Real-time PCR-based system for simultaneous quantification of human papillomavirus types associated with high risk of cervical cancer

Prevalence, viral load, and physical status of HPV 16 and 18 in cervical adenosquamous carcinoma

Adenosquamous carcinoma of the uterine cervix is a rare mixture of malignant squamous and glandular epithelial elements and accounts for approximately 10% of cervical carcinomas. The aims of the present study were to evaluate the prevalence, physical status, and viral load of HPV 16 and 18 in adenosquamous carcinoma. Formalin-fixed paraffin-embedded tissue samples from 20 cases of histologically diagnosed adenosquamous carcinoma were examined. The squamous and glandular components were separately microdissected and analyzed for their HPV DNA subtype, viral load, and physical status using real-time polymerase chain reaction (PCR). The percentages of HPV 16- and 18-positive cases among all the HPV-positive cases were 36.8% (7/19) and 57.9% (11/19) in the squamous epithelial elements and 33.3% (6/18) and 61.1% (11/18) in the glandular elements, respectively. PCR analysis with E2 primers revealed that seven of eleven (63.6%) HPV 18-positive cases had the pure integrated form in both elements. The mean HPV 16 DNA copy numbers/cell was 7.22 in the squamous elements and 1.33 in the glandular elements (p=0.04) while the corresponding mean HPV 18 DNA copy numbers/cell was 1.50 and 0.89, respectively. The prevalence of HPV 18 in adenosquamous carcinoma was high and many HPV 18-positive cases were the pure integrated form resulting in very low copy numbers/cell. It is possible that more aggressive transformation with early integration of HPV 18 results in cases with greater chromosomal instabilities, higher growth rates, and rapid progression.

Persistent high-risk human papillomavirus infections and other end-point markers of progressive cervical disease among women prospectively followed up in the New Independent States of the Former Soviet Union and the Latin American Screening study cohorts

BACKGROUND

New end points are needed in future human papillomavirus (HPV) vaccine efficacy studies that accurately predict disease progression.

OBJECTIVES

Potential intermediate end points were analyzed in the combined New Independent States of the Former Soviet Union (NIS) and the Latin American Screening (LAMS) study cohorts.

STUDY DESIGN AND METHODS

Data files of 2 international screening trials, the NIS (n = 3187) and the LAMS (n = 12,114) study cohorts, were combined, and a subcohort of 1865 (n = 854 and n = 1011 for the NIS and the LAMS, respectively) women prospectively followed up for 19.7 (median, 22.2) months was analyzed for different intermediate end-point markers of disease progression to squamous intraepithelial lesion (SIL), cervical intraepithelial neoplasia grade 1 and higher (CIN1+), and CIN grade 2 and higher (CIN2+) as terminal events.

RESULTS

: Altogether, 131 (7.0%), 90 (4.8%), and 39 (2.1%) cases progressed to SIL, CIN1+, and CIN2+, respectively, progression times being equal in the NIS (11.9, 16.8, and 19.6 months) and LAMS (13.6, 14.1, and 15.4 months) cohorts (P = 0.931, P = 0.335, and P = 0.535). The 2 most powerful end-point markers of disease progression to CIN2+ were high-grade squamous intraepithelial lesions based on Papanicolaou test results at 6-month (odds ratio [OR] = 47.1; 95% confidence interval [CI], 17.3-128.7) and 12-month (OR = 21.5; 95% CI, 5.1-90.8) follow-up visits, with longitudinal positive and negative predictive values of 42.1% and 98.0% (6 months) and 33.3% and 97.7% (12 months). Of the virological end points, more than 6 months of persistent high-risk HPV (HR-HPV) was the most powerful predictor of progression to CIN1+ (OR = 18.6; 95% CI, 2.5-136.5), with longitudinal positive and negative predictive values of 10.3% and 99.4%, respectively. No additional benefit was obtained using more than 12 months of persistent HR-HPV end point.

CONCLUSIONS

High-grade squamous intraepithelial lesion based on a Papanicolaou test results at 6- or 12-month follow-up visits was the most powerful end point, either considering cytological end points alone or in comparison to any of the virological end points. Of the virological end points, more than 6-month HR-HPV persistence criteria give the most powerful estimate of a progressive disease.

Use of FTA card for dry collection, transportation and storage of cervical cell specimen to detect high-risk HPV

BACKGROUND

The FTA elute micro card, which enable the collection, transport, and archiving of DNA could be an attractive alternative to a liquid based collection system for detection of human papillomavirus (HPV).

OBJECTIVES

To develop a method based on the FTA elute micro card for dry collection of cervical epithelial cell samples, suitable for subsequent PCR-based HPV testing.

STUDY DESIGN

The method was evaluated by a comparison of the DNA collected by cytobrush and the regular FTA elute micro card from 50 cervical cell samples. The method was then used to estimate the DNA amount in 1040 samples applied to the indicating FTA elute micro card.

RESULT

The agreement in HPV positivity between the cytobrush and FTA samples (94%) was excellent (kappa=0.88, 95% CI 0.748-1). All the 1040 samples on the indicating FTA card had sufficient amounts of genomic DNA (>10 copies of a single copy gene) to be suitable for HPV typing. In 53 of the 1040 women the day in the menstrual cycle was noted, and the copy number during follicular phase day 9-13 was found to be statistically significantly lower than for the other three stages in the menstrual cycle (day 4-8, 14, >14) and during menopause.

CONCLUSION

The indicating FTA elute micro card represents a suitable medium for collection of cervical cell samples, although follow-up studies are needed to verify the detection of low frequency HPV types.

Laser capture microdissection of cervical human papillomavirus infections: copy number of the virus in cancerous and normal tissue and heterogeneous DNA methylation

Research on the pathogenicity of human papillomaviruses (HPVs) during cervical carcinogenesis often relies on the study of homogenized tissue or cultured cells. This approach does not detect molecular heterogeneities within the infected tissue. It is desirable to understand molecular properties in specific histological contexts. We asked whether laser capture microdissection (LCM) of archival cervical tumors in combination with real-time polymerase chain reaction and bisulfite sequencing permits (i) sensitive DNA diagnosis of small clusters of formalin-fixed cells, (ii) quantification of HPV DNA in neoplastic and normal cells, and (iii) analysis of HPV DNA methylation, a marker of tumor progression. We analyzed 26 tumors containing HPV-16 or 18. We prepared DNA from LCM dissected thin sections of 100 to 2000 cells, and analyzed aliquots corresponding to between nine and 70 cells. We detected nine to 630 HPV-16 genome copies and one to 111 HPV-18 genome copies per tumor cell, respectively. In 17 of the 26 samples, HPV DNA existed in histologically normal cells distant from the margins of the tumors, but at much lower concentrations than in the tumor, suggesting that HPVs can infect at low levels without pathogenic changes. Methylation of HPV DNA, a biomarker of integration of the virus into cellular DNA, could be measured only in few samples due to limited sensitivity, and indicated heterogeneous methylation patterns in small clusters of cancerous and normal cells. LCM is powerful to study molecular parameters of cervical HPV infections like copy number, latency and epigenetics.

High-throughput two-step LNA real time PCR assay for the quantitative detection and genotyping of HPV prognostic-risk groups

BACKGROUND

Human papillomavirus (HPV) infection is a necessary event in the development of cervical carcinoma. High risk (HR) HPV genotypes, however, may progress differentially from low grade lesions to malignancy.

OBJECTIVES

The necessity to genotype and quantify HPV-DNA in cervical screening programs, in the follow up post-surgical treatments and in monitoring the effectiveness of HPV vaccination programs, requires access to economical, high-throughput and flexible molecular technologies.

STUDY DESIGN

A high-throughput two-step LNA real time PCR assay was developed consisting of real time PCR reactions with fluorescent Locked Nucleic Acid (LNA) probes. The first step permits classification into three prognostic-risk groups of nine HR HPV genotypes (16, 18, 31, 33, 35, 45, 52, 56 and 58) most frequently found associated with cervical lesions in Europe. The second step allows us to genotype/quantify the HPV-DNA only when clinical, epidemiological or prophylactic aims exist.

RESULTS

The specificity, repeatability, detection and quantitation limit, and linearity of the assay were evaluated and appear to be in agreement with guidelines for the validation of analytical procedures. The overall genotype concordance on cervical samples between our assay and INNOLiPA test was 94% (k 0.83) indicating good agreement.

CONCLUSIONS

The two-step PCR assay can give much information relative to the predictive value of different HR HPV types and can quantify the genotype-specific viral load. In particular, its ability to detect and quantify nine HR HPV genotypes can help provide more efficient and successful patient care and may be useful for the monitoring of the efficacy of HPV vaccines.

Comparison between the Hybrid Capture 2 and the hpVIR real-time PCR for detection of human papillomavirus in women with ASCUS or low grade dysplasia

BACKGROUND

Human papillomavirus (HPV) testing is an important part of cervical carcinoma screening, and the most widely used assay for detection of HPV is Hybrid Capture 2 (HC2).

OBJECTIVES

We compare the HC2 with the real-time PCR hpVIR assay for detection of HPV in follow-up smears of 398 women diagnosed with atypical squamous cells of unknown significance (ASCUS) or low grade cervical intraepithelial neoplasia (CIN 1) in their initial smear.

STUDY DESIGN

The two assays target the same set of high-risk (HR) HPVs with exception of HPV68. hpVIR identify individual or groups of HPV types as well as their viral load, while HC2 identify HR HPVs without specification of type.

RESULTS

34% (131/391) of the women were positive with HC2 and 45% (175/391) with hpVIR. 16% (63/391) were positive only with hpVIR and among those with cytology available 6% (3/52) had a CIN 2. The 3% (13/391) of women positive only with HC2 either contained low-risk HPVs or copy numbers below the cut-off for the hpVIR assay.

CONCLUSION

The hpVIR assay has a similar sensitivity and specificity as HC2, but hpVIR detect a higher frequency of high-risk HPV infections.

Prevalence and viral load of oncogenic human papillomavirus types associated with cervical carcinoma in a population of North Italy

A cross-sectional study was carried out in a population of North Italy to determine the prevalence of eight oncogenic human papillomavirus (HPV) types most commonly found in cervical carcinoma and to study the relationship between HPV DNA loads and severity of disease. A total of 597 cervical samples obtained from patients with pathological findings (n = 472) and from women with normal cytology (n = 125) were analyzed by means of normalized Real-time PCR assays to quantify HPV-16, -18, -31, -45, and -33 group (including -33, -52, -58, -67); the normalization of oncogenic HPV viral load was carried out by quantitation of a single copy gene. The two most common oncogenic HPV types found were 16 and 31 (24.3% and 22.9% of pathological samples, respectively); multiple infections were demonstrated in 22% of pathological samples. Overall, the HPV total viral load was found to increase with increasing severity of associated lesions, although a stronger association was observed only for HPV-31 and HPV-16 (gamma = 0.49 and 0.41, respectively) as compared to HPV-18 and -33 group (gamma = 0.19 and 0.02, respectively). However, we found that high levels of HPV-31 or 33 group DNA could be prognostic of minor oncogenic risk for high-grade squamous intraepithelial lesions (H-SIL) (age adjusted odds ratio [AORs] = 1.57 and 1.26, respectively) than HPV-16 and HPV-18 (AORs = 30 and 8, respectively). The AORs also increased with HPV total viral load and reached a maximum of AORs = 15.7. Thus, HPV load is a type-dependent risk marker for the development of H-SIL.

Low prevalence of human papillomavirus in squamous-cell carcinoma limited to oral cavity proper

Several investigations have reported that the human papillomavirus may play a role in head and neck squamous-cell carcinoma development and may have a prognostic impact. However, inconsistent results regarding human papillomavirus prevalence have been obtained so far. Variables which may account for these discrepancies may be related to site of the samples' origin, detection methods and sample size. The aim of this study is to evaluate the presence of high-risk type human papillomavirus in a large, well defined sample of squamous-cell carcinoma limited to the oral cavity in its strictest definition-ie with no pharynx or larynx cancers included-by means of quantitative real-time polymerase chain reaction, a method which ensures high sensitivity and offers the opportunity to exclude false-positive results. Data were obtained from 314 squamous-cell carcinoma limited to oral cavity proper, indicated that the prevalence of high-risk human papillomavirus was as low as 2% (CI 0.6-3). Matched pairs case-control analysis indicated that the prevalence among controls did not significantly differ with respect to cases and thus did not support a major role for the human papillomavirus in the etiology of squamous-cell carcinoma of the oral cavity.

Influence of human papillomavirus type 16 (HPV-16) E2 polymorphism on quantification of HPV-16 episomal and integrated DNA in cervicovaginal lavages from women with cervical intraepithelial neoplasia

Integrated human papillomavirus type 16 (HPV-16) viral loads are currently estimated by quantification with real-time PCR of HPV-16 E6 (RT-E6 and HPV-16 PG) and E2 (RT-E2-1) DNA. We assessed the influence of HPV-16 E2 polymorphism on quantification of integrated HPV-16 DNA in anogenital specimens. HPV-16 E2 was sequenced from 135 isolates (123 from European and 12 from non-European lineages). An assay targeting conserved HPV-16 E2 sequences (RT-E2-2) was optimized and applied with RT-E6 and RT-E2-1 on 139 HPV-16-positive cervicovaginal lavages collected from 74 women [58 human immunodeficiency virus (HIV)-seropositive and 16 HIV-seronegative]. Ratios of HPV-16 copies measured with RT-E2-2 and RT-E2-1 obtained with African 2 (median=3.23, range=1.92-3.49) or Asian-American (median=3.78, range=1.47-37) isolates were greater than those obtained with European isolates (median=1.02, range=0.64-1.80; P<0.02 for each comparison). The distribution of HPV-16 E2 copies measured in 139 samples with RT-E2-2 (median=6150) and RT-E2-1 (median=8960) were different (P<0.0001). The risk of high-grade cervical intraepithelial neoplasia (CIN-2,3) compared with women without CIN was increased with higher HPV-16 total [odds ratio (OR)=2.17, 95 % confidence interval (CI)=1.11-4.23], episomal (OR=2.14, 95 % CI=1.09-4.19), but not for HPV-16 integrated viral load (OR=1.71, 95 % CI=0.90-3.26), after controlling for age, race, CD4 count, HIV and HPV-16 polymorphism. The proportion of samples with an E6/E2 ratio >2 in women without squamous intraepithelial lesion (7 of 35) was similar to that of women with CIN-2,3 (5 of 11, P=0.24) or CIN-1 (5 of 14, P=0.50). HPV-16 E2 polymorphism was a significant factor that influenced measures of HPV-16 integrated viral load.

Critical evaluation of HPV16 gene copy number quantification by SYBR green PCR

BACKGROUND

Human papilloma virus (HPV) load and physical status are considered useful parameters for clinical evaluation of cervical squamous cell neoplasia. However, the errors implicit in HPV gene quantification by PCR are not well documented. We have undertaken the first rigorous evaluation of the errors that can be expected when using SYBR green qPCR for quantification of HPV type 16 gene copy numbers. We assessed a modified method, in which external calibration curves were generated from a single construct containing HPV16 E2, HPV16 E6 and the host gene hydroxymethylbilane synthase in a 1:1:1 ratio.

RESULTS

When testing dilutions of mixed HPV/host DNA in replicate runs, we observed errors in quantifying E2 and E6 amplicons of 5-40%, with greatest error at the lowest DNA template concentration (3 ng/microl). Errors in determining viral copy numbers per diploid genome were 13-53%. Nevertheless, in cervical keratinocyte cell lines we observed reasonable agreement between viral loads determined by qPCR and Southern blotting. The mean E2/E6 ratio in episome-only cells was 1.04, but with a range of 0.76-1.32. In three integrant-only lines the mean E2/E6 ratios were 0.20, 0.72 and 2.61 (values confirmed by gene-specific Southern blotting). When E2/E6 ratios in fourteen HPV16-positive cervical carcinomas were analysed, conclusions regarding viral physical state could only be made in three cases, where the E2/E6 ratio was < or = 0.06.

CONCLUSION

Run-to-run variation in SYBR green qPCR produces unavoidable inaccuracies that should be allowed for when quantifying HPV gene copy number. While E6 copy numbers can be considered to provide a useable indication of viral loads, the E2/E6 ratio is of limited value. Previous studies may have overestimated the frequency of mixed episomal/integrant HPV infections.

Human papillomavirus in cervical cancer screening: important role as biomarker

Cervical cytology screening has reduced cervical cancer morbidity and mortality but shows important shortcomings in terms of sensitivity and specificity. Infection with distinct types of human papillomavirus (HPV) is the primary etiologic factor in cervical carcinogenesis. This causal relationship has been exploited for the development of molecular technologies for viral detection to overcome limitations linked to cytologic cervical screening. HPV testing has been suggested for primary screening, triage of equivocal Pap smears or low-grade lesions and follow-up after treatment for cervical intraepithelial neoplasia. Determination of HPV genotype, viral load, integration status and RNA expression could further improve the effectiveness of HPV-based screening and triage strategies. The prospect of prophylactic HPV vaccination stresses the importance of modification of the current cytology-based screening approach.

Prevalence of HPV genotypes determined by PCR and DNA sequencing in cervical specimens from French women with or without abnormalities

BACKGROUND

Epidemiological data on human papillomavirus (HPV) are needed to estimate potential changes in type distribution induced by recent HPV vaccination strategies.

OBJECTIVES AND STUDY DESIGN

The epidemiological distribution of HPV in 669 cervical specimens from French women with and without cytological abnormalities was evaluated using type-specific PCR or sequencing. The results were compared with those obtained using the Digene high-risk Hybrid Capture 2 (HR-HC2) assay.

RESULTS

The overall prevalence of HPV was high (45.3%) in our study population. 285 of the 291 HPV-positive samples were typed. The distribution frequency concerned 34 different genotypes, with HPV16 being the most prevalent (32.6%). Other genotypes present were HPV31 (7.4%), HPV18, HPV 52 (both 6.0%), HPV6 (5.3%) and HPV66 (4.2%). The respective frequencies of all other genotypes were below 4%. The agreement with HR-HC2 was 78.8%. The distribution frequency data were also analyzed relatively to cytological and histological results. Our method enables the diagnosis of HPV infections with the additional advantage of genotyping.

CONCLUSION

HPV infections in the area of France studied here involve numerous HPV types, but the high cumulative prevalences of types 16, 18, 6 and 11 (44.6% in total) would suggest a major impact of vaccination on these genotypes.

Comparison of MY09/11 consensus PCR and type-specific PCRs in the detection of oncogenic HPV types

The causal relationship between persistent infection with high-risk HPV and cervical cancer has resulted in the development of HPV DNA detection systems. The widely used MY09/11 consensus PCR targets a 450bp conserved sequence in the HPV L1 gene, and can therefore amplify a broad spectrum of HPV types. However, limitations of these consensus primers are evident, particularly in regard to the variability in detection sensitivity among different HPV types. This study compared MY09/11 PCR with type-specific PCRs in the detection of oncogenic HPV types. The study population comprised 15, 774 patients. Consensus PCR failed to detect 522 (10.9%) HPV infections indicated by type-specific PCRs. A significant correlation between failure of consensus PCR and HPV type was found. HPV types 51, 68 and 45 were missed most frequently. The clinical relevance of the HPV infections missed by MY09/11 PCR was reflected in the fraction of cases with cytological abnormalities and in follow-up, showing 104 (25.4%) CIN2+ cases. The MY09/11 false negativity could be the result of poor sensitivity, mismatch of MY09/11 primers or disruption of L1 target by HPV integration or DNA degradation. Furthermore, MY09/11 PCR lacked specificity for oncogenic HPVs. Diagnostic accuracy of the PCR systems, in terms of sensitivity (MY09/11 PCR: 87.9%; type-specific PCRs: 98.3%) and specificity (MY09/11 PCR: 38.7%; type-specific PCRs: 76.14%), and predictive values for histologically confirmed CIN2+, suggest that type-specific PCRs could be used in a clinical setting as a reliable screening tool.

Correlation between laminin-5 immunohistochemistry and human papillomavirus status in squamous cervical carcinoma

BACKGROUND

Human papillomavirus (HPV) plays a critical role in the carcinogenesis of squamous cervical carcinoma. Integration of viral DNA into the host genome is a major contributing factor to malignant transformation. Viral load may influence integration.

AIMS

To compare HPV status (type, viral load, integration status) between normal samples, carcinoma in situ and invasive carcinoma in order to elucidate the role of HPV in progression to invasive lesions.

METHODS

The study population comprised 10 biopsy samples from each diagnostic group. Laminin-5 immunohistochemistry was performed to distinguish invasive carcinoma from non-invasive high-grade lesions. Real-time PCR was used to detect specific HPV types, viral load and integrated HPV, with quantification of viral E2 and E6 genes.

RESULTS

Invasive carcinomas contained a higher number of laminin-5 immunoreactive cells as compared to non-invasive lesions. Almost all samples contained HPV, with a higher viral load and copy number of HPV16 integrated in E2 in cases of laminin-5 immunoreactivity and cases of invasive carcinoma. High HPV16 viral load was associated with more integrated copies in E2.

CONCLUSIONS

HPV is important in progression from carcinoma in situ to invasive carcinoma. Viral load and HPV integration influence the development of cervical cancer towards invasiveness. Overall HPV status may be more predictive of patient outcome and may influence patient management.

Improved endocervical sampling and HPV viral load detection by Cervex-Brush Combi

OBJECTIVE

Liquid-based cytology (LBC) for cervical screening is becoming increasingly used. Together with SurePath LBC, various collecting devices can be utilized, among which the Cervex-Brush is the most widely used. The new Rovers Cervex-Brush Combi combines the advantages of the Cervex-Brush with the EndoCervex-Brush increasing sampling of the endocervical canal. The objective of this study was to analyse and to compare the Cervex-Brush Combi with the Cervex-Brush for the collection of squamous and endocervical cells, human papillomavirus (HPV) typing/quantification and disease detection in SurePath LBC.

METHODS

Using either the Cervex-Brush or the Cervex-Brush Combi 100 consecutive SurePath LBC samples were collected using each brush type. All 200 slides were read by the FocalPoint and screened by guided screening using slide wizards. The viral load of HPV type 16 E7, 18 E7, 31 E6, 33 L1, 33 E6, 35 E4, 39 E7, 45 E7, 51 E6, 52 L1, 52 E7, 53 E6, 56 E7, 58 L1, 58 E6, 59 E7, 66 E6 and 68 E7 was determined using a TaqMan-based real-time quantitative PCR analysis.

RESULTS

The mean number of sampled squamous cells did not differ between the two brush types (54 963 versus 54 595 cells). The use of the Cervex-Brush Combi, however, resulted in a two- to threefold increase in the number of sampled endocervical cells (P < 0.00001). Using the Cervex-Brush Combi slightly more lesions were detected (three versus two low-grade squamous intraepithelial lesions), and resulted in the detection of more atypical squamous cells of undetermined significance (six versus three). In the Cervex-Brush group, 60% (3/5) of abnormal smears were positive for oncogenic HPV types, whereas 66.7% (6/9) of abnormal smears in the Cervex-Brush Combi group tested positive. The median HPV viral load for samples taken with the Cervex-Brush Combi was 0.1825 copies/cell and was significantly higher than in samples taken with the Cervex-Brush (0.0042 copies/cell) (P = 0.02).

CONCLUSION

Sampling with the Cervex-Brush Combi resulted in the collection of the same amount of squamous cells, but in a two to threefold harvest of endocervical cells. This led to the detection of a higher viral load for oncogenic HPV and an increase in the number of detected abnormal smears.

Distribution and viral load of eight oncogenic types of human papillomavirus (HPV) and HPV 16 integration status in cervical intraepithelial neoplasia and carcinoma

Current human papillomavirus (HPV) DNA testing using pooled probes, although sensitive, lacks specificity in predicting the risk of high-grade cervical intraepithelial neoplasia (CIN 2/3) progression. To evaluate selected HPV genotyping, viral load, and viral integration status as potential predictive markers for CIN progression, we performed HPV genotyping in formalin-fixed, paraffin-embedded cervical tissue with cervical carcinoma (29 cases) and CINs (CIN 1, 27 cases; CIN 2, 28 cases; CIN 3, 33 cases). General HPVs were screened using consensus primers GP5+/GP6+ and PGMY09/11. HPV genotyping and viral load measurement were performed using quantitative real-time PCR for eight oncogenic HPV types (16, 18, 31, 33, 35, 45, 52, and 58). HPV 16 viral integration status was evaluated by measuring HPV 16 E2/E6 ratio. We observed that HPV DNA positivity increased in parallel with the severity of CINs and carcinoma, with 59% positivity in CIN 1, 68% in CIN 2, 76% in CIN 3, and 97% in carcinoma (P trend=0.004). The eight oncogenic HPV types were significantly associated with CIN 2/3 (81%) and carcinoma (93%) (odds ratio (OR), 15.0; 95% confidence interval (CI), 5.67-39.76; P<0.0001) compared with the unknown HPV types (OR, 2.87; 95% CI, 0.89-9.22; P=0.08). HPV 16 was the predominant oncogenic HPV type in CIN 2/3 (51%) and carcinoma (71%) and integrated significantly more frequently in carcinoma than in CIN 2/3 (P=0.004). No significant differences in viral load were observed across the disease categories. Our findings suggest that selected genotyping for the eight oncogenic HPV types might be useful in separating women with a higher risk of CIN progression from those with a minimal risk. We also conclude that the HPV 16 integration status has potential to be a marker for risk assessment of CIN progression.

Evaluation of combined general primer-mediated PCR sequencing and type-specific PCR strategies for determination of human papillomavirus genotypes in cervical cell specimens

A strategy combining human papillomavirus general primer (mainly the PGMY primers)-directed PCR sequencing and type-specific PCR is presented. DNA samples were first tested in general primer-mediated PCR. The amplified fragments of positive samples after ethidium bromide-stained DNA gel analysis were further sequenced, and corresponding DNA samples were further analyzed by PCR using type-specific primers for human papillomavirus (HPV) types 16, 18, 31, and 52. The comparison of the results of 157 samples analyzed by this strategy in parallel with the Hybrid Capture 2 tests and with the HPV INNO-LiPA (Innogenetics line probe assay) shows that this method is suitable for HPV detection and genotyping in cervical cell samples. Although the PCR sequencing method is as sensitive as the HPV INNO-LiPA for HPV detection, our method allows the identification of a broader range of HPV types. In contrast, the HPV INNO-LiPA was less time-consuming and better identified coinfections.

Type-Specific Persistence of High-Risk Human Papillomavirus Infections in the New Independent States of the former Soviet Union Cohort Study

BACKGROUND

Prospective follow-up studies have recently suggested that persistent high-risk human papillomavirus (HPV) infections play a key role in the progression of CIN lesions and in the development of cervical cancer. However, data on type-specific persistence, viral integration, and the role of multiple infections are scanty.

MATERIALS AND METHODS

A cross-sectional/cohort study was conducted between 1998 and 2002 in three New Independent States of the former Soviet Union comprising a cohort of 3,187 women, of whom 854 women were followed up for a mean of 17 months (SD, 11.6). HPV genotyping was done with real-time PCR, detecting HPV types 16, 18/45, 31, 33/52/58, 35, and 39. The integration status of HPV16 was examined by using a novel Taqman-based PCR method.

RESULTS

The mean clearance time for the individual high- risk-type infection was 16.5 months (range = 0.9-34.9 months). HPV16 and HPV31 were the most persistent infections (clearance times = 18.1 and 16.2 months, respectively), whereas HPV39 infections cleared most rapidly. The mean copies per cell in HPV18/45, HPV31, HPV33/52/58, and HPV39 infections were higher in persisting HPV infections than in HPV infections that cleared, but the difference was not significant. Integration of HPV16 was not found to correlate with HPV persistence.

CONCLUSIONS

A large proportion of women remained high-risk HPV positive after 18 months. Coinfection with multiple HPV types, viral load, or integration status did not correlate with persistence of high-risk HPV infections.

Prevalence of the most common high-risk HPV genotypes among women in three new independent states of the former Soviet Union

Type distribution of HPV has been studied in different geographic regions, but the data are scanty from the new independent states of the former Soviet Union. Here the HPV prevalence and distribution of the most frequent high-risk HPV types among 3,187 women at different risk for HPV and cervical intraepithelial neoplasia in Russia, Belarus, and Latvia is reported. HPV detection, type distribution and viral load analysis in DNA samples from cervical scrapes were done with real-time PCR-based assay detecting HPV types 16, 18, 31, 33, 35, 39, 45, 52, and 58. The overall HPV prevalence was 31.2%, HPV16 was the most prevalent type followed by HPV31 and HPV33 group. The overall HPV prevalences in Russia, Belarus and Latvia were 33.4%, 27.5%, and 26.2%. The type distributions were similar in these countries, except for Latvia where HPV39 was the third prevalent genotype. HPV prevalence was highest (40.8%) among women from sexually transmitted disease clinic, followed by 30.9% among gynecological outpatients and 27.2% in screening patients. HPV detection increased with cytological abnormality (P = 0.0001) and lesion grade in the biopsy (P = 0.0001), from 27% to 72% in normal samples to cancer, and from 64% to 77% in cervical intraepithelial neoplasia 1 to cancer. The normalized viral loads varied greatly between and among different HPV-types. The mean log HPV33 group copies/cell increased from negative for intraepithelial lesions to cancer (P = 0.049). Distribution of the most common high-risk HPV-types seems to be similar in these countries as reported in other major geographical regions.

Prevalence of high risk human papillomavirus types among Nicaraguan women with histological proved pre-neoplastic and neoplastic lesions of the cervix

OBJECTIVES

To determine the prevalence of high risk human papillomavirus (HPV) types in Nicaraguan women with histological proved pre-neoplastic and neoplastic cervical lesions, and to assess its potential impact on preventive strategies.

METHODS

206 women with histopathological confirmed cervical lesions (CIN I or worse) were screened for HPV DNA on a liquid based cytology sample, using an HPV short fragment polymerase chain reaction based assay. HPV positive samples were genotyped with a reverse hybridisation line probe assay (Lipa). HPV negative samples were re-analysed using type specific real time polymerase chain reaction.

RESULTS

Of all lesions CIN II or worse, 12% tested negative. Prevalence of high risk HPV increased from 48.1% in cervical intraepithelial neoplasia I (CIN I) to 94.7% in invasive squamous cervical carcinoma (SCC). The most prevalent high risk HPV types were, in order of prevalence rate, HPV 16, 58, 31 and 52. HPV 16 and/or HPV 31 were present in 63.2% of SCC cases.

CONCLUSION

Targeting HPV 16 and 31 with prophylactic vaccines could possibly have an important impact on the incidence of invasive cervical carcinoma in Nicaragua. Further research is needed to define the oncogenic potential of other high prevalent HPV genotypes. Meanwhile, primary prevention and cervical cancer screening programmes should be optimised.

Determination of HPV type 16 and 18 viral load in cervical smears of women referred to colposcopy

It has been recognized that human papillomavirus infection is the major causal factor for high-grade cervical lesions. The aim of the study was to evaluate the relationship between HPV 16 and 18 viral loads and cervical status in different age strata. A duplex real time PCR method was devised to determine HPV 16 and 18 viral load per million of human cells using an in house plasmidic construct as a standard of quantification. The 151 cervical scrapes were collected before colposcopic examination from either abnormal cervico-vaginal smear (group 1, 97 patients) or from post treatment clinical follow-up (group 2, 54 patients). In women aged 30-40, the HPV16 viral loads were significantly higher in high-grade squamous intraepithelial lesion than in low-grade squamous intraepithelial lesion in both groups and HPV18 in group 1. In women aged 20-30 of group 1, high HPV viral load was associated in few cases with high-grade squamous intraepithelial lesion or low-grade squamous intraepithelial lesion, and surprisingly in some patients with normal cervix. HPV 16 and 18 viral loads are related to the severity of cervical lesion, and may be useful in the clinical management of cervical lesions. A specific follow-up may be useful for those with high viral load despite normal cervix.

High-risk human papilloma virus (HPV) and survival in patients with esophageal carcinoma: a pilot study

BACKGROUND

Human papilloma virus (HPV) in patients with esophageal carcinoma has previously been studied with an average detection rate of 15%, but the role of HPV in relation to survival is less clear. In cervical cancer, lung cancer and tonsil cancer HPV viral load is a predictive factor for survival and outcome of treatment. The primary aim was to study the spectrum of high-risk HPV types in esophageal tumors. Secondary, as a pilot study we investigated the association between HPV status and the survival rates.

METHODS

We compared both the presence and the viral load of high-risk HPV types 16, 18, 31, 33, 39, 45, 52, 58, and 67 in relation to clinical data from patients with esophageal carcinoma. Survival data and tumor samples were retrieved from 100 patients receiving treatment at the Department of Oncology, Uppsala Hospital, Uppsala, Sweden. The tumor samples were investigated for HPV viral load using real-time PCR.

RESULTS

HPV 16 was detected in 16% of the patients; no other HPV type was detected. HPV 16 infection had no significant effect on survival (p = 0.72). Also, HPV 16 did not improve survival after treatment (radiotherapy or chemotherapy).

CONCLUSION

Only HPV 16 was detected among the patients. HPV 16 in esophageal carcinoma patients did not influence survival or improve therapy response. However, given the size of the study there is a need to examine a larger cohort in order to understand in more detail the effect of high risk HPV types in esophageal carcinoma.

Early integration of high copy HPV16 detectable in women with normal and low grade cervical cytology and histology

BACKGROUND

Integration of human papillomavirus (HPV) DNA has been considered a late event in cervical carcinogenesis. However, integrated forms of HPV were recently detected in cancer precursor lesions using a new real time polymerase chain reaction (PCR) to detect the deletions at the 3362-3443 region of HPV16 E2 OBJECTIVE: To study the frequency of HPV16 DNA integration in cervical lesions and compare the sensitivity of an additional upstream region of the E2 ORF (2962-3138) in detecting HPV integration.

METHODS

Using the TaqMan based PCR, HPV16 positive DNA samples were analysed in 164 cervical scrapings from women participating in a multicentre screening trial. Biopsy confirmation was available in 62 cases.

RESULTS

Primers targeting the 3362-3443 region detected the majority of E2 deletions. In only 23% of the samples was the E2 upstream region equal or better target than the 3362-3443 region. Mixed (episomal/integrated) pattern was the most prevalent physical state of HPV16, also present in PAP smears with normal morphology. Pure integrated form was most prevalent in HSIL and cancer lesions, but also detectable in low grade abnormalities (NSIL, ASC-US, LSIL). Women with only integrated HPV16 were almost 10 years older than those with episomal HPV16. Viral load of integrated HPV16 was related to cytological abnormality (p = 0.003) but not to histology.

CONCLUSIONS

Integrated HPV16 is present in low grade cervical lesions, mostly mixed with the episomal form. Women with the pure integrated form of HPV16 are older than those with the other forms.

HPV testing in cervical screening

High-risk human papillomavirus (hrHPV) bearing cervical intraepithelial neoplasia (CIN) is considered, as the real precursor lesion of cervical cancer and persistence of an hrHPV infection is necessary for the progression to cervical cancer. This knowledge warrants the use of hrHPV testing as an adjunct to cervical cytology in population-based screening programmes and for monitoring therapy efficacy of high-grade CIN lesions. Replacement of cytology by hrHPV testing altogether is considered, but for this to be (cost-) effective, accurate information about the specificity of the hrHPV test is required. Additional test systems that can be used to stratify women with a positive hrHPV test are HPV genotyping, viral load analysis and hrHPV mRNA analysis. The need for HPV genotyping of cervical smears is illustrated by the increased risk for high-grade cervical lesions associated with HPV types 16 and 18. In particular, for women who have normal but persistently (>1 year) HPV18-positive smears, endocervical curettage is suggested (evidently considering the age and possible future pregnancies of the respective woman) because HPV18 is associated with glandular lesions in the cervix, which are difficult to detect by cytology.

High level of correlation of human papillomavirus-16 DNA viral load estimates generated by three real-time PCR assays applied on genital specimens

Human papillomavirus-16 (HPV-16) viral load could be a biomarker predictive of the presence of high-grade cervical lesions. Recently, several real-time PCR assays have been developed to accurately measure HPV-16 viral load. However, results from various reports using these assays cannot be compared because interassay test correlation has not been documented. The variability of HPV-16 DNA quantitation was assessed by comparing three real-time PCR assays (HPV-16 L1, HPV-16 E6, and HPV-16 E6 PG) applied on 144 genital samples (125 cervicovaginal lavages and 19 specimens collected using vaginal tampons) obtained from 84 women (66 HIV seropositive and 18 HIV seronegative). Correlation was greater between the HPV-16 E6 assays [correlation coefficient (rho) = 0.92] than between each E6 assay and HPV-16 L1 assay (rho = 0.83 and 0.84, respectively). The median HPV-16 copies measured by HPV-16 E6 PG (14,609 HPV-16 copies/2 muL sample) and HPV-16 E6 (18,846 HPV-16 copies/2 muL) were similar (P = 0.27) but were both greater than the median HPV-16 copies measured with the L1 assay (4,124 HPV-16 copies/2 muL; P < 0.001). Correlations between HPV-16 E6 assays were similar for samples containing non-European (rho = 0.93) or European (rho = 0.95) variants. However, the correlation between HPV-16 L1 and HPV-16 E6 PG or HPV-16 E6 was lower for specimens containing non-European variants (rho = 0.80 and 0.76, respectively) compared with specimens containing European variants (rho > 0.85). HPV-16 DNA quantity estimated with the three assays was comparable although lower with the HPV-16 L1 assay. The level of correlation depended on viral polymorphism, viral load, and cervical disease status.

Interaction of host and viral risk factors for development of cervical carcinoma in situ

Infection by oncogenic human papillomavirus (HPV) is a necessary but not sufficient cause of cervical carcinoma. Several host genetic and viral factors have been reported to increase the risk of carcinoma development given an HPV infection. In our study, we have analysed the contribution of HPV 16 E6 sequence subtype and allelic variation at human leukocyte antigen (HLA) class II loci to the risk of developing cervical carcinoma in situ. Non-European-like HPV 16 E6 sequence subtypes were not found to be associated with an increased risk of cervical carcinoma, as compared to European-like variants. However, an association was found between the HPV 16 E6 L83V variant and the DR*04-DQ*03 haplotype. This association has been observed in several independent studies and shows that both the host HLA class II genotype and viral subtype will affect the risk of an infection progressing into cervical carcinoma.

Dynamics of HPV16 DNA load reflect the natural history of cervical HPV-associated lesions

BACKGROUND

High burden of high risk human papillomavirus (HR HPV) has been shown to be predictive for the development of high grade cervical lesions and invasive cancers. However, low viral load cannot inevitably exclude progression towards cervical diseases. Moreover, few studies addressed whether viral load could predict infection clearance.

OBJECTIVES

We carried out a retrospective study to analyze the variations of HPV16 load over time as a predictive marker of clinical outcome.

STUDY DESIGN

The population consisted of 38 women who were found HR HPV positive by HCII test at study entry. Among them, 13 had developed a CIN2/3 (cases) and 25 had a negative HCII test and a normal cytology (controls) at study exit. The HPV16 DNA loads were quantified in 132 longitudinal cervical samples using quantitative real-time PCR.

RESULTS

At study entry, the median of HPV16 load was not statistically different between controls and cases. However, when using a cut-off value of 200 copies/10(3) cells, the rate of cumulative incidence of CIN2/3 at 18 months increased from 14% in women with a load<or=200 copies/10(3) cells to 48% in women with a load>200 copies/10(3) cells. The longitudinal analysis performed on follow-up samples showed that in cases the progression to CIN2/3 was linked to HPV16 burden increasing over time, whereas in controls a decrease of at least 1 log HPV16 DNA load was observed over>or=2 time points.

CONCLUSIONS

These results show that kinetics of HPV load, rather than a single HPV detection, might be more reliable to estimate whether a HPV infection will progress or be cleared.

Type distribution, viral load and integration status of high-risk human papillomaviruses in pre-stages of cervical cancer (CIN)

A series of 176 archival cervical intraepithelial neoplasia (CIN) was analysed for the presence, viral load and integration status of ‘high-risk’ types of human papillomavirus (HR-HPV). The samples were assayed using newly developed methods based on real-time PCR. Two methods for the extraction of DNA from the paraffin-embedded biopsies were compared: a protocol based on the MagNA pure system (Roche) and a Qiagen spin column kit (Qiagen). It was possible to amplify 94% (166) of the samples. Of these, 36, 63 and 80% of the CIN I, II and III cases contained HR-HPV. HPV 16 was the most prevalent, and was found in 20, 28 and 46% of the CIN I, II and III cases, respectively. The second most frequent HR-HPV was type 33 group, and in CIN II it was as prevalent as HPV 16. The median number of copies of HR-HPV per cell was not significantly different in the CIN I, II and III cases, but there was a wide range of viral load values over several magnitudes, regardless of the grade of CIN. All samples were found to contain integrated forms of HPV 16, frequently mixed with an episomal form.

Nucleic acid testing for viral burden and viral genotyping

BACKGROUND

Molecular diagnostics plays an important role in the diagnosis and clinical management of a wide array of infectious diseases.

METHODS

Advances in molecular technology and methods of detecting nucleic acid sequences have revolutionized the field of virology. These developments are reflected by the rapid diagnosis and monitoring of viral agents as well as assessment of clinical disease associated with viral infections. In addition to many commercially available molecular based assays, many laboratories offer in-house developed assays for a variety of viral targets. The introduction of real-time PCR technology has made a large impact on virology testing.

CONCLUSIONS

The role of real-time PCR for the diagnosis of viral infections is enhanced by the accuracy, rapidity and ability to quantitate viral target sequences.

An inter-platform repeatability study investigating real-time amplification of plasmid DNA

Background

The wide variety of real-time amplification platforms currently available has determined that standardisation of DNA measurements is a fundamental aspect involved in the comparability of results.

Statistical analysis of the data arising from three different real-time platforms was conducted in order to assess inter-platform repeatability. On three consecutive days two PCR reaction mixes were used on each of the three amplification platforms – the LightCycler^®, ABI PRISM^® 7700 and Rotor Gene 3000™. Real-time PCR amplification using a fluorogenic 5' exonuclease assay was performed in triplicate on negative controls and DNA plasmid dilutions of 10⁸–10² copies to give a total of 24 reactions per PCR experiment.

Results

The results of the statistical analyses indicated that the platform with the most precise repeatability was the ABI PRISM^® 7700 when coupled with the FastStart PCR reaction mix. It was also found that there was no obvious relationship between plasmid copy number and repeatability. An ANOVA approach identified the factors that significantly affected the results, in descending order of magnitude, as: plasmid copy number, platform, PCR reaction mix and day (on which the experiment was performed).

Conclusion

In order to deliver useful, informative genetic tests, standardisation of real-time PCR detection platforms to provide repeatable, reliable results is warranted. In addition, a better understanding of inter-assay and intra-assay repeatability is required.

High levels of HPV-16 DNA are associated with high-grade cervical lesions in women at risk or infected with HIV

OBJECTIVE

To examine associations between levels of episomal and integrated human papillomavirus (HPV) 16 DNA and the grade of cervical disease.

DESIGN

Cross-sectional data were obtained from a cohort of women with and without HIV infection and with high-risk sexual behaviour.

METHODS

Episomal and integrated HPV-16 DNA loads were measured in cervicovaginal lavages collected from 75 women (58 HIV seropositive, 17 HIV seronegative) using real-time polymerase chain reaction assays, controlling for cell content and the presence of inhibitors.

RESULTS

HPV-16 viral loads were significantly higher in women with high-grade squamous intraepithelial lesions (n = 6) than in women with normal cytology (n = 44), whether total (10(8.28) versus 10(5.10) HPV-16 DNA copies/microg DNA), episomal (10(7.99) versus 10(4.61)) or integrated (10(7.95) versus 10(4.77)) HPV-16 viral loads were measured (P < 0.02 for each comparison). Thirty-nine women had colposcopy [11 normal cervix, 16 cervical intraepithelial neoplasia (CIN) 1, six CIN 2, six CIN 3] and 24 additional women had three consecutive normal cytology smears. Controlling for age, race, CD4 cell count and HIV status, total (OR 3.5, 95% CI 1.2-10.4; P = 0.02), episomal (OR 2.9, 95% CI 1.2-7.4; P = 0.02,) and integrated (OR 1.6, 95% CI 1-2.6; P = 0.05) HPV-16 DNA loads were significantly associated with CIN 2,3, but the differences between CIN 1 and CIN 2,3 were not significant (P > 0.06). A greater amount of cellular DNA was collected from women with CIN 2,3 (P = 0.007).

CONCLUSION

Higher HPV-16 DNA loads are associated with cervical lesions detected by either histology or cytology. No additional information is gained by measuring integrated or episomal over total HPV-16 DNA loads.

High viral loads of human papillomavirus predict risk of invasive cervical carcinoma

High loads of human papillomavirus (HPV) 16 and HPV 18/45 increase the risk of developing invasive cervical carcinoma, revealing higher risk in percentiles of highest viral loads for HPV 16 (odds ratio (OR) 58.7, 95% confidence interval (CI) 21.9–151.4) compared to HPV 18/45 (OR 3.3, 95% CI 1.5–7.2). Thus, HPV load is a type-dependent risk marker for invasive carcinoma.

Determination of Human Papillomavirus (HPV) Load and Type in High-Grade Cervical Lesions Surgically Resected from HIV-Infected Women during Follow-up of HPV Infection

BACKGROUND

The role of human papillomavirus (HPV) load and the importance of multiple-strain HPV infections as biomarkers for the development of cervical disease were evaluated in human immunodeficiency virus (HIV)-positive women.

METHODS

A total of 108 samples were analyzed, 64 of which were obtained from 16 HIV-positive women who underwent surgical resection of the cervical cone for treatment of a histologically confirmed high-grade cervical intraepithelial neoplasm (cases) and 44 of which were obtained from 22 HIV-positive women who had high-risk HPV but a negative colposcopy result (controls). Each patient underwent periodic examinations at 6-12-month intervals that included colposcopy, Papanicolaou testing, biopsy (if indicated), and cervical brushing for HPV testing. Viral typing was performed by reverse dot-blot hybridization and quantification of viral load by in-house real-time PCR and commercial assays.

RESULTS

Analysis of the cervical-brush samples collected when high-grade squamous intraepithelial lesions were diagnosed revealed that all cases had HPV loads that were significantly higher than those of controls (P=.0004 and P=.0003, by PCR and the Hybrid Capture 2 index [Digene], respectively). Decreasing concentrations of HPV load were observed when comparing samples obtained before and after treatment (P<.0001). The number and type of HPV strains that were detected were not statistically different between cases and controls.

CONCLUSIONS

The significantly higher HPV load detected in women with high-grade cervical dysplasia, as well as the dramatic decrease in the load after surgical removal of the lesion, suggest that HPV load is a possible prognostic marker of high-grade SIL.

HLA class II allele control of HPV load in carcinomain situ of the cervix uteri

Human papillomavirus (HPV) infection is the most important risk factor for development of cervical carcinoma. Carriers of certain HLA class II alleles, e.g., DRB1*1501 and DQB1*0602, are more prone to HPV 16 infection and cervical carcinoma, whereas other alleles, e.g., DRB1*1301 and DQB1*0603, render carriers less susceptible to the disease. In our study comprising 484 cases and 601 controls, we examine the effect of HLA class II alleles on viral load of the oncogenic types HPV 18/45 and HPV 31 and risk of developing cervical carcinoma in situ. We find that carriers of the commonly reported protective DRB1*1301 and DQB1*0603 alleles have lower HPV 18/45 load compared to noncarriers and a lower risk of developing HPV 18/45-positive cervical carcinoma. This provides further evidence that the HLA class II-mediated immune response to HPV is important for controlling viral load and outcome of an infection.

High risk HPV load estimated by Hybrid Capture II® correlates with HPV16 load measured by real-time PCR in cervical smears of HPV16-infected women

BACKGROUND

High risk human papillomavirus (HR-HPV) load determined by quantitative methods has already been considered as highly predictive of future development of high grade cervical lesions. Some studies also demonstrated that Hybrid Capture II (HCII) results can be considered as a reflection of HPV DNA load, while others did not. HCI assay, well suited for routine HR-HPV screening, is not especially dedicated for quantitative use. However, we have recently shown that women with high viral loads assessed by HCII were at increased risk of cervical precancer.

OBJECTIVES

The aim of the study was to determine if the values given by the HCII assay can be considered as quantitative.

STUDY DESIGN

We used a real-time PCR allowing precise quantification of both HPV16 genome and albumin gene to normalize the measuring HPV16 load in cervical cells and to compare the data with those obtained by HCIIin a series of 40 HR-HPV positive samples.

RESULTS

Reproducibility of the HPV16 real-time PCR, assessed from nine independent experiments of serial dilutions of SiHa cell DNA, was reflected in coefficients of variation for standard curves of crossing point (Cp) values below 5%. The HPV16 loads with a broad individual variability were significantly related to the cumulative load estimated by HCII and did not depend on the cellularity of samples.

CONCLUSIONS

We assume that the HCII values can be used as a quantitative measure of HR-HPV DNA, so long as cervical specimens are collected using standardized protocols.

Epidemiological and clinical aspects of human papillomavirus detection in the prevention of cervical cancer

Cervical cancer is a major cause of death, and the second most frequent cancer in women worldwide. Many studies have indicated a causal relation between genital human papillomavirus (HPV) infections and cervical cancer. High-risk HPV genotypes have been detected in almost 100% of all cervical cancers, and the process of HPV mediated carcinogenesis has been partly clarified. The concept that HPV is a obligatory cause in cervical cancer development has lead to extensive research regarding the incorporation of HPV detection in (1) cervical cancer prevention programs, (2) triage of women with abnormal cervical scrapes in the screening program, and (3) follow-up of patients treated for cervical intraepithelial neoplasia (CIN). Epidemiological studies indicate that 50% of women becoming sexually active contract a genital HPV infection within 2 years. The lifetime risk of a genital HPV infection is estimated to be 80%, but very few of these women will develop cervical cancer. Several studies have shown that the persistence of genital HPV infections is especially related to the development of cervical cancer. As a result, HPV detection at a single moment was shown to be of limited clinical value in the triage of patients with abnormal cervical scrapes, or during follow-up after treatment for CIN. Furthermore, major variations in the sensitivity of different HPV detection methods, as well as differences in HPV detection related to the menstrual cycle, have shown that many facts regarding HPV transmission, replication, and detection need to be clarified, before HPV detection can be of clinical value.

Type-specific associations of human papillomavirus load with risk of developing cervical carcinomain situ

We have previously shown that high human papillomavirus (HPV) 16 load in Papanicolaou smears negative for dysplasia is strongly associated with risk for carcinoma in situ (CIS) of the cervix. Here we study the amount of HPV DNA for some of the most frequent high-risk HPV types as determinants of progression to cervical CIS. Real-time PCR is used to estimate the normalized viral load of HPV 16, 18, 31, 33, 35, 39, 45, 52, 58 and 67 in 457 cases of cervical CIS and 552 matched population controls. A total of 2,747 archival Pap smears from gynecologic health examinations, collected over a period of up to 26 years, were analyzed to assess viral load during the infection history. Cervical smear samples differ widely in amount of DNA, underscoring the need for normalization of HPV load to number of cells in the sample. The risk of developing cervical CIS increases with higher viral load for most of the HPV types studied. The range of copy numbers per cell does not differ between HPV types but the odds ratio for CIS in the percentile with highest viral load is substantially higher for HPV 16 (OR = 36.9; 95% CI = 8.9-153.2) than for HPV 31 (OR = 3.2; 95% CI = 1.1-9.1) or HPV 18/45 (OR = 2.6; 95% CI = 1.0-6.4). Therefore, HPV viral load may be predictive of future risk of cervical CIS at a stage when smears are negative for squamous abnormalities, but differences between HPV types need closer attention.