Distribution of human papillomavirus 58 and 52 E6/E7 variants in cervical neoplasia in Chinese women

Distribution of HPV types among women with HPV-related diseases and exploration of lineages and variants of HPV 52 and 58 among HPV-infected patients in China: A systematic literature review

To summarize the distribution of types of human papillomavirus (HPV) associated with HPV-related diseases and investigate the potential causes of high prevalence of HPV 52 and 58 by summarizing the prevalence of lineages, sub-lineages, and mutations among Chinese women. We searched PubMed, EMBASE, CNKI, and WanFang from January, 2012 to June, 2023 to identify all the eligible studies. We excluded patients who had received HPV vaccinations. Data were summarized in tables and cloud/rain maps. A total of 102 studies reporting HPV distribution and 15 studies reporting HPV52/HPV58 variants were extracted. Among Chinese women, the top five prevalent HPV types associated with cervical cancer (CC) were HPV16, 18, 58, 52, and 33. In patients with vaginal cancers and precancerous lesions, the most common HPV types were 16 and 52 followed by 58. For women with condyloma acuminatum (CA), the most common HPV types were 11 and 6. In Chinese women with HPV infection, lineage B was the most prominently identified for HPV52, and lineage A was the most common for HPV58. In addition to HPV types 16, which is prevalent worldwide, our findings revealed the unique high prevalence of HPV 52/58 among Chinese women with HPV-related diseases. HPV 52 variants were predominantly biased toward lineage B and sub-lineage B2, and HPV 58 variants were strongly biased toward lineage A and sub-lineage A1. Further investigations on the association between the high prevalent lineage and sub-lineage in HPV 52/58 and the risk of cancer risk are needed. Our findings underscore the importance of vaccination with the nine-valent HPV vaccine in China.

E7 Oncogene HPV58 Variants Detected in Northeast Brazil: Genetic and Functional Analysis

Cervical cancer is associated with persistent infections by high-risk Human Papillomavirus (HPV) types that may have nucleotide polymorphisms and, consequently, different oncogenic potentials. Therefore, this study aimed to evaluate the genetic variability and structural effects of the E7 oncogene of HPV58 in cervical scraping samples from Brazilian women. The study was developed with patients from hospitals in the metropolitan area of Recife, PE, Brazil. The most frequent HPV types were, in descending order of abundance, HPV16, 31, and 58. Phylogenetic analysis demonstrated that the isolates were classified into sublineages A2, C1, and D2. Two positively selected mutations were found in E7: 63G and 64T. The mutations G41R, G63D, and T64A in the E7 protein reduced the stability of the protein structure. Utilizing an NF-kB reporter assay, we observed a decrease in the NK-kB pathway activity with the HPV58-E7 variant 54S compared to the WT E7. The other detected E7 HPV58 variants presented similar NF-kB pathway activity compared to the WT E7. In this study, it was possible to identify mutations that may interfere with the molecular interaction between the viral oncoproteins and host proteins.

Genetic variability in the E6 and E7 oncogenes of HPV52 and its prevalence in the Taizhou area, China

Background

Human papillomavirus (HPV) 52 is one of the prevalent oncogenic HPV genotypes in East Asia. Chinese women have the highest susceptibility to the HPV52 type, but research data on HPV52 genetic variability and its carcinogenicity in China is lacking.

Methods

The present study aimed to investigate the genetic variability of HPV52 currently circulating among Chinese women by PCR sequencing the entire E6 and E7 oncogenes. HPV52 sequence alignment, genetic heterogeneity analyses and maximum-likelihood phylogenetic tree construction were performed by BioEdit software and MEGA X software.

Results

Between 2016 and 2018, the overall HPV infection rate was 21.3%, of which HPV52 was the most prevalent high-risk type (17.2%) in the Taizhou area, China. A total of 339 single HPV52-positive samples were included in this study. We obtained 27 distinct variation patterns of HPV52 with the accession GenBank numbers ON529577-ON529603. Phylogenetic analysis showed that 96.6% of HPV52 variants belonged to lineage B, which seemed to be uniquely defined by G350T, A379G (K93R) in the E6 gene and C751T, A801G in the E7 gene. Due to the dominance of lineage B in our study population, the results could not be used to assess the association of the HPV52 (sub)lineage with the risk of cervical lesions. In addition, no significant trends were observed between the nucleotide substitutions of HPV52 variants and the risk of cervical carcinogenesis.

Conclusion

Our data showed that HPV52 variants were strongly biased towards lineage B. These results confirmed that cervical lesions in the Taizhou area are highly attributable to HPV52, which may be due to the high infection rate of lineage B in the population.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12985-022-01929-5.

Genetic variability of E6 and E7 genes of human papillomavirus type 58 in Jingzhou, Hubei Province of central China

BACKGROUND

Cervical cancer is a common malignant tumor in women, with a high mortality rate, has great harm to women's health. Long-term and persistent infection of high-risk human papillomavirus (HR-HPV) is the main reason of the occurrence and development of cervical cancer.

METHODS

The infection rate of HPV-58 is higher in the Jingzhou area. In this study, 172 complete HPV-58 E6-E7 sequences were amplified by polymerase chain reaction (PCR), the amplified products were sequenced, and the gene variations of HPV-58 E6-E7 were analyzed. A Neighbor-Joining phylogenetic tree was constructed by MEGA 11. The secondary structure of E6 and E7 protein was investigated. PAML X was used to analyze the selective pressure. The B cell epitopes of E6 and E7 proteins in HPV-58 were predicted by ABCpred server.

RESULTS

In E6 sequences, 10 single nucleotide variants were observed, including 7 synonymous and 3 non-synonymous variants. In E7 sequences, 12 single nucleotide variants were found, including 3 synonymous variants and 9 non-synonymous variants. There are 5 novel variants. The phylogenetic analysis showed that all the E6-E7 sequences were distributed in A lineage. No positively selected site was found in E6 sequence, but G63 in E7 sequences was identified as positively selected site. Some amino acid substitutions affected multiple B cell epitopes.

CONCLUSION

Various E6 and E7 mutational data may prove useful for development of better diagnostic and vaccines for the region of Jingzhou, Hubei province of central China.

Genetic variation of E6 and E7 genes of human papillomavirus 52 from Central China

Cervical cancer is the fourth most common malignant tumor in women worldwide and is closely related to human papillomavirus (HPV). Women have the highest susceptibility to HPV-52 type in Jingzhou, China. In this study, E6-E7 sequences of 183 HPV-52 positive samples were amplified by a polymerase chain reaction and sequenced. HPV-52 E6-E7 gene variations were analyzed. The phylogenetic tree was constructed using the Kimura 2-parameter method. The secondary structure of the protein was analyzed. The selective pressure to E6-E7 genes was estimated using PAML. In addition, the B cell epitopes of the E6-E7 sequences in HPV-52 were predicted by the ABCpred server. In E6 sequences, 15 single nucleotide variants were observed, including 6 nonsynonymous variants and 9 synonymous variants. In E7 sequences, 19 single nucleotide variants occurred, including 10 nonsynonymous variants and 9 synonymous variants. Six amino acid variants, including 3 nonconservative substitutions, were found in sequences encoding the alpha helix. Eight amino acid variants, including three nonconservative substitutions, occurred in sequences encoding the strand. Through phylogenetic analysis, the E6-E7 sequences were mainly distributed in B lineage. In HPV-52 E6-E7 sequences, no positively selected site was found. The nonconservative substitutions, such as K93R, K93E in E6, T37I, and D38N in E7, affected multiple hypothetical epitopes in the B cell. This study provides information for the investigation of HPV epidemic characters. The discovery of new variants of HPV-52 may lay the basis for the development of the virus diagnosis, further study of cervical cancer, and vaccine design in Central China.

HPV58 E7 Protein Expression Profile in Cervical Cancer and CIN with Immunohistochemistry

Background: The persistent infection of high-risk human papillomavirus (HR-HPV) is one of the most common causes of cervical cancer worldwide, and HPV type 58 (HPV58) is the third most common HPV type in eastern Asia. The E7 oncoprotein is constitutively expressed in HPV58-associated cervical cancer cells and plays a key role during tumorigenesis. This study aimed to assess the HPV58 E7 protein expression in the tissues of cervical cancer and cervical intraepithelial neoplasia (CIN).

Methods: A total of 67 HPV58-positive cervical samples were collected, including 25 cervical cancer samples and 42 CIN samples. All the tissues were examined by HPV58 E7, p16^INK4a and Ki67 immunohistochemistry (IHC). At last, we analyzed their association with clinical and pathological variables.

Results: HPV58 E7 expression was detected in 96% of the HPV58 DNA-positive cervical cancer tissues and 85.7% of HPV58-positive CIN tissues. 65 samples of cervical cancer and CIN tissues had p16-positive staining, while 59 samples were Ki-67 positive.

Conclusions: HPV58 E7 protein is highly expressed in both cervical cancer and CIN tissues. HPV58 E7 IHC could be sensitive and specific for evaluating HPV-driven cervical cancer and pre-cancerous lesions, in combination with p16 and Ki-67 IHC.

Oncogenicitiy Comparison of Human Papillomavirus Type 52 E6 Variants

Human papillomavirus (HPV) infection contributes to virtually all cases of cervical cancer, the fourth most common cancer affecting women worldwide. The oncogenicity of HPV is mainly attributable to the E6 and E7 oncoproteins. HPV-52 is the seventh most common HPV type globally, but it has a remarkably high prevalence in East Asia. In previous studies it has been speculated that the oncogenicity might vary among different HPV-52 variants. In the present study, we compared the oncogenicity of E6 derived from the HPV-52 prototype and three commonly found variants, V1 (K93R), V2 (E14D/V92L) and V3 (K93R/N122K), through molecular and phenotypic approaches. We demonstrated that cells containing V1 achieved higher colony formation and showed greater cell migration ability when compared to other variants, but no difference in cell immortalization ability was observed. At the molecular level, the three variants formed complexes with E6-associated protein (E6AP) and p53 as efficiently as the prototype. They degraded p53 and PSD95/Dlg/ZO-1(PDZ) proteins, including MAGI-1c and Dlg, to a similar extent. They also exhibited a similar subcellular localization, and shared a half-life of approximately 45 min. Our findings provide a clearer picture of HPV-52 E6 variant oncogenicity, which is important for further studies aiming to understand the unusually high prevalence of HPV-52 among cervical cancers in East Asia.

Oncogenic comparison of human papillomavirus type 58 E7 variants

Human papillomavirus 58 (HPV58) ranks the second or third in East Asian cervical cancers. Current studies on HPV58 are scarce and focus on the prototype. Previously, we identified the three most common circulating HPV58 E7 strains contained amino acid alterations: G41R/G63D (51%), T20I/G63S (22%) and T74A/D76E (14%) respectively. Among them, the T20I/G63S variant (V1) had a stronger epidemiological association with cervical cancer. We therefore suggested that V1 possessed stronger oncogenicity than the other two variants. Here, we performed phenotypic assays to characterize and compare their oncogenicities with HPV58 E7 prototype. Our results showed that overexpression of V1 conferred a higher colony-forming ability to primary murine epithelial cells than prototype (P < 0.05) and other variants, implicating its higher immortalising potential. Further experiments showed that both V1 and prototype enhanced the anchorage-independent growth of NIH/3T3 cells (P < 0.001), implicating their stronger transforming power than the two other variants. Moreover, they possessed an increased ability to degrade pRb (P < 0.001), which is a major effector pathway of E7-driven oncogenesis. Our work represents the first study to compare the oncogenicities of HPV58 E7 prototype and variants. These findings deepened our understanding of HPV58 and might inform clinical screening and follow-up strategy.

Genetic variability and oncogenic risk association of human papillomavirus type 58 E6 and E7 genes in Taizhou area, China

It is well recognized that the association of human papillomavirus (HPV) and cervical carcinogenesis is based on the presence of HPV DNA sequence. The E6 and E7 oncoproteins encoded by high-risk HPV types play a key role in carcinogenesis. HPV58 type accounts for a larger share of cervical disease in China, whereas data on HPV58 genetic variability in China is limited. We aimed to evaluate the diversity of HPV58 genetic variants by sequencing the entire E6 and E7 genes. Phylogenetic trees were constructed by Maximum likelihood method by MEGA 5.05 software. In this study, the overall HPV infection rate was 22.6% (2891/12780) in Southeast China and the prevalence of HPV58 infection rate was 2.6% (335/12780). 26 nucleotides substitutions were observed in E6 and E7 genes with 10 novel substitutions and 17 non-synonymous substitutions. We obtained 25 distinct variation patterns which the accession GenBank numbers as MH348918-MH348942. All of HPV58 variants belong to lineage A, while no lineage B, C and D were detected in Taizhou area, Southeast China. The sublineage A1, A2, and A3 variants were found in 136 (68.3%), 39 (19.6%), and 24 (12.1%) of HPV58 isolates, respectively. The sublineage A3 variants with T20I/G63S substitutions at E7 oncoprotein carried a significantly higher risk for high-grade cervical intraepithelial neoplasia (CIN2 or worse, CIN2+) when compared with other HPV58 variants (odds ratio = 4.41, P < 0.05). Nevertheless, there was no association between HPV58 (sub) lineages and cervical lesions. These data provide the critical characteristics of HPV58 variants to assist further investigation of carcinogenic association and the development of next generation vaccines and diagnostic assays in China.

The polymorphisms of LCR, E6, and E7 of HPV-58 isolates in Yunnan, Southwest China

Backgroud

Variations in HPV LCR/E6/E7 have been shown to be associated with the viral persistence and cervical cancer development. So far, there are few reports about the polymorphisms of the HPV-58 LCR/E6/E7 sequences in Southwest China. This study aims to characterize the gene polymorphisms of the HPV-58 LCR/E6/E7 sequences in women of Southwest China, and assess the effects of variations on the immune recognition of viral E6 and E7 antigens.

Methods

Twelve LCR/E6/E7 of the HPV-58 isolates were amplified and sequenced. A neighbor-joining phylogenetic tree was constructed by MEGA 7.0, followed by the secondary structure prediction of the related proteins using PSIPRED v3.3. The selection pressure acting on the HPV-58 E6 and E7 coding regions was estimated by Bayes empirical Bayes analysis of PAML 4.8. Meanwhile, the MHC class-I and II binding peptides were predicted by the ProPred-I server and ProPred server. The transcription factor binding sites in the HPV-58 LCR were analyzed using the JASPAR database.

Results

Twenty nine SNPs (20 in the LCR, 3 in the E6, 6 in the E7) were identified at 27 nucleotide sites across the HPV-58 LCR/E6/E7. From the most variable to the least variable, the nucleotide variations were LCR > E7 > E6. The combinations of all the SNPs resulted in 11 unique sequences, which were clustered into the A lineage (7 belong to A1, 2 belong to A2, and 2 belong to A3). An insertion (TGTCAGTTTCCT) was found between the nucleotide sites 7280 and 7281 in 2 variants, and a deletion (TTTAT) was found between 7429 and 7433 in 1 variant. The most common non-synonymous substitution V77A in the E7 was observed in the sequences encoding the α-helix. 63G in the E7 was determined to be the only one positively selected site in the HPV-58 E6/E7 sequences. Six non-synonymous amino acid substitutions (including S71F and K93 N in the E6, and T20I, G41R, G63S/D, and V77A in the E7) were affecting multiple putative epitopes for both CD4⁺ and CD8⁺ T-cells. In the LCR, C7265G and C7266T were the most variable sites and were the potential binding sites for the transcription factor SOX10.

Conclusion

These results provide an insight into the intrinsic geographical relatedness and biological differences of the HPV-58 variants, and contribute to further research on the HPV-58 epidemiology, carcinogenesis, and therapeutic vaccine development.

Electronic supplementary material

The online version of this article (10.1186/s12985-018-0986-7) contains supplementary material, which is available to authorized users.

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.

Production of Polyclonal Antibody to the HPV58 E7 Protein and Its Detection in Cervical Cancer

The persistent infection of high-risk human papillomavirus (HPV) is one of the most common causes of cervical cancer worldwide, and HPV type 58 is the third most common HPV type in eastern Asia. The E7 oncoprotein is constitutively expressed in HPV58-associated cervical cancer cells and plays a key role during tumorigenesis. To study the biological function of HPV58 E7 and to characterize E7 protein-host cell interactions, we cloned the human HPV58 E7 gene and produced specific E7 antibodies. The HPV58 E7 gene was cloned into a prokaryotic expression vector, pGEX-4T2. The recombinant plasmid pGEX-4T2-(HPV58-E7) was transformed into Escherichia coli DH5α and expressed as a fusion protein containing a GST tag. After purification and removal of the GST affinity tag, the E7 protein was used as an antigen for the production of antiserum in rabbits. The specificity of the purified HPV58 E7 antibody was detected by western blotting, immunofluorescence and immunohistochemistry analysis. These methods demonstrated that the polyclonal antibody could specifically recognize the endogenous and the recombinant HPV58 E7 proteins. Immunohistochemistry analysis indicated that the E7 protein was localized in the nucleus of cervical cancer cells.

Genetic variability in E6, E7, and L1 genes of human papillomavirus genotype 52 from Southwest China

Human papillomavirus (HPV) is the major causative agent of cervical cancer, which accounts for the second highest cancer burden in women worldwide. HPV-52, the prevalent subtype in Asia, especially in southwest China, was analyzed in this study. To analyze polymorphisms, intratypic variants, and genetic variability in the E6-E7 (n=26) and L1 (n=53) genes of HPV-52, these genes were sequenced and the sequences were submitted to GenBank. Phylogenetic trees were constructed using the neighbor-joining and Kimura 2-parameters methods, followed by analysis of the diversity of secondary structure. Finally, we estimated the selection pressures acting on the E6-E7 and L1 genes. Fifty-one novel variants of HPV-52 L1, and two novel variants of HPV-52 E6-E7 were identified in this study. Thirty single nucleotide changes were observed in HPV-52 E6-E7 sequences with 19/30 non-synonymous mutations and 11/30 synonymous mutations (five in the alpha helix and five in the beta sheet). Fifty-five single nucleotide changes were observed in HPV-52 L1 sequences with 17/55 non-synonymous mutations (seven in the alpha helix and fourteen in the beta sheet) and 38/55 synonymous mutations. Selective pressure analysis predicted that most of these mutations reflect positive selection. Identifying new variants in HPV-52 may inform the rational design of new vaccines specifically for women in southwest China. Knowledge of genetic variation in HPV may be useful as an epidemiologic correlate of cervical cancer risk, or may even provide critical information for developing diagnostic probes.

Geographical distribution and risk association of human papillomavirus genotype 52-variant lineages

Human papillomavirus (HPV) genotype 52 is commonly found in Asian cases of cervical cancer but is rare elsewhere. Analysis of 611 isolates collected worldwide revealed a remarkable geographical distribution, with lineage B predominating in Asia (89.0% vs 0%-5.5%; P(corrected) < .001), whereas lineage A predominated in Africa, the Americas, and Europe. We propose that the name "Asian lineage" be used to denote lineage B, to signify this feature. Preliminary analysis suggested a higher disease risk for lineage B, although ethnogeographical confounders could not be excluded. Further studies are warranted to verify whether the reported high attribution of disease to HPV52 in Asia is due to the high prevalence of lineage B.

Genetic variability of HPV-58 E6 and E7 genes in Southwest China

HPV accounts for most of incidence of cervical cancer. Genetic variations of E6 and E7 may be associated with the development of cervical cancer in specific geographic regions. HPV-58 has been found to be a relatively prevalent high-risk HPV among southwest Chinese women. To explore gene intratypic variations and polymorphisms of HPV-58 E6 and E7 genes originating in Southwest China, a total of 2000 scraped cell samples were collected for DNA extraction and HPV typing. Then, the E6 and E7 genes of HPV-58 (n=22) were sequenced and compared to others submitted to GenBank, followed by an analysis of the diversity of secondary structure by DNASTAR software. Phylogenetic trees were then constructed by Neighbor-Joining and the Kimura 2-parameters methods, followed by an analysis of selection pressures acting on the E6/E7 genes by PAML software. 22 were HPV-58 positive among 215 high-risk types' samples. The nucleotide variation rate of E6 was 86.36% (19/22) among the 22 HPV-58 E6 sequences studied. 4 single nucleotide changes were identified among the E6 sequences with 3/4 synonymous mutations (C187T, A260C, C307T) and 1/4 non-synonymous mutations (A388C, from Lys to Asn, in alpha helix). The most common mutations of E6 genes are the C307T and A388C. 8 single nucleotide changes were identified among the HPV-58 E7 sequences with 2/8 synonymous mutations (T726C, T744G) and 6/8 non-synonymous mutations (G599A, C632T, G694A, G760A, G761A, T803C). The nucleotide variation rate of E7 was 72.73% (17/22). The most common mutations of E7 genes are C632T, G694A, T744G, G760A (from Gly to Ser, in turn), G761A and T803C. The phylogenetic analyses demonstrate that all HPV-58 E6/E7 variants identified belonged to the Southeast Asia lineage. There was no evidence of positive selection in the sequence alignment of HPV-58 E6 and E7 genes.

E6 and E7 variants of human papillomavirus-16 and -52 in Japan, the Philippines, and Vietnam

Human papillomavirus (HPV) has several intragenotypic variants with different geographical and ethnic distributions. This study aimed to elucidate the distribution patterns of E6 and E7 (E6/E7) intragenotypic variants of HPV type 16 (HPV-16), which is most common worldwide, and HPV-52, which is common in Asian countries such as Japan, the Philippines, and Vietnam. In previous studies, genomic DNA samples extracted from cervical swabs were collected from female sex workers in these three countries and found to be positive for HPV-16 or HPV-52. Samples were amplified further for their E6/E7 genes using type-specific primers and analyzed genetically. Seventy-nine HPV-16 E6/E7 genes were analyzed successfully and grouped into three lineages: European (Prototype), European (Asian), and African-2. The prevalences of HPV-16 European (Prototype)/European (Asian) lineages were 19.4%/80.6% (n = 31) in Japan, 75.0%/20.8% (n = 24) in the Philippines, and 0%/95.8% (n = 24) in Vietnam. The 109 HPV-52 E6/E7 genes analyzed successfully were grouped into four lineages, A-D; the prevalences of lineages A/B/C/D were, respectively, 5.1%/92.3%/0%/2.6% in Japan (n = 39), 34.4%/62.5%/0%/3.1% in the Philippines (n = 32), and 15.8%/73.7%/7.9%/2.6% in Vietnam (n = 38). The distribution patterns of HPV-16 and HPV-52 lineages in these countries differed significantly (P < 0.000001 and P = 0.0048, respectively). There was no significant relationship between abnormal cervical cytology and either HPV-16 E6/E7 lineages or specific amino acid mutations, such as E6 D25E, E6 L83V, and E7 N29S. Analysis of HPV-16 and HPV-52 E6/E7 genes can be a useful molecular-epidemiological tool to distinguish geographical diffusion routes of these HPV types in Asia.

Genetic variability in L1 and L2 genes of HPV-16 and HPV-58 in Southwest China

HPV account for most of the incidence of cervical cancer. Approximately 90% of anal cancers and a smaller subset (<50%) of other cancers (oropharyngeal, penile, vaginal, vulvar) are also attributed to HPV. The L1 protein comprising HPV vaccine formulations elicits high-titre neutralizing antibodies and confers type restricted protection. The L2 protein is a promising candidate for a broadly protective HPV vaccine. In our previous study, we found the most prevalent high-risk HPV infectious serotypes were HPV-16 and HPV-58 among women of Southwest China. To explore gene polymorphisms and intratypic variations of HPV-16 and HPV-58 L1/L2 genes originating in Southwest China, HPV-16 (L1: n = 31, L2: n = 28) and HPV-58 (L1: n = 21, L2: n = 21) L1/L2 genes were sequenced and compared to others described and submitted to GenBank. Phylogenetic trees were then constructed by Neighbor-Joining and the Kimura 2-parameters methods (MEGA software), followed by an analysis of the diversity of secondary structure. Then selection pressures acting on the L1/L2 genes were estimated by PAML software. Twenty-nine single nucleotide changes were observed in HPV-16 L1 sequences with 16/29 non-synonymous mutations and 13/29 synonymous mutations (six in alpha helix and two in beta turns). Seventeen single nucleotide changes were observed in HPV-16 L2 sequences with 8/17 non-synonymous mutations (one in beta turn) and 9/17 synonymous mutations. Twenty-four single nucleotide changes were observed in HPV-58 L1 sequences with 10/24 non-synonymous mutations and 14/24 synonymous mutations (eight in alpha helix and four in beta turn). Seven single nucleotide changes were observed in HPV-58 L2 sequences with 4/7 non-synonymous mutations and 3/7 synonymous mutations. The result of selective pressure analysis showed that most of these mutations were of positive selection. This study may help understand the intrinsic geographical relatedness and biological differences of HPV-16/HPV-58 and contributes further to research on their infectivity, pathogenicity, and vaccine strategy.

Geographical distribution and oncogenic risk association of human papillomavirus type 58 E6 and E7 sequence variations

Human papillomavirus (HPV) 58 accounts for a notable proportion of cervical cancers in East Asia and parts of Latin America, but it is uncommon elsewhere. The reason for such ethnogeographical predilection is unknown. In our study, nucleotide sequences of E6 and E7 genes of 401 HPV58 isolates collected from 15 countries/cities across four continents were examined. Phylogenetic relationship, geographical distribution and risk association of nucleotide sequence variations were analyzed. We found that the E6 genes of HPV58 variants were more conserved than E7. Thus, E6 is a more appropriate target for type-specific detection, whereas E7 is more appropriate for strain differentiation. The frequency of sequence variation varied geographically. Africa had significantly more isolates with E6-367A (D86E) but significantly less isolates with E6-203G, -245G, -367C (prototype-like) than other regions (p ≤ 0.003). E7-632T, -760A (T20I, G63S) was more frequently found in Asia, and E7-793G (T74A) was more frequent in Africa (p < 0.001). Variants with T20I and G63S substitutions at E7 conferred a significantly higher risk for cervical intraepithelial neoplasia grade III and invasive cervical cancer compared to other HPV58 variants (odds ratio = 4.44, p = 0.007). In conclusion, T20I and/or G63S substitution(s) at E7 of HPV58 is/are associated with a higher risk for cervical neoplasia. These substitutions are more commonly found in Asia and the Americas, which may account for the higher disease attribution of HPV58 in these areas.

Human papillomavirus type 52 polymorphism and high-grade lesions of the uterine cervix

The association between polymorphism of human papillomavirus type 52 (HPV52) and high-grade cervical intraepithelial neoplasia (CIN2,3) was investigated in Canadian women. HPV-52-positive endocervical specimens collected from 216 women selected from a total of 3,614 participants recruited in two case-control and two cohort studies conducted in Canada, were further analyzed by PCR-sequencing of the LCR and E6 gene. Overall, the HPV52 LCR prototype was detected more frequently in Caucasian women (69 of 132, 52.3%, 95% confidence interval (CI): 43.8%-60.6%) than in non-Caucasian women (15 of 48, 31.3%, 95% CI 19.9%-45.4%). In two cohort studies, HPV52 prototype was detected in seven of 15 (46.7%, 95% CI 24.8-69.9) HPV52 persistent infections and 14 of 35 (40.0%, 95% CI 25.5-56.5) transient infections (p = 0.76). In two case-control studies, 30 participants did not have CIN, 18 had low-grade CIN (CIN1), 64 had CIN2,3, seven had cervical cancer and the diagnosis was undefined for 27 women. Variant MTL-52-LCR-02 was detected more frequently in women with cancer (28.6%, 95% CI 7.6%-64.8%) than in women without cancer or CIN2,3 (0%, 95% CI 0.0%-9.2%; p = 0.015). CIN2,3 risk was significantly associated with a deletion at nucleotide position 7695 in the LCR (OR 4.9, 95% CI 1.2-20.8), the T7744C variation in the LCR (OR 5.7, 95% CI 1.1-32.0), and the K93R variation in E6 (OR 6.9, 95% CI 1.3-36.8), after adjusting for age, detection of HPV16 or 18 and study site. These findings indicate that HPV52 polymorphism influences risk of CIN-2,3 and possibly invasive cancer.

Genomic polymorphism of human papillomavirus type 52 in women from Northeast China

Human papillomavirus (HPV) 52 is an oncogenic HPV type prevalent in Asia. The aim of the study was to analyze HPV 52 genetic variations in women from Northeast China. To explore the intratypic variants of HPV 52, the genomic regions of L1, E6, E7 and long control region (LCR) of HPV 52, which have been identified in women from Northeast China by HPV GenoArray test, were analyzed. Twenty-five mutations were identified in the regions examined. Of the mutations found in the L1 gene, three novel nonsynonymous mutations of C5640T, A5641T and G5642A were located within the region that encodes the binding domain of neutralizing antibodies against HPV 52. Although four variations were identified in HPV 52 E6 and E7 genes, no significant association was found between the mutations and the cytological lesion of the patients. Eight mutations, including a novel CTT7681−7683 deletion, found in the LCR of HPV 52 encompassed the known transcription binding sites, which may possibly affect the transcription of the oncogenic genes of E6 and E7. The most prevalent HPV 52 variant in women from northeastern China belongs to clade L1-LN-A. The genetic variations of HPV 52, including three novel nonsynonymous mutations of C5640T, A5641T and G5642A in the L1 gene and a novel CTT7681−7683 deletion in the LCR, were first documented in strains from women in Northeast China. The statistical result showed no associations between the variants and the severities of the infected women. These findings provide new data regarding gene variations of HPV 52.

Genotyping of 11 human papillomaviruses by multiplex PCR with a GeXP analyzer

A new, rapid, and high-throughput method was developed for simultaneous detection of 11 human papillomavirus (HPV) genotypes including nine high-risk types (HPV16, 18, 31, 33, 35, 39, 52, 58, and 66) and two low-risk types (HPV6 and 11) in a single tube by multiplex PCR based on a GenomeLab Gene Expression Profiler (GeXP) analyzer (GeXP-PCR). Eleven sets of chimeric primers were used to initiate the PCR, and one pair of universal primers was used for the subsequent cycles of the PCR. The specificity of GeXP-PCR for each HPV type was examined with clinical samples of single type HPV infection tested previously. The sensitivity of GeXP-PCR was evaluated by performing the assay on serial 10-fold dilutions of cloned PCR products. The GeXP-PCR achieved a sensitivity of 100 copies when all of the 11 pre-mixed plasmids containing HPV targets were present. Analyses of 124 clinical specimens using the GeXP-PCR demonstrated that the GeXP-PCR assay had comparable sensitivity and specificity to those of reported multiple PCR assay and an increased detection of HPV 11 in samples with mixed infections. In conclusion, the GeXP-PCR is a fast, sensitive, and high throughput method for the detection of multiple HPV infections.

Visual detection of high-risk human papillomavirus genotypes 16, 18, 45, 52, and 58 by loop-mediated isothermal amplification with hydroxynaphthol blue dye

A simple, rapid, sensitive, qualitative, colorimetric loop-mediated isothermal amplification (LAMP) with hydroxynaphthol blue dye (HNB) was established to detect high-risk human papillomavirus (HPV) genotypes 16, 18, 45, 52, and 58. All initial validation studies with the control DNA proved to be type specific. The colorimetric type-specific LAMP assay could achieve a sensitivity of 10 to 100 copies at 63°C for 65 min, comparable to that of real-time PCR. In order to evaluate the reliability of HPV type-specific LAMP, the assay was further evaluated with HPV DNAs from a panel of 294 clinical specimens whose HPV status was previously determined with a novel one-step typing method with multiplex PCR. The tested panel comprised 108 HPV DNA-negative samples and 186 HPV-DNA-positive samples of 14 genotypes. The results showed that the sensitivity of HPV type-specific LAMP for HPV types 16, 18, 45, 52, and 58 was 100%, 100%, 100%, 100%, and 100%, respectively, and the specificity was 100%, 98.5%, 100%, 98.8%, and 99.2%, respectively, compared with a novel one-step typing method with multiplex PCR. No cross-reactivity with other HPV genotypes was observed. In conclusion, this qualitative and colorimetric LAMP assay has potential usefulness for the rapid screening of HPV genotype 16, 18, 45, 52, and 58 infections, especially in resource-limited hospitals or rural clinics of provincial and municipal regions in China.