Intratype variations of HPV 31 and 58 in Italian women with abnormal cervical cytology

Characteristics of human papillomavirus infection among females and the genetic variations of HPV18 and HPV58 in Henan province, China

The present study aims to investigate the genotype distribution of Human papillomavirus (HPV) and variations of HPV18 and HPV58 infection among 6538 females in Luoyang city during 2019-2021. The overall positive rate of females with HPV infection was 12.34%, with 9.74% were infected with single HPV and 2.60% with multiple HPVs. The prevalent rate of high-risk HPV (HR-HPV) was 9.85% and the top five HR-HPV genotypes were HPV52 (1.94%), HPV16 (1.93%), HPV58 (1.48%), HPV51 (1.02%) and HPVV39 (0.99%). Two peaks of HPV infections rates were observed in females aged ≤ 20 and 61-65 years old. To characterize mutations, 39 HPV18 and 56 HPV58 L1, E6 and E7 genes were sequenced and submitted to GenBank. In the HPV18 E6-E7-L1 sequences, 38 nucleotides changes were observed with 10/38 were non-synonymous mutations (5 in E6 gene, 1 in E7 gene and 4 in L1 gene). In the HPV58 E6-E7-L1 sequences, 53 nucleotides changes were observed with 23/53 were non-synonymous mutations (3 in E6 gene, 5 in E7 gene and 15 in L1 gene). Phylogenetic analysis based on L1 gene showed that 92.3% (36/39) of HPV18 isolates fell into sublineage A1 and 7.7% (3/39) belonged to A5. For HPV58, 75.0% (42/56) isolates belonged to sublineage A1 and 25.0% (14/56) were sublineage A2. There was no association between amino mutation and cervical lesions. The present study provides basic information about the distribution, genotypes and variations of HPV among females population in Luoyang city, which would assist in the formulation of HPV screening and vaccination programs and preventive strategies for HPV-attributable cancer in this region.

Functional evaluation of human papillomavirus type 31 long control region variants

Persistent infections by high-risk human papillomavirus (HR-HPV) are a necessary condition, but not sufficient for cervical cancer development. Genetic variants of HR-HPV appear to be related to the risk of persistent infections. The study performed a functional evaluation of variants of the HPV-31 promoter region (LCR). For this, cloning and subcloning of variants HPV-31/UFPE-21 HPV-31/UFPE-89, HPV-31/UFPE-66, E2 gene and prototype HPV-31 were performed. Transfection with different concentrations of E2 was done and the concentration of 25 ng was determined to be ideal for LCR activation. HPV-31/UFPE-21 and HPV-31/UFPE-89 have a greater ability to alter Nluc reporter gene expression levels and HPV-31/UFPE-66 showed decreased levels of gene expression of Nluc reporter gene compared to control. Statistical analysis showed a significant difference between the polymorphic LCR regions and the control (p < 0.0001). A more refined profile of variants of HPV-31 and its importance for the prognosis of cervical lesions begins to be drawn.

Phylogeny and polymorphism in the long control regions E6, E7, and L1 of HPV Type 56 in women from southwest China

Globally, human papillomavirus (HPV)‑56 accounts for a small proportion of all high‑risk HPV types; however, HPV‑56 is detected at a higher rate in Asia, particularly in southwest China. The present study analyzed polymorphisms, intratypic variants, and genetic variability in the long control regions (LCR), E6, E7, and L1 of HPV‑56 (n=75). The LCRs, E6, E7 and L1 were sequenced using a polymerase chain reaction and the sequences were submitted to GenBank. Maximum‑likelihood trees were constructed using Kimura's two‑parameter model, followed by secondary structure analysis and protein damaging prediction. Additionally, in order to assess the effect of variations in the LCR on putative binding sites for cellular proteins, MATCH server was used. Finally, the selection pressures of the E6‑E7 and L1 genes were estimated. A total of 18 point substitutions, a 42‑bp deletion and a 19‑bp deletion of LCR were identified. Some of those mutations are embedded in the putative binding sites for transcription factors. 18 single nucleotide changes occurred in the E6‑E7 sequence, 11/18 were non‑synonymous substitutions and 7/18 were synonymous mutations. A total 24 single nucleotide changes were identified in the L1 sequence, 6/24 being non‑synonymous mutations and 18/24 synonymous mutations. Selective pressure analysis predicted that the majority of mutations of HPV‑56 E6, E7 and L1 were of positive selection. The phylogenetic tree demonstrated that the isolates distributed in two lineages. Data on the prevalence and genetic variation of HPV‑56 types in southwest China may aid future studies on viral molecular mechanisms and contribute to future investigations of diagnostic probes and therapeutic vaccines.

Ancient Evolution and Dispersion of Human Papillomavirus 58 Variants

Human papillomavirus 58 (HPV58) is found in 10 to 18% of cervical cancers in East Asia but is rather uncommon elsewhere. The distribution and oncogenic potential of HPV58 variants appear to be heterogeneous, since the E7 T20I/G63S variant is more prevalent in East Asia and confers a 7- to 9-fold-higher risk of cervical precancer and cancer. However, the underlying genomic mechanisms that explain the geographic and carcinogenic diversity of HPV58 variants are still poorly understood. In this study, we used a combination of phylogenetic analyses and bioinformatics to investigate the deep evolutionary history of HPV58 complete genome variants. The initial splitting of HPV58 variants was estimated to occur 478,600 years ago (95% highest posterior density [HPD], 391,000 to 569,600 years ago). This divergence time is well within the era of speciation between Homo sapiens and Neanderthals/Denisovans and around three times longer than the modern Homo sapiens divergence times. The expansion of present-day variants in Eurasia could be the consequence of viral transmission from Neanderthals/Denisovans to non-African modern human populations through gene flow. A whole-genome sequence signature analysis identified 3 amino acid changes, 16 synonymous nucleotide changes, and a 12-bp insertion strongly associated with the E7 T20I/G63S variant that represents the A3 sublineage and carries higher carcinogenetic potential. Compared with the capsid proteins, the oncogenes E7 and E6 had increased substitution rates indicative of higher selection pressure. These data provide a comprehensive evolutionary history and genomic basis of HPV58 variants to assist further investigation of carcinogenic association and the development of diagnostic and therapeutic strategies.IMPORTANCE Papillomaviruses (PVs) are an ancient and heterogeneous group of double-stranded DNA viruses that preferentially infect the cutaneous and mucocutaneous epithelia of vertebrates. Persistent infection by specific oncogenic human papillomaviruses (HPVs), including HPV58, has been established as the primary cause of cervical cancer. In this work, we reveal the complex evolutionary history of HPV58 variants that explains the heterogeneity of oncogenic potential and geographic distribution. Our data suggest that HPV58 variants may have coevolved with archaic hominins and dispersed across the planet through host interbreeding and gene flow. Certain genes and codons of HPV58 variants representing higher carcinogenic potential and/or that are under positive selection may have important implications for viral host specificity, pathogenesis, and disease prevention.

E6 and E7 Gene Polymorphisms in Human Papillomavirus Types-58 and 33 Identified in Southwest China

Cancer of the cervix is associated with infection by certain types of human papillomavirus (HPV). The gene variants differ in immune responses and oncogenic potential. The E6 and E7 proteins encoded by high-risk HPV play a key role in cellular transformation. HPV-33 and HPV-58 types are highly prevalent among Chinese women. To study the gene intratypic variations, polymorphisms and positive selections of HPV-33 and HPV-58 E6/E7 in southwest China, HPV-33 (E6, E7: n = 216) and HPV-58 (E6, E7: n = 405) E6 and E7 genes were sequenced and compared to others submitted to GenBank. Phylogenetic trees were constructed by Maximum-likelihood and the Kimura 2-parameters methods by MEGA 6 (Molecular Evolutionary Genetics Analysis version 6.0). The diversity of secondary structure was analyzed by PSIPred software. The selection pressures acting on the E6/E7 genes were estimated by PAML 4.8 (Phylogenetic Analyses by Maximun Likelihood version4.8) software. The positive sites of HPV-33 and HPV-58 E6/E7 were contrasted by ClustalX 2.1. Among 216 HPV-33 E6 sequences, 8 single nucleotide mutations were observed with 6/8 non-synonymous and 2/8 synonymous mutations. The 216 HPV-33 E7 sequences showed 3 single nucleotide mutations that were non-synonymous. The 405 HPV-58 E6 sequences revealed 8 single nucleotide mutations with 4/8 non-synonymous and 4/8 synonymous mutations. Among 405 HPV-58 E7 sequences, 13 single nucleotide mutations were observed with 10/13 non-synonymous mutations and 3/13 synonymous mutations. The selective pressure analysis showed that all HPV-33 and 4/6 HPV-58 E6/E7 major non-synonymous mutations were sites of positive selection. All variations were observed in sites belonging to major histocompatibility complex and/or B-cell predicted epitopes. K93N and R145 (I/N) were observed in both HPV-33 and HPV-58 E6.

L1 and L2 gene polymorphisms in HPV-58 and HPV-33: implications for vaccine design and diagnosis

Background

Cervical cancer is associated with infection by certain subtypes of human papillomavirus (HPV). The L1 protein comprising HPV vaccine formulations elicits high-titre neutralizing antibodies and confers protection against specific HPV subtypes. HPV L2 protein is an attractive candidate for cross-protective vaccines. HPV-33 and HPV-58 are very prevalent among Chinese women.

Methods

To study the gene intratypic variations and polymorphisms of HPV-33 and HPV-58 L1/L2 in Sichuan China, HPV-33 and HPV-58 L1 and L2 genes were sequenced and compared with other genes submitted to GenBank. Phylogenetic trees were constructed by maximum-likelihood and the Kimura 2-parameters methods (MEGA 6). The secondary structure was analyzed by PSIPred software, and HPV-33 and HPV-58 L1 homology models were created by SWISS-MODEL software. The selection pressures acting on the L1/L2 genes were estimated by PAML 4.8.

Results

Among 124 HPV-33 L1 sequences 20 single nucleotide mutations were observed included 8/20 non-synonymous and 12/20 synonymous mutations. The 101 HPV-33 L2 sequences included 12 single nucleotide mutations comprising 7/12 non-synonymous and 5/12 synonymous mutations. The 223 HPV-58 L1 sequences included 32 single nucleotide mutations comprising 9/32 non-synonymous and 23/32 synonymous mutations. The 201 HPV-58 L2 sequences comprised 26 single nucleotide mutations including 9/26 non-synonymous and 17/26 synonymous mutations. Selective pressure analysis showed that most of the common non-synonymous mutations showed a positive selection. HPV-33 and HPV-58 L2 were more stable than HPV-33 and HPV-58 L1.

Conclusions

HPV-33 and HPV-58 L2 were better candidates as clinical diagnostic targets compared with HPV-33 and HPV-58 L1. Clinical diagnostic probes and second-generation polyvalent vaccines should be designed on the basis of the unique sequence of HPV-33 and 58 L1/L2 variations in Sichuan, to improve the accuracy of clinical detection and the protective efficiency of vaccines.

Electronic supplementary material

The online version of this article (doi:10.1186/s12985-016-0629-9) contains supplementary material, which is available to authorized users.

Phylogenetic and functional analysis of sequence variation of human papillomavirus type 31 E6 and E7 oncoproteins

High-risk human papillomaviruses (HPV) are the causative agents of cervical and other anogenital cancers as well as a subset of head and neck cancers. The E6 and E7 oncoproteins of HPV contribute to oncogenesis by associating with the tumour suppressor protein p53 and pRb, respectively. For HPV types 16 and 18, intratypic sequence variation was shown to have biological and clinical significance. The functional significance of sequence variation among HPV 31 variants was studied less intensively. HPV 31 variants belonging to different variant lineages were found to have differences in persistence and in the ability to cause high grade cervical intraepithelial neoplasia. In the present study, we started to explore the functional effects of natural sequence variation of HPV 31 E6 and E7 oncoproteins. The E6 variants were tested for their effects on p53 protein stability and transcriptional activity, while the E7 variants were tested for their effects on pRb protein level and also on the transcriptional activity of E2F transcription factors. HPV 31 E7 variants displayed uniform effects on pRb stability and also on the activity of E2F transcription factors. HPV 31 E6 variants had remarkable differences in the ability to inhibit the trans-activation function of p53 but not in the ability to induce the in vivo degradation of p53. Our results indicate that natural sequence variation of the HPV 31 E6 protein may be involved in the observed differences in the oncogenic potential between HPV 31 variants.

Lineages of oncogenic human papillomavirus types other than type 16 and 18 and risk for cervical intraepithelial neoplasia

BACKGROUND

Data on clinical outcomes of infection with variants of oncogenic human papillomavirus (HPV) types other than HPV16 and HPV18 are rare. We investigated intratypic variations in non-HPV16/18 oncogenic types and their corresponding relationships with cervical intraepithelial neoplasia grades 2-3 (CIN2/3).

METHODS

Study subjects were women who were positive for one or more of 11 non-HPV16/18 oncogenic types. Subjects were followed every six months for two years for detection of HPV and cervical lesions. Variant lineages were defined by sequencing the 3' part of the long control region and the entire E6/E7 region of HPV genome. Lineage-associated risk of CIN2/3 was assessed using logistic regression with generalized estimating equations.

RESULTS

A total of 4591 type-specific HPV infections among 2667 women were included in the analysis. The increase in risk of CIN2/3 was statistically significant for women with HPV31 A or B compared with C variants, HPV33 A1 compared with B variants, HPV45 A3 or B2 compared with B1 variants, HPV56 B compared with A2 variants, and HPV58 A1 or A3 compared with C variants. For these five types, the adjusted odds ratio associated with CIN2/3 was 2.0 (95% confidence interval [CI] = 1.5 to 2.6) for infections with single-type high-risk (HR) variants, 1.7 (95% CI = 1.0 to 2.7) for infections with two or more types but only one HR variant, and 5.3 (95% CI = 3.1 to 8.4) for infections with HR variants of two or more types as compared with those with single-type non-HR variants. The likelihood of CIN2/3 was similar for women with HPV16 infection and for those with HPV58 A1 variant infection.

CONCLUSIONS

These findings suggest that for a given HPV type, intratypic nucleotide changes may alter phenotypic traits that affect the probability of neoplasia.

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.

A low density microarray method for the identification of human papillomavirus type 18 variants

We describe a novel microarray based-method for the screening of oncogenic human papillomavirus 18 (HPV-18) molecular variants. Due to the fact that sequencing methodology may underestimate samples containing more than one variant we designed a specific and sensitive stacking DNA hybridization assay. This technology can be used to discriminate between three possible phylogenetic branches of HPV-18. Probes were attached covalently on glass slides and hybridized with single-stranded DNA targets. Prior to hybridization with the probes, the target strands were pre-annealed with the three auxiliary contiguous oligonucleotides flanking the target sequences. Screening HPV-18 positive cell lines and cervical samples were used to evaluate the performance of this HPV DNA microarray. Our results demonstrate that the HPV-18's variants hybridized specifically to probes, with no detection of unspecific signals. Specific probes successfully reveal detectable point mutations in these variants. The present DNA oligoarray system can be used as a reliable, sensitive and specific method for HPV-18 variant screening. Furthermore, this simple assay allows the use of inexpensive equipment, making it accessible in resource-poor settings.

Sequence variation of human papillomavirus type 31 long control region: phylogenetic and functional implications

About one-third of human papillomavirus (HPV) types infect the anogenital tract. High-risk genital HPV types (such as HPV 16, 18, 31, 33, and 35) are linked causally to the development of cervical cancer. The long control region (LCR) of the HPV genome regulates the replication and transcription of the viral genome. In this study, the functional significance of nucleotide sequence variation within the LCR of HPV 31 was investigated. The LCR was amplified by polymerase chain reaction (PCR) from 41 HPV 31 positive cervical samples of Hungarian women. A phylogenetic tree constructed from the nucleotide sequences of the LCR variants revealed the presence of three intratypic variant lineages of HPV 31, in accordance with previous results. In order to explore the functional consequences of sequence variation in the LCR of HPV 31, selected LCR variants were cloned into a luciferase reporter vector, transfected into C33-A cells and tested in luciferase reporter assays. Significant differences were found between the transcriptional activities of HPV 31 LCR variants belonging to different variant lineages. As the LCR is governing the transcription of the E6 and E7 oncogenes, the differences in the transcriptional activities of LCR variants may be associated with differences in their oncogenic potential.

Differential presence of Papillomavirus variants in cervical cancer: an analysis for HPV33, HPV45 and HPV58

BACKGROUND

Certain human papillomaviruses (HPVs) are the causative agents of cervical carcinomas in humans. The identification of the link between infection and cancer has resulted in the successful establishment of clinical strategies such as screening or vaccination programs, aiming to prevent this pathology. More than 150 different HPVs have been described and classified and the large majority of them are not related to cancer. The genus Alphapapillomavirus encompasses many PVs, some of which are identified in humans as oncogenic, according to the epidemiological connection between infection and cervical cancer. Variants of some of these "high-risk" HPVs may have an increased involvement in cervical cancer, although definitive data are still wanting. The aim of the present work was to analyze the presence of HPV33, HPV45 and HPV58 variants in cases of cervical cancer.

METHODS

Samples from cervical lesions in the context of different cervical cancer surveys were analyzed for presence of HPV DNA. Samples positive for HPV33, HPV45 or HPV58 DNA were selected and the E6/E7 genes were amplified and sequenced. The phylogenetic relationships of these sequences were inferred using an evolutionary placement algorithm and accordingly classified at the variant level.

RESULTS

All viral E6/E7 sequences were successfully placed in the classification schemes of the corresponding viruses. For HPV33 (n=23), 45 (n=61) or 58 (n=29), the distribution of variants found in cases of cervical cancer is not a random sample of the corresponding diversity. In all three HPVs, the respective A variants were more prevalent in the viral DNA-positive cases of cervical cancer analyzed. This is the first study trying to discern the phylogenetic connection between variants of the oncogenic HPV33, 45 and 58, and squamous cell carcinoma of the cervix.

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.

Susceptibility to cervical cancer: an overview

Cervical cancer is the second most common cancer in females worldwide. It is well-established that Human Papillomavirus (HPV) infections play a critical role in the development of cervical cancer. However, a large number of women infected with oncogenic HPV types will never develop cervical cancer. Thus, there are several external environment and genetic factors involved in the progression of a precancerous lesion to invasive cancer. In this review article, we addressed possible susceptible phenotypes to cervical cancer, focusing on host genome and HPV DNA variability, multiple HPV infections, co-infection with other agents, circulating HPV DNA and lifestyle.

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.