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

Evolutionary analysis of JC polyomavirus in Misiones' population yields insight into the population dynamics of the early human dispersal in the Americas

BACKGROUND

JC polyomavirus (JCV) has an ethno-geographical distribution across human populations.

OBJECTIVE

Study the origins of the population of Misiones (Argentina) by using JCV as genetic marker.

METHODS

Viral detection and characterization was conducted by PCR amplification and evolutionary analysis of the intergenic region sequences.

RESULTS

22 out of 121 samples were positive for JCV, including 5 viral lineages: MY (n = 8), Eu-a (n = 7), B1-c (n = 4), B1-b (n = 2) and Af2 (n = 1). MY sequences clustered within a branch of Native American origin that diverged from its Asian counterpart about 21,914 years ago (HPD 95% interval 15,383-30,177), followed by a sustained demographic expansion around 5000 years ago.

CONCLUSIONS

JCV in Misiones reflects the multiethnic origin of the current population, with an important Amerindian contribution. Analysis of the MY viral lineage shows a pattern consistent with the arrival of early human migrations to the Americas and a population expansion by the pre-Columbian native societies.

Genetic variation in the E6 and E7 genes of human papillomavirus type 16 in northeastern Argentina

The province of Misiones is considered a region with a high mortality rate due to cervical cancer (CC). To gain insight into this problem, we explored the association between genetic variation in the E6 and E7 oncogenes of HPV16 and the risk of CC. We studied 160 women with cytological diagnoses of negative for intraepithelial lesion or malignity, low-grade squamous intraepithelial lesion, and high-grade squamous intraepithelial lesion/CC and a positive test for HPV16 infection. The genetic characterization of E6 and E7 genes was undertaken through PCR amplification and direct Sanger sequencing. Phylogenetic classification was conducted using Bayesian methods. To estimate the odds ratio (OR) for an association between genetic variants in the E6 and E7 genes and the risk of CC, we used ordinal logistic regression adjusted by age. The final data set comprised 112 samples. Diagnostic single-nucleotide polymorphisms (SNPs) and phylogenetic trees confirmed the presence of Lineage A (95.5%) and D (4.5%) in the samples. For the E6 gene, we identified eleven different sequences, with the most common ones being Lineage A E6 350G (58.9%) and E6 350T (37.5%). The E6 350G was associated with progression to HSIL/CC, with an OR of 19.41 (4.95-76.10). The E7 gene was more conserved than E6, probably due to the functional constraints of this small protein. Our results confirmed the association of the E6 350G SNP with a higher risk of developing CC. These data will contribute to understanding the biological bases of CC incidence in this region.

Molecular epidemiology and phylogenetic analysis of human papillomavirus infection in women with cervical lesions and cancer from the coastal region of Ecuador

The aim of the present study was to gather information regarding the molecular epidemiology of Human papillomavirus (HPV) and related risk factors in a group of women with low- and high-grade cervical lesions and cancer from the coastal region of Ecuador. In addition, we studied the evolution of HPV variants from the most prevalent types and provided a temporal framework for their emergence, which may help to trace the source of dissemination within the region. We analyzed 166 samples, including 57 CIN1, 95 CIN2/3 and 14 cancer cases. HPV detection and typing was done by PCR-sequencing (MY09/MY11). HPV variants and estimation of the time to most recent common ancestor (tMRCA) was assessed through phylogeny and coalescence analysis. HPV DNA was found in 54.4% of CIN1, 74.7% of CIN2/3 and 78.6% of cancer samples. HPV16 (38.9%) and HPV58 (19.5%) were the most prevalent types. Risk factors for the development of cervical lesions/cancer were the following: three or more pregnancies (OR=4.3), HPV infection (OR=3.7 for high-risk types; OR=3.5 for HPV16), among others. With regard to HPV evolution, HPV16 isolates belonged to lineages A (69%) and D (31%) whereas HPV58 isolates belonged only to lineage A. The period of emergence of HPV16 was in association with human populations (tMRCA=91052 years for HPV16A and 27000 years for HPV16D), whereas HPV58A preceded Homo sapiens evolution (322257 years). This study provides novel data on HPV epidemiology and evolution in Ecuador, which will be fundamental in the vaccine era.

Different Association of Human Papillomavirus 16 Variants with Early and Late Presentation of Cervical Cancer

The median age of cervical cancer (CC) presentation coincides with the mean age of menopause presentation (49 years) in Mexico. Here, we investigated the association between different HPV16 variants and early (≤ 49 years) or delayed (≥ 50 years) CC presentation. We conducted a case-case study that included 462 CCs, 386 squamous cell carcinomas (SCC), 63 adenocarcinomas (ACC), and 13 additional cell types. Variants were identified by PCR and DNA sequencing. The risk conferred by each variant for developing CC earlier than 50 years was analyzed using a univariate logistic regression model considering old-aged patients (≥ 50 years) and non-HPV16 cases as the reference variables. Overall, the frequency of HPV16 was 50.9%, and the only identified variants were the European A1/2 (31.2%) and the Asian-American D2 (10.8%), and D3 (8.9%). D2 was mainly associated with ≤ 49-year-old patients (15.9%); A1/2 was uniformly distributed between the two age groups (~31%), whereas D3 increased with age to a frequency of 11.8% in the older group. Only the D2 variant conferred a 3.3-fold increase in the risk of developing CC before 50 years of age (OR = 3.3, 95% CI = 1.7-6.6, p < 0.001) in relation with non-HPV16 cases. Remarkably, this risk was higher for ACC (OR = 6.0, 95% CI = 1.1-33, p < 0.05) than for SCC (OR = 2.8, 95% CI = 1.3-5.9, p < 0.01). Interestingly, when analyzing only the HPV16-positive CC, D2 increases (OR = 2.5, 95% CI = 1.2-5, p < 0.05) and D3 decreases (OR = 0.45, 95% CI 0.2-0.9, p < 0.05) the risk to develop CC before 50 years old in relation with A1/2 variant. These results indicated that D2 variant is associated with early and D3 with delayed CC presentation, whereas A1/2 variant was uniformly distributed between the two age groups.

Genetic variability and phylogeny analysis of partial L1 gene of human papillomavirus variants in Buenos Aires, Argentina

In the present study, the molecular characterization of HPV variants 16, 18, 31, 58, 6 and 11 within the MY06/MY11 L1 genomic region was performed in 128 sequences. For HPV 16, all of the sequences analyzed had a 3 nucleotide insertion resulting in the insertion of serine in the L1 protein sequence; and 4 sequences had at least one single nucleotide polymorphism (SNP). Twelve base substitutions were detected in HPV 58, 6 SNPs produced amino acid changes, and the other SNPs detected were found to be silent mutations. For HPV 31, 25 SNPs were detected as silent mutations. Of the 8 SNPs detected on HPV 18, three produced amino acid changes, the remaining SNPs detected were silent mutations. For HPV 6, 10 SNPs were detected and none of them produced amino acid changes. From the 16 sequences analyzed for HPV 11, two SNPs were detected and neither of them produced amino acid substitutions. Phylogenetic trees were constructed for HPV 16, HPV 18, HPV 31, HPV 58, HPV 6 and HPV 11. In the current study 8 new variants were identified based on sequencing of the L1 region. Changes in the L1 region of the HPV genome may be important for discriminating the infectious potential of different variants, as well as in defining epitopes relevant to vaccine design. The findings of this study indicate that there are new variants of HPV circulating in Argentina, which need to be confirmed by further analyses of the complete HPV genome.

Identification and validation of immunogenic potential of India specific HPV-16 variant constructs: In-silico &in-vivo insight to vaccine development

Cervical cancer is one of the most common gynecological cancers in the world but in India, it is the top most cancer among women. Persistent infection with high-risk human papillomaviruses (HR-HPVs) is the most important risk factor. The sequence variation(s) in the most common HR-HPV i.e. HPV type 16 leads to altered biological functions with possible clinical significance in the different geographical locations. Sixteen major variants (V1-V16) in full length L1 gene of HPV-16 were identified following analysis of 250 prospectively collected cervical cancer tissue biopsies and their effect on immunogenicity was studied. The effect of these major variations on the epitopes were predicted by in silico methods and the immunogenicity of variants and respective reference DNA vaccine constructs were evaluated by administration of prepared DNA vaccine constructs in female BALB/c mice to evaluate antibody titer. In the present study, L500F (V16) variation showed a significant ~2.7 fold (p < 0.002) increase in antibody titer, whereas T379P (V8) showed ~0.4 fold (p < 0.328) decrease after final injection. These results showed a promising roadmap for the development of DNA based vaccine and for the generation of effective response, though there is a need to study more prevalent variants of HPV in the Indian population.