Increase of integration events and infection loads of human papillomavirus type 52 with lesion severity from low-grade cervical lesion to invasive cancer

Infection load and the integration of human papillomaviruses (HPV) have been implicated as determinants for oncogenesis, but whether variation among different HPV types exists remains unclear. We investigated 91 women infected with HPV type 52 (HPV-52), a type that is rare worldwide but common in East Asia. The median viral load increased with the severity of the lesion (248 copies/cell equivalent for normal/cervical intraepithelial neoplasia [CIN] grade 1, 402 copies/cell equivalent for CIN 2, 523 copies/cell equivalent for CIN 3, and 1,435 copies/cell equivalent for invasive cancer). The proportion of specimens with integration increased significantly with the severity of the lesion (P < 0.001). The viral load was associated with the physical status of the viral genome, with higher levels for the pure episomal form (P = 0.001). Infection status should be considered when interpreting viral load data for HPV-52, as single infections with this HPV type were found to have marginally higher viral loads than coinfections (P = 0.051). All except one sample had E2 disruption restricted to only a part of the gene. Integration is a critical step in HPV-52-induced carcinogenesis. The profile of E2 disruption was different from that described for HPV-16, with the amino-terminal region being most frequently involved. Selecting the appropriate E2 region for amplification is critical in studying the integration of HPV-52. In summary, the HPV-52 viral load and the integrated proportion increased with the severity of the cervical lesions but had a different pattern than that of HPV-16.     

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.     

Cross-Reactivity,Epitope Spreading,and De Novo Immune Stimulation Are Possible Mechanisms of Cross-Protection of Nonvaccine Human Papillomavirus (HPV) Types in Recipients of HPV Therapeutic Vaccines

Numerous versions of human papillomavirus (HPV) therapeutic vaccines designed to treat individuals with established HPV infection, including those with cervical intraepithelial neoplasia (CIN), are in development because approved prophylactic vaccines are not effective once HPV infection is established. As human papillomavirus 16 (HPV-16) is the most commonly detected type worldwide, all versions of HPV therapeutic vaccines contain HPV-16, and some also contain HPV-18. While these two HPV types are responsible for approximately 70% of cervical cancer cases, there are other high-risk HPV types known to cause malignancy. Therefore, it would be of interest to assess whether these HPV therapeutic vaccines may confer cross-protection against other high-risk HPV types. Data available from a few clinical trials that enrolled subjects with CINs regardless of the HPV type(s) present demonstrated clinical responses, as measured by CIN regression, in subjects with both vaccine-matched and nonvaccine HPV types. The currently available evidence demonstrating cross-reactivity, epitope spreading, and de novo immune stimulation as possible mechanisms of cross-protection conferred by investigational HPV therapeutic vaccines is discussed.     

Evaluation of a commercialized in situ hybridization assay for detecting human papillomavirus DNA in tissue specimens from patients with cervical intraepithelial neoplasia and cervical carcinoma

To evaluate a commercialized in situ hybridization (ISH) assay for detecting human papillomavirus (HPV) DNA, we compared the ability of a new ISH probe, Inform HPV III (Ventana Medical Systems, Tucson, AZ), to that of PCR assays to detect HPV DNA in cervical tissue specimens with normal cervix (20 cases), cervical intraepithelial neoplasia (CIN; CIN 1, 27 cases; CIN 2, 28 cases; and CIN 3, 33 cases), and cervical carcinoma (29 cases). General HPV DNA was detected using consensus primer-mediated PCR assays. HPV genotyping was performed by using EasyChip HPV blot (King Car Yuan Shan Institute, I-Lan, Taiwan). HPV16 integration status (E2/E6 ratio) was determined by using quantitative real-time PCR. Our findings showed that the ISH and PCR had fair to good agreements in detecting HPV DNA across all CIN categories without significant differences (Kappa coefficient, 0.34 to 0.63; P = 0.13 to 1.0). However, ISH detected significantly fewer HPV-positive cases in carcinoma than PCR did (Kappa coefficient, 0.2; P = 0.03). Eleven cases with ISH⁻ PCR⁺ results had HPV types that can be detected by Inform HPV III. Five carcinoma cases with ISH⁻ PCR⁺ results showed a significantly higher level of integrated HPV16 (P = 0.008) than did the ISH⁺ cases. As a consequence, lower copy numbers of episomal HPV16 in carcinoma might be the cause for the false-negative ISH results. Although the punctate signal pattern of HPV significantly increased with the severity of disease (P trend = 0.01), no significant difference in the HPV16 integration status was observed between the cases with a punctate signal only and the cases with mixed punctate and diffuse signals (P = 0.4). In conclusion, ISH using the Inform HPV III probe seems comparable to PCR for detecting HPV DNA in cervical tissue with CINs. False-negative ISH results appear to be associated with the lower copy numbers of the episomal HPV16 but not with the ability of the Inform HPV III probe to detect specific HPV types. In addition, signal patterns, especially a mixed punctate and diffuse pattern of HPV, cannot be reliably used to predict viral integration status.     

Cervicovaginal, oral, and serum IgG and IgA responses to human papillomavirus type 16 in women with cervical intraepithelial neoplasia

Oncogenic human papillomaviruses (HPVs) are obligate mucosal pathogens and typically cause localized infections. The mucosal surface of the genital tract also provides the first line of defense against genital HPV infection. Although local antibody production following HPV-infection has been demonstrated, their role in protection from cervical disease is unclear. This study evaluated oral and cervical HPV infection and the associated linkage between HPV-16 oral, cervical and serum antibody responses in 103 women with varying grades of cervical intraepithelial neoplasia (CIN). We found that HPV-16 was the most prevalent cervical HPV infection (30/103, 29.1%) but was only detected in 1.1% (1/91) of the oral samples. Both the frequency and magnitude of HPV-16-specific cervical IgA was significantly elevated in women with CIN 2/3 compared with women with CIN 1 (P = 0.0073 frequency; P = 0.0045 magnitude). Women with cervical HPV-16 infection had significantly higher magnitude and frequency of cervical HPV-16 IgA responses than women without cervical HPV-16 DNA (P = 0.0002 frequency; P = 0.0052 magnitude). Despite our contention that mucosal HPV-16 antibody responses within distinct mucosal compartments may be linked, the concordance analysis carried out within and between mucosal compartments and serum suggests that no such linkage exists and that these compartments may be functioning independently of one another. An HPV-16 specific antibody response in one mucosal compartment in women with CIN is therefore not predictive of a response at another.     

Numerical aberrations of chromosome 1 in cervical intraepithelial neoplasia are strongly associated with infection with high-risk human papillomavirus types

The aims of this study were to assess the relationships between numerical aberrations of chromosome 1 and the presence of high-risk human papillomavirus (HPV). Five normal samples, 11 CIN1, 13 CIN2, 18 CIN3, and nine carcinomas were studied by in situ hybridization (ISH), using a DNA probe for the centromere of chromosome 1 (cen#1) and a DNA probe cocktail for HPV types 16 and 18. A short fragment polymerase chain reaction hybridization line probe assay (SPF-PCR-LiPA) technique was used to detect 25 HPV types. The mean number of cen#1 per nucleus (chromosome index, CI) was measured, and the fractional areas of dysplastic epithelium with HPV16/18 infection and with cen#1 aneusomy were estimated. Disomy was found in all normal epithelium and in 36% of CIN1. Tetrasomy was observed in 64% of CIN1, 15% of CIN2, and 17% of CIN3. Hyper-tetrasomy was observed in 77% of CIN2, 83% of CIN3, and 100% of invasive carcinomas. High-risk HPVs were present in 20%, 75%, and 94% of disomic, tetrasomic, and hyper-tetrasomic lesions, respectively. The mean CI value was significantly higher in the lesions infected with high-risk HPV than in the lesions not infected by high-risk HPV (p < 0.001), due to the significantly higher prevalence of hyper-tetrasomy. The ISH study disclosed that HPV16/18 was exclusively found within dysplastically altered epithelium. The area with aneusomy is mostly enclosed within the area infected with HPV. In 83% of the HPV16/18-positive CIN lesions, the fractional area of HPV-infected epithelium was equal to, or larger than, the fractional area with aneusomy. In conclusion, aneusomy for chromosome 1 is strongly associated with high-grade CIN lesions and infection with high-risk HPV; it is likely that the occurrence of numerical aberrations of chromosome 1 is preceded by infection with high-risk HPV.     

Estimation of prognoses for cervical intraepithelial neoplasia 2 by p16INK4a immunoexpression and high-risk HPV in situ hybridization signal types

The present study used immunohistochemical staining and in situ hybridization (ISH) to examine whether progression of cervical intraepithelial neoplasia, grade 2 (CIN 2) can be predicted by p16INK4a immunoexpression and high-risk human papilloma virus (HPV) ISH signal types. We studied 52 cases histologically diagnosed with CIN 2: dysplasia regressed in 28 cases; 13 cases progressed to CIN 3; and CIN 2 persisted in 11 cases. Expression of p16INK4a and high-risk HPV signal both related to grade of CIN. Stronger p16INK4a immunoexpression and a higher frequency of expression of a punctate nuclear signal were observed in CIN 2 lesions before progression compared with those before regression. CIN 2 cases in which moderate to strong immunoexpression of p16INK4a and a punctate signal were observed simultaneously progressed to CIN 3 in 10 (91%) of 11 cases. CIN 2 cases with moderate to strong immunoexpression of p16INK4a and a high-risk HPV punctate signal should be treated because of the great risk of progression.     

Integrated human papillomavirus type 16 is frequently found in cervical cancer precursors as demonstrated by a novel quantitative real-time PCR technique

In contrast to cervical cancer, integration of human papillomavirus (HPV) DNA into the host genome has been considered a rare event in cancer precursor lesions (cervical intraepithelial neoplasia [CIN]). With our new real-time PCR method, we demonstrated that integrated HPV type 16 (HPV16) is already present in CIN lesions. The physical state of HPV16 and the viral load were simultaneously detected. A unique region of the E2 open reading frame (ORF) that is most often deleted during HPV16 integration is targeted by one set of PCR primers and a probe, and another set targets the E6 ORF. In episomal form, both targets should be equivalent, while in integrated form, the copy numbers of E2 would be less than those of E6. The method was tested with DNAs from 31 cervical lesions (non-CIN to CINIII) from 24 women prospectively followed up for 10 years. This report presents viral load and integration results from the largest series of CIN lesions described to date. Only one sample contained exclusively episomal HPV16 DNA, and this lesion regressed spontaneously. Samples from another patient, with only integrated HPV16, rapidly progressed from CINI to CINIII in 2 years. In all other patients, episomal and integrated forms of HPV16 DNA were found to coexist. Rapid progression of the CIN lesions was closely associated with a heavy load of integrated HPV16. Thus, the method described here is a very sensitive tool with which to assess the physical state of HPV, which is useful in predicting disease progression.     

Detection of human papillomavirus genotypes with liquid bead microarray in cervical lesions of northern Chinese patients

Human papillomavirus (HPV) is the main cause of cervical cancer. Blending multiplex polymerase chain reaction (PCR) amplification and multiplex hybridization to liquid bead microarray (LBMA), we detected and identified 25 common HPV genotypes using type-specific primers for HPV E6 and E7 genes in cervical lesions of northern Chinese patients. Of the 511 cervical samples, 349 (68.3%) were found to be HPV positive by HPV-LBMA. The distribution was 22 HPV positive of 100 in the control group (22%), 41 of 80 with chronic cervicitis (51%), 80 of 99 with cervical intraepithelial neoplasia (CIN) I (81%), 46 of 56 with CIN II (82%), 67 of 74 with CIN III (90%), and 93 of 102 with invasive cervical carcinoma (91%). HPV-16 was the most frequent genotype in the CIN and cervical cancer groups. The most common genotypes were HPV-16 (28%), HPV-58 (14%), HPV-52 (14%), HPV-18 (8%), and HPV-33 (7%) in the CIN group, and HPV-16 (63%), HPV-52 (9%), HPV-18 (7%), HPV-58 (7%), and HPV-33 (5%) in the cervical cancer group. HPV-LBMA found multiple genotypes in 1 of 22 control (4%), 64 of 193 CIN (33%), and 22 of 93 cervical cancer (24%). The HPV-LBMA results were compatible with those of PCR and DNA sequencing. HPV-LBMA is a simple, high-throughput method that provides useful information on viral genotype and multiple HPV infections in cervical lesions. In northern China, the most common high-risk HPV genotypes seem to be HPV types 16, 58, 52, 18, and 33. Genetic information on HPV in cervical specimens could provide particular benefits in the management of cervical lesions.     

A comparison of the detection of biomarkers in infections due to low risk versus high-risk human papillomavirus types

Adjunctive immunohistochemistry tests for human papillomavirus (HPV) infection include p16 and Ki67 as well as the more recently discovered biomarkers importin-β, exportin-5, Mcl1, and PDL1. The purpose of this study was to compare the expression of these biomarkers in HPV infection due to the high-risk types such as HPVs 16, 18, 31, 33, 35, and 51 versus lesions that contain the low risk types HPV 2, 6 or 11. We studied 35 lesions with low risk HPV types (verruca vulgaris = 10 cases, condyloma acuminatum = 15 cases, CIN 1 with HPV 6/11 = 10 cases) and 25 CIN 1 or 2 lesions with a high-risk HPV type. The 25 high-risk positive CIN 1–2 cases had strong expression of the panel p16, Ki67, importin-β, exportin-5, Mcl1, and PDL1 where each protein localized to the cells in the parabasal aspect of the lesion. In comparison, neither p16, importin-β, exportin-5, Mcl1, nor PDL1 were increased in the epithelia of the lesions with the low risk HPV types; Ki67 showed variable expression. HPV viral capsid L1 protein and viral DNA were excellent markers of infection in the lesions with low risk types. Thus, p16, importin-β, exportin-5, Mcl1, and PDL1 are not only biomarkers of high-risk HPV infection but can also differentiate such lesions from those that contain low risk HPV types. Low risk HPV infections can be best differentiated from their mimics by viral L1 capsid detection and/or HPV DNA by in situ hybridization.     

Human papillomavirus type 16 integration in cervical carcinoma in situ and in invasive cervical cancer

Integration of human papillomavirus type 16 (HPV-16) into the host DNA has been proposed as a potential marker of cervical neoplastic progression. In this study, a quantitative real-time PCR (qRT-PCR) was used to examine the physical status of HPV-16 in 126 cervical carcinoma in situ and 92 invasive cervical cancers. Based on criteria applied to results from this qRT-PCR assay, HPV-16 was characterized in carcinoma in situ cases as episomal (61.9%), mixed (i.e., episomal and integrated; 29.4%), and integrated (8.7%) forms. In invasive cervical cancer samples, HPV-16 was similarly characterized as episomal (39.1%), mixed (45.7%), and integrated (15.2%) forms. The difference in the frequency of integrated or episomal status estimated for carcinoma in situ and invasive cervical cancer cases was statistically significant (P = 0.003). Extensive mapping analysis of HPV-16 E1 and E2 genes in 37 selected tumors demonstrated deletions in both E1 and E2 genes with the maximum number of losses (78.4%) observed within the HPV-16 E2 hinge region. Specifically, deletions within the E2 hinge region were detected most often between nucleotides (nt) 3243 and 3539. The capacity to detect low-frequency HPV-16 integration events was highly limited due to the common presence and abundance of HPV episomal forms. HPV-16 E2 expressed from intact episomes may act in trans to regulate integrated genome expression of E6 and E7.     

Physical state of HPV16 and chromosomal mapping of the integrated form in cervical carcinomas.

Using a procedure based on restriction enzyme cleavage, self-ligation, and inverse polymerase chain reaction (rliPCR), the authors investigated 18 cervical intraepithelial neoplasia III (CIN III) cases and 37 invasive squamous carcinomas for integration of human papillomavirus type 16 (HPV16). All eighteen CIN III cases (severe dysplasia or high-grade squamous intraepithelial lesion) were found to harbor episomal HPV, but one of the samples contained mixed episomal and integrated forms. Seventeen of 37 invasive cervical carcinoma samples were identified previously as containing the completely integrated HPV16 genome by using PCR covering the entire E1/E2 gene, and this was confirmed by rliPCR in 16 cases. One case, however, showed a low level of episomal deoxyribonucleic acid in addition to the predominant integrated form. Of the remaining 20 carcinoma samples showing episomal forms in the previous analysis, 14 were found to contain integrated forms using rliPCR, and four contained multimeric episomal forms. Thus, in total, 31 of 37 of the carcinomas (84%) showed the integrated HPV16 genome. The rliPCR product from five carcinoma cases was cloned into a plasmid vector and used as a template for "primer walking" deoxyribonucleic acid sequencing to deduce human sequences flanking the integrated HPV genome. Based on this information, bacterial artificial chromosome (BAC) and P1-derived artificial chromosome (PAC) clones were obtained and used as probes in fluorescent in situ hybridization experiments on human metaphase chromosomes. The results of the fluorescent in situ hybridization experiments showed evidence for HPV16 integration in chromosome regions 1q25, 3q28, 6p25, 11p13, and 18q22. Sixteen carcinoma samples, containing episomal HPV16, were sequenced in the long control region. Evidence for changes in E2 binding or silencer YY1 sequences was found in only two samples.     

Analysis by Multiplex PCR of the Physical Status of Human Papillomavirus Type 16 DNA in Cervical Cancers

Integration of human papillomavirus (HPV) DNA occurs early in cancer development and is an important event in malignant transformation of cervical cancer. Integration of HPVs preferentially disrupts or deletes the E2 open reading frame, which results in the loss of its expression. The preferential disruption of the E2 gene causes the absence of the E2 gene sequences in the PCR product following integration. Twenty-two carcinomas positive for HPV type 16 (HPV-16) DNA were first tested for the disruption of the E2 gene by PCR. A specific fragment of the E2 gene was not amplified in 10 cases, suggesting integration of HPV DNA into the host genome. Next, multiplex PCR for the HPV E2 and E6 genes was carried out in the remaining 12 cases. Copy numbers of both genes should be equivalent in episomal forms, while the E2 gene copy number will be smaller than that for E6 following the preferential disruption of the E2 gene in concomitant forms. Although relative ratios of HPV E2 to E6 PCR products (E2/E6 ratios) ranged from 1.40 to 2.34 in 10 of 12 cases, multiplex PCR products from 2 cases displayed extremely low ratios of 0.69 and 0.61. Southern blot hybridization with an HPV-16 probe revealed that only in these two cases was both episomal and integrated HPV DNA being carried simultaneously. Thus, multiplex PCR for the E2 and E6 genes of HPV-16 DNA following PCR for the E2 gene can distinguish the pure episomal form from a mixed form of episomal and integrated HPV DNA. Clinical application of this technique will help researchers to understand the implication of the integration of HPV DNA for cervical carcinogenesis and cervical cancer progression.     

p16 expression in relation to human papillomavirus in anogenital lesions

Recent studies have revealed that cervical cancers associated with high-risk human papillomavirus (HPV) showed overexpression of the p16 protein, a cyclin-dependent kinase inhibitor. The expression of this cell cycle regulator in lesions of the anogenital region in association with HPV physical status (episomal or integrated) has not been studied at the present time. In this report, immunohistochemical analysis of p16 and HPV detection by in situ hybridization were performed on 110 formalin-fixed and paraffin-embedded samples of anogenital lesions. The results showed strong diffuse p16 staining in all integrated high-risk HPV-positive lesions, whereas most episomal HPV-positive lesions or HPV-negative lesions showed no p16 immunostaining. However, there were a few HPV-negative lesions or lesions with episomal HPV harboring p16 overexpression. On the other hand, some lesions were p16 negative while showing the presence of high-risk HPV in its episomal form. In conclusion, screening for p16 overexpression in cutaneomucous lesions of the anogenital region allowed good discrimination between HPV-integrated lesions and lesions harboring episomal HPV or no HPV. But p16 overexpression was not always predictive of the presence of high-risk HPV; moreover, absence of p16 immunostaining observed in some high-risk HPV lesions suggested that limiting the screening to p16 would exclude some patients harboring high-risk HPV from any follow-up.     

Physical status of HPV-16 in esophageal squamous cell carcinoma.

BACKGROUND: Infection with high-risk human papillomavirus (HPV) has been implicated as one of the risk factors of esophageal squamous cell carcinoma (ESCC). Integration of viral DNA into host genome is essential for carcinogenesis since it promotes disruption of the HPV E2 gene, leading to abnormal expression of E6 and E7 oncoproteins. OBJECTIVES AND STUDY DESIGN: To investigate the viral integration status of HPV-16 infection in ESCC, 35 HPV-positive ESCC specimens collected from Chinese patients were subject to real-time quantitative PCR for determination of physical status of HPV-16 by analyzing the ratios of E2 to E6 genes. RESULTS: Our results showed that only 8.6% (3/35) of the HPV-16 positive specimens harbored exclusively the episomal form (i.e. E2/E6 ratio > or = 1), whereas the remaining 91.4% contained either only the integrated form (5.7%, with E2/E6 ratio = 0) or a mixture of episomal and integrated forms of viral molecules (85.7%, with E2/E6 ratios > 0 but < 1). Amongst the 30 cancer specimens carrying mixed integrated and episomal forms, 28 had E2/integrated E6 ratios of less than 1, indicating a predominance of integrated form of viral genes in these lesions. CONCLUSION: Our finding of frequent integration of viral DNA in the host genome suggests that integration HPV-16 is common in ESCC from Chinese patients and implies that HPV infection may play a role in the pathogenesis of ESCC.     

Episomal and integrated human papillomavirus in cervical neoplasia shown by non-isotopic in situ hybridisation.

It was postulated that non-isotopic in situ hybridisation (NISH) signal types 1-3 for human papillomavirus in cervical biopsy specimens represent episomal or integrated virus. The aim of this study was to validate this hypothesis by independent molecular techniques. Fresh cervical intraepithelial neoplasia (CIN) and squamous cell cancer (SCC) tissue were examined for NISH signal pattern by hybridising with digoxigenin labelled HPV 16. DNA was extracted from the same samples and analysed by restriction endonuclease digestion and Southern blotting to determine the physical state of the viral genome. Six CIN biopsy specimens showed a type 1 NISH signal for HPV 16. On Southern analysis these biopsy specimens contained only episomal HPV 16. Three SCC with a type 2 NISH signal contained integrated HPV 16 by Southern analysis. Two specimens, a CIN 3 and an SCC with a type 3 NISH signal for HPV 16, showed the presence of both episomal and integrated HPV 16 with conventional Southern analysis and two dimensional gel electrophoresis. These results show that episomal HPV can be reliably determined by NISH type 1 signal, integrated HPV by type 2, and a combination of both episomal and integrated HPV, by a type 3 signal in archival paraffin wax embedded cervical biopsy specimens. This will add another variable to the epidemiological studies of HPV infection. In particular, it will now allow retrospective studies to be done to define the role of episomal and integrated HPV in the evolution of cervical intraepithelial neoplasia and other cervical disease associated with this virus.     

Association of human beta-herpesviruses with the development of cervical cancer: bystanders or cofactors

BACKGROUND/AIM: Human papillomaviruses (HPVs) are important, but not sufficient, for the development of cervical cancer. All three human beta-herpesviruses--cytomegalovirus (CMV) and human herpesviruses (HHV) types 6 and 7--have been detected in the cervix. In addition, CMV and HHV-6 can interact with HPVs in vivo. This study examined the possible role of beta-herpesviruses in cervical cancer development. METHODS: HPV, CMV, HHV-6, and HHV-7 were detected by the polymerase chain reaction using cervical scrapes taken at colposcopy from 388 women. HPV types were identified using restriction fragment length polymorphisms. Colposcopy guided biopsies were taken from abnormal areas, and the histological findings were regarded as the final diagnoses. The associations between herpesvirus infection and the degree of cervical lesion were analysed with respect to HPV status. RESULTS: Of the 388 women, 51.8% had a normal cervix, 14.4% had cervical intraepithelial neoplasia grade 1 (CIN1), 8.2% had CIN2, 19.3% had CIN3, and 6.2% had invasive carcinoma. Overall, the positive rates for high, intermediate, and low risk HPVs were 18.8%, 21.4%, and 5.2%, respectively. Fifteen patients harboured HPVs for which the genotype could not be identified. Positive rates for CMV, HHV-6, and HHV-7 were 9.5%, 3.6%, and 3.4%, respectively. HPV positive patients carried a higher risk for high grade lesions (CIN2/3 or carcinoma) (odds ratio (OR), 5.24; 95% confidence interval (CI), 3.19 to 8.62; chi 2 = 51.79; p < 0.001), whereas those positive for CMV, HHV-6, or HHV-7 did not. Thirteen of 131 patients with high grade lesions had HPV/herpesvirus coinfections, but no association with the cervical lesion was noted. Furthermore, positive rates for herpesviruses among HPV negative, high/intermediate risk HPV negative, and high risk HPV negative subgroups were similarly low and without a significant association. CONCLUSIONS: The ubiquitous nature of herpesviruses may pose difficulty in elucidating their pathogenic role. These results indicate that CMV, HHV-6, and HHV-7 are bystanders rather than cofactors in the oncogenesis of cervical cancer.