11 and C. trachomatis exposures antagonizing the carcinogenic effects of HPV16.

IgG antibodies to human papillomavirus 16, 52, 58, and 6 L1 capsids: case-control study of cervical intraepithelial neoplasia in Japan

In Japan, human papillomavirus (HPV) 16, 52, and 58 are most commonly associated with cervical intraepithelial neoplasia (CIN). By contrast, HPV6 is primarily associated with genital warts. This study was designed to evaluate the association between IgG antibody responses to common HPVs and the risk of CIN development within a Japanese population. CIN cases (n = 141) and controls (n = 109) were tested for cervical HPV DNA and serum IgG antibodies to L1 capsids of HPV16, 52, 58, and 6. Seropositivity to HPV16, 52, and 58 L1 capsids was significantly higher in CIN cases than in controls: 27%, 21%, and 31% versus 16%, 11%, and 11%, respectively (P < 0.05). HPV6 L1 seropositivity was not significantly associated with CIN lesions (P = 0.11). Presence of viral DNA for either HPV16, 52, or 58 correlated with a significant antibody response against the homologous L1 capsids but not heterologous L1 capsids. Furthermore, seropositivity to multiple types of HPV16, 52, and 58 was more strongly associated with an increased risk of CIN development than seropositivity to a single type (P for trend <0.001). These findings indicate that IgG antibodies to L1 capsids of HPV16, 52, and 58 represent an increased risk of CIN development, with antibodies to multiple types being indicative of a further increase in risk. The presence of CIN lesions in women with seropositivity to multiple types suggests that viral exposure to a given type may not be protective against infections by other types and subsequent CIN development.

Repetitive and consistent cervicovaginal exposure to certain viral pathogens appears to protect against their sexual acquisition in some women: potential mechanisms

Several groups have proposed that human female promiscuity or polyandry, with repetitive and consistent cervicovaginal exposure to human immunodeficiency virus type 1 (HIV-1), can lead to protection against sexual acquisition of HIV-1 in some of these women. The mechanism of this phenomenon, the highly exposed persistently HIV-seronegative (HEPS) state, is unknown. Thus far, it has been correlated with viral epitope-specific immune responses in only about half of the women evaluated. But when present, these responses decline rapidly following interruption of pathogen exposure, and correlate with prompt acquisition of HIV. I have extended the concept of HEPS to another sexually transmitted viral pathogen, human papillomavirus (HPV). Supporting clinical and immunological information were identified from a literature search using PubMed as well as several sets of epidemiological data, including longitudinal surveys of HIV-1 incidence among female commercial sex workers (CSWs) in Africa and Thailand, and follow-up of a Danish cohort of CSWs and a large group of Brazilian women, both at high risk for HPV infection. These studies suggest that male-to-female penile-vaginal transmission of at least two viruses, HIV-1 and HPV, is blocked by local mucosal responses, immunologic or otherwise, which require repetitive, uninterrupted exposure to pathogen. Exploration of the mechanisms underlying such ostensibly protective responses may facilitate development of STD vaccines.

Development of an automated extraction procedure for detection of human papillomavirus DNA in liquid based cytology samples

Liquid based cytology samples are being used increasingly to improve cervical screening and have the advantage that residual cell suspension is available for other tests such as human papillomavirus (HPV) detection. However, as the transport medium is optimised for downstream cytology, problems can be experienced during extraction of nucleic acid. This study aimed to develop a robust protocol for automated extraction of HPV DNA from cervical, liquid based cytology samples using a high throughput robotic system. Considerable modification of existing clinical extraction protocols for swab specimens, together with optimisation of required sample input volume was required to reduce sample blockage during the extraction to acceptable levels. The blockage rate and optimal processing volume was assessed by extracting a fixed volume (1/4) of re-suspended material from the centrifuged pellets of 10, 5 and 1 ml aliquots of 200 specimens. Analysis revealed 17.5% blockage with specimens originating from 10 ml aliquots; 3% with 5 ml and no blockage with 1 ml aliquots of the same samples. A 3% blockage level is acceptable for an automatic well clearance procedure to be followed. HPV testing of the extracts by real-time PCR showed a 1.5% loss of sensitivity in extracts originating from 1 ml aliquots as compared with 5 ml aliquots with a consequent loss of detectable HPV genotypes after reverse hybridisation. In short, 5 ml of liquid based cytology specimen is recommended for nucleic acid extraction, to allow optimal detection of HPV types in clinical samples while retaining maximum efficiency of the robotic extraction procedure.

The theoretical population-level impact of a prophylactic human papilloma virus vaccine

BACKGROUND

The ongoing development of a vaccine against human papillomavirus (HPV) raises important questions about the impact of various vaccination strategies.

METHODS

Two mathematical models are developed to explore the population-level impact of an HPV vaccine. The first model focuses on the infection process and the second on the disease process (specifically, cervical carcinoma and cancer).

RESULTS

Both population characteristics (, sexual mixing and rates of sex partner change) and vaccine characteristics affect the steady state prevalence of HPV that would be expected if a vaccine program is implemented. Under a particular set of assumptions, we find that vaccinating both men and women against a specific HPV type would result in a 44% decrease in prevalence of that type whereas vaccinating only women would result in a 30% reduction. We also find that if a vaccine gives protection against some, but not all, high risk types of HPV, the reduction in disease may be less than the reduction in HPV because the remaining high risk HPV types may replace the disease caused by the eliminated types.

CONCLUSIONS

A multivalent vaccine containing the majority of disease-causing HPV types would greatly reduce the need for colposcopy, biopsy and treatment. However, it is unlikely that Pap-screening programs would become redundant unless the vaccine is highly effective and coverage is widespread. In contrast to less common infections that are primarily restricted to core groups, targeting the vaccine towards the most sexually active individuals is less effective for a common sexually transmitted infection such as HPV.

A prospective study of the relationship between prediagnostic human papillomavirus seropositivity and HPV DNA in subsequent cervical carcinomas

Several prospective studies with invasive carcinoma as endpoint have supported Human Papillomavirus as a cause of cervical carcinoma. However, the largest study used seroepidemiology and did not analyse presence of Human Papillomavirus DNA in the subsequent tumour. Linkage of serum bank registries and cancer registries had identified 196 women with a registered cervical carcinoma after donation of a serum sample. For the present study, biopsies for 127 cases could be located, verified to contain invasive carcinoma and be amplified by PCR. Three control women who had remained alive and without cervical carcinoma during an equal length of follow-up had been matched to each of the case women and tested for HPV antibodies. Presence of Human Papillomavirus DNA in the tumours was analysed by general primer and type specific PCR. HPV16-seropositive women had a relative risk of 4.4 (95% CI: 2.2-8.8) to develop cervical carcinoma carrying HPV16 DNA. By contrast, there was no excess risk for Human Papillomavirus 16-seropositive women to develop cervical carcinoma devoid of HPV16 DNA. Prediagnostic HPV16 seropositivity was strongly correlated with later HPV16 DNA positivity of the tumour (P<0.001) and prediagnostic HPV18 seropositivity correlated with HPV18 DNA in the tumour (P<0.03). The link between prediagnostic seropositivity and type of viral DNA in the cancer implies that the carcinogenic effect of infection with these viruses is dependent on persistent presence of type-specific viral DNA.

Clustering of seropositivities for sexually transmitted infections

BACKGROUND

Serology for different sexually transmitted infections (STIs) is useful for epidemiologic studies on the spread of STIs in different populations. Studying whether seropositivities for different STIs cluster could be useful, both for development of improved serologic markers of sexual behavior in populations and for understanding how STIs may differ in terms of the dynamics of their spread.

GOAL

To evaluate the degree of clustering of different STIs in relation to sexual history.

STUDY DESIGN

An age- and sexual history-stratified subsample of 275 women from a survey of healthy Swedish women seeking contraceptive advice was tested for human papillomavirus (HPV) types 6, 11, 16, 18, and 33; Chlamydia trachomatis; herpes simplex virus 2 (HSV-2); and human herpesvirus 8.

RESULTS

Significant clustering was observed only for HPV types 6 and 11; for HPV types 16, 18, and 33; and for C trachomatis and HSV-2. The serologic marker that correlated best with lifetime number of sex partners was HPV type 16 (odds ratio [OR], 10.2; 95% CI, 3.8-27.6). The combined serologic marker that correlated most highly with sexual history was joint positivity for HPV types 16 and 33 (OR, 25.5; 95% CI, 5.4-120.4).

CONCLUSIONS

The degree of clustering between different STIs varies from nonexistent to strong, implying that different STIs commonly have very different transmission dynamics. Certain combinations of STI serologic tests may be useful in epidemiologic studies for predicting sexual behavior in groups.

Immunity to oncogenic human papillomaviruses

The establishment of human papillomavirus (HPV) infection as a major cause of several human cancer forms, notably cervical cancer, has spurred development of prophylactic and/or therapeutic HPV vaccines for prevention of cervical neoplasia. Knowledge of the immunity to HPV forms the basis for such endeavors.

METHOD

A literature review of humoral and cellular immunity to HPV. The overview on human leukocyte antigen (HLA) and cervical cancer was expanded to a formal metaanalysis, where relevant articles were located by Medline search and citation analysis and graded by preassigned quality criteria on study design.

RESULTS

The antibody response to the HPV particle is dominated by a neutralizing antibody response to a typespecific, conformationally dependent immunodominant epitope. Vaccines based on viral particles lacking the viral genome (virus-like particles, VLPs) have been highly successful in preventing and treating HPV infection in several animal model systems. In humans, the serum antibody response to VLPs is stable over time, also after the HPV infection has been cleared, resulting in HPV serology being used as a marker of cumulative HPV exposure in spite of the fact that a significant proportion of HPV-exposed subjects fail to seroconvert. More than 90% of HPV infections will clear spontaneously. The factors that determine whether an HPV infection is cleared or persists and increases the risk for cancer are not known, but cellular immunity is implicated. Several HLA class II haplotypes are associated with cervical cancer: DQw3 increases and DR13 decreases the risk for cervical cancer in general (odds ratios (OR) and 95% confidence intervals (CI): 1.25(1.15-1.37) and 0.69 (0.56-0.85), respectively); DR15 increases the risk for HPV16-carrying cancer (OR: 1.47; CI: 1.20-1.81); and DR7 may be either protective or increase the risk. Most cervical cancers have downregulated the expression of at least one HLA class I antigen, whereas class II expression is increased in infected epithelium. A Th2 cytokine profile is associated with progression to cervical cancer. HPV-antigen-specific proliferative responses have been detected in many studies, although it is not entirely clear whether these responses are HPV type specific or may be cross-reactive between HPV types. Specific cytotoxic T lymphocyte (CTL) responses were originally reported in only a minority of infected subjects, typically cancer patients, but with advancing technology, specific CTLs can be stimulated from about half of the women with HPV-carrying disease. In animal model systems, CTL responses can mediate clearance.

CONCLUSION

The antibody response to HPV is a mediator of type-specific protective immunity, which forms the basis for prophylactic vaccine candidates. The cellular immunity to HPV is implicated as an important factor in cervical carcinogenesis, but the main targets and types of responses that mediate HPV clearance are not established.