High Whole-Genome Sequence Diversity of Human Papillomavirus Type 18 Isolates

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.

Phylogenetic Analysis of HPV16 Isolated from Women with Cervical Cancer Based on L2 Gene Partial Sequence in the Province of Dhi-Qar, Iraq

BACKGROUND: As a causative agent for cervical cancer, the human papillomavirus (HPV) is well-recognized. Being a high-risk form, HPV16 is considered and has been confirmed to be associated specifically with cancer of the cervix. AIM: HPV16’s phylogenetic tree and genetic diversity are well known worldwide, but in Iraq, documents on HPV16 genetic diversity among women with cervical cancer are lacking; therefore, the present study focused on phylogenetic analysis of HPV16 isolated cervical cancer based on L2 gene partial sequence. METHODOLOGY: The current study focused on the investigation of HPV16 in women who suffer from cervical cancer. This survey was performed on 93 adult females suffering from cervical cancer during the period from 2017 to 2020. For the molecular study, DNA was extracted and subjected to a polymerase chain reaction (PCR) for detection and amplification of minor capsidprotein L2 gene. Nucleotide sequences of amplified capsid L2 gene were searched using the advanced simple local alignment search tool at GenBank (BLAST). RESULTS: Genetic screening on HPV16 L2 gene by conventional PCR showed that 60 (65%) of cervical cancer cases infected by HPV16 while only 5 (8%) of the healthy control group are positive for HPV16. The results of the NCBI-BLAST homology sequence showed that genetic variation appeared in four strains from five strains of HPV16. CONCLUSION: HPV16 from the main causative factors for cervical cancer with high genetic variation.

HPV16 and HPV18 type-specific APOBEC3 and integration profiles in different diagnostic categories of cervical samples

Human papillomavirus (HPV) 16 and 18 are the most predominant types in cervical cancer. Only a small fraction of HPV infections progress to cancer, indicating that additional factors and genomic events contribute to the carcinogenesis, such as minor nucleotide variation caused by APOBEC3 and chromosomal integration. We analysed intra-host minor nucleotide variants (MNVs) and integration in HPV16 and HPV18 positive cervical samples with different morphology. Samples were sequenced using an HPV whole genome sequencing protocol TaME-seq. A total of 80 HPV16 and 51 HPV18 positive samples passed the sequencing depth criteria of 300× reads, showing the following distribution: non-progressive disease (HPV16 n = 21, HPV18 n = 12); cervical intraepithelial neoplasia (CIN) grade 2 (HPV16 n = 27, HPV18 n = 9); CIN3/adenocarcinoma in situ (AIS) (HPV16 n = 27, HPV18 n = 30); cervical cancer (HPV16 n = 5). Similar numbers of MNVs in HPV16 and HPV18 samples were observed for most viral genes, with the exception of HPV18 E4 with higher numbers across clinical categories. APOBEC3 signatures were observed in HPV16 lesions, while similar mutation patterns were not detected for HPV18. The proportion of samples with integration was 13% for HPV16 and 59% for HPV18 positive samples, with a noticeable portion located within or close to cancer-related genes.

Lineage analysis of human papillomavirus type 18 based on E6 region in cervical samples of Iranian women

Distinct human papillomavirus (HPV) 18 variants are thought to differ in oncogenic potential and geographic distribution. As such, understanding the regional variants of HPV 18 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 18 in normal cells, premalignant, and malignant samples collected from the cervix. In total, 99 samples of HPV 18 were analyzed by polymerase chain reaction and sequencing. In overall, lineages A was identified in all study subjects, among which sublineage A4 was dominant although the difference observed was not statistically significant with regard to different stages of disease. Sublineage A4 comprised 90.9% of samples and the remaining were belonged to sublineages A1, A2, A3, and A5 at the frequency of 6.1%, 1%, 1%, and 1%, respectively. In conclusion, our findings clearly highlight the sublineage A4 of HPV 18 as the most dominant variant in Iran.

Fifteen new nucleotide substitutions in variants of human papillomavirus 18 in Korea : Korean HPV18 variants and clinical manifestation

High-risk human papillomavirus (HPV) infection is an essential factor for the development of cervical cancer. HPV18 is the second most common carcinogenic HPV type following HPV16, but the lineages of HPV18 have been less well studied than those of HPV 16. The purpose of this study was to analyze the nucleotide variants in the E6, E7, and L1 genes of HPV18, to assess the prevalence of HPV18 variants in Korea and to explore the relationship between HPV18 genetic variants and the risk for cervical cancer.

A total of 170 DNA samples from HPV18-positive cervical specimens were collected from women admitted to a secondary referral hospital located in Seoul. Among them, the lineages of the 97 samples could be successfully determined by historical nomenclature.

All the studied HPV 18 variants were lineage A. Sublineages A1 and A4 comprised 91.7% (89/97) and 1.0% (1/97), respectively. Sublineages other than A1 or A4 comprised 7.2% (7/97). We identified 15 new nucleotide substitutions among 44 nucleotide substitutions: C158T, T317G, T443G, A560G, A5467G, A5560C, A5678C, A6155G, G6462A, T6650G, G6701A, T6809C, A6823G, T6941C and T6953C. Among them, 6 substitutions at positions 317, 443, 5467, 5560, 6462, and 6823 resulted in amino acid changes (E6: F71L and N113K; L1: H13R, H44P, A345T, and N465S, respectively). The pathologic results were classified as normal in 25.8% (25/97) of the women, atypical squamous cells of undermined significance (ASCUS) in 7.2% (7/97), cervical intraepithelial neoplasia (CIN) 1 in 36.1% (35/97), CIN2/3 in 19.6% (18/97), and carcinoma in 12.4% (12/97). There was no significant association between the HPV18 sublineages and the severity of pathologic lesion or the disease progression.

This study is the first to analyze the distribution of HPV18 variants in Korean and to associate the results with pathologic findings. Although the HPV18 variants had no significant effect on the degree and progression of the disease, the newly discovered nonsynonymous mutation in L1 might serve as a database to determine vaccine efficacy in Korean women.

HPV16 whole genome minority variants in persistent infections from young Dutch women

BACKGROUND

Chronic infections by one of the oncogenic human papillomaviruses (HPVs) are responsible for near 5% of the global cancer burden and HPV16 is the type most often found in cancers. HPV genomes display unexpected levels of variation when deep-sequenced. Minor nucleotide variations (MNVs) may reveal HPV genomic instability and HPV-related carcinogenic transformation of host cells.

OBJECTIVES

The objective of this study was to investigate HPV16 genome variation at the minor variant level on persisting HPV16 cervical infections from a population of young Dutch women.

STUDY DESIGN

15 HPV16 infections were sequenced using a whole-HPV genome deep sequencing protocol (TaME-seq). One infection was followed over a three-year period, eight were followed over a two-year period, three were followed over a one-year period and three infections had a single sampling point.

RESULTS AND CONCLUSIONS

Using a 1% variant frequency cutoff, we find on average 48 MNVs per HPV16 genome and 1717 MNVs in total when sequencing coverage was >100 × . We find the transition mutation T > C to be the most common, in contrast to other studies detecting APOBEC-related C > T mutation profiles in pre-cancerous and cancer samples. Our results suggest that the relative mutagenic footprint of HPV16 genomes may differ between the infections in this study and transforming lesions. In addition, we identify a number of MNVs that have previously been associated with higher incidence of high-grade lesions (CIN3+) in a population study. These findings may provide a starting point for future studies exploring causality between emerging HPV minor genomic variants and cancer development.

Abundance of HPV L1 Intra-Genotype Variants With Capsid Epitopic Modifications Found Within Low- and High-Grade Pap Smears With Potential Implications for Vaccinology

Background: The aim of this study was to explore the Human Papillomavirus (HPV) genotype composition and intra-genotype variants within individual samples of low- and high-grade cervical cytology by deep sequencing. Clinical, cytological, sequencing, and functional/structural data were forged into an integrated variant profiling pipeline for the detection of potentially vaccine-resistant genotypes or variants.

Methods: Low- and high-grade intraepithelial lesion (LSIL and HSIL) cytology samples with +HPV were subjected to amplicon (L1 gene fragment) sequencing by dideoxy (Sanger) and deep methods. Taxonomic, abundance, diversity, and phylogenetic analyses were conducted to determine HPV genotypes/sub-lineages, relative abundance, species diversity and phylogenetic distances within and between samples. Variant detection and functional analysis of translated L1 amino acid sequences determined structural variations of interest.

Results: Pure and mixed HPV infections were common among LSIL (n = 6) and HSIL (n = 6) samples. Taxonomic profiling revealed loss of species richness and gain of dominance by carcinogenic genotypes in HSIL samples. Phylogenetic analysis showed excellent correlation between HPV-type specific genetic distances and carcinogenic potential. For combined LSIL/HSIL samples (n = 12), 11 HPV genotypes and 417 mutations were detected: 375 single-nucleotide variants (SNV), 29 insertion/deletion (indel), 12 multi-nucleotide variants (MNV), and 1 replacement variant. The proportion of nonsynonymous mutations was lower for HSIL (0.38) than for LSIL samples (0.51) (p < 0.05). HPV variant analysis pinpointed nucleotide-level mutations and amino acid-level structural modifications.

Conclusion: HPV L1 intra-host and intra-genotype variants are abundant in LSIL and HSIL samples with potential functional/structural consequences. An integrated multi-omics approach to variant analysis may provide a sensitive and practical means of detecting changes in HPV evolution and dynamics within individuals or populations.

Prevalence of oncogenic Human papillomavirus and genetic diversity in the L1 gene of HPV16 HPV 18 HPV31 and HPV33 found in women from Vojvodina Province Serbia

The main purpose of this paper is to estimate the pre-vaccination prevalence of 12 hrHPV types among 564 women from Vojvodina province (Serbia). The corrected contingency coefficient (Ccorr) was used to estimate the importance of association of examined HPV types and cytological diagnosis. The highest association with the abnormal cytology was observed for HPV 16 (Ccorr = 0.493) in all age groups of participants. The effect of HPV 16 was especially clear within the group of women older than 35 years (Ccorr = 0.691), compared with women younger than 35 (Ccorr = 0.333). The molecular characterization at the level of L1 gene of HPV 16, 18, 31 and 33 variants was for the first time assessed in our region. Nearly all HPV 16 isolates cluster with variant lineage A (96.4%) the remaining isolates clustering with variant lineage D. All of HPV 18 and HPV 33 isolates are clustering within the lineage A while isolates of HPV 31 group with lineages A and C. This contributes to understanding of intrinsic geographical and biological differences of examined HPV types and could be useful for development of cervical cancer screening strategies in Vojvodina (Serbia) and diagnosis of HPV related cervical cancer in general.

Genetic diversity and phylogenetic analysis of HPV 16 & 18 variants isolated from cervical specimens of women in Saudi Arabia

Human papillomavirus (HPV) are well known to be associated with the development of cervical cancer. HPV16 and HPV 18 are known as high-risk types and reported to be predominantly associated with cervical cancer. The prevalence and genetic diversity of HPV have been well documented globally but, in the Kingdom of Saudi Arabia, data on HPV genetic diversity are lacking. In this study, we have analyzed the genetic diversity of both HPV16 and HPV18 based on their L1 gene sequence because L1 gene is a major capsid protein gene and has been utilized to develop a prophylactic vaccine. In January 2011-2012, a total of forty samples from cervical specimens of women in Saudi Arabia were collected. The association of HPV16, HPV18 was detected by polymerase chain reaction, sequenced and submitted to GenBank. The sequences identity matrix and the phylogenetic relationship were analyzed with selected HPVs. The highest sequence identity (99.5%) for HPV16 and (99.3%) for HPV was observed with selected HPVs. The phylogenetic analysis results showed that HPVs from Saudi Arabia formed a closed cluster with African, Asian, East Asian as well as American HPVs distributed into multiple linages from various geographical locations. The results provided the valuable information about genetic diversity, but there is an urgent need to generate full genome sequence information which will provide a clearer picture of the genetic diversity and evolution of HPVs in Saudi Arabia. In conclusion, the generated data will be highly beneficial for developing molecular diagnostic tools, analyzing and correlating the epidemiological data to determine the risk of cervical cancer and finally to develop a vaccine for Saudi Arabian population.