Phylogenomic Analysis of Human Papillomavirus Type 31 and Cervical Carcinogenesis: A Study of 2093 Viral Genomes.

Human papillomavirus (HPV) type 31 (HPV31) is closely related to the most carcinogenic type, HPV16, but only accounts for 4% of cervical cancer cases worldwide. Viral genetic and epigenetic variations have been associated with carcinogenesis for other high-risk HPV types, but little is known about HPV31. We sequenced 2093 HPV31 viral whole genomes from two large studies, one from the U.S. and one international. In addition, we investigated CpG methylation in a subset of 175 samples. We evaluated the association of HPV31 lineages/sublineages, single nucleotide polymorphisms (SNPs) and viral methylation with cervical carcinogenesis. HPV31 A/B clade was >1.8-fold more associated with cervical intraepithelial neoplasia grade 3 and cancer (CIN3+) compared to the most common C lineage. Lineage/sublineage distribution varied by race/ethnicity and geographic region. A viral genome-wide association analysis identified SNPs within the A/B clade associated with CIN3+, including H23Y (C626T) (odds ratio = 1.60, confidence intervals = 1.17-2.19) located in the pRb CR2 binding-site within the E7 oncogene. Viral CpG methylation was higher in lineage B, compared to the other lineages, and was most elevated in CIN3+. In conclusion, these data support the increased oncogenicity of the A/B lineages and suggest variation of E7 as a contributing risk factor.

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.

Structural and functional impacts of E5 genetic variants of human papillomavirus type 31.

Persistent infections caused by high-risk human papillomavirus (HR-HPV) are important, for the development of cervical lesions, but environmental and genetic factors are also related in the process of carcinogenesis. Among the genetic factors, the genetic variants of HR-HPV appear to be related to the risk of persistent infections. Therefore, the present study investigates variants of HPV31 E5 oncogene in cervical scraping samples from Brazilian women to assess their functional and structural effects, in order to identify possible repercussions of these variants on the infectious and carcinogenic process. Our results detected nucleotide changes previously described in the HPV31 E5 oncogene, which may play a critical role in the development of cancer due to its ability to promote cell proliferation and signal transmission. In our study, the interaction percentage of the 31E5 sequence generated by the Immune Epitope Server database and the Analysis Resource (IEDB) allowed us to include possible immunogenic epitopes with the MHC-I and MHC-II molecules, which may represent a possible relationship between protein suppression of the immune system. In the structural analysis of the HPV31 E5 oncoprotein, the N5D, I48 V, P56A, F80I and V64I polymorphisms can be found inserted within transmembrane regions. The P56A mutation has been predicted to be highly stabilizing and, therefore, can cause a change in protein function. Regarding the interaction of the E5 protein from HPV31 with the signaling of NF-kB pathway, we observed that in all variants of the E5 gene from HPV-31, the activity of the NF-kB pathway was increased compared to the prototype. Our study contributes to a more refined design of studies with the E5 gene from HPV31 and provides important data for a better understanding of how variants can be distinguished under their clinical consequences.

The distribution and common amino acid polymorphisms of human papillomavirus (HPV)-31 variants in 2700 women from Northern China.

To investigate the distribution of Human papillomavirus (HPV)-31 A, B and C variants as well as the common amino acid polymorphisms in Chinese women, all 14 HPV-31 positive cervical exfoliated cell specimens identified from a descriptive study including ∼2700 women from Northern China were analyzed. HPV-31 positive specimens were identified by Mass Spectrometry and the fragments of partial Long Control Region, E6 and E7 were amplified and directly sequenced or cloned into vector and then sequenced to confirm the variant information. HPV-31 prevalence in Northern Chinese female population was 0.52%. Six different sequences represented all 14 isolates, and these isolates were subsequently classified into variant lineage A (9), B (0) and C (5) by phylogenetic analysis. Five common amino acid polymorphism sites (2 in E6 and 3 in E7) and a novel non-synonymous mutation were detected in the current study. Our investigation suggested that HPV-31 was much less detected in Chinese women population than that in western countries. A and C variants were commonly detected while B variants were rarely detected in this population.

Human papillomavirus genotype distribution and E6/E7 oncogene expression in Turkish women with cervical cytological findings.

BACKGROUND: Infection with certain human papillomavirus (HPV) genotypes is the most important risk factor related with cervical cancer. The objective of the present study was to investigate the prevalence of HPV infection, the distribution of HPV genotypes and HPV E6/E7 oncogene mRNA expression in Turkish women with different cervical cytological findings in Mersin province, Southern Turkey. MATERIALS AND METHODS: A total of 476 cytological samples belonging to women with normal and abnormal cervical Pap smears were enrolled in the study. For the detection and genotyping assay, a PCR/direct cycle sequencing approach was used. E6/E7 mRNA expression of HPV-16, 18, 31, 33, and 45 was determined by type-specific real-time NASBA assay (NucliSENS EasyQ(®)HPV v1.1). RESULTS: Of the 476 samples, 106 (22.3%) were found to be positive for HPV DNA by PCR. The presence of HPV was significantly more common (p<0.001) in HSIL (6/8, 75%) when compared with LSIL (6/14, 42.9%), ASC-US (22/74, 29.7%) and normal cytology (72/380, 18.9%). The most prevalent genotypes were, in descending order of frequency, HPV genotype 66 (22.6%), 16 (20.8%), 6 (14.2%), 31 (11.3%), 53 (5.7%), and 83 (4.7%). HPV E6/E7 oncogene mRNA positivity (12/476, 2.5%) was lower than DNA positivity (38/476, 7.9%). CONCLUSIONS: Our data present a wide distribution of HPV genotypes in the analyzed population. HPV genotypes 66, 16, 6, 31, 53 and 83 were the predominant types and most of them were potential carcinogenic types. Because of the differences between HPV E6/E7 mRNA and DNA positivity, further studies are required to test the role of mRNA testing in the triage of women with abnormal cervical cytology or follow up of HPV DNA positive and cytology negative. These epidemiological data will be important to determine the future impact of vaccination on HPV infected women in our region.

Persistence of newly detected human papillomavirus type 31 infection, stratified by variant lineage.

Variants of human papillomavirus (HPV) type 31 have been shown to be related both to risk of cervical lesions and racial composition of a population. It is largely undetermined whether variants differ in their likelihood of persistence. Study subjects were women who participated in the ASCUS-LSIL Triage Study and who had a newly detected HPV31 infection during a two-year follow-up with six-month intervals. HPV31 isolates were characterized by sequencing and assigned to one of three variant lineages. Loss of the newly detected HPV31 infection was detected in 76 (47.5%) of the 160 women (32/67 with A variants, 16/27 with B variants and 28/66 with C variants). The adjusted hazard ratio associating loss of the infection was 1.2 (95% CI, 0.7-2.1) for women with A variants and 2.1 (95% CI, 1.2-3.5) for women with B variants when compared with those with C variants. Infections with A and C variants were detected in 50 and 41 Caucasian women and in 15 and 23 African-American women, respectively. The likelihood of clearance of the infection was significantly lower in African-American women with C variants than in African-American women with A variants (p = 0.05). There was no difference in the likelihood of clearance between A and C variants among Caucasian women. Our data indicated that infections with B variants were more likely to resolve than those with C variants. The difference in clearance of A vs. C variants in African-Americans, but not in Caucasians, suggests a possibility of the race-related influence in retaining the variant-specific infection.

Association of human papillomavirus type 31 variants with risk of cervical intraepithelial neoplasia grades 2-3.

Although the lineages of human papillomavirus type 31 (HPV31) variants are recognized, their clinical relevance is unknown. The purpose of our study was to examine risk of cervical intraepithelial neoplasia Grades 2-3 (CIN2/3) by HPV31 variants. Study subjects were women who participated in the atypical squamous cells of undetermined significance and low-grade squamous intraepithelial lesion Triage Study and who had HPV31 infections detected at one or more visits. They were followed semi-annually over 2 years for detection of HPV DNA and cervical lesion. HPV31 isolates were characterized by DNA sequencing and assigned into 1 of 3 variant lineages. CIN2/3 was histologically confirmed in 127 (27.0%) of the 470 HPV31-positive women, 83 diagnosed at the first HPV31-positive visit and 44 thereafter. The odds ratio for the association of 2-year cumulative risk of CIN2/3 was 1.7 (95% CI: 1.0-2.9) for infections with A variants and 2.2 (95% CI: 1.2-3.9) for infections with B variants as compared to those with C variants. Among women without CIN2/3 at the first HPV31-positive visit, the risk of subsequent CIN2/3 was 2.2-fold greater for those with A variants (95% CI: 1.0-4.8) and 2.0-fold greater for those with B variants (95% CI: 0.9-4.9) as compared to those with C variants. Similar associations were observed when CIN3 was used as the endpoint. The findings from our study help to tag HPV31 variants that differ in risk of CIN2/3 and to explain in part why some HPV31 infections regress spontaneously and others lead to disease progression.

Genetic variability and phylogeny of high risk HPV type 16, 18, 31, 33 and 45 L1 gene in Greek women.

The present study explores nucleotide variability, phylogeny and association with cervical neoplasia in high risk HPV types 16, 18, 31, 33 and 45 collected from Greek women. Of the 1894 women undergoing routine cervical cytology examination, 160 samples test positive for single infections of HPV type 16 (n = 104), HPV 31 (n = 40), HPV 33 (n = 7), HPV 18 (n = 5), and HPV 45 (n = 4) were typed by microarrays method, amplified by PCR then sequenced and phylogenetically analyzed. For HPV 16, 9 variants with nucleotide variations were included into the study. For HPV 31, 33, 18 and 45, nucleotide variations were identified in 6, 4, 2 and 3 variants, respectively. The Bayesian inference and Maximum Parsimony methods were used in order to construct the phylogenetic trees. When types were analyzed independently HPV 16 (European and non-European) and HPV 18 (African and non-African) formed distinct clades. The genomic characterization of HPV variants will be important for illuminating the geographical relatedness and biological differences and for the determination of their risk.