Human papillomaviral load changes in low-grade squamous intraepithelial lesions of the uterine cervix

Evaluation of Viral Load as a Triage Strategy With Primary High-Risk Human Papillomavirus Cervical Cancer Screening

OBJECTIVE

The aim of the study was to evaluate the human papillomavirus (HPV) viral load combined with cytology as a secondary screening strategy after primary HPV screening.

MATERIALS AND METHODS

The data referring to direct Hybrid Capture 2 (HC2), cytology, and histology from Shenzhen Cervical Cancer Screening Trial II were re-analyzed to determine the correlation between viral load and cervical lesions. In addition, algorithms using different viral loads as cut points for immediate colposcopy plus cytology triage were compared with several recommended or controversial primary screening methods.

RESULTS

A total of 8,556 women with a mean age of 38.9 years were included in the analysis, of which 13.67% tested high-risk HPV positive with a prevalence of 2.72% for cervical intraepithelial neoplasia 2+ (CIN 2+) and 1.65% for CIN 3+. A significant correlation was observed between increasing relative light units/control (RLU/CO) values and worsening cervical lesions. The mean RLU/CO values for negative, CIN 1, CIN 2, CIN 3, and cancer were 6.86, 119.43, 410.90, 449.39, and 853.26, respectively. A larger proportion of HPV infections with relative high viral load (≥10 RLU/CO) were found in higher-grade lesions. The algorithm using 10 or greater RLU/CO as cut point for immediate colposcopy followed by triage cytology for the other positive (≥1 < 10 RLU/CO) had sensitivity of 93.13%/96.45% and specificity of 92.32%/91.44% for CIN 2+/3+, and the colposcopy referral rate was 10.00%.

CONCLUSIONS

Human papillomavirus viral load level is positively associated with cervical lesion grade. Ten relative light units/control or greater is a viable threshold for immediate colposcopy whereas 1 or greater or less than 10 RLU/CO is advised to reflex cytology for optimizing sensitivity and specificity, as well as referral rates.

Implications of semi-quantitative HPV viral load estimation by Hybrid capture 2 in colposcopy practice

OBJECTIVE

High viral load of oncogenic human papillomavirus (HPV) significantly increases risk of CIN 2 or worse (CIN 2+) lesions. Semi-quantitative estimation of oncogenic HPV viral load by Hybrid Capture 2 (HC2) correlates well with viral load estimated by real-time polymerase chain reaction. We correlated viral load estimated by HC2 with colposcopy and histology diagnosis, to determine if high viral load could detect the CIN 2+ lesions missed by colposcopy in HPV positive women.

METHODS

Using HPV testing by HC2, 39,728 women were screened. Positive results were categorized into low-positive, intermediate, and high viral load groups, based on relative light unit/cut-off ratios. HPV-positive and some HPV-negative women underwent colposcopy and biopsy.

RESULTS

A total of 278 CIN 2+ lesions were detected. Detection rate of CIN 2+ was significantly higher in intermediate and high viral load groups. Nearly half (48.3%) of CIN 2+ and 80.4% of CIN 3+ lesions missed or under-diagnosed by colposcopy had viral load in intermediate to high ranges. Risk of CIN 2+ in the high viral load group was 46 times higher than HPV-negative women, even when colposcopy was apparently normal.

DISCUSSION

Women with intermediate or high viral load should have multiple punch biopsies, even if colposcopy is apparently normal or suggests low grade lesions. Women with high viral load and suspected low grade lesion on colposcopy may be considered for 'see-and-treat', as their risk of CIN 2+ is nearly 200 times higher than HPV-negative women.

Low initial human papillomavirus viral load may indicate worse prognosis in patients with cervical carcinoma treated with surgery

Objective

To evaluate the prognostic implication of human papillomavirus (HPV) viral load in cervical cancer patients who underwent radical hysterectomy.

Methods

We conducted a retrospective review of patients with stage IA2 through stage IIIA cervical carcinoma who underwent radical hysterectomy at Sun Yat-sen University Cancer Center between January 2005 and December 2009. Patients who had undergone preoperative hybrid capture 2 testing to detect HPV DNA were included. A total of 346 patients positive for HPV DNA were enrolled and stratified into two groups according to the median HPV viral load.

Results

HPV viral load was significantly correlated with lymphovascular space invasion (p=0.026) and deep stromal invasion (p=0.024). However, other factors, such as age, stage, histologic grade, histologic type, lymph node metastasis, and tumor size, were not significantly associated with viral load. Low HPV viral load was correlated with poor disease-free survival in univariate analysis (p=0.037) and multivariate analysis (p=0.027). There was no significant difference in overall survival with regard to initial HPV viral load.

Conclusion

Low initial HPV viral load may be a poor prognostic factor for cervical cancer patients who have undergone radical hysterectomy.

Clinical performance of multiplex high-risk e6 mrna expression in comparison with hpv dna subtypes for the identification of women at risk of cervical cancer

We compared multiplex E6 messenger ribonucleic acid (mRNA) tests using real-time quantitative reverse transcriptase polymerase chain reactions (PCR) with human papillomavirus (HPV) DNA subtypes using a MY11/GP6+ PCR-based reverse-blot assay to identify cervical intraepithelial neoplasias of grade 2 or worse (CIN2+). In total, 684 women were studied, of whom 377 (55%) were diagnosed with CIN2+ histologically. The specificity of HPV mRNA to predict histological CIN2+ was higher than that of HPV DNA (81.3% vs. 44.2%). The odds ratios (ORs) to predict histological CIN2+ in women with positive for type 16, 18, 31, and 45 E6 mRNA or by HPV DNA detection were 7.1 (95% confidence interval [CI] 3.9-13.1) and 2.5 (95%CI 1.9-3.5), respectively, compared to those with negative for E6 mRNA or HPV DNA. The OR to predict histological CIN2+ in women with a cytological grade <CIN2+ and positive for type 16, 18, 31, and 45 E6 mRNA was 9.7 (95%CI 3.2-29.2), compared to those with a cytological grade <CIN2+, and negative for E6 mRNA (OR = 1), those with a cytological grade CIN2+, and negative for mRNA (OR = 6.9, 95%CI 4.4-10.8), and those with a cytological grade CIN2+ and positive for mRNA (OR = 28.0, 95%CI 9.8-79.6). As a HPV DNA positive triage, the OR to predict histological CIN2+ in women with a cytological grade <CIN2+ and positive for mRNA was higher than those with negative for mRNA (OR:12.8 [95%CI 3.6-5.4] vs. OR:1.6 [95%CI 0.9-2.9]). In conclusion, multiplex HPV E6 mRNA detection can be used as a triage for women with cytological grade <CIN2+.

Increased alpha-9 human papillomavirus species viral load in human immunodeficiency virus positive women

BACKGROUND

Persistent high-risk (HR) human papillomavirus (HPV) infection and increased HR-HPV viral load are associated with the development of cancer. This study investigated the effect of human immunodeficiency virus (HIV) co-infection, HIV viral load and CD4 count on the HR-HPV viral load; and also investigated the predictors of cervical abnormalities.

METHODS

Participants were 292 HIV-negative and 258 HIV-positive women. HR-HPV viral loads in cervical cells were determined by the real-time polymerase chain reaction.

RESULTS

HIV-positive women had a significantly higher viral load for combined alpha-9 HPV species compared to HIV-negative women (median 3.9 copies per cell compared to 0.63 copies per cell, P = 0.022). This was not observed for individual HPV types. HIV-positive women with CD4 counts >350/μl had significantly lower viral loads for alpha-7 HPV species (median 0.12 copies per cell) than HIV-positive women with CD4 ≤350/μl (median 1.52 copies per cell, P = 0.008), but low CD4 count was not significantly associated with increased viral load for other HPV species. High viral loads for alpha-6, alpha-7 and alpha-9 HPV species were significant predictors of abnormal cytology in women.

CONCLUSION

HIV co-infection significantly increased the combined alpha-9 HPV viral load in women but not viral loads for individual HPV types. High HR-HPV viral load was associated with cervical abnormal cytology.

Cervical preneoplasia biomarkers: a conundrum for the community based gynecologic surgical pathologist

The integration of high-risk (HR) human papillomavirus (HPV) in the cell genome is an essential step in the oncogenic pathway of lower ano-genital HPV-related squamous preinvasive and invasive lesions. The expression of HR-HPV surrogate biomarkers of HR-HPV integration by immunohistocytochemistry (IHC) serves as a diagnostic and/or a prognostic tool of cervical preinvasive lesions. IHC is claimed to decrease the interobserver variability in the diagnosis of histomorphologically equivocal lesions, and to be helpful in evaluating the potentiality of regression, persistence or progression. The most common biomarkers used in cervical pathology are p16^INK4a, Ki-67, the HPV capsid L1 antigen, and ProEXc. Critical review of the literature shows a great variability in the diagnostic accuracy, risk evaluation, and relative distribution of these biomarkers in low and high grade preinvasive lesions. Review of the literature suggests that currently dual IHC with p16 and L1 provide the best diagnostic and prognostic evaluation of lesions diagnosed histomorphologically as low and high-grade.

Distribution of human papillomavirus genotypes, assessment of HPV 16 and 18 viral load and anal related lesions in HIV positive patients: a cross-sectional analysis

Natural history of anal intraepithelial neoplasia and anal cancer is not fully understood. Factors associated with cytological abnormalities and predictors of progression to high-grade anal intraepithelial neoplasia still deserve investigation. The aim of this cross-sectional study was to assess the prevalence of HPV types, the relationship between HPV genotypes, HPV 16/18 viral load and cytological abnormalities in male and female HIV-infected patients. One hundred and twenty-two (72.6%) patients were infected with HPV, 75 (61%) had multiple HPV infection, and 94 (77%) had high-risk HPV infection. The most frequently identified HPV types were HPV 16 (64%), HPV 6 (39%), HPV 18 (31%), HPV 53 (14.7%), HPV 33 (10.6%), HPV 11 (8.2%), HPV 70 (5.7%), and HPV 61 (4.9%). The HPV types which were most frequently found in combination were HPV 6 + 16 (9.8%), 6 + 16 + 18 (8.2%), 16 + 18 (6.6%), 6 + 18 (4.9%), 16 + 33 (3.3%), 16 + 53 (3.3%). Median HPV16 and 18 viral loads were 6.1 log10 copies/10(6) cells [IQR 5.0-7.3] and 6.1 log10 copies/10(6) cells [IQR 5.7-6.0], respectively. Male gender (P = 0.03, OR: 1.2 [1.0-1.4]) and homo/bisexual transmission routes (P = 0.044, OR: 1.4 [1.0-1.9]) were associated with HPV 16 infection. An HPV 16 viral load cut-off ≥5.3 log10 copies/10(6) cells and a CD4+ cell count ≤200/µl were independent factors associated with abnormal cytology. In the absence of national consensus guidelines, a strict regular follow-up at shorter intervals is recommended for HIV-infected patients with abnormal cytology, especially low grade squamous intraepithelial lesions, an HPV 16 viral load ≥5.3 log/10(6) cells and a CD4+ cell count ≤200/µl.

Detection of the human papillomavirus 58 physical state using the amplification of papillomavirus oncogene transcripts assay

HPV 58 is detected commonly in cervical cancer in East Asian countries. To evaluate the HPV 58 physical state, the amplification of papillomavirus oncogene transcripts (APOT) and hybridisation assays were established. Episome- and integrate-derived transcripts were confirmed by direct sequencing. Twenty-nine HPV 58 positive samples from various cervical lesions were used. The results showed that the episome-derived transcripts were recognised as two major specific amplified products (1040 and 714 bp). Two splice donor sites were mapped to the 5' splice site of the E1 gene on SD898 and SD899 and spliced to the 3' acceptor site of the E4 gene on SA3353, SA3356 and SA3365. The episome-derived transcripts were found 100% in normal cervical epithelia and low-grade lesions (9/9 cases) while the integrate-derived transcripts were detected in 13.3% of high-grade lesions (2/15 cases) and in 20% of carcinomas (1/5 cases). HPV 58 integration sites were found on chromosomes 4q21, 12q24 and 18q12. Using the established APOT assay, the results revealed not only novel information on the HPV 58 transcription patterns of episomal transcripts, but also integration site. The APOT assay is a reliable and useful tool for the detection of the HPV 58 physical state and its oncogene expression.

Significance of HPV 16 and 18 viral load quantitation in women referred for colposcopy

The clinical utility of HPV 16 and 18 viral loads remains debated. The aim of this study was to assess the clinical significance of HPV 16 and 18 viral load and to determine a cut-off for optimal prediction of grade 2 or higher cervical intraepithelial neoplasia among patients referred to colposcopy. A total of 186 cervico-vaginal specimens harboring HPV 16 and/or 18 obtained at the time of colposcopy from patients without previous cervical neoplasia were tested for HPV 16 and 18 detection and quantitation using quantitative duplex real-time PCR method. Grade 2 or higher cervical intraepithelial neoplasia was diagnosed in 87 (46.8%) cases. Only HPV 16 median viral load increased significantly with the lesion grade: 9.1 × 10(4) in normal cervix or grade 1 cervical intraepithelial lesion versus 4.0 × 10(6) copies per million cells in grade 2 or higher cervical intraepithelial lesion (P < 0.001). The highest predictive value for grade 2 or higher cervical intraepithelial lesion was observed with a HPV 16 viral load cut-off of 3.0 × 10(6) copies per million cells (91% specificity, 58.2% sensitivity). Using this cut-off, the highest predictive value of HPV 16 viral load was observed among those referred for previous low-grade abnormal cervical cytology (96.4% specificity, 88% sensitivity). HPV 18 quantitation showed very poor predictive value. Specific attention should be given when performing colposcopic examination of women with an HPV 16 viral load higher than 3.0 × 10(6) copies per million cells, especially among those referred after a low-grade abnormal cytology.

Type-specific interaction between human papillomavirus type 58 E2 protein and E7 protein inhibits E7-mediated oncogenicity

Human papillomavirus type 58 (HPV-58) is a very common HPV type in eastern Asia. Little is known about its biology and tumorigenesis. In this study, HPV-58 E2 protein (58E2) was found to interact with E7 protein (58E7), and the hinge domain of 58E2 was shown to be responsible for binding to the 58E7 protein. Interestingly, the E2-E7 interaction appears to be HPV type-specific, as we found that the HPV-16 E2 could not bind to the 58E7 protein, and neither did 58E2 interact with HPV-16 E7. The biological consequence(s) of the E2-E7 interaction in HPV-58, especially in viral tumorigenesis, was investigated. Results showed that, through interacting with 58E7, 58E2 prevented E7-induced retinoblastoma protein (pRb) degradation and prolonged the half-life of pRb in cells. Additionally, 58E2 abrogated 58E7-induced cell proliferation. These observations collectively suggest that direct interaction with 58E7 is another mechanism for 58E2 to inhibit 58E7-associated carcinogenesis in addition to regulating expression of the 58E7 gene.

Integration of human papillomavirus correlates with high levels of viral oncogene transcripts in cervical carcinogenesis

A prospective, cross-sectional study was conducted to investigate the correlation between the integration of high-risk human papillomavirus and disease severity of cervical lesions. 720 liquid-based cytology specimens including 422 normal cytology, 78 low-grade squamous intraepithelial lesions, 172 high-grade squamous intraepithelial lesions, and 48 women with cervical cancers were examined using HPV blot and type-specific E6 PCR. Positive HPV DNA types 16, 18, 52 and 58 were examined for viral DNA using real-time PCR. Expression of E6 transcripts was 89.5% (pure integration), 71.7% (mixed type), and 47.1% (pure episomal) (p<0.0001). Geometric mean levels ranged from 110.6 (episomal form) to 508.4 (mixed form), and 5966.2 (integration form) by real-time PCR (p<0.0001). Geometric mean levels of E6 transcript in HPV 16, 18, 52, and 58 correlated with the severity of cervical lesions and the physical integration state of the viral genome (p<0.0001). We conclude that this is the first paper to point out that integration of high-risk HPVs not only 16 and 18 but also 52 and 58 is correlated with high levels of oncogene transcripts from normal cervix, CIN to cervical cancer.

Viral load in the natural history of human papillomavirus type 16 infection: a nested case-control study

BACKGROUND

Viral load may influence the course of human papillomavirus type 16 (HPV-16) infection.

METHODS

This case-control study was nested within the 2-year Atypical Squamous Cells of Undetermined Significance and Low-Grade Squamous Intraepithelial Lesion Triage Study, in which women were followed semiannually for HPV and cervical intraepithelial neoplasia (CIN). Case patients (n = 62) were women diagnosed with CIN3 following HPV-16-positive detection at a follow-up visit. HPV-16-positive controls (n = 152) without CIN2 or CIN3 were matched to cases based on the follow-up visit in which viral load was measured. Real-time polymerase chain reaction was used for HPV-16 DNA quantification.

RESULTS

The risk of CIN3 increased with increasing HPV-16 DNA load at the follow-up visit (odds ratio, 1.63; 95% confidence interval, 1.33-1.99 per 1 log(10) unit increase); the association was not affected by whether HPV-16 was present at enrollment. When HPV-16 was present at both enrollment and follow-up, viral load remained high among cases (P = .77) but decreased substantially among controls (P = .004). Among women with HPV-16 found initially during follow-up, viral load in the first HPV-16-positive sample was associated with short-term persistence; load was higher in those with infection, compared with those without infection, 1 visit after the initial positivity (P = .001).

CONCLUSIONS

Viral load of newly detected infections and changes in viral load predict persistence and progression of HPV-16 infections.

Type-specific human papillomavirus oncogene messenger RNA levels correlate with the severity of cervical neoplasia

This study aimed to evaluate whether quantitation of high-risk human papillomavirus (HR-HPV) E6 messenger RNA (mRNA) can be a potential biomarker for detecting the severity of cervical lesions. HPV genotyping was performed using a modified MY11/GP6+ PCR for HPV DNA amplification, followed by HPV genotype-specific hybridization with on a gene chip. E6 type-specific PCR was used to validate multiple infections. Quantitative real-time reverse transcriptase (QRT-PCR) and real-time PCR used to measure mRNA levels and DNA viral loads of 6 HPV oncogenic types (HPV 16, 18, 31, 33, 52 and 58) in 720 liquid-based cytology samples. The HPV DNA and RNA measurements were correlated with cervical lesions diagnosed by histopathologic examination. mRNA transcripts in the 6 types HPV DNA-positive cases was lower in normal women and <CIN 1 (23%), women with CIN 1 (54%), CIN2+ (77%) and CIN3+ (80%) (p < 0.001). Geometric mean mRNA levels ranged from 24.5 (copies per 50 ng total RNA) in normal women and <CIN 1 to 210.8 in those with CIN 1, 629.0 in CIN2+ and 699.0 in CIN3+ (p < 0.0001). Trends of increasing viral mRNA with severity of histopathologic diagnosis were significant for HPV 16, 18, 52 and 58 transcripts but not for HPV 31 and 33 transcripts. However, geometric mean DNA viral loads of HPV 16, 18, 52 and 58 DNA did not significantly increase with the severity of cervical dysplasia. Therefore, quantitative HPV E6 mRNA levels of high-risk HPV types are potentially useful biomarkers for distinguishing among HPV infections, cervical precancerous lesions and cancer.

Human papilloma virus genotyping, variants and viral load in tumors, squamous intraepithelial lesions, and controls in a north Indian population subset

A study of human papilloma virus (HPV) types and variants is important for developing preventive protocols and appropriate intervention targets. The presence of HPV types, their variants, and viral load in a population subset from North India was studied. Polymerase chain reaction (PCR) and line blots were used for HPV genotyping; HPV 16 and 18 viral loads were measured using real-time PCR. Variant analysis was done by sequencing of the PCR-amplified E6/E7 regions of HPV 16 and the long control region and E6/E7 regions of HPV 18. The 93.6%, 78.6%, and 10% of tumors, squamous intraepithelial lesions (SILs), and controls were HPV-positive, respectively. The most commonly observed type was HPV 16. Human papilloma virus 73 which is uncommonly observed was seen in 2 tumors. Multiple infections were more common in controls and SILs than tumors. The majority (86.4%) of the HPV 16-positive and all of the HPV 18-positive samples belonged to the European variant class. Five novel nonsynonymous changes were seen in the HPV 16-positive and 2 in HPV 18-positive samples. There was a significant increase in viral loads from controls through SILs to tumors, but no significant differences in viral loads were observed between different stages of cancer. In tumors, a significant increase in HPV 16 viral loads was seen with increasing age. The study shows a similar HPV type and variant distribution to European studies, with some differences in type distribution. Viral load does not appear to be good marker for stage wise progression and intralesional variability may affect its use as a differentiating parameter between high-grade squamous intraepithelial lesion and low-grade squamous intraepithelial lesions.

Is human papillomavirus viral load a clinically useful predictive marker? A longitudinal study

BACKGROUND

It has been suggested that in women who test positive for high-risk human papillomavirus (HPV) types, viral load can distinguish women who are at increased risk of cervical neoplasia from those who are not.

METHODS

Quantitative PCR (qPCR) was used to measure HPV copy number in serial samples taken from 60 and 58 young women previously found to have incident cervical HPV16 or HPV18 infections, respectively, using GP5+/GP6+ primers; women provided at least three samples for qPCR testing, at least one of which was positive.

RESULTS

A 10-fold increase in HPV16 or HPV18 copy number was associated with a modestly increased risk of acquiring a cytologic abnormality [HPV16: hazards ratio, 1.76 (95% confidence interval, 1.38-2.25); HPV18: hazards ratio, 1.59 (95% confidence interval, 1.25-2.03)]. However, in most women, copy number increased during follow-up, before decreasing again. In women with a HPV16 infection, the median copy number per 1,000 cells was 7.7 in their first qPCR HPV-positive sample, 1,237 in the sample yielding the maximum copy number, and 7.8 in their last qPCR HPV-positive sample; corresponding copy numbers for women with HPV18 infection were 2.3, 87, and 2.4. Maximum HPV16 and HPV18 copy number did not differ significantly between women who acquired an incident cervical cytologic abnormality and those who did not.

CONCLUSION

Whereas large relative increases in copy number are associated with an increased risk of abnormality, a single measurement of viral load made at an indeterminate point during the natural history of HPV infection does not reliably predict the risk of acquiring cervical neoplasia. Therefore, a single measure of HPV viral load cannot be considered a clinically useful biomarker.

Low initial human papilloma viral load implicates worse prognosis in patients with uterine cervical cancer treated with radiotherapy

PURPOSE

To evaluate whether human papillomavirus (HPV) viral load measured in cervical smear and HPV type 18 are associated with radiotherapy outcomes in uterine cervical cancer. PATIENTS AND METHODS HPV DNA: was semiquantitatively measured in the cervical smears of 169 radiotherapy patients. HPV viral load was classified as low or high according to median HPV DNA titer and examined for its prognostic value. The multivariable Cox proportional hazards model was used to adjust for covariates. A relapse-predicting model was constructed to classify three risk groups for disease-free survival (DFS), which were used for internal validation.

RESULTS

Patients with lower HPV viral load showed worse DFS in univariate analysis. HPV type 18, younger patient age, stage group, nodal status, histologic grade, and histologic type were other prognostic factors for poor DFS. Among these factors, all except stage group were associated with HPV viral load. Multivariate analysis showed the strong influence of HPV viral load for poor DFS. The prognostic model developed using our outcome data performed well in predicting the risk of relapse.

CONCLUSION

Our data suggest that HPV viral load is a strong independent prognostic factor for DFS. HPV type 18 showed a significant relationship with poor radiotherapy outcome in univariate analysis, but not in multivariate analysis.

Human papillomavirus type 18 DNA load and 2-year cumulative diagnoses of cervical intraepithelial neoplasia grades 2-3

BACKGROUND

The clinical relevance of the amount of human papillomavirus type 18 (HPV18) DNA in cervical tissue (ie, HPV18 DNA load) is unknown.

METHODS

Study subjects were 303 women who were HPV18 positive at enrollment into the Atypical Squamous Cells of Undetermined Significance (ASC-US) and Low-Grade Squamous Intraepithelial Lesion (LSIL) Triage Study. HPV18 DNA load, expressed as copies of HPV18 per nanogram of cellular DNA, at enrollment was quantitatively measured. Subjects were followed up semiannually for a period of 2 years for detection of cervical intraepithelial neoplasia 2-3 (CIN2-3). A linear regression model was used to examine associations of CIN2-3 with HPV18 DNA load. All statistical tests were two-sided.

RESULTS

CIN2-3 was confirmed in 92 of 303 (30.4%) HPV18-positive women. Among women without CIN2-3, HPV18 DNA load was positively associated with increasing severity of cervical cytology at enrollment (Ptrend < .001). However, among those with CIN2-3, HPV18 DNA load was not associated with severity of cervical cytology at enrollment (Ptrend = .33). The ratios of geometric means of HPV18 DNA load at enrollment among women with CIN2-3, relative to those without, were 6.06 (95% confidence interval [CI] = 0.31 to 117.92) for those with normal cytology at enrollment, 0.50 (95% CI = 0.10 to 2.44) for those with ASC-US, 0.11 (95% CI = 0.03 to 0.46) for those with LSIL, and 0.07 (95% CI = 0.01 to 0.80) for those with high-grade squamous intraepithelial lesion (HSIL). After adjusting for age and coinfection with other high-risk HPVs, a statistically significant association of lower HPV18 DNA load with CIN2-3 was observed among women with LSIL or HSIL at enrollment (P = .02). Within the 2-year period, HPV18 DNA load was unrelated to the timing of CIN2-3 diagnosis. Overall results were similar when the outcome was CIN3.

CONCLUSIONS

HPV18 DNA load was higher for women with LSIL or HSIL at enrollment with no evidence of CIN2-3 during the 2-year follow-up period than it was for women with CIN2-3. Thus, testing for high levels of HPV18 DNA does not appear to be clinically useful.

Effect of cervical cytologic status on the association between human papillomavirus type 16 DNA load and the risk of cervical intraepithelial neoplasia grade 3

BACKGROUND

Although correlations between cervical cytologic status and both human papillomavirus (HPV) load and histopathologic status are recognized, it is largely undetermined whether the association between the HPV DNA load and the risk of cervical intraepithelial neoplasia grade 3 (CIN-3) differs on the basis of cervical cytologic findings.

METHODS

Study subjects were 821 women enrolled in the ASCUS-LSIL Triage Study who tested positive for HPV-16 at entry. Women were followed semiannually for 2 years. The baseline HPV-16 load was measured by real-time polymerase chain reaction.

RESULTS

CIN-3 was confirmed in 286 (34.8%) of 821 women during the 2-year follow-up period. The adjusted odds ratio (OR) of the 2-year cumulative risk of CIN-3 was 1.46 (95% confidence interval [CI], 1.29-1.64) per 1 log(10) increase in virus load. The ORs varied from 1.66 (95% CI, 1.16-2.37) for women with normal cytologic findings at enrollment to 0.86 (95% CI, 0.61-1.20) for those with high-grade squamous intraepithelial lesions. Among women with normal cytologic findings at enrollment, the area under the receiver operating characteristic curve for detection of CIN-3 on the basis of the virus load was 0.70 (95% CI, 0.61-0.78).

CONCLUSION

The HPV-16 DNA load was associated with the risk of developing CIN-3, but the associations varied with cytologic findings at the time of virus load measurement. The clinical usefulness of measuring the HPV-16 load as a means to detect CIN-3 was minimal, even in women with normal cytologic findings.

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.