Genetic variability in E6 and E7 oncogenes of human papillomavirus Type 16 from Congolese cervical cancer isolates

Distribution of human papillomavirus among Vietnamese women with cervical cancer and unusual genetic variability of HPV16

HPV16, with typical mutations that differ in geographical distribution and carcinogenic potency, has implications for cervical cancer screening, clinical diagnosis, and treatment. DNASTAR and MEGA were used to identify HPV16 variants and construct a phylogenetic tree. The most prevalent HPV genotypes were HPV16 (63.9%), HPV18 (26.7%), and other HPV (6.9%). HPV16 alterations were found in all E6, E7, and L1 genes, including 15 missense and 18 synonymous mutations. Missense mutations include R10G, Q14H, D25E, H78Y, L83V (E6); M29V, R35K, L78R, L95P (E7); H73Y, T176 N, N178T, T317P, T386S, L472F/I (L1). HPV16 sublineages include A1 (17.2%), A2 (0.9%), A3 (56.0%), A4 (19.0%), D1 (4.3%), and D3 (2.6%). Although several mutations in the oncoproteins E6, E7, and L1 have been detected, mutations known to be associated with cervical cancer risk, such as D25E and L83V, occur at a relatively low frequency. This suggests that HPV16 mutations are associated with cervical cancer through a complicated mechanism.

Diversity of cervicovaginal human papillomavirus (HPV) genotypes and naturally occurring E6/E7 DNA polymorphisms of HPV-16 in Ghana

Human papillomavirus (HPV) E6 and E7 oncogene expression is essential for cervical carcinogenesis. Evidence exists that E6/E7 variants may have different transforming activities while the risk of HPV-16 variants (A/D) differs by race/ethnicity. We determined the type-specific diversity of HPV infection in women with high grade cervical disease or cervical cancer in Ghana and investigated naturally occurring E6/E7 DNA variants in this population. HPV genotyping was carried out on 207 cervical swab samples collected from women referred to a gynaecology clinic at two teaching hospitals in Ghana. HPV-16, HPV-18 and HPV-45 were detected in 41.9%, 23.3% and 16.3% of cases respectively. HPV-16 E6/E7 DNA sequencing was performed in 36 samples. Thirty samples contained E6/E7 variants of the HPV-16-B/C lineage. 21/36 samples were of the HPV-16C1 sublineage variant and all contained the E7 A647G(N29S) single nucleotide polymorphism (SNP). This study reveals the diversity of E6/E7 DNA and the dominance of HPV16 B/C variants in cervicovaginal HPV infection in Ghana. Type-specific HPV diversity analysis indicates that most Ghanaian cervical disease cases are vaccine preventable. The study provides an important baseline from which for the impact of vaccine and antivirals on clinically relevant HPV infection and associated disease can be measured.

Genetic Variability in the E6, E7, and L1 Genes of Human Papillomavirus Types 16 and 18 among Women in Saudi Arabia

Cervical cancer is the eighth most frequent cancer in Saudi Arabia, and most cases are associated with human papillomavirus (HPV) types 16 and 18. HPV-induced carcinogenesis may be associated with the intra-type variant, genetic mutation, or the continuous expression of viral oncogenes E6 and E7. Infection efficiency and virus antigenicity may be affected by changes in the L1 gene. Thus, this retrospective cohort study analyzed E6, E7, and L1 gene mutations in cervical specimens collected from Saudi women positive for HPV16 or HPV18 infection. HPV16 and HPV18 lineages in these specimens were predominantly from Europe. The L83V mutation in the E6 gene of HPV16 showed sufficient oncogenic potential for progression to cervical cancer. By contrast, the L28F mutation in the E7 gene of HPV16 was associated with a low risk of cervical cancer. Other specific HPV16 and HPV18 mutations were associated with an increased risk of cancer, cancer progression, viral load, and age. Four novel mutations, K53T, K53N, R365P, and K443N, were identified in the L1 gene of HPV16. These findings for HPV16 and HPV18 lineages and mutations in the E6, E7, and L1 genes among women in Saudi Arabia may inform the design and development of effective molecular diagnostic tests and vaccination strategies for the Saudi population.

Characterization of Human Papillomavirus 16 from Kinshasa (Democratic Republic of the Congo)-Implications for Pathogenicity and Vaccine Effectiveness

Human Papillomavirus (HPV) type 16 is the main etiological agent of cervical cancer worldwide. Mutations within the virus genome may lead to an increased risk of cancer development and decreased vaccine response, but there is a lack of information about strains circulating in Sub-Saharan Africa. Endocervical cytology samples were collected from 480 women attending a voluntary cervical cancer screening program at Monkole Hospital and four outpatient centers in Kinshasa, Democratic Republic of the Congo (DRC). The prevalence of HPV infection was 18.8% and the most prevalent high-risk types were HPV16 (12.2%) followed by HPV52 (8.8%) and HPV33/HPV35 (7.8% each). HPV16 strains were characterized: 57.1% were classified as C lineage; two samples (28.6%) as A1 and one sample belonged to B1 lineage. HPV33, HPV35, HPV16, and HPV58 were the most frequent types associated with low-grade intraepithelial lesion while high-grade squamous intraepithelial lesions were predominantly associated with HPV16. Several L1 mutations (T266A, S282P, T353P, and N181T) were common in Kinshasa, and their potential effect on vaccine-induced neutralization, especially the presence of S282P, should be further investigated. Long control region (LCR) variability was high with frequent mutations like G7193T, G7521A, and G145T that could promote malignancy of these HPV16 strains. This study provides a helpful basis for understanding HPV16 variants circulating in Kinshasa and the potential association between mutations of LCR region and malignancy and of L1 and vaccine activity.

E6/E7 Variants of Human Papillomavirus 16 Associated with Cervical Carcinoma in Women in Southern Mexico

Persistent infection with the human papillomavirus 16 (HPV 16) is the cause of half of all cervical carcinomas (CC) cases. Moreover, mutations in the oncoproteins E6 and E7 are associated with CC development. In this study, E6/E7 variants circulating in southern Mexico and their association with CC and its precursor lesions were evaluated. In total, 190 DNA samples were obtained from scrapes and cervical biopsies of women with HPV 16 out of which 61 are from patients with CC, 6 from patients with high-grade squamous intraepithelial lesions (HSIL), 68 from patients with low-grade squamous intraepithelial lesions (LSIL), and 55 from patients without intraepithelial lesions. For all E7 variants found, the E7-C732/C789/G795 variant (with three silent mutations) was associated with the highest risk of CC (odd ratio (OR) = 3.79, 95% confidence interval (CI) = 1.46–9.85). The analysis of E6/E7 bicistron conferred to AA-a*E7-C732/C789/G795 variants revealed the greatest increased risk of CC (OR = 110, 95% CI = 6.04–2001.3), followed by AA-c*E7-C732/C789/G795 and A176/G350*E7-p. These results highlight the importance of analyzing the combinations of E6/E7 variants in HPV 16 infection and suggest that AA-a*E7-C732/C789/G795, AA-c*E7-C732/C789/G795, and A176/G350*E7-p can be useful markers for predicting CC development.

Metabolic Reprogramming in Cancer: Role of HPV 16 Variants

Metabolic reprogramming is considered one of the hallmarks in cancer and is characterized by increased glycolysis and lactate production, even in the presence of oxygen, which leads the cancer cells to a process called “aerobic glycolysis” or “Warburg effect”. The E6 and E7 oncoproteins of human papillomavirus 16 (HPV 16) favor the Warburg effect through their interaction with a molecule that regulates cellular metabolism, such as p53, retinoblastoma protein (pRb), c-Myc, and hypoxia inducible factor 1α (HIF-1α). Besides, the impact of the E6 and E7 variants of HPV 16 on metabolic reprogramming through proteins such as HIF-1α may be related to their oncogenicity by favoring cellular metabolism modifications to satisfy the energy demands necessary for viral persistence and cancer development. This review will discuss the role of HPV 16 E6 and E7 variants in metabolic reprogramming and their contribution to developing and preserving the malignant phenotype of cancers associated with HPV 16 infection.

Human Papillomavirus Selected Properties and Related Cervical Cancer Prevention Issues

High-risk human papillomavirus strains are widely known to be the causative agents responsible for cervical cancer development. Aggregated damage caused by papillomaviruses solely is estimated in at least 5% of all malignancies of the human body and 16% in cancers that affect the female genital area. Enhanced understanding of the complex issue on how the high extent of carcinogenicity is eventually formed due to the infection by the Papoviridae family would contribute to enhancing current prevention strategies not only towards cervical cancer, but also other HPV associated cancers. This review article is aimed at presenting the key points in two directions: the current cervical cancer prevention and related aspects of HPV behavior. Virtually all applied technologies related to HPV diagnostics and screening programs, such as HPV tests, colposcopy-based tests (VIA/VILI), conventional and liquid-based cytology, currently available are presented. Issues of availability, advantages, and drawbacks of the screening programs, as well as vaccination strategies, are also reviewed in the article based on the analyzed sources. The current point of view regarding HPV is discussed with emphasis on the most problematic aspect of the HPV family concerning the observed increasing number of highly carcinogenic types. Present trends in HPV infection diagnostics throughout the human fluids and tissues are also reported, including the latest novelties in this field, such as HPV assay/self-sample device combinations. Besides, a brief outline of the related prevention issues in Kazakhstan, the leading country of Central Asia, is presented. Kazakhstan, as one of the post-soviet middle-income countries, may serve as an example of the current situation in those terrains, concerning the implementation of globally accepted cervical cancer prevention strategies. Along with positive achievements, such as the development of a nationwide screening program, a range of drawbacks is also analyzed and discussed.

Genetic variability and functional implication of HPV16 from cervical intraepithelial neoplasia in Shanghai women

Human papillomavirus (HPV)16 gene mutation is usually associated with persistent HPV infection and cervical intraepithelial neoplasia (CIN). However, the functional implications of HPV16 mutations remain poorly understood.145 LCR/E6/E7 of the HPV16 isolates were amplified and sequenced, and HPV16 integration status was detected. In total, 89 SNPs (68 in the LCR, 13 in E6, 8 in E7) were discovered, 11 of which were nonsynonymous mutations (8 in E6, 3 in E7). The H85Y and E120D variants in E6 were significantly reduced in the high-grade squamous intraepithelial lesion (HSIL) group compared to the <HSIL group (P = .046 and .005), conversely the N29S in E7(P = .01). Amino acid substitutions (D32N/E, E36Q, H85Y, and E120D in E6 and N29H/S and R77C in E7) were predicted to have an effect on conserved structural and functional residues, and five amino acid substitutions (H85Y, E36Q, I34L, and D32E in E6; R77C in E7) would potentially change the secondary structure. "6329G>T," a potential binding site for TATA-binding protein, is the most common in LCR variants. A4 (Asian) was associated with an increased risk of HSIL compared to A1-3(P = .009). The H85/E120 in E6 and N29 in HPV16 E7 might play a critical role in carcinogenesis by disrupting p53 and Rb degradation due to affecting their interaction, respectively. In a word, the findings in this study provide preventative and therapeutic interventions of HPV16 -related cervical lesions/cancer.

Molecular characterisation of genital human papillomavirus among women in Southwestern, Nigeria

Background

Persistent infections with high-risk genital Human papillomavirus (HPV) especially types 16 and 18, are associated with cervical cancer. However, distribution of HPV types varies greatly across geographical regions and the available vaccines target only few types. This study was designed to determine the HPV types circulating in Southwestern Nigeria, thereby providing necessary information for effective control of the virus.

Methods

Endocervical swab samples were collected from a total of 295 consenting women attending routine cervical cancer screening, STI clinics and community-based outreach programme. Viral DNA was extracted from the samples and the consensus region of the HPV DNA was amplified by PCR using GP-E6/E7 primers. Type-specific nested multiplex PCR and Sanger sequencing were used to genotype the HPV isolates.

Results

In this study, 51 (17.3%) individuals were positive for HPV DNA using consensus primers that target the E6/E7 genes but only 48 (16.3%) were genotyped. A total of 15 HPV types (HPV-6, 16, 18, 31, 33, 35, 42, 43, 44, 52, 58, 66, 74, 81, 86) were detected, with HPV-31 being the most predominant (32.8%), followed by HPV-35 (17.2%) and HPV-16 (15.5%). Two rare HPV types; 74 and 86 were also detected. The HPV-74 isolate had three nucleotide (CCT) insertions at E7 gene that translated into amino acid proline. Highest nucleotide substitutions (n = 32) were found in HPV-44 genotype. Among positive individuals, 20.8% had dual infections and 86.2% had High-risk HPV types.

Conclusions

Multiple Human papillomavirus types co-circulated in the study. Most of the circulating Human papillomavirus are high-risk type with type 31 being the most predominant. Although the implication of HPV-74 with proline insertion detected for the first time is unknown, it may have effect on the transformation potential of the virus. Polyvalent HPV vaccine will be more effective for the infection control in Nigeria.

Mutational landscape and intra-host diversity of human papillomavirus type 16 long control region and E6 variants in cervical samples

Human papillomavirus genotype 16 (HPV16) is the most frequent high-risk HPV (HR-HPV) identified in cervical precursor lesions and cervical cancer (CC) worldwide. The oncogenic potential of HPV16 is partly dependent on the lineage involved in the infection and the presence of clinically relevant mutations. In this report, we present the distribution of HR-HPV and the mutational profile and intra-host variability of HPV16 lineages, based on analysis of the long control region (LCR) and the E6 gene in samples with normal cytology (n = 39), squamous intraepithelial lesions (n = 25), and CC (n = 39). HR-HPV genotyping was performed using multiplex real-time PCR. HPV16 lineage assignments and mutation frequencies were determined by conventional PCR and Sanger DNA sequencing, and intra-patient viral populations were analyzed using next-generation sequencing (NGS). The most frequent HR-HPV type was HPV16, followed by HPV31 and HPV18. The frequency of HPV16 sublineages was A1/A2 > D2 > D3 and B1. Moreover, the most frequent mutations, both in samples from this study and in the available sequences from Mexican isolates in the GenBank database were LCR-G7518A, which is involved in carcinogenesis, and E6-T350G (producing L83V), associated with persistence of infection. Otherwise, deep sequencing revealed high conservation of viral lineages and mutations, independently of the stages studied. In conclusion, the high frequency and stability of these molecular markers, as well as the circulating viral lineages, could be related to the incidence of CC associated with HPV16. Hence, they deserve a broader analysis to determine the risk of specific populations for progression of the disease.

Differences in the viral genome between HPV-positive cervical and oropharyngeal cancer

Human papillomavirus (HPV)-driven oropharyngeal cancer incidence in the United States has steadily increased in the past decades and has now become the most frequently diagnosed HPV-associated cancer type, surpassing cervical cancer. Variations in the HPV genome correlate with tumorigenic risk, and the distribution of genetic variants is extensively studied in cervical cancer, but very little is known about new mutations or the distribution of HPV types and variants in oropharyngeal cancer. Here we present an archival tissue cohort study that compares genomic characteristics of HPV associated with cervical versus oropharyngeal tumors using DNA sequence analysis. We found HPV16 to be more prevalent in oropharyngeal samples than in cervical samples (91.2% versus 52.9%), while HPV18 (1.5% versus 18.2%) and HPV45 (0.7% versus 9.9%) were much less prevalent. Differences between cervix and oropharynx in HPV16 variants distribution were more subtle, but the combined European + Asian (EUR+AS) variant group was more prevalent (90.2% versus 71.4%), while the American Asian 1 + American Asian 2 (AA1+AA2) variant group was much less prevalent (4.4% versus 22.5%) in oropharyngeal cancers. HPV prevalence in oropharyngeal cancers showed an increasing trend from 60% in 2003 to 80% in 2016. We also identified over nine times more nonsynonymous mutations in the HPV E6 gene amplified from oropharyngeal samples, but for E7 the difference in mutation rates between the two anatomical locations was not significant. Overall, we showed that HPV genome in oropharyngeal cancer presents important differences when compared to cervical cancer and this may explain the distinct pathomechanisms and susceptibility to treatment of HPV-associated oropharyngeal cancer.

Performance of OncoE6 cervical test with collection methods enabling self-sampling

BACKGROUND

The paradigm shift from cytological screening to Human Papillomavirus (HPV)-based screening for cervical cancer allows the introduction of new technologies in sample collection and diagnostics. The OncoE6™ Cervical Test (OncoE6 Test) is a rapid, easy-to-use lateral flow method detecting HPV16/18 E6 oncoproteins that has proven to detect high-grade cervical lesions with high specificity. If compatible with self-collection samples, this technology might allow for decentralized screening of hard-to-reach populations.

METHODS

For technical validation, cervicovaginal lavages were collected from 20 patients with confirmed HPV16+ or HPV18+ invasive cervical cancer. Cervical smears were collected by polyester-tipped swabs and cytobrushes. All samples were applied to the OncoE6 Test and cytobrush samples additionally genotyped.

RESULTS

Lavage, swab, and cytobrush revealed concordant outcome in 18/20 samples. HPV types corresponded with the HPV genotyping by GP5+/6+ PCR analyses. Due to a rare mutation found in the E6 antibody binding site one sample was not detected, another sample had very low cellularity.

CONCLUSIONS

Overall, vaginal lavages are technically adequate for the OncoE6 Test. Combining self-sampling with oncoprotein rapid testing to detect women with highest risk for severe dysplasia or cancer may allow for secondary cancer prevention in settings where other screening modalities were unsuccessful to date.

Analysis of human papillomavirus 16 E6, E7 genes and Long Control Region in cervical samples from Uruguayan women

OBJECTIVE

This study aims to investigate the HPV16 variant distribution by sequence analyses of E6, E7 oncogenes and the Long Control Region (LCR), from cervical cells collected from Uruguayan women, and to reconstruct the phylogenetic relationships among variants.

METHODS

Forty-seven HPV16 variants, obtained from women with HSIL, LSIL, ASCUS and NILM cytological classes were analyzed for LCR and 12 were further studied for E6 and E7. Detailed sequence comparison, genetic heterogeneity analyses and phylogenetic reconstruction were performed.

RESULTS

A high variability was observed among LCR sequences, which were distributed in 18 different variants. E6 and E7 sequences exhibited novel non-synonymous substitutions. Uruguayan sequences mainly belonged to the European lineage, and only 5 sequences clustered in non-European branches; 3 of them in the Asian-American and North-American linage and 2 in an African branch. Additionally, 6 new variants from European and African clusters were identified.

CONCLUSIONS

HPV16 isolates mainly belonged to the European lineage, though strains from African and Asian-American lineages were also identified. Herein is reported for the first time the distribution and molecular characterization of HPV16 variants from Uruguay, providing novel insights on the molecular epidemiology of this infectious disease in the South America.

SYNOPSIS

A high variability among HPV 16 isolates mainly belonged to European lineage, provides an extensive sequence dataset from a country with high burden of cervical cancer.

Prevalence and Risk Factors for Genital Human Papillomavirus Infections Among Women in Southwest Nigeria

There is a great variation in the prevalence of cervical HPV infection worldwide with some of the highest rates being found in African women. Early onset of sexual activity (≤ 15 age), multiparity and sexual promiscuity have been recognized as some of the significant risk factors for HPV infection. In Nigeria, there is scarcity of data on the degree of relationship between these factors and the prevalence of HPV infection. Thus, this study was designed to determine the prevalence of genital HPV infection with its potential risk factors among women in Southwest Nigeria. Cervical swab specimen was collected from 295 consenting women including those presenting for routine cervical cancer screening, STI clinic attendees and women who attended community based outreach programmes. Viral DNA was extracted from the swab samples using commercially available DNA extraction Kit and amplified by PCR using two set of consensus primers (PGMY09/11 and degenerate GP-E6/E7). Fifty-five samples were positive to HPV DNA giving a prevalence of 18.6%. Risk factors such as lack of formal education (P-value: 0.003), divorcee (P-value: 0.019), polygamy (P-value: 0.027), unemployment (P-value: 0.023), low income earnings (P-value: 0.018), younger age (<18years) at sexual debut (P-value: 0.039) and passive smoking (P-value: 0.017) were significantly associated with HPV infection. High HPV prevalence and associated risk factors observed in this study shows the continuous transmission of the virus in Southwest Nigeria. Hence, enlarged monitoring including intense public awareness and cervical cancer screening is urgently needed for prevention and control strategies.

Codon optimization of Iranian human papillomavirus Type 16 E6 oncogene for Lactococcus lactis subsp. cremoris MG1363

Aim: The present study aimed to investigate the effect of codon optimization on E6 recombinant protein production in Lactococcus lactis. Method: Here we define the construction of shuttle vector harboring wild-type and codon-optimized HPV16 E6 oncogene, with maximum number of infrequent codons exchanged with codons that are frequently used in Lactococcus lactis subsp. cremoris MG1363. Results: Hence, the codons encoding 159 amino acids were modified, in which a total of 91 codons were changed, resulting in approximately threefold increase in protein expression of recombinant E6 (rE6). Conclusion: Our data revealed that codon usage optimization according to L. lactis desired codon usage can dramatically increase the expression of HPV16 E6, suggesting that this strategy is a valuable approach for immunization through DNA vaccine.

Efficient production and optimization of E7 oncoprotein from Iranian human papillomavirus type 16 in Lactococcus lactis using nisin-controlled gene expression (NICE) system

The present work was aimed at investigating the expression and optimization of a human papillomavirus (HPV) type 16 gene encoding oncoprotein E7 in Lactococcus lactis. We genetically engineered Lactococcus lactis using nisin-controlled gene expression (NICE) system pNZ8148 to express the native and codon optimized E7 oncogenes isolated from Iranian HPV-16. The results of optimizing fermentation showed, the concentration of produced protein was expressively improved by 10 ng/mL nisin after 3.5, and 4 h induction for NZ9000 harboring the codon-optimized, and native E7 respectively. Furthermore the recombinant NZ9000 strains expressed rE7 by maximum value of 4.7 (Codon-optimized), and 1.82 μg/mL (Native) in static flask experiments at initial glucose concentrations of 50 and 75 g/L respectively. The rE7 yield was further enriched in batch fermenter experiments using controlled pH. Thus, the overall production of rE7 under optimized conditions accumulated in the cytoplasm to nearly 33.25 μg/mL by L. lactis NZ9000 containing codon-optimized E7, which was over ∼2.7-fold higher compared to the NZ9000 having native E7 strain (12.01 μg/mL). Accordingly, the maximum biomass production was calculated 4.87, and 1.51 g/L respectively.

Association of HLA-DRB1, HLA-DQB1 Polymorphisms with HPV 16 E6 Variants among Young Cervical Cancer Patients in China

Potential correlation of human papillomavirus (HPV) 16 E6 variants and human leukocyte antigen (HLA) class II polymorphisms has been suggested in patients with cervical cancer, so far little information is available about the possible interaction between E6 variants and HLA class II variability during the obviously accelerated progression to cervical cancer in young women. In this study, we aimed to explore the association between the HPV16 E6 variants and HLA-DRB1, DQB1 alleles in a Chinese young cervical cancer population. The HLA-DRB1, HLA-DQB1 polymophisms were genotyped by low-resolution polymerase chain reaction (PCR) with sequence-specific primer. HPV16 E6 DNA was tested by Sanger fluorescent dye dideoxy-termination technique. The difference of DRB1, DQB1 polymorphisms between young cervical cancer patients (≤35ys, n=61) and older ones (>35ys, n=85) and the association with E6 variants were analyzed. Results showed that the distribution pattern of HLA-DRB1, DQB1 alleles was different between young cervical cancer patients and older ones. The allele frequency of DQB1*0501 in young patients was significantly lower than older ones (6.6% vs. 23.5%, p<0.05). The HPV16 E6 A4 lineage was the exclusive type observed in young patients, and its prevalence was significantly higher than that of older cases (82.86% vs.41.94%, p<0.05). DRB1*03 was not found in young patients positive for the HPV16 E6 A4 lineage, whereas it was observed in 19.2 % older patients with A4 positive(Pc<0.05). In conclusion, specific association between certain HPV16 E6 variant and genetic polymorphisms of HLA may play a role during the progression of early onset cervical cancer in young patients. Certain HLA-DRB1 and HLA-DQB1 alleles may be related to the A4 lineage among young cervical cancer patients, which was the unique HPV16 E6 variant found in Chinese young patients. Our finding may provide an insight into the pathogenic factors that associated with cervical cancer in young women.

Codon Usage Optimization and Construction of Plasmid Encoding Iranian Human Papillomavirus Type 16 E7 Oncogene for Lactococcus Lactis Subsp. Cremoris MG1363

HPV 16 intratypic sequence variations has been recognized in association with oncogenic potential diverge and geographic distribution. This study aimed to investigate nucleotide modifications and optimization of HPV 16 E7 regions from Iranian infected women. Cervical biopsies from 79/163 HPV 16 positive cancer patients detected in our study were analyzed by PCR in a couple of cloning of a complete ORF of the E7 gene, and sequencing. The most frequently observed variant was C196T in E7 which led to an amino acid change of R66W. In addition, only one common variant T234G was identified from all specimens, but it did not lead to any amino acid change. We also detected nucleotide variations A86G, and C188T in samples. Among 99 codons in E7 gene, 56 codons were improved for Lactococcus lactis subsp. cremoris MG1363 resulting in a reduced G+C content from 43.1% to 34.0%. Also, the AT%, ENC, and CAI values were 66, 20±1.1, and 1.000 instead of 56.90, 60 ±1.1, and 0.406 respectively. Finally we constructed expression vector pNZ8148 encoding optimized E7 oncoprotein of HPV 16. This study declared for the first time, the genetic variations of HPV 16 E7 in IRAN. We conclude that plasmid pNZ8148-HPV 16-opti E7 can be potential vaccine candidates in the future.

Variants of human papillomaviruses 16 (HPV16) in Uigur women in Xinjiang, China

BACKGROUND

Persistent infection of high-risk human papillomaviruses 16 (HPV16) has been considered as the leading cause of cervical cancer. In this study we assessed HPV16 sequence variation and genetic diversity of HPV16 variants in cervical cancer in Uigur women in Xinjiang, China. We analyzed the nucleotide sequences of the open reading frames of E6 and E7, and part of the open reading frames of L1 of HPV16 in Uigur women.

METHODS

Biopsies of histologically confirmed HPV16 infections with cervical cancer were obtained from 43 Uigur women in Xinjiang, China. E6, E7 and L1 genes of HPV16 of all samples were amplified and sequenced; the sequences were used in phylogenetic analysis of HPV16 variants.

RESULTS

Our analysis revealed nine nucleotide changes in E6 (five changes), E7 (one change) and L1 (three changes) gene. The most frequently observed variations were T350G (79.1 %). One variation T295G (D64E) at E6 were detected in 6 cases (KT959536, KT959542, KT959546, KT959550, KT959553, KT959558). Deletion (464Asp) along with insertion (448Ser) were observed in L1 (100 %). Most variants were European lineage (97.7 %); only one belongs to Asia variants with common T178G (D25E) in E6 and A647G (N29S) in E7.

CONCLUSION

The most prevalent HPV16 variants in the Uigur women we studied were of the European lineage. Our results indicate that HPV16 European lineage may serve as a harmful factor associated with the development and progression of cervical cancer.