Inger Gustavsson

Real-Time PCR-Based System for Simultaneous Quantification of Human Papillomavirus Types Associated with High Risk of Cervical Cancer

ABSTRACT We have previously shown that women with a high titer of human papillomavirus type 16 (HPV16) in cervical epithelial cells have an increased risk of developing cervical carcinoma in situ. In order to study the relationship between viral DNA amount and risk of cervical carcinoma for the HPV types most commonly found in cervical tumors, we developed a real-time PCR assay for the detection and quantification of HPV16, -18, -31, -33, -35, -39, -45, -52, -58, and -67. These HPV types are analyzed in two reaction tubes, allowing for independent quantification of three viral types, or groups of viral types, in each reaction. A separate reaction is used for estimating the number of a nuclear single-copy gene and is used to calculate the HPV copy number per genomic DNA equivalent in the sample. The system has a dynamic range from 102 to 107 HPV copies per assay and is applicable to both fresh clinical samples and DNA extracted from archival samples. Reconstitution experiments, made to mimic infections with several HPV types, shows that individual HPV types can be detected in a mixture as long as they represent 1 to 10% of the main type. The system was evaluated with respect to technical specificity and sensitivity, reproducibility, reagent stability, and sample preparation protocol and then used to analyze clinical samples. This homogeneous assay provides a fast and sensitive way for estimating the viral load of a series of the most frequent oncogenic HPV types in biopsies, as well as cervical smear samples.

Type-specific associations of human papillomavirus load with risk of developing cervical carcinoma in 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.

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.

Genome-wide Association Study of Susceptibility Loci for Cervical Cancer

BACKGROUND Cervical carcinoma has a heritable genetic component, but the genetic basis of cervical cancer is still not well understood. METHODS We performed a genome-wide association study of 731 422 single nucleotide polymorphisms (SNPs) in 1075 cervical cancer case subjects and 4014 control subjects and replicated it in 1140 case subjects and 1058 control subjects. The association between top SNPs and cervical cancer was estimated by odds ratios (ORs) and 95% confidence intervals (CIs) with unconditional logistic regression. All statistical tests were two-sided. RESULTS Three independent loci in the major histocompatibility complex (MHC) region at 6p21.3 were associated with cervical cancer: the first is adjacent to the MHC class I polypeptide-related sequence A gene (MICA) (rs2516448; OR = 1.42, 95% CI = 1.31 to 1.54; P = 1.6×10(-18)); the second is between HLA-DRB1 and HLA-DQA1 (rs9272143; OR = 0.67, 95% CI = 0.62 to 0.72; P = 9.3×10(-24)); and the third is at HLA-DPB2 (rs3117027; OR=1.25, 95% CI = 1.15 to 1.35; P = 4.9×10(-8)). We also confirmed previously reported associations of B*0702 and DRB1*1501-DQB1*0602 with susceptibility to and DRB1*1301-DQA1*0103-DQB1*0603 with protection against cervical cancer. The three new loci are statistically independent of these specific human leukocyte antigen alleles/haplotypes. MICA encodes a membrane-bound protein that acts as a ligand for NKG2D to activate antitumor effects. The risk allele of rs2516448 is in perfect linkage disequilibrium with a frameshift mutation (A5.1) of MICA, which results in a truncated protein. Functional analysis shows that women carrying this mutation have lower levels of membrane-bound MICA. CONCLUSIONS Three novel loci in the MHC may affect susceptibility to cervical cancer in situ, including the MICA-A5.1 allele that may cause impaired immune activation and increased risk of tumor development.

Variants of chemokine receptor 2 and interleukin 4 receptor, but not interleukin 10 or Fas ligand, increase risk of cervical cancer

Cervical cancer is caused by persistent infection of oncogenic human papillomavirus (HPV). Most infected women clear the virus without developing cervical lesions and it is likely that immunological host factors affect susceptibility to cervical cancer. The impact of the human leukocyte antigen (HLA) locus on the risk of cervical cancer is established and several other genes involved in immunological pathways have been suggested as biologically plausible candidates. The aim of this study was to examine the potential role of polymorphisms in 4 candidate genes by analysis of 1,306 familial cervical cancer cases and 288 controls. The following genes and polymorphisms were studied: Chemokine receptor 2 (CCR‐2) V64I; Interleukin 4 receptor α (IL‐4R) I75V, S503P and Q576R; Interleukin 10 (IL‐10) −592; and Fas ligand (FasL) −844. The CCR‐2 64I variant was associated with decreased risk of cervical cancer; homozygote carriers of the 64I variant had an odds ratio of 0.31 (0.12–0.77). This association was detected in both carriers and noncarriers of the HLA DQB1*0602 cervical cancer risk allele. The IL‐4R 75V variant was associated with increased risk of cervical tumors, cases homozygote for 75V had an odds ratio of 1.91 (1.27–2.86) with a tendency that the association was stronger in noncarriers of the DQB1*0602 allele. We did not find any association for IL‐10 −592, or FasL −844, previously reported to be associated with cervical cancer in the Dutch and Chinese populations, respectively.

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.

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

BackgroundHuman 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.MethodsWe 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.ResultsHPV 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).ConclusionOnly 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.

Primary high-risk HPV screening for cervical cancer in post-menopausal women

OBJECTIVE The present study was conducted to examine the value of screening for high-risk HPV in post-menopausal women. METHODS A cohort of post-menopausal women (n=2113), age range 55-76 years, from Uppsala County, Sweden, were offered testing for both high-risk HPV and a Pap smear in the gynaecological screening during 2008-2010. For the HPV test the cervical smear sample was applied to a filter paper matrix, an indicating FTA elute card and HPV typing performed using a real-time PCR assay. Histological verified CIN2+ lesion was used as an end-point measurement. RESULTS High-risk HPV were found in 6.2% (95% CI 5.2-7.3%) of the women (n=130) and 22% (95% CI 14-32%) (n=17) of these had CIN2+ lesions based on histology. The Pap smear taken in conjunction with the HPV test was abnormal in 9.7% (95% CI 5.7-16.3%) (n=12) of HPV positive women. Among HPV positive women with an abnormal Pap smear, the frequency of histology verified CIN2+ lesions was 67% (95% CI 38-86%) (n=8), as compared to 14% (95% CI 7-24%) (n=9) in HPV positive women with a normal smear. The prevalence of HPV16 in CIN2+ lesions (29%, 95% CI 22-37%) in post-menopausal women was less than half of previous estimates in pre-menopausal women from this population. CONCLUSIONS Most histological CIN2+ lesions in post-menopausal women are not recognized by a single Pap smear. A large fraction of pre-invasive cervical cancer cases in post-menopausal women result from infections by HPV types not included in the present vaccine formulas.

Type-specific detection of high-risk human papillomavirus (HPV) in self-sampled cervicovaginal cells applied to FTA elute cartridge

BACKGROUND Most procedures for self-sampling of cervical cells are based on liquid-based media for transportation and storage. An alternative is to use a solid support, such as dry filter paper media. OBJECTIVES To evaluate if self-sampling of cervicovaginal fluid using a cytobrush (Viba-brush; Rovers Medical Devices B.V., Oss, The Netherlands) and a solid support such as the Whatman Indicating FTA Elute cartridge (GE Healthcare, United Kingdom) can be used for reliable typing of human papillomavirus (HPV), as compared to cervical samples obtained by a physician using a cytobrush and the indicating FTA Elute Micro card and biopsy analysis. STUDY DESIGN A total of 50 women with a previous high-risk (HR) HPV positive test were invited to perform self-sampling using the Viba-brush and the FTA cartridge and thereafter a physician obtained a cervical sample using the cytobrush and a FTA card, together with a cervical biopsy for histology and HPV typing. Detection of HR-HPV types 16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58 and 59 was performed using three multiplex real-time polymerase chain reaction (PCR) assays. RESULT All samples contained sufficient amounts of genomic DNA and the self-samples yielded on average 3.5 times more DNA than those obtained by the physician. All women that were positive for HR-HPV in the biopsy sample also typed positive both by self-sampling and physician-obtained sampling. For women with a histological diagnosis of cervical intraepithelial neoplasia grades 2-3 (CIN 2-3) all three HPV samples showed 100% concordance. A higher number of women were HPV positive by self-sampling than by physician-obtained sampling or by biopsy analysis. CONCLUSION The Viba-brush and the FTA cartridge are suitable for self-sampling of vaginal cells and subsequent HR-HPV typing.

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.