Human papillomavirus 16 E6 polymorphisms in cervical lesions from different European populations and their correlation with human leukocyte antigen class II haplotypes

Epidemiology of HPV-associated cancers past, present and future: towards prevention and elimination

Cervical cancer is the first cancer deemed amenable to elimination through prevention, and thus lessons from the epidemiology and prevention of this cancer type can provide information on strategies to manage other cancers. Infection with the human papillomavirus (HPV) causes virtually all cervical cancers, and an important proportion of oropharyngeal, anal and genital cancers. Whereas 20th century prevention efforts were dominated by cytology-based screening, the present and future of HPV-associated cancer prevention relies mostly on HPV vaccination and molecular screening tests. In this Review, we provide an overview of the epidemiology of HPV-associated cancers, their disease burden, how past and contemporary preventive interventions have shaped their incidence and mortality, and the potential for elimination. We particularly focus on the cofactors that could have the greatest effect on prevention efforts, such as parity and human immunodeficiency virus infection, as well as on social determinants of health. Given that the incidence of and mortality from HPV-associated cancers remain strongly associated with the socioeconomic status of individuals and the human development index of countries, elimination efforts are unlikely to succeed unless prevention efforts focus on health equity, with a commitment to both primary and secondary prevention.

HPV16 Intratypic Variants in Head and Neck Cancers: A North American Perspective

Human papillomavirus (HPV) is the major causative agent for cervical and many head and neck cancers (HNCs). HPVs randomly acquire single nucleotide polymorphisms (SNPs) that may become established via positive selection. Within an HPV type, viral isolates differing by <2% in the L1 region are termed "variants" and classified based on combinations of SNPs. Studies in cervical cancer demonstrate clear differences between HPV16 intratypic variants in terms of persistence of infection, tumor histology, cancer risk, and death. Much less is known about the frequency of HPV16 variants in HNC, and their effects on clinical outcomes. We combined HPV16 positive (HPV16+) HNC samples from a local Southwestern Ontario, Canada cohort with those from the Cancer Genome Atlas to create a larger North American cohort of 149 cases with clinical data and determined the distribution of intratypic variants and their impact on clinical outcomes. Most isolates were lineage A, sublineage A1, or A2, with roughly half exhibiting the T350G polymorphism in E6. Univariable analysis identified significant differences between 350T and 350G intratypic variants in clinical T, N, and O staging, as well as disease-free survival. Multivariable analysis failed to identify any clinical factor as a statistically significant covariate for disease-free survival differences between 350T and 350G. Significant differences in several measures of B-cell mediated immune response were also observed between 350T and 350G intratypic variants. We suggest that HPV genetic variation may be associated with HNC clinical characteristics and may have prognostic value.

Genetic Variability in the E6/E7 Region of Human Papillomavirus 16 in Women from Ecuador

Human Papillomavirus (HPV) infection is associated with intraepithelial neoplasia and cervical cancer (CC). Ecuador has a high prevalence of cervical cancer, with more than 1600 new cases diagnosed annually. This study aimed to analyze oncogenes E6 and E7 of HPV16 in samples collected from women with cancerous and precancerous cervical lesions from the Ecuadorian coast. Twenty-nine women, including six with ASCUS, three with LSIL, thirteen with HSIL, and seven with Cacu, were analyzed. The most common SNPs were E6 350G or L83V (82.6%) and E6 145T/286A/289G/335T/350G or Q14H/F78Y/L83V (17.4%). Both variants are reported to be associated with an increased risk of cervical cancer in worldwide studies. In contrast, all E7 genes have conserved amino-acid positions. Phylogenetic trees showed the circulation of the D (26.1%) and A (73.9) lineages. The frequency of D was higher than that reported in other comparable studies in Ecuador and Latin America, and may be related to the ethnic composition of the studied populations. This study contributes to the characterization of the potential risk factors for cervical carcinogenesis associated with Ecuadorian women infected with HPV16.

Human papillomavirus genomics: Understanding carcinogenicity

Human papillomavirus (HPV) causes virtually all cervical cancers and many cancers at other anatomical sites in both men and women. However, only 12 of 448 known HPV types are currently classified as carcinogens, and even the most carcinogenic type - HPV16 - only rarely leads to cancer. HPV is therefore necessary but insufficient for cervical cancer, with other contributing factors including host and viral genetics. Over the last decade, HPV whole genome sequencing has established that even fine-scale within-type HPV variation influences precancer/cancer risks, and that these risks vary by histology and host race/ethnicity. In this review, we place these findings in the context of the HPV life cycle and evolution at various levels of viral diversity: between-type, within-type, and within-host. We also discuss key concepts necessary for interpreting HPV genomic data, including features of the viral genome; events leading to carcinogenesis; the role of APOBEC3 in HPV infection and evolution; and methodologies that use deep (high-coverage) sequencing to characterize within-host variation, as opposed to relying on a single representative (consensus) sequence. Given the continued high burden of HPV-associated cancers, understanding HPV carcinogenicity remains important for better understanding, preventing, and treating cancers attributable to infection.

The T350G Variation of Human Papillomavirus 16 E6 Gene Prevails in Oropharyngeal Cancer from a Small Cohort of Greek Patients

Recent trends have shown a dramatic rise in the incidence of oropharyngeal squamous cell carcinoma strongly associated with high-risk human papillomavirus (HPV) of type 16. The genetic variability of HPV16 has been extensively studied in cervical cancer but there are very limited published data concerning the genetic variations of this HPV type in oropharyngeal cancer. In the present study, the genetic variations of HPV16 E6 gene sequences originated from a small cohort of Greek patients diagnosed with oropharyngeal cancer were assessed. The vast majority of the sequences clustered within the European variant branch. The T350G variation was found to be the predominant one. This finding may indicate the need for further studies that could explain the possible impact of this variant in the pathomechanisms of oropharyngeal cancer.

Determination of Human Papillomavirus Type 18 Lineage of E6: A Population Study from Iran

The epidemiological studies in Iran on HPV18 nucleotide changes are rare. This type of virus is prevalent in the Iranian population. Therefore, in the present study, we aimed to identify the genetic variability in HPV18 in the E6 region to evaluate the prevalence of lineage distribution and sublineages in a sample population in Iran. Overall, 60 HPV18 confirmed cases were investigated between 2019 and 2021. The specimens were collected, and molecular genotyping was done using the Linear Array HPV Genotyping Test. DNA extraction was performed by a viral DNA/RNA kit. The HPV E6 gene was amplified by using type-specific primers designed according to the HPV18 genome prototype sequence. The sequencing of the E6 region was successfully done on 43 samples which were then compared to the reference sequence. The most frequent sublineage of HPV18 in this study was A4 (69.7%), followed by A1 (18.6%) and A3 (11.6%). Neither A2 nor A5 sublineage was not detected in this study. The related nucleotide acid changes according to the main references were as follows: A3: T104C/T232G/T485C/C549A, A4: T104C/T485C/C549A. The predominance of A lineage with the high frequency of A4 sublineage was found in the present research. The importance of sublineages in susceptibility to a progressive form of infection requires to be more investigated among the different population.

Genetic variability of the HPV16 early genes and LCR. Present and future perspectives

Human papillomavirus 16 (HPV16) infection is the aetiologic factor for the development of cervical dysplasia and is regarded as highly carcinogen, because it is implicated in more than 50% of cervical cancer cases, worldwide. The tumourigenic potential of HPV16 has triggered the extensive sequence analysis of viral genome in order to identify nucleotide variations and amino acid substitutions that influence viral oncogenicity and subsequently the initiation and progression of cervical cancer. Nowadays, specific mutations of HPV16 DNA have been associated with an increased risk of high-grade squamous intraepithelial lesions and invasive cervical cancer (ICC) development, including E6: Q14H, H78Y, L83V, Ε7: N29S, S63F, E2: H35Q, P219S, T310K, E5: I65V, whereas highly conserved regions of viral DNA have been extensively characterised. In addition, numerous novel HPV16 mutations are observed among the studied populations from various geographic regions, hence advocating that different HPV16 strains seem to emerge with different tumourigenic capacities. The present review focuses on the variability of the early genes and the long control region, emphasising on the association of specific mutations with the development of severe dysplasia. Finally, it evaluates whether specific regions of HPV16 DNA are able to serve as valuable biomarkers for cervical cancer risk.

Lineage analysis of human papillomavirus types 31 and 45 in cervical samples of Iranian women

Knowing the regional lineages/sublineages of human papillomavirus 31 (HPV 31) and 45 would be of great importance for further evolutionary, epidemiological, and biological analysis. In this regard, to characterize more common lineages and sublineages of HPV 31 and 45, the sequence variations of E6 gene were investigated in normal, premalignant, and malignant samples collected from the cervix in Iran. In total, 54 HPV 31- and 24 HPV 45-positive samples were analyzed by hemi-nested polymerase chain reaction (PCR) and nested-PCR, respectively. All PCR products were subjected to direct sequencing analysis. The results indicated that all three lineages A, B, and C were detected in HPV 31-positive samples; among which HPV 31 lineage A was dominant as it was found in 66.7% of all samples. HPV 31 lineages B and C were identified in 5.5% and 27.8% of samples, respectively. In HPV 45-infected samples, lineage B comprised of 62.5% of all samples and the remaining 37.5%  belonged to lineage A. In conclusion, our findings showed that lineage A of HPV 31 was predominant in Iran. Lineage B of HPV 45 was also dominant among Iranian women. However, further studies with larger sample size should be addressed to estimate the pathogenicity risk of HPV 31 or HPV 45 lineages/sublineages in the development of cervical cancer among Iranian women.

Distribution of HPV 16 E6 gene variants in screening women and its associations with cervical lesions progression

The aim of this study is to investigate distribution of human papillomavirus (HPV) 16 variants in screening healthy women and the potential association between HPV 16 variants and progression of cervical lesions. For this study a total of 2000 healthy women in Tianjin urban area and 212 patients who were HPV 16 positive and underwent colposcopy were analyzed for HPV 16 variants by pyrosequencing. The results show that the HPV 16 was the most prevalent genotype in Tianjin healthy women and five HPV 16 variant types were detected. The HPV 16 variants were determined by sequencing parital E6 region and the detected variants were European prototype E-T350 (E-p), E-G350, E-C109 G, Asian (As) and Asian-American (AA), among which the E-p variant was the most prevalent (82.76%) followed by As variant. Interestingly, in patients with suspected cervical lesions the most prevalent variant was As variant (54.9%) by increasing significance with severity of cervical diseases (OR 4.337; 95% CI 1.248-15.067; P = 0.021), and followed by HPV 16 E-p variant while E-G350 variant only appeared in HSIL and cervical cancer. Our results show that HPV 16 E-p variant was more prevalent than As in Tianjin healthy screening women while As variant was the most frequently type in HSIL and cervical cancer. It is suggested that the mutation of HPV 16 Asian variants, comparing with HPV 16 E-p variants, might contribute to the transformation from HPV 16 persistent infection to cervical cancer.

Identification of human papillomavirus type 16 variants circulating in the Calabria region by sequencing and phylogenetic analysis of HPV16 from cervical smears

Sequence analysis of HPV16 isolates reveals the presence of genome variants with characteristic mutations. The HPV16 variants have different geographical distribution and diverge into four phylogenetic lineages (A, B, C and D) and 16 sub-lineages: A1, A2, A3 (previously known as European variants), A4 (Asian variant), B1, B2, B3, B4, C1, C2, C3, and C4 (African variants), D1 (North-American variant), D2, D3 (Asian-American variants) and D4. Population studies showed that infections with viruses belonging to specific HPV16 sublineages confer different risks of viral persistence and cancer. In this study, 39 HPV16-positive cervical smears from European women living in Calabria (Italy) were analyzed for the presence of HPV16 variants. Cervical DNA extracts were processed by PCR to amplify L1, the Long Control Region (LCR), E6 and E7, which were sequenced. The sequences were concatenated and the 3169 nucleotides long fragments were characterized by BLAST and phylogenetic analysis. A total of 96 Single Nucleotide Polymorphism (SNPs) were detected, 29 of which mapping in the L1, 45 in the LCR, 15 in the E6 and 7 in the E7. The most common SNP was the T350G (29/39 samples, 74.4%), causing the L83 V amino acid change in the E6. Most of the HPV16 isolates (89.7%) had 99% of nucleotide (nt) identity to members of the A1 and A2 sublineages, while 4 isolates had 99% nt identity to members of the B2, B4, C1 and D4 sublineages. In conclusion, viruses belonging to the A1, A2, B2, B4, C1 and D4 HPV16 sublineages were found to circulate in the Calabria region.

Human papillomavirus genome variants and head and neck cancers: a perspective

Human papillomaviruses (HPV) cause infections that are responsible for diverse clinical manifestations from benign conditions to invasive cancer. As different HPV types are associated with variable pathogenic potential, minor genetic variations within a given high-risk HPV type might also be associated with distinct oncogenic capacities, through variable ability of persistence or risk of progression to precancer/cancer. Most recent HPV variant studies in the cervix using latest sequencing technology confirmed that minor changes in the HPV genome can have a major influence on carcinogenesis and have revealed key data that help better understand the carcinogenicity of HPV at a molecular level. Here we review the limited number of studies on HPV genome variants in head and neck cancers (HNC) and discuss their implications for cancer research in the light of accumulated knowledge for the cervix. Challenges in transposing HPV variant studies from the lower anogenital to the upper aerodigestive tract are also discussed, highlighting the main gaps of knowledge in the field of HPV-induced HNC. Specifically in the head and neck region, the lack of characterisation of precancerous lesions and the difficulty in sampling normal tissue will challenge the development of accurate studies. Although there is so far no indication that HPV variant research in HNC could directly translate into clinical application, such research is expected to be useful to disentangle unanswered questions in the pathogenesis of HNC. Yet, history of HPV variant research suggests that, to be successful, studies will require large international collaborative efforts.

The Intersection of HPV Epidemiology, Genomics and Mechanistic Studies of HPV-Mediated Carcinogenesis

Of the ~60 human papillomavirus (HPV) genotypes that infect the cervicovaginal epithelium, only 12–13 “high-risk” types are well-established as causing cervical cancer, with HPV16 accounting for over half of all cases worldwide. While HPV16 is the most important carcinogenic type, variants of HPV16 can differ in their carcinogenicity by 10-fold or more in epidemiologic studies. Strong genotype-phenotype associations embedded in the small 8-kb HPV16 genome motivate molecular studies to understand the underlying molecular mechanisms. Understanding the mechanisms of HPV genomic findings is complicated by the linkage of HPV genome variants. A panel of experts in various disciplines gathered on 21 November 2016 to discuss the interdisciplinary science of HPV oncogenesis. Here, we summarize the discussion of the complexity of the viral–host interaction and highlight important next steps for selected applied basic laboratory studies guided by epidemiological genomic findings.

Genetic variability in E5, E6, E7 and L1 genes of human papillomavirus type 31

Human papillomavirus (HPV) type 31 is an important pathogenic subtype associated with cervical cancer. The aims of the present study were to analyze E5, E6, E7 and L1 gene mutations of HPV‑31 among females, and to elucidate the evolutionary associations between them. In total, 87 positive samples were collected. The E5, E6, E7 and L1 genes were amplified by polymerase chain reaction and sequenced. Subsequently, two phylogenetic trees were constructed from the nucleotide sequences of the E5, E6 and E7 and the L1 variants of HPV‑31. In total, 31 mutation sites of E5, E6 and E7 genes were identified, of which 16 were non‑synonymous. T4053A (F80I), C285T (H60Y), C520T (A138V) and A743G (K62E) were the most common non‑synonymous mutations. A total of 30 mutation sites of L1 genes were identified, of which four were non‑synonymous. The most common non‑synonymous mutations of L1 genes were A6350G (T29A) and C6372A (T36N). By phylogenetic analysis, A and C variants were most frequently detected, while B variants were less frequently detected in this population. The sequence variation data obtained in the present study provides a foundation for future research regarding HPV‑induced oncogenesis, and may prove valuable for developing diagnostic probes and in the design of HPV vaccines for targeted populations.

Association of codon 72 polymorphism of p53 with the severity of cervical dysplasia, E6-T350G and HPV16 variant lineages in HPV16-infected women

Purpose. Polymorphic variability in the tumour-suppressor protein p53 at codon 72 has a considerable impact on cervical cancer development. The present study clarified the association between p53 codon 72 genotypes and the risk of cervical disease in Greek patients. We also examined whether the presence of specific p53 genotypes in combination with HPV16 variants or E6 T350G sequence variation can modify an individual's susceptibility to cervical disease.Methodology. The analysis of p53 genotypes was performed through PCR-RFLP. Sequence and phylogenetic tree analyses of the HPV16 E6 gene were also performed in order to identify HPV16 variants and T350G sequence variation.Results/Key findings. The outcomes of the present analysis revealed that women who are homozygous for the arg genotype are at a 4.17-fold higher risk of developing HPV16-associated HSIL+ (OR=4.17, 95 % CI:1.48-4.9, P=0.0049). Moreover, p53 arg/arg patients infected by an HPV16 prototype strain were associated with an increased risk of more severe lesions, while a significant relationship between the p53 arg/arg genotype in patients with T350G sequence variation and the risk of high-grade squamous intraepithelial lesions (HSILs) was revealed.Conclusion. The oncogenic potential of the virus is increased by the presence of the p53 arg/arg genotype in the Greek population in such a way that the specific protein interaction E6 (L83V)-p53 (Arg-72) can modify an individual's susceptibility to cervical disease.

Human papillomavirus type 16 lineage analysis based on E6 region in cervical samples of Iranian women

It is suggested that distinct HPV 16 variants differ in oncogenic potential and geographic distribution. As such, understanding the regional variants of HPV 16 would be of great importance for evolutionary, epidemiological and biological analysis. In this regard, the sequence variations of E6 gene were investigated to characterize more common variants of HPV 16 in normal cells, premalignant and malignant lesions of the cervix. In total, 106 isolates of HPV 16 were analyzed by PCR and sequencing. Overall, two different lineages (A and D) were identified. Lineage D comprised 70.7% of samples and the remaining 29.3% belonged to lineage A. Regarding to cytology/histology, lineage D was dominant in both normal+CIN I-II and CIN III+ICC groups as it was detected in 80% and 66.2% of cases, respectively. The comparison of the lineages between different groups (35 normal+CIN I-II samples and 71 CIN III+ICC samples) revealed that lineage A is more prevalent in cervical cancer cases (7 (20%) vs. 24 (33.8%)) although the difference observed did not reach statistical significance (p=0.07). In conclusion, our findings confirm that HPV lineages A and D are more prevalent in Iran, with the lineage D as the most dominant in all studied groups.

Association between human papillomavirus type 16 E6 and E7 variants with subsequent persistent infection and recurrence of cervical high-grade squamous intraepithelial lesion after conization

The study aimed to detect the variants of human papillomavirus (HPV) type 16 E6 and E7 in patients with cervical high-grade squamous intraepithelial lesion (HSIL), and to determine the existence and recurrence of persistent infection after treatment with loop electrosurgical excision procedure (LEEP). Preoperatively collected cervical exfoliated cells from 100 HPV 16 positive HSIL patients enrolled in the study were used to test for E6 and E7 variants. Follow-ups which included TCT, HPV test, and colposcopy were performed every 3 months after the operation, and colposcopic biopsy and endocervical curettage were performed for patients with abnormalities. Patients were followed for 2 years, and recurrence was defined as detecting low-grade squamous intraepithelial lesion (LSIL) or relapse of HSIL in 1 year. In 81% of patients, the E6 variant was the Asian prototype (As.P), 14% of patients had the European variant, 2% had the European prototype (EP), and 3% had the African 1 variant (Af1). The HPV16 could be easily cleared by LEEP in patients with As.P. Persistent infection or recurrence was very rare in this group. The patients with European variants T350G or A442C had a significantly higher incidence of persistent and recurring HPV16 infection. In conclusion, (i) in most cases, As.P caused HSIL. (ii) The European variant E6 T350G/A442C may be associated with higher rates of recurring and persistent HPV16 infection after the LEEP. (iii) The E7 gene mutation may not be a risk factor for recurring HSIL caused by HPV16 or persistent infection. J. Med. Virol. 88:1982-1988, 2016. © 2016 Wiley Periodicals, Inc.

Analysis of human papillomavirus 16 variants and risk for cervical cancer in Chinese population

HPV16 is the most carcinogenic HPV type, but only a minority of HPV16 infections progress to cancer. Intratype genetic variants of HPV16 have been suggested to confer differential carcinogenicity. To investigate risk implications of HPV16 variants among Chinese women, a case-control study was conducted with 298 cervical cancer patients and 85 controls (all HPV16-positive). HPV16 isolates were predominantly of the A variant lineage, and variants of A4 (previously named "Asian") sublineage were common. A4/Asian variants were significantly associated with increased risk of cervical cancer compared to A1-3 (OR=1.72, 95% CI=1.04-2.85). Furthermore, a meta-analysis including 703 cases and 323 controls from East Asia confirmed the association (OR=2.82, 95% CI=1.44-5.52). In conclusion, A4 variants appear to predict higher risk of cervical cancer among HPV16-positive women, which may provide clues to the genetic basis of differences in the carcinogenicity of HPV16 variants.

The human papillomavirus 16 European-T350G E6 variant can immortalize but not transform keratinocytes in the absence of E7

Human papillomavirus type 16 is commonly implicated in HPV-related cancers. However, only a small number of infected individuals progress to this stage. Epidemiological evidence demonstrated that oncogenic risk is population-specific and variations within the viral oncogene, E6, have been suggested to play a role in these findings. Of focus in this study is the European-T350G variant, which is characterized by an L>V amino acid substitution at residue 83 of the prototype E6 protein. To elucidate the functional effects of this polymorphism, we followed keratinocytes transduced with E-T350G E6 for over 60 passages and compared them to keratinocytes transduced, in parallel, with prototype or Asian-American (Q14H/L83V/H78Y) E6. We found that although E-T350G E6 immortalized transduced keratinocytes in the absence of E7, these cells were not fully transformed. We also found that E-T350G down-regulated E-cadherin compared to the other variants, providing a possible link between its population-based oncogenicity and host genetic variations.

Prevalence of human papillomavirus types in cervical cancerous and precancerous lesions of Ecuadorian women

Human Papillomavirus (HPV) is the most common sexually transmitted infection worldwide and it is responsible for most cases of uterine cancer. In Ecuador there is limited information about HPV types (and variants) in cancerous lesions; however, identifying the type-specific HPV prevalence in cervical lesions of women living in Ecuador is important to better predict the impact of HPV prophylactic vaccination in this country. We studied the prevalence of HPV types in cervical cancerous or precancerous lesions from 164 Ecuadorian women and found that 86.0% were HPV positive. The most common types were HPV16 (41.8%) and HPV58 (30.5%). Interestingly, HPV18 was detected only in 2.8% of the HPV-positive samples. Fifteen DNA sequences (genes E6 and L1) from 16 samples positive for HPV16 belonged to the European lineage, considered one of the least carcinogenic lineages, and 1 (6.25%) to the Asian-American lineage. Similar analysis in 12 HPV58 positive samples showed that 10 (83.3%) sequences grouped in sublineage A2, which belongs to the oldest HPV58 lineage, 1 belonged to A3 and 1 to lineage C. This study suggests that the currently used HPV vaccines (bivalent and tetravalent) may have lower effectiveness in Ecuador than in other geographic locations where HPV18 is more prevalent.

MBL2 polymorphisms in women with atypical squamous cells of undetermined significance

Infection with high risk Human papillomavirus (HPV) is the main known cause of cervical cancer. HPV induces different grades of lesions: among them, Atypical squamous cells of undetermined significance are abnormal lesions that could evolve in pre-cancer lesions or spontaneously regress. The mannose binding lectin (MBL) is an innate immunity serum protein also found in cervico-vaginal mucosa, whose expression is known to be affected by polymorphisms in exon 1 and promoter of the MBL2 gene. In the present study the possible association between MBL2 functional polymorphisms and susceptibility to develop atypical squamous cells of undetermined significance was investigated in a group of women from North-East of Italy, stratified for HPV infection status. The MBL2 D and O alleles and the deficient producer combined genotypes, responsible for low MBL production, were more represented among atypical squamous cells of undetermined significance positive women than healthy controls and the results were confirmed when only HPV negative samples were considered. These results suggest a possible involvement of MBL2 functional polymorphisms in atypical squamous cells of undetermined significance susceptibility.

Genetic characterization and clinical implications of human papillomavirus type 16 (HPV16) variants from northeastern Argentina

BACKGROUND

Human papillomavirus type 16 (HPV16) plays a central role in the development of cervical cancer. Worldwide studies indicate the existence of HPV16 variants that show different geographic distributions and oncogenic potential.

OBJECTIVE

Our goal was to describe the genetic variation of HPV16 isolates identified in urban women with different grades of cervical lesions living in northeastern Argentina.

STUDY DESIGN

We analyzed 116 HPV16-positive cervical samples (16 NLIM, 62 L-SIL, 16 H-SIL and 22 cervical cancer) from patients attending health centers in Misiones (Argentina) during 2006-13. HPV16 isolates were genetically characterized through PCR amplification and direct sequencing of 364 bp within the long control region, and the resulting sequences classified into variants based on phylogenetic analysis (lineages A, B, C and D). A potential association between HPV16 variants and lesion grade was evaluated through an odds ratio (OR) test. A temporal framework for the origin of HPV16 variants was assessed through coalescence analysis (BEAST v 1.7.5).

RESULTS

Phylogenetic analysis of HPV16 sequences showed that 92.1% of the samples clustered with lineage A, and 6.9% to lineage D. HPV16 variants from lineage D were more frequently associated with high-grade lesions and cancer (HSIL+) than lineage A variants at an OR of 13.8 (1.6-117.0). The time to most common recent ancestor (tMCRA) of all variants was 119,103 years before present (HPD 95%=48,486-197,239), a date consistent with the time frame for modern human evolution.

CONCLUSION

Our results suggest that HPV16 variants from lineage D may represent an additional risk factor for the development of cervical cancer in women living in northeastern Argentina. This study provides new information about viral isolates present in Argentina that will contribute to the monitoring of HPV16 infection in the vaccine era.

Human papillomavirus 16 non-European variants are preferentially associated with high-grade cervical lesions

HPV16 accounts for 50–70% of cervical cancer cases worldwide. Characterization of HPV16 variants previously indicated that they differ in risks for viral persistence, progression to cervical precancer and malignant cancer. The aim of this study was to examine the association of severity of disease with HPV16 variants identified in specimens (n = 281) obtained from a Cervical Pathology and Colposcopy outpatient clinic in the University Hospital of Espírito Santo State, Southeastern Brazil, from April 2010 to November 2011. All cytologic and histologic diagnoses were determined prior to definitive treatment. The DNA was isolated using QIAamp DNA Mini Kit and HPV was detected by amplification with PGMY09/11 primers and positive samples were genotyped by RFLP analyses and reverse line blot. The genomes of the HPV16 positive samples were sequenced, from which variant lineages were determined. Chi² statistics was performed to test the association of HPV16 variants between case and control groups. The prevalence of HR-HPV types in <CIN1, CIN2 and CIN3+ were 33.7%, 84.4% and 91.6%, respectively. Thirty-eight of 49 (78%) HPV16 positive samples yielded HPV16 sequence information; of which, 32 complete genomes were sequenced and an additional 6 samples were partially sequenced. Phylogenetic analysis and patterns of variations identified 65.8% (n = 25) as HPV16 European (E) and 34.2% (n = 13) as non-European (NE) variants. Classification of disease into CIN3+ vs. <CIN3 indicated that NE types were associated with high-grade disease with an OR = 4.6 (1.07–20.2, p = 0.05). The association of HPV16 NE variants with an increased risk of CIN3+ is consistent with an HPV16 genetically determined enhanced oncogenicity. The prevalence of genetic variants of HPV16 is distributed across different geographical areas and with recent population admixture, only empiric data will provide information on the highest risk HPV16 variants within a given population.

Intratypic variants of human papillomavirus type 16 and risk of cervical neoplasia in Taiwan

The associations between variants of human papillomavirus (HPV) 16 and risk of cervical neoplasia have been reported, but nucleotide variations of HPV 16 in Asian populations and their association with cervical neoplasia have not been evaluated extensively. During 1991-1992, 11,923 women from seven townships in Taiwan were enrolled. The HPV DNA in cervical cells was detected and genotyped using EasyChip HPV blot. Nucleotide variations in the long control region (LCR), E6, and E7 genes were determined using DNA sequencing for 170 HPV 16-positive cervical samples. The Asian variant was the most prevalent variant (81.8%) of HPV 16 in Taiwan, and was also associated with increased prevalence of histologically confirmed cervical intraepithelial neoplasia grade 3 or worse, showing an age-adjusted odds ratio (exact confidence limits) of 10.70 (1.62-451.05; P = 0.0049) compared to the HPV 16 European variant. Similar significant associations with cervical intraepithelial neoplasia grade 3 or worse were also observed for distinct nucleotide substitutions, including T178A/G, A647G, A7730C/G, T7781C, G7842A, and C24T/G. These results demonstrate that non-European variants (non-E) of HPV 16, predominantly Asian variants, are associated with increased risk for severe cervical neoplasia, compared with European variants. Molecular mechanisms accounting for varied cervical neoplasia risk among different HPV 16 variants warrant further investigation.

Human papillomavirus 33 worldwide genetic variation and associated risk of cervical cancer

Human papillomavirus (HPV) 33, a member of the HPV16-related alpha-9 species group, is found in approximately 5% of cervical cancers worldwide. The current study aimed to characterize the genetic diversity of HPV33 and to explore the association of HPV33 variants with the risk for cervical cancer. Taking advantage of the International Agency for Research on Cancer biobank, we sequenced the entire E6 and E7 open reading frames of 213 HPV33-positive cervical samples from 30 countries. We identified 28 HPV33 variants that formed 5 phylogenetic groups: the previously identified A1, A2, and B (sub)lineages and the novel A3 and C (sub)lineages. The A1 sublineage was strongly over-represented in cervical cases compared to controls in both Africa and Europe. In conclusion, we provide a classification system for HPV33 variants based on the sequence of E6 and E7 and suggest that the association of HPV33 with cervical cancer may differ by variant (sub)lineage.

Human papillomavirus type 16 E6 variants in France and risk of viral persistence

Background

Only a small portion of HPV 16 infections persist and can lead to cervical intraepithelial lesions and cancer. Factors that favour HPV persistence versus clearance are still poorly understood, but several studies have suggested that HPV intra-type variants may influence persistence and clinical outcome. The aim of this study was to assess the possible association between HPV 16 variants and the risk for viral persistence in the general population of France.

Methods

One hundred and forty two women infected with HPV 16 with normal cytology, without previous treatment for cervical lesions, and with a valid second follow-up visit 4 to 16 months later, were selected from patients participating in routine cervical cancer screening in the Reims HPV Primary Screening Cohort Study. HPV intra-type variants were determined by sequencing the HPV 16 E6 open reading frame, and were compared for viral persistence at the second visit using odds ratios (OR) to estimate relative risk.

Results

Although no statistically significant differences in risk for persistence were observed by the HPV 16 variant lineage, European variants containing the polymorphism 350 T (EUR-350 T) appeared to persist more often than those containing 350 G (EUR-350 G) (OR = 1.6, 95% CI = 0.8-3.4).

Conclusions

No strong differences were observed in the risk of viral persistence for the HPV 16 variants that predominate in France.

HPV16 genetic variation and the development of cervical cancer worldwide

BACKGROUND

Factors that favour a small proportion of HPV16 infections to progress to cancer are still poorly understood, but several studies have implicated a role of HPV16 genetic variation.

METHODS

To evaluate the association between HPV16 genetic variants and cervical cancer risk, we designed a multicentre case-control study based on HPV16-positive cervical samples (1121 cervical cancer cases and 400 controls) from the International Agency for Research on Cancer biobank. By sequencing the E6 gene, HPV16 isolates were classified into variant lineages and the European (EUR)-lineage isolates were subclassified by the common polymorphism T350G.

RESULTS

Incidence of variant lineages differed between cases and controls in Europe/Central Asia (P=0.006, driven by an underrepresentation of African lineages in cases), and South/Central America (P=0.056, driven by an overrepresentation of Asian American/North American lineages in cases). EUR-350G isolates were significantly underrepresented in cervical cancer in East Asia (odds ratio (OR)=0.02 vs EUR-350T; 95% confidence interval (CI)=0.00-0.37) and Europe/Central Asia (OR=0.42; 95% CI=0.27-0.64), whereas the opposite was true in South/Central America (OR=4.69; 95% CI=2.07-10.66).

CONCLUSION

We observed that the distribution of HPV16 variants worldwide, and their relative risks for cervical cancer appear to be population-dependent.

A comprehensive review on host genetic susceptibility to human papillomavirus infection and progression to cervical cancer

Cervical cancer is the second most common cancer in women worldwide. This is caused by oncogenic types of human papillomavirus (HPV) infection. Although large numbers of young sexually active women get HPV-infected, only a small fraction develop cervical cancer. This points to different co-factors for regression of HPV infection or progression to cervical cancer. Host genetic factors play an important role in the outcome of such complex or multifactor diseases such as cervical cancer and are also known to regulate the rate of disease progression. The aim of this review is to compile the advances in the field of host genetics of cervical cancer. MEDLINE database was searched using the terms, ‘HPV’, ‘cervical’, ‘CIN’, ‘polymorphism(s)’, ‘cervical’+ *the name of the gene* and ‘HPV’+ *the name of the gene*. This review focuses on the major host genes reported to affect the progression to cervical cancer in HPV infected individuals.

Characterization and whole genome analysis of human papillomavirus type 16 e1-1374^63nt variants

BACKGROUND

The variation of the most common Human papillomavirus (HPV) type found in cervical cancer, the HPV16, has been extensively investigated in almost all viral genes. The E1 gene variation, however, has been rarely studied. The main objective of the present investigation was to analyze the variability of the E6 and E1 genes, focusing on the recently identified E1-1374^63nt variant.

METHODOLOGY/PRINCIPAL FINDINGS

Variation within the E6 of 786 HPV16 positive cervical samples was analyzed using high-resolution melting, while the E1-1374^63nt duplication was assayed by PCR. Both techniques were supplemented with sequencing. The E1-1374^63nt duplication was linked with the E-G350 and the E-C109/G350 variants. In comparison to the referent HPV16, the E1-1374^63nt E-G350 variant was significantly associated with lower grade cervical lesions (p = 0.029), while the E1-1374^63nt E-C109/G350 variant was equally distributed between high and low grade lesions. The E1-1374^63nt variants were phylogenetically closest to E-G350 variant lineage (A2 sub-lineage based on full genome classification). The major differences between E1-1374^63nt variants were within the LCR and the E6 region. On the other hand, changes within the E1 region were the major differences from the A2 sub-lineage, which has been historically but inconclusively associated with high grade cervical disease. Thus, the shared variations cannot explain the particular association of the E1-1374^63nt variant with lower grade cervical lesions.

CONCLUSIONS/SIGNIFICANCE

The E1 region has been thus far considered to be well conserved among all HPVs and therefore uninteresting for variability studies. However, this study shows that the variations within the E1 region could possibly affect cervical disease, since the E1-1374^63nt E-G350 variant is significantly associated with lower grade cervical lesions, in comparison to the A1 and A2 sub-lineage variants. Furthermore, it appears that the silent variation 109T>C of the E-C109/G350 variant might have a significant role in the viral life cycle and warrants further study.

Whole genome sequencing and evolutionary analysis of human papillomavirus type 16 in central China

Human papillomavirus type 16 plays a critical role in the neoplastic transformation of cervical cancers. Molecular variants of HPV16 existing in different ethnic groups have shown substantial phenotypic differences in pathogenicity, immunogenicity and tumorigenicity. In this study, we sequenced the entire HPV16 genome of 76 isolates originated from Anyang, central China. Phylogenetic analysis of these sequences identified two major variants of HPV16 in the Anyang area, namely the European prototype (E(p)) and the European Asian type (E(As)). These two variants show a high degree of divergence between groups, and the E(p) comprised higher genetic diversity than the E(As). Analysis with two measurements of genetic diversity indicated that viral population size was relatively stable in this area in the past. Codon based likelihood models revealed strong statistical support for adaptive evolution acting on the E6 gene. Bayesian analysis identified several important amino acid positions that may be driving adaptive selection in the HPV 16 population, including R10G, D25E, L83V, and E113D in the E6 gene. We hypothesize that the positive selection at these codons might be a contributing factor responsible for the phenotypic differences in carcinogenesis and immunogenicity among cervical cancers in China based on the potential roles of these molecular variants reported in other studies.

Human papillomavirus (HPV) 16 E6 variants in tonsillar cancer in comparison to those in cervical cancer in Stockholm, Sweden

Background

Human papillomavirus (HPV), especially HPV16, is associated with the development of both cervical and tonsillar cancer and intratype variants in the amino acid sequence of the HPV16 E6 oncoprotein have been demonstrated to be associated with viral persistence and cancer lesions. For this reason the presence of HPV16 E6 variants in tonsillar squamous cell carcinoma (TSCC) in cervical cancer (CC), as well as in cervical samples (CS), were explored.

Methods

HPV16 E6 was sequenced in 108 TSCC and 52 CC samples from patients diagnosed 2000–2008 in the County of Stockholm, and in 51 CS from young women attending a youth health center in Stockholm.

Results

The rare E6 variant R10G was relatively frequent (19%) in TSCC, absent in CC and infrequent (4%) in CS, while the well-known L83V variant was common in TSCC (40%), CC (31%), and CS (29%). The difference for R10G was significant between TSCC and CC (p = 0.0003), as well as between TSCC and CS (p = 0.009). The HPV16 European phylogenetic lineage and its derivatives dominated in all samples (>90%).

Conclusion

The relatively high frequency of the R10G variant in TSCC, as compared to what has been found in CC both in the present study as well as in several other studies in different countries, may indicate a difference between TSCC and CC with regard to tumor induction and development. Alternatively, there could be differences with regard to the oral and cervical prevalence of this variant that need to be explored further.

Rare human papillomavirus 16 E6 variants reveal significant oncogenic potential

The aim of this study was to determine whether low prevalence human papillomavirus (HPV) 16 E6 variants differ from high prevalence types in their functional abilities. We evaluated functions relevant to carcinogenesis for the rarely-detected European variants R8Q, R10G and R48W as compared to the commonly detected L83V. Human immortalized keratinocytes (NIKS) stably transduced with the E6 variants were used in most functional assays. Low and high prevalence E6 variants displayed similar abilities in abrogation of growth arrest and inhibition of p53 elevation induced by actinomycin D. Differences were detected in the abilities to dysregulate stratification and differentiation of NIKS in organotypic raft cultures, modulate detachment induced apoptosis (anoikis) and hyperactivate Wnt signaling. No distinctive phenotype could be assigned to include all rare variants. Like L83V, raft cultures derived from variants R10G and R48W similarly induced hyperplasia and aberrantly expressed keratin 5 in the suprabasal compartment with significantly lower expression of keratin 10. Unlike L83V, both variants, and particularly R48W, induced increased levels of anoikis upon suspension in semisolid medium. R8Q induced a unique phenotype characterized by thin organotypic raft cultures, low expression of keratin 10, and high expression of keratins 5 and 14 throughout all raft layers. Interestingly, in a reporter based assay R8Q exhibited a higher ability to augment TCF/β-catenin transcription. The data suggests that differences in E6 variant prevalence in cervical carcinoma may not be related to the carcinogenic potential of the E6 protein.

Distribution of human papillomavirus type 16 E6 and E7 gene variants in the progression of cervical dysplasia in Korean women

AIM

This cross-sectional, hospital-based study examined the distribution of human papillomavirus 16 E6 and E7 gene variants in Korean women with cervical lesions of varying degrees.

MATERIAL & METHODS

One hundred and forty-one Korean women (median age 43 years; range 22-65 years) with human papillomavirus 16 single infections were included. The human papillomavirus 16 E6/E7 sequences were amplified from cytology specimens. The distribution of human papillomavirus 16 variations with respect to cervical lesion was examined by the exact Mantel-Haenszel linear trend test (P(trend) ) and Fisher's exact test (P).

RESULTS

Human papillomavirus 16 E6 and E7 gene variants were identified in a total of 100 women (70.9%). The most prevalent human papillomavirus 16 variants were E6 Thymine178Guanine (number = 70, 49.6%) and E7 Adenine647Guanine (number = 75, 53.2%). Human papillomavirus 16 E6 Thymine178Guanine and E7 Adenine647Guanine were significantly related to the degree of cervical neoplasia (P(trend) = 0.0002, P< 0.0001; P(trend) < 0.0001, P < 0.0001, respectively). The odds ratio of human papillomavirus 16 E6 Thymine178Guanine to predict progression to cervical intraepithelial neoplasia 2-3 and invasive cancer was 2.37 (95% confidence interval 1.03-5.45) and 9.07 (95% confidence interval 2.86-28.72), respectively. The odds ratio of E7 Adenine647Guanine to predict progression to cervical intraepithelial neoplasia 2-3 and invasive cancer was 3.65 (95% confidence interval 1.16-8.51) and 9.07 (95% confidence interval 2.86-28.72), respectively.

CONCLUSION

The distribution of HPV variants appears to be related to geographic difference. Human papillomavirus 16 E6 Thymine178Guanine and E7 Adenine647Guanine can be used as the candidate marker for the progression of the cervical neoplasia.

Risks for persistence and progression by human papillomavirus type 16 variant lineages among a population-based sample of Danish women

BACKGROUND

Little is known about factors determining HPV16 persistence and progression, but several studies have suggested that genetic variants may play a role.

METHODS

HPV16-positive women with normal cytology in a large Danish cohort were reassessed for HPV16 status at 2 years and followed-up for cervical intraepithelial neoplasia 3 or worse (CIN3+) over 11 years through linkage with a national pathology database. Relative risks for clearance, persistence, and progression were compared with different HPV16 variant lineages based upon E6 gene sequencing.

RESULTS

Sixty-two (23.7%) of 261 HPV16 infections were persistent at 2 years, and 32 (51.6%) persistent infections progressed to CIN3+. The majority of baseline infections belonged to the European lineage (97.3%), with EUR-350T and EUR-350G accounting for 61.3% and 36.0% of infections, respectively. At two years, the proportion of HPV16 infections that persisted was significantly higher for EUR-350T (28.2%) than EUR-350G (15.9%) variants (odds ratio = 2.06, 95% CI, 1.04-4.25). This increased risk for persistence was consistent both in the absence (OR = 2.16, 95% CI, 0.84-6.26) or presence (OR = 1.89, 95% CI, 0.76-5.15) of progression to CIN3+. Among persistent HPV16 infections, there was no significant difference in risk of progression to CIN3+ between EUR-350T and EUR-350G sub-lineages, which were both associated with a substantial absolute risk (>50%) of CIN3+.

CONCLUSIONS

Significant differences in risk for persistence exist between the HPV16 variants that predominate in Europe.

IMPACT

Understanding the genetic basis of HPV16 persistence and carcinogenicity may help unravel important interactions between HPV16 and the host immune system.

Human papillomavirus (HPV) genotypes and HPV16 variants and risk of adenocarcinoma and squamous cell carcinoma of the cervix

OBJECTIVE

Human papillomavirus (HPV) genotypes have been extensively studied in uterine cervix squamous cell carcinoma and HPV16 variants have been found to be associated with increased cancer risk, but few reports have been published on genotype distribution and HPV16 variant prevalence in adenocarcinoma tumors. The objective of this study was to analyze viral genotypes and HPV16 intratypic variants in cervical adenocarcinoma and squamous cell carcinoma of Italian women.

METHODS

A total of 39 invasive adenocarcinoma and 132 squamous cell carcinoma were reviewed and classified according to the modified WHO classification. HPV sequences were detected by nested PCR, using the broad spectrum consensus-primer pairs MY09/MY11 and the GP5+/GP6+ system, and genotyped by nucleotide sequence analysis. The HPV16-positive cases were amplified with E6-specific oligonucleotides and amplimers subjected to direct nucleotide sequence for variant identification.

RESULTS

The prevalence rate of any HPV infection was 72% in adenocarcinoma, and 85% in cervical squamous cell carcinoma. Among the 140 HPV-positive cancer cases, a total of nine mucosal HPV genotypes (HPV16, 18, 31, 33, 35, 39, 45, 58, 82) epidemiologically classified as carcinogenic or probably carcinogenic viruses were identified. The HPV type 16 was the most common viral type representing 64% and 73% of all infections in adenocarcinoma and squamous cell carcinoma, respectively. The E6 nucleotide sequence analysis of HPV16 isolates allowed the identification of Asian American (AA) variants in 33% of adenocarcinoma and in 20% of squamous cell carcinoma suggesting their stronger association with cancer of glandular origin.

CONCLUSION

These results suggest that HPV16 has a high prevalence in both invasive adenocarcinoma and squamous cell carcinoma from Italian patients. Moreover this study confirms previous observations, summarized in a systematic review of the literature, on the increased cancer risk of HPV16 AA class in adenoglandular cancer, possibly related to their more oncogenic behavior compared to HPV16 European variants.

E6 molecular variants of human papillomavirus (HPV) type 16: an updated and unified criterion for clustering and nomenclature

Reports on taxonomic identification of E6/HPV 16 variants, don't have a worldwide, updated and unified criterion for clustering and nomenclature. Our aim was to update the existing criterion and propose a new one for clustering and nomenclature for E6/HPV 16 molecular variants based on the descriptive and comparative analyses of nucleotide sequences. A systematic search of the publications between 1991 and 2010 was carried out in PUBMED and manually. 240 E6/HPV 16 variants were identified. 157 were classified as European (E), 24 as Asian (As), 14 as Asian American (AA), 11 as North American 1 (NA 1), 19 as African 1 (Af 1) and 15 as African 2 (Af 2). Three classes were determined for the E, 3 each for the As, Af 2 and AA branches, 4 classes for the NA 1 and 6 for the Af 1 branch. This study reports our results and proposes an updated criterion for clustering and nomenclature that will be useful for E6 variant identification.

Unique variants of human papillomavirus genotypes 52 and 58 and risk of cervical neoplasia

Human papillomavirus (HPV) 52 and 58 are oncogenic HPV types prevalent in Asia. Our study aims to explore intratypic variants of HPV 52 and 58 in Taiwan. A total of 11,923 women were enrolled from seven townships in 1991-1992. HPV DNA in their cervical cells was detected and typed by EasyChip® HPV blot. Among 424 participants infected with HPV 52 and/or 58, nucleotide variations were determined in cervical cell samples of 406 participants by the polymerase chain reaction sequencing of the long control region, E6 and E7 genes. Nonprototype-like variants including lineages B and C were detected in 278 (99.3%) of 280 HPV 52 samples. The prototype and prototype-like group (lineage A) of HPV58 was found in 132 (98.5%) of 134 HPV 58 samples, with sublineage A1, A2 and A3 variant in 14.2, 27.6 and 56.7%, respectively. Among women infected with single HPV 52 type, the C variant (vs. B variant) was associated with an increased prevalence of cytologically diagnosed high-grade squamous intraepithelial lesion or worse lesions showing an age-adjusted odds ratio (95% confidence interval, CI) of 5.2 (1.0-27.6) and an increased prevalence of histologically confirmed high-grade cervical intraepithelial neoplasia or more severe lesions with an age-adjusted odds ratio (95% CI) of 7.6 (1.3-43.8). It was concluded that frequency distributions of HPV 52 and 58 variants in Taiwan were different from those in European and American populations. The association between C variant of HPV 52 and prevalence of cervical neoplasia needs further validation.

Human papillomavirus type 16 e6 gene variations in young Chinese women with cervical squamous cell carcinoma

Human papillomavirus (HPV) 16 E6 gene mutation is considered an important genetic change in cervical lesion progression. To explore the possible association of specific HPV16 E6 sequence variations with the development of invasive cervical squamous cell carcinoma (SCC) in young women, we examined the distribution of HPV16 E6 variants in a Chinese cervical SCC population and analyzed the difference between younger patients (≤35 years, n = 50) and older ones (>35ys, n = 71). Human papillomavirus type 16 E6 DNA was amplified by polymerase chain reaction and sequenced by Sanger fluorescent dye dideoxy-termination method. Analysis revealed that the most frequently found variation in this Chinese population was the EV (As) lineage (65.45%). In addition, the EV (As) lineage seems more common and uniform in younger patients than other lineages, and it may be associated with early age at diagnosis of cervical SCC in young women.

[Human papillomavirus type 16 variant analysis of upstream regulatory region and E6, E7 oncogene from cervical cancer patients in Beijing]

To investigate distributional characteristics of mutations of HPV16 upstream regulatory region (URR) and E6 and E7 oncogene in the patients with cervical cancer in Beijing and to explore the potential association between oncogenesis of cervical cancer and HPV variants in this region, cervical cancer tissue from 31 cases with positive HPV16 were subjected to regular DNA extraction procedure. The corresponding primers were then designed to amplify the target sequence of URR, E6 and E7. The PCR products were sequenced and blast analysis against GenBank was carried out to evaluate the gene mutation and identify the phylogenetic branches. Among all the cases studied, URR was found to be the most frequent mutation fragments, followed by E7, and E6 was the most conservative sequence. A total of 8 hot mutation spot was identi-fied, which were URR G7521A (100%), C7435G (96.77%), C24T (45.16%), A7729C (45.16%), G7839A (45.16%), E6 T178G (41.94%), E7 A647G (45.16%), and T846C (45.16%). The most frequent HPV 16 branch was type As (54.84%), followed by type E (45.16%). Our results suggested that the mutations of G7521A, A7729C, G7839A, T178G, T350G, A647G, and G658A were likely to be associated with the enhanced oncogenic potential of HPV16 and oncogenesis of cer-vical cancer. In Beijing area, two major branches of HPV16 were type As and E. This finding provides valuable information for HPV vaccine development and infection treatment. Type As and E variants had different distributions among various ages and clinic stage groups. It might lead to a new explanation for the getting younger trend of cervical cancer.

The immortalizing and transforming ability of two common human papillomavirus 16 E6 variants with different prevalences in cervical cancer

Persistent infection with high-risk human papillomaviruses (HPVs), especially type 16 has been undeniably linked to cervical cancer. The Asian-American (AA) variant of HPV16 is more common in the Americas than the prototype in cervical cancer. The different prevalence is based on three amino acid changes within the E6 protein denoted Q14H/H78Y/L83V. To investigate the mechanism(s) behind this observation, both E6 proteins, in the presence of E7, were evaluated for their ability to extend the life span of and transform primary human foreskin keratinocytes (PHFKs). Long-term cell culture studies resulted in death at passage 9 of vector-transduced PHFKs (negative control), but survival of both E6 PHFKs to passage 65 (and beyond). Compared with E6/E7 PHFKs, AA/E7 PHFKs were significantly faster dividing, developed larger cells in monolayer cultures, showed double the epithelial thickness and expressed cytokeratin 10 when grown as organotypic raft cultures. Telomerase activation and p53 inactivation, two hallmarks of immortalization, were not significantly different between the two populations. Both were resistant to anoikis at later passages, but only AA/E7 PHFKs acquired the capacity for in vitro transformation. Proteomic analysis revealed markedly different protein patterns between E6/E7 and AA/E7, particularly with respect to key cellular metabolic enzymes. Our results provide new insights into the reasons underlying the greater prevalence of the AA variant in cervical cancer as evidenced by characteristics associated with higher oncogenic potential.

Developments in therapeutic human papillomavirus vaccination

Much progress has been made in the prevention and therapy of premalignant and malignant dysplasia caused by human papillomavirus by encouraging screening programs and recently by introducing preventive vaccines. To further reduce the worldwide burden of HPV-associated cancer supplementation of the established therapies with immunotherapeutic methods would have the potential for significant impact. Dysplastic epithelial lesions and cancer of the anogenital and the oropharyngeal region show strong association with HPV. Therefore cervical carcinoma and HPV-associated squamous cell carcinoma of the head and neck differ from most other malignancies in that they harbour HPV-derived antigens. Expression of the viral oncogenes is mandatory to maintain the cancerous phenotype. These antigens are unique to the tumour and attractive targets for "proof of concept" studies in the development of therapeutic vaccines showing the general applicability of tumour vaccination and prove the correlation of immune response and clinical response. To date numerous clinical trials have been performed with candidate vaccines predominantly testing the efficacy for cervical cancer and its precursors. Although a naturally induced anti-HPV T cell response in patients was shown, clinical success of therapeutic vaccines was sparse. This may be attributed to immunosuppression, immunoselection, and immunoediting by the tumour cells. Factors of the individual that led to the failure of autonomous clearance of the initial infection may also contribute. Overriding this failure, reversing immunosuppression and application of vaccines in early stages of the disease is the key task for the future. The aim of this article is to summarize recent developments of therapeutic vaccines and discuss obstacles that hinder their success.

Papillomavirus and disease in humans and animals

Papillomavirus (PV) induces exophytic lesions (papillomas, warts) and flat lesions (flat warts, cervical intraepithelial neoplasia) in cutaneous and mucosal epithelia. The lesions are usually benign and generally regress without eliciting any serious clinical problems in a host but occasionally persist. Persistent lesions can be debilitating and can also provide a focus for malignant transformation to squamous cell carcinoma, particularly in the presence of environmental or genetic cofactors. This has been experimentally demonstrated in animals, particularly in cattle, where bovine PV (BPV)-induced papillomas progress to cancer of the upper gastrointestinal (GI) tract and the urinary bladder in animals exposed to bracken fern in the pasture, and in rabbits, where the progression of skin papillomas to squamous cell carcinoma depends on a particular variant of cottontail rabbit PV (CRPV) and on the major histocompatibility complex (MHC) class II haplotype of the animal. In this review, various aspects of the biology of BPV and CRPV are described and compared with those of human PV, including viral genome structure, regulation of transcription of the viral oncogenes, function of the viral oncoproteins, co-operation between virus and cofactors, virus latency, immunity and vaccination.

Genetic epidemiology of glioblastoma multiforme: confirmatory and new findings from analyses of human leukocyte antigen alleles and motifs

Background

Human leukocyte antigen (HLA) class I genes mediate cytotoxic T-lymphocyte responses and natural killer cell function. In a previous study, several HLA-B and HLA-C alleles and haplotypes were positively or negatively associated with the occurrence and prognosis of glioblastoma multiforme (GBM).

Methodology/Principal Findings

As an extension of the Upper Midwest Health Study, we have performed HLA genotyping for 149 GBM patients and 149 healthy control subjects from a non-metropolitan population consisting almost exclusively of European Americans. Conditional logistic regression models did not reproduce the association of HLA-B*07 or the B*07-Cw*07 haplotype with GBM. Nonetheless, HLA-A*32, which has previously been shown to predispose GBM patients to a favorable prognosis, was negatively associated with occurrence of GBM (odds ratio = 0.41, p = 0.04 by univariate analysis). Other alleles (A*29, A*30, A*31 and A*33) within the A19 serology group to which A*32 belongs showed inconsistent trends. Sequencing-based HLA-A genotyping established that A*3201 was the single A*32 allele underlying the observed association. Additional evaluation of HLA-A promoter and exon 1 sequences did not detect any unexpected single nucleotide polymorphisms that could suggest differential allelic expression. Further analyses restricted to female GBM cases and controls revealed a second association with a specific HLA-B sequence motif corresponding to Bw4-80Ile (odds ratio = 2.71, p = 0.02).

Conclusions/Significance

HLA-A allelic product encoded by A*3201 is likely to be functionally important to GBM. The novel, sex-specific association will require further confirmation in other representative study populations.

Association of HLA-DRB1, interleukin-6 and cyclin D1 polymorphisms with cervical cancer in the Swedish population--a candidate gene approach

High-risk human papillomavirus (hrHPV) infection is the major risk factor for cervical cancer (CxCa). The role of genetic susceptibility in the disease has been suggested, but the existing data lack consistency. We conducted a nested case-control study on 973 CxCa cases and 1,763 matched controls, from two Swedish population-based cohorts to examine the association of common genetic variants with CxCa risk. Human leukocyte antigen (HLA) alleles and 24 other polymorphisms in 14 genes were selected on the basis of reported association or mechanistic plausibility with an HPV infection or cervical cancer development. Genotyping was conducted using multiplex PCR and Luminex technology. A significant association of CxCa with various polymorphisms was observed: rs1800797 in the IL-6 gene (odds ratio [OR] = 0.88, 95% confidence intervals [CI]: 0.79-0.99); rs1041981 in the LTA gene (OR = 0.87, 95% CI: 0.78-0.98), and rs9344 in the CCND1 gene (OR = 1.14, 95% CI: 1.02-1.27), for those individuals carrying the rare allele. Additionally, the alleles 0401 and 1501 of the HLA class II DRB1 locus were associated with an increased risk (OR = 1.23, 95% CI: 1.04-1.45 and OR = 1.29, 95% CI: 1.11-1.50, respectively), and allele 1301 was associated with decreased risk (OR = 0.59, 95% CI: 0.47-0.73). The effects of CCND1 and the HLA*DRB1 alleles were independent of the effect of smoking. We did not find any association of risk with polymorphisms in genes related to the innate immune system. In conclusion, our study provides evidence for genetic susceptibility to CxCa due to variations in genes involved in the immune system and in cell cycle.

Mannose-binding lectin in high-risk human papillomavirus infection

OBJECTIVE

Mannose-binding lectin (MBL) is a serum lectin that mediates phagocytosis and activates complement. We investigated the association of mbl-2 functional polymorphisms with human papillomavirus (HPV) infection, which is a primary etiologic factor for cervical cancer.

STUDY DESIGN

The frequencies of haplotypes and genotypes of mbl-2 exon1 and promoter region variants were analyzed in 150 patients with HPV and 277 control subjects with no HPV. Unconditional logistic regression analysis was performed to evaluate an association between specific mbl-2 alleles and susceptibility to HPV infection.

RESULTS

The frequency of high-producer mbl-2 genotypes was higher in patients with HPV than in control subjects with no HPV (P = .001). The genotype of the mbl-2 gene polymorphisms represented the least significant risk for the group with HPV.

CONCLUSION

Certain polymorphisms in the MBL promoter region are increased among cervical samples that demonstrate HPV infection. This finding suggests a potential link between MBL and high-risk HPV infection.