Human Papillomavirus 16 DNA Methylation Patterns and Investigation of Integration Status in Head and Neck Cancer Cases.

Persistent high-risk human papillomavirus (HPV) infection is a pivotal factor in the progression of cervical cancer. In recent years, an increasing interest has emerged in comprehending the influence of HPV on head and neck squamous cell carcinoma (HNSCC). Notably, it is well established that HPV-associated HNSCC show cases with distinct molecular and clinical attributes compared to HPV-negative cases. The present study delves into the epigenetic landscape of HPV16, specifically its L1 gene and untranslated region (UTR), through pyrosequencing, while the HPV16 DNA physical status was evaluated using E2/E6 ratio analysis in HPV16-positive HNSCC FFPE biopsies. Our findings reveal substantial methylation across six sites within the HPV16 L1 gene and seven sites in the UTR. Specifically, methylation percentages of two L1 CpG sites (7136, 7145) exhibit significant associations with tumor histological grade (p < 0.01), while proving concurrent methylation across multiple sites. The HPV16 DNA physical status was not correlated with the methylation of viral genome or tumor characteristics. This is the first study that examines epigenetic modifications and the HPV16 DNA physical status in Greek HNSCC patients. Our findings suggest an orchestrated epigenetic modulation among specific sites, impacting viral gene expression and intricate virus-host interactions.

Mutation Profile of HPV16 L1 and L2 Genes in Different Geographic Areas.

The causal relationship between HPV and cervical cancer in association with the high prevalence of high risk HPV genotypes led to the design of HPV vaccines based on the major capsid L1 protein. In recent years, capsid protein L2 has also become a focal point in the field of vaccine research. The present review focuses on the variability of HPV16 L1 and L2 genes, emphasizing the distribution of specific amino acid changes in the epitopes of capsid proteins. Moreover, a substantial bioinformatics analysis was conducted to describe the worldwide distribution of amino acid substitutions throughout HPV16 L1, L2 proteins. Five amino acid changes (T176N, N181T; EF loop), (T266A; FG loop), (T353P, T389S; HI loop) are frequently observed in the L1 hypervariable surface loops, while two amino acid substitutions (D43E, S122P) are adjacent to L2 specific epitopes. These changes have a high prevalence in certain geographic regions. The present review suggests that the extensive analysis of the amino acid substitutions in the HPV16 L1 immunodominant loops may provide insights concerning the ability of the virus in evading host immune response in certain populations. The genetic variability of the HPV16 L1 and L2 epitopes should be extensively analyzed in a given population.

Association of p16 (CDKN2A) polymorphisms with the development of HPV16-related precancerous lesions and cervical cancer in the Greek population.

The tumor suppressor protein p16 plays a fundamental role in cell cycle regulation and exerts a protective effect against tumor growth. Two different polymorphisms at positions 540 and 580 at the 3'UTR of exon 3 of p16 gene are implicated in several types of cancer, while their role in cervical cancer development remains rather vague. In the present study, we investigated for the impact of p16 genotypes/haplotypes on patients' vulnerability to cervical disease and examined whether these factors can be used as progression markers in the Greek population. A total of 96 HPV16 positive samples and histologically confirmed as LSIL (42 samples), HSIL (44 samples), and cervical cancer cases (10 samples) along with 50 control cases were tested. The identification of p16 polymorphisms was performed by PCR-RFLP methodology. The present analysis revealed that women with p16 540 CG/GG genotype are at a 2.7-fold higher risk of developing HPV16-associated HSIL (OR = 2.7, 95%CI: 1.01-6.6, P = 0.028). The G allele can be regarded as a risk factor of developing HSIL in the Greek population (OR = 2.7, 95%CI: 1.2-5.9, P = 0.012). Moreover, p16 polymorphism C580T is not associated with the growth of cervical lesion in Greek patients, while 540G/580C haplotype can be regarded as a risk haplotype of developing HSIL (OR = 3.67, 95%CI: 1.56-8.6, P = 0.0019). Our results demonstrated that p16 C540G polymorphism influence patients' susceptibility to more severe dysplasia and consequently this polymorphism could potentially emerge as a valuable biomarker for HSIL development in the Greek population.

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.

Determination of human papillomavirus 16 physical status through E1/E6 and E2/E6 ratio analysis.

Human papillomavirus (HPV) 16 genome integration into the host chromosome is a crucial event during the life cycle of the virus and a major step towards carcinogenesis. The integration of HPV16 DNA promotes a constitutive high expression level of E6 and E7 oncoproteins, resulting in the extensive proliferation of the infected epithelial cells. In the present report the physical status of the HPV16 genome was studied, through determination of E1/E6 and E2/E6 DNA copy number ratios in 61 cervical samples of low- and high-grade malignancy and 8 cervical cancer samples, all of them associated with HPV16 infection. The selection of E1, E2 and E6 amplification target regions was performed according to the most prevalent deleted/disrupted sites of E1 and E2 genes. For this target selection we also considered the most conserved regions of E1, E2 and E6 genes among the same HPV16 isolates that were recently reported by our group. The analysis of HPV16 DNA form revealed a significant association among the mixed DNA forms in low-grade and high-grade malignancies, (χ(2), P<0.01). The comparative analysis of E1/E6 and E2/E6 in the same cervical samples provides an accurate picture of HPV16 DNA form and may reveal whether different HPV16 DNA integrants coexist in the same cervical sample or not. This study proposes that E1/E6 and E2/E6 ratios determine with accuracy the HPV16 DNA integration pattern and may predict multiple integration events in the examined sample, thus providing significant information about the progression of cervical dysplasia.

Combined 5' UTR RFLP analysis and VP1 sequencing for epidemic investigation of enteroviruses.

Enteroviruses, the main cause of aseptic meningitis, consist of 100 serotypes, and many of them have been associated with large outbreaks. In the present study, a comparison of RFLP analysis of the 5' untranslated region (5'UTR) and sequencing of both the 5'UTR and VP1 regions was conducted for epidemiological linkage of 27 clinical enterovirus strains. The clinical enterovirus strains were clustered into five restriction profile groups. Even though the restriction profile clusters of clinical isolates were not related to those of the respective prototype strains, epidemiological relationships between the members of each cluster were observed. The restriction profile clusters in the 5'UTR corresponded to the phylogenetic clusters in the VP1 genomic region. The incongruence between the topology of Gior strain in 5'UTR and VP1 phylogenetic trees indicates a recombination event. The proposed RFLP assay in combination with VP1 sequencing can offer crucial epidemiological information about the circulating enteroviruses.

Full-genome sequence analysis of a multirecombinant echovirus 3 strain isolated from sewage in Greece.

An echovirus 3 (Echo3) strain (strain LR31G7) was isolated from a sewage treatment plant in Greece in 2005. Full-genome molecular, phylogenetic, and SimPlot analyses were conducted in order to reveal the evolutionary pathways of the isolate. Nucleotide and phylogenetic analyses of part of the VP1 genomic region revealed that the isolated strain correlates with Echo3 strains isolated during the same year in France and Japan, implying that the same virus circulated in Europe and Asia. LR31G7 was found to be a recombinant that shares the 3' part of its genome with an Echo25 strain isolated from asymptomatic infants in Norway in 2003. Nucleotide and SimPlot analyses of the VP1-2A junction, where the recombination was located, revealed the exact recombination breakpoint (nucleotides 3357 to 3364). Moreover, there is evidence that recombination events had occurred in 3B-3D region in the evolutionary history of the isolate. Our study indicates that recombination events play major roles in enterovirus evolution and that the circulation of multirecombinant strains with unknown properties could be potentially dangerous for public health.

Partial 3D gene sequences of Coxsackie viruses reveal interspecies exchanges.

The 3D region of 46 clinical Coxsackievirus strains, primarily belonging to the human enterovirus B species (HEV-B), were analyzed using nucleotide distance matrices and phylogeny software. The conclusions from previously analyzed genomic regions (VP1-2A-2B-2C) of the aforementioned strains revealed that enteroviruses' inheritance is being guided by gene adaptation among viruses of different serotypes. In this report the comparison of partial VP1 and 3D gene phylogenies presented an obvious incongruence. Moreover, the phylogeny of 3D sequences of the strains revealed an unexpected (and for the first time reported) homology among strains of different species. The observations of our study indicate that conversion events such as multiple mutations or recombination among strains and unknown donors may occur during the evolution of circulating strains, leading, probably, to viruses with altered genome and virulence.

Detection of unusual mutation within the VP1 region of different re-isolates of poliovirus Sabin vaccine.

In the present study, a genomic analysis of full VP1 sequence region of 15 clinical re-isolates (14 healthy vaccinees and one bone marrow tumor patient) was conducted, aiming to the identification of mutations and to the assessment of their impact on virus fitness, providing also insights relevant with the natural evolution of Sabin strains. Clinical re-isolates were analyzed by RT-PCR, sequencing and computational analysis. Some re-isolates were characterized by an unusual mutational pattern in which non-synonymous mutations outnumbered the synonymous ones. Furthermore, the majority of amino-acid substitutions were located in the capsid exterior, specifically in N-Ags, near N-Ags and in the north rim of the canyon. Also mutations, which are well-known determinants of attenuation, were identified. The results of this study propose that some re-isolates are characterized by an evolutionary pattern in which non-synonymous mutations with a direct phenotypic impact on viral fitness are fixed in viral genomes, in spite of synonymous ones with no phenotypic impact on viral fitness. Results of the present retrospective characterization of Sabin clinical re-isolates, based on the full VP1 sequence, suggest that vaccine-derived viruses may make their way through narrow breaches and may evolve into transmissible pathogens even in adequately immunized populations. For this reason increased poliovirus laboratory surveillance should be permanent and full VP1 sequence analysis should be conducted even in isolates originating from healthy vaccinees.