HPV18 L1 and long control region sequences variation and E6/E7 differential expression in nasopharyngeal and cervical cancers: a comparative study

BACKGROUND

The role of high-risk human papillomaviruses (hr-HPVs) in cervical cancer (CC) pathogenesis has long been established. Knowledge about the involvement of hr-HPVs in the etiology of nasopharyngeal cancers (NPC) was not well appreciated until the early 2000s when a clear link began to emerge. However, it is not clear whether HPV oncogenesis in the different epithelial cancers is associated with L1 gene and long-control region (LCR) sequences variation. This study aimed to investigate the HPV18 L1 gene and LCR sequences variation in cervical and nasopharyngeal biopsies, and assessed E6 and E7 genes expression level in both cancers.

METHOD

Four-hundred and three (403) formalin-fixed paraffin-embedded tissues originating from nasopharyngeal (NPC) (279) and cervical (CC) (124) sites were collected from a pathology laboratory, Pathologist Without Borders, Accra, Ghana. Haematoxylin and eosin staining was carried out to confirm the presence of cancer on prepared biopsy sections. DNA was extracted from the confirmed cancer biopsies, followed by PCR using MY09/GP5+ /6+ primers to detect the presence of HPV and specific primers for the amplification of L1 gene and LCR. Sanger sequencing was carried out to determine HPV genotypes, and L1 and LCR sequences variant of HPV18s in CC and NPC biopsies. The HPV18 E6/E7 mRNA expression pattern in both cancers was determined using RT-qPCR.

RESULTS

Most of the NPC (45%) and CC (55%) biopsies were HPV18 positive. Comparison of HPV18 L1 sequences obtained from cervical and nasopharyngeal cancer tissues, the L1 sequences from the NPC were highly dissimilar with a 59-100% variation among themselves, and in relation to the reference strains. However, the L1 sequences from the CC were more similar with a 91.0-100% variation among the amplified sequences. Also, the LCR sequences from CC were quite different relative to that of NPC. Results for the differential expression of E6/E7 in the two cancers showed a higher fold change in E6 expression in the CC tissues than the NPC tissues while a reverse expression pattern was found for E7 gene.

CONCLUSION

The current study reports for the first-time variations in HPV18 L1 and LCR sequences, and differential expression of E6/E7 genes in NPC compared to CC, suggesting a possible adaptation mechanism of the virus at different cancer sites.

Genetic diversity and bioinformatic analysis in the L1 gene of HPV genotypes 31, 33, and 58 circulating in women with normal cervical cytology

BACKGROUND

HPV-31, -33, and -58, along with HPV-45 and -52, account for almost 11% of HPV-associated cancers. Our previous studies showed that after HPV-16 and -51, HPV-58 was common and HPV-31 was as frequent as HPV-18 among Iranian women with normal cytology. Hence, in this study, we aimed to investigate the intra-type variations in L1 genes of HPV-58, -31, and -33 to find the predominant lineages circulating in women with normal cytology.

METHODS

Complete coding sequencing of the L1 gene was amplified and nucleotide and amino acid sequences were compared to those of the references. The selective pressure on L1 protein and whether the variations of the L1 genes embed in L1 loops, or N-glycosylated sites were also investigated.

RESULTS

B1, A, and A1 (sub)lineages were common in the HPV-58, -33, and -31 samples, respectively. Ninety nucleotide mutations were observed. Twenty nine nucleotide changes corresponded to nonsynonymous substitutions in which seventeen mutations were located in L1 loops. Only one codon position in HPV-58 sequences was found as the positive selection. No difference was observed in N-glycosylation sites between reference and understudied amino acid sequences.

CONCLUSION

In the current study, we reported, for the first time, the (sub) lineages, amino acid, and genetic diversity in the L1 gene of circulating HPV-58, -33, and -31, in women with normal cytology, in Iran. Such studies can not only have epidemiological values, but also aid to set vaccination programs.

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.

Inducible expression of human papillomavirus-16 L1 capsomeres in the plastomes of Nicotiana tabacum: Transplastomic plants develop normal flowers and pollen

Human papillomavirus type-16 (HPV-16) is the major HPV type involved in causing cervical cancer among women. The disease burden is high in developing and underdeveloped countries. Previously, the constitutive expression of HPV-16 L1 protein led to male sterility in transplastomic tobacco plants. Here, the HPV-16 L1 gene was expressed in chloroplasts of Nicotiana tabacum under the control of an ethanol-inducible promoter, trans-activated by nucleus-derived signal peptide. Plants containing nuclear component were transformed with transformation vector pEXP-T7-L1 by biolistic gun. The transformation and homoplasmic status of transformed plants was verified by polymerase chain reaction and Southern blotting, respectively. Protein was induced by spraying 5% ethanol for 7 consecutive days. The correct folding of L1 protein was confirmed by antigen-capture ELISA using a conformation-specific antibody. The L1 protein accumulated up to 3 μg/g of fresh plant material. The L1 protein was further purified using affinity chromatography. All transplastomic plants developed normal flowers and produced viable seeds upon self-pollination. Pollens also showed completely normal structure under light microscope and scanning electron microscopy. These data confirm the use of the inducible expression as plant-safe approach for expressing transgenes in plants, especially those genes that cause detrimental effects on plant growth and morphology.

Genetic diversity in L1 ORF of human papillomavirus in women with cervical cancer with and without human immunodeficiency virus in Botswana and Kenya

BACKGROUND

The variation of human papillomavirus (HPV) genotypes shapes the risks of cervical cancer and these variations are not well defined in Africa. Nucleotide changes within the L1 gene, nucleotide variability, and phylogeny were explored in relation to HIV in samples from Botswana and Kenya.

METHODS

A total of 98 HPV-positive cervical samples were sequenced to identify different HPV variants. Phylogenetic inferences were used to determine HPV genotypes and investigate the clustering of sequences between women living with HIV (WLWHIV) and -women not living with HIV (WNLWHIV).

RESULTS

Out of 98 generated sequences, 83.7% (82/98) participants had high-risk (HR) HPV genotypes while 16.3% (16/98) had low-risk (LR) HPV genotypes. Among participants with HR-HPV genotypes, 47.6% (39/82) were coinfected with HIV. The prevalence of HR-HPV genotypes was statistically higher in the Botswana population compared to Kenya (p-value < 0.001). Multiple amino acid mutations were identified in both countries. Genetic diversity differed considerably among WLWHIV and WNLWHIV. The mean pairwise distances between HPV-16 between HIV and HIV/HPV as well as for HPV-18 were statistically significant. Six (6) new deleterious mutations were identified in the HPV genotypes based on the sequencing of the L1 region, HPV-16 (L441P, S343P), HPV-18 (S424P), HPV-45 (Q366H, Y365F), and HPV-84 (F458L). The majority of the patients with these mutations were co-infected with HIV.

CONCLUSIONS

Genomic diversity and different genomic variants of HPV sequences were demonstrated. Candidate novel mutations within the L1 gene were identified in both countries which can be further investigated using functional assays.

Worldwide genetic variations in high-risk human papillomaviruses capsid L1 gene and their impact on vaccine efficiency

BACKGROUND

Human papillomavirus is the most common sexually transmitted infection. It is associated with different cancers, mainly cervical cancer, which remains the fourth most frequent cancer among women worldwide; it is also related to anogenital (anus, vulvar, vagina, and penis) and oropharyngeal cancers. Vaccination against HPV infection is the major way of prevention, and it has demonstrated impressive efficacy in reducing cervical cancer incidence. Nowadays, all the licensed HPV recombinant vaccines were designed based on HPV major capsid L1 protein. However, some variations in the HPV L1 gene sequence may induce structural changes within the L1 protein, which may alter the affinity and interaction of monoclonal antibodies (MAbs) with L1 protein epitopes, and influence host immune response and recognition. Hence, the importance of accuracy in delineating epitopes relevant to vaccine design and defining genetic variations within antigenic regions in the L1 gene to predict its impact on prophylactic vaccine efficiency. The present review reports the sequence variations in HR-HPV L1 gene isolates from different countries around the world, which may help to understand the effect of HPV L1 gene variations on vaccine efficiency.

METHODS

Research studies were retrieved from PubMed, Google Scholar, Science direct, and the National Center for Biotechnology Information (NCBI) database. A total of 31 articles describing genetic variations within the major capsid L1 gene and conducted in Africa, Europe, America and Asia were found. Only 26 studies conducted on HPV16, 18, 31, 33, 58, 45 and 52 which are the targets of HPV prophylactic vaccines, and which reported genetic variations within the L1 gene, were selected and evaluated in this review.

FINDINGS

We found a total of 87, 49, 11, 7, 22, 3, and 17 non-synonymous single nucleotide polymorphisms (SNPs) within HPV16, HPV18, HPV31, HPV58, HPV45, and HPV52 L1 gene, respectively. Four mutations were frequently observed in HPV16 L1 sequences: T353P in the HI loop, H228D in the EF loop, T266A in the FG loop, and T292A in the FG loop. Two mutations in HPV58 L1 sequences: T375N in the HI loop and L150F in the DE loop. Three mutations in HPV33 L1 sequences: T56N in the BC loop, G133S in the DE loop, T266K in the FG loop. Other mutations were found in HPV18, HPV45, and HPV52 L1 sequences. Some were found in different countries, and others were specific to a given population. Furthermore, some variations were located on peptide binding epitopes and lead to a modification of epitopes, which may influence MAbs interactions. Others need further investigations due to the lack of studies.

CONCLUSION

This study investigated the major capsid L1 genetic diversity of HPV16, 18, 31, 33, 58, 45, and 52 circulating in different populations around the world. Further investigations should be conducted to confirm their effect on immunogenicity and prophylactic vaccine efficiency.

HPV16 L1 diversity and its potential impact on the vaccination-induced immunity

Human Papillomavirus 16 (HPV16) is the most oncogenic HPV and the most associated genotype with cervical cancer development and progression. Currently, all developed vaccines are targeting HPV16 and were designed based on the major L1 capsid protein. Thus, evaluation of the diversity of HPV16 L1 sequence, mainly in the antigenic regions, will be of a great interest to assess the efficacy of the prophylactic vaccines and to predict the impact of genetic variations in these regions on the vaccination-induced immunity. A total of 377 HPV16 L1 sequences, published in public domain GenBank database, from the Americas, Africa, Asia, and Europe were collected and assembled. A total of 626 mutation events affecting 83 distinct nucleotides into the five antigenic regions of L1 gene of HPV16 were reported, and most SNPs were located in DE (27.38%, 23/83) and FG (31%, 26/83) loops. Overall, 4 mutations were frequently found in HPV16 sequences: T176N and N181T in EF loop; A266T in the FG loop and T353P/I/N HI loop. Of particular interest, some SNPs are ubiquitous and were found in all populations whereas others were population specific and their presence was limited to one or 2 at the maximum. Association between mutations in the antigenic regions and ethnicity was also investigated and showed that mutations in BC and DE loops were present with no significant difference in sequences from Europe, Asia, America and Africa. However, most mutations in FG loop are reported in sequences from European cases and are less pronounced in cases from America and Asia, whereas mutations EF and HI loops prevail in Asian cases. These data highlight a high number of variant amino acid residues that could affect the vaccination-induced immunity and impact the effectiveness of the prophylactic vaccination to fight against HPV, warranting the need of further investigation for vaccines and natural history studies of HPV16.

Genetic characterization of a putative new type of bovine papillomavirus in the Xipapillomavirus 1 species in a Brazilian dairy herd

Currently, bovine papillomavirus types are divided into five genera, namely, Deltapapillomavirus, Epsilonpapillomavirus, Xipapillomavirus, Dyoxipapillomavirus, and Dyokappapapillomavirus. In the recent decades, the characterization of numerous putative and novel bovine papillomavirus types from cattle in several geographic regions, has revealed the occurrence of a high viral diversity. In this study, we describe the identification and characterization of a putative new bovine papillomavirus type within species Xipapillomavirus 1 of Xipapillomavirus genus. The detection of the viral types identified in the skin warts was obtained by polymerase chain reaction assays targeting the L1 gene, followed by direct sequencing of the generated amplicons. The partial L1 sequences revealed that bovine papillomavirus types 6, 10, and 11, the putative new bovine papillomavirus type designated BPV/CHI-SW2, and an unreported putative new bovine papillomavirus type (named BPV/BR-UEL08) were associated with cutaneous papillomatosis in the cows from the dairy herd investigated. Phylogenetic reconstruction based on the L1 gene revealed that the BPV/BR-UEL08 isolate clustered with other bovine papillomaviruses classified in the Xipapillomavirus genus, being closely related to representatives of the species Xipapillomavirus 1. Investigations focusing on the molecular epidemiology of bovine papillomaviruses related to clinical outcomes in cattle are of fundamental importance to determine the actual genetic diversity and prevalent viral types to be included in vaccines for cattle.

Genetic variability of human papillomavirus type 66 L1 gene among women presenting for cervical cancer screening in Chile

The high-risk human papillomaviruses (HR-HPVs) are involved in the development of cervical cancer. Nevertheless, there are differences in the oncogenic potential among them. HPV-16 and HPV-18 are associated with approximately 70% of cancer worldwide, and both types are the most extensively studied HR-HPV. Great variations in the prevalence of HR-HPV have been described in different countries. The impact of these variations on the epidemiology of lesions and cervical cancer is currently unknown. A high prevalence of HPV-66 has been detected in Chile. Here, we have analyzed the genetic variability of the L1 gene from HPV-66-infected Chilean women. Higher order interactions between identified mutations were analyzed by co-variation and cluster analyses. Antigenic-index alterations following L1 mutations and B-cell epitopes were predicted by BcePred algorithm. HPV-66 L1 sequences clustered phylogenetically into two main clades. The genetic variability in the HPV-66 L1 gene involved thirty nucleotide changes. Four of these were for the first time identified in this study. Some of these variants are embedded in the B-cell epitope regions. Amino acid homology in the immunodominant epitopes of HPV-66 L1 protein (DE, FG and H1 loops) was 42.9-59.1% and 28.6-68.9% compared with HPV-16 and HPV-18, respectively. The results of this research suggest that the neutralizing epitopes of HPV-66 are antigenically different compared to HPV-16 and HPV-18. Our findings show the need to perform new structural and immunological studies on HPV-66 L1 protein to evaluate the cross-protection conferred by current HPV vaccines.

Methylation of the L1 gene and integration of human papillomavirus 16 and 18 in cervical carcinoma and premalignant lesions

High-risk human papillomavirus (HPV) is the primary cause of cervical carcinoma (CC). Viral integration into the host chromosomes is associated with neoplastic progression, and epigenetic changes may occur as a result. The objective of the present study was to analyze HPV L1 gene methylation and to compare the use of quantitative polymerase chain reaction (qPCR), in situ hybridization (ISH) and L1 methylation analysis as methods for detecting HPV integration. Cervical scrapes or biopsy samples positive for HPV 16 or 18, from 187 female patients with CC, squamous intraepithelial lesions (SILs) or no intraepithelial lesion (non-IL) were analyzed. Methylation of the L1 gene was determined using bisulfite modification followed by PCR, and HPV integration was subsequently analyzed. HPV 16 L1 gene methylation was revealed to increase with histological grade, with statistically significant differences observed as follows: Low-grade SIL vs. CC, P<0.0001 and non-IL vs. CC, P<0.0001. HPV 18 L1 gene methylation also increased according to histological grade, however, no statistically significant differences were observed. Methylation at CpG site 5608 of the HPV 16 L1 gene was associated with all grades of cervical lesions, whereas methylation at CpG site 5617 demonstrated the strongest association with CC (odds ratio, 42.5; 95% confidence interval, 4.7-1861; P<0.0001). The concordance rates between the various methods for the detection of the physical status of HPV 16 and HPV 18 were 96.1% for qPCR and ISH, 76.7% for qPCR and L1 gene methylation, and 84.8% for ISH and L1 gene methylation. In conclusion, methylation of the HPV 16 L1 gene increases significantly according to the grade of the cervical lesion, and methylation at CpG sites 5608 and 5617 of this gene may be used as prognostic biomarkers. ISH and L1 gene methylation have good concordance with qPCR with regards to the detection of HPV integration. Therefore, these are useful methods in determining the physical state of HPV.

Quantitative methylation analysis of human papillomavirus 16L1 gene reveals potential biomarker for cervical cancer progression

Human papillomavirus 16 is the most prevalent type found in cervical cancer worldwide, accounting for >50% of all cases. Quantitative methylation analysis of human papillomavirus 16L1 gene within 5' (CpGs 5600, 5606, 5609, 5615) and 3' (7136 and 7145) regions to determine potential biomarker for cervical cancer progression was performed in exfoliated cervical cells collected from 101 Thai women of precancerous and cancerous lesions. Intermediate to high methylation levels (>20%) were detected in HPV16 5'L1 regions especially CpG 5600 of all cancerous (100%) and 50% of CIN3 samples, whereas normal/CIN1 samples (80%) showed methylation levels <20%. Our results indicate the potential use of HPV 16L1 gene methylation at specific site as a biomarker for prognostic cervical cancer screening, however, suitable cutoff should be further evaluated in a larger sample size.

Genetic variability and lineage phylogeny of human papillomavirus type-16 and -53 based on the E6, E7, and L1 genes in Southwest China

Human papillomaviruses (HPVs) are circular double-stranded DNA viruses that are highly prevalent in the general population, and account for the cervical cancer burden in women worldwide. In this study, we analyzed HPV-16, the most prevalent type worldwide, and HPV-53, a possible high-risk type from infected women in Southwest China. To characterize mutations, intratypic variants, and genetic variability in the E6, E7, and L1 genes of HPV-16 (n=97) and HPV-53 (n=15), these genes were sequenced and submitted to GenBank. Phylogenetic trees were constructed using Bayesian trees, followed by secondary structure analysis and B-cell epitope prediction. Moreover, the selection pressures of the E6, E7, and L1 genes were estimated. In total, 27 novel variants of HPV-16 and 11 novel variants of HPV-53 were identified. In the HPV-16 E6-E7-L1 sequences, 73 nucleotide changes were observed with 40/73 being non-synonymous mutations (two in the alpha helix and five in the beta sheet) and 33/73 being synonymous. In the HPV-53 E6-E7-L1 sequences, 64 nucleotide changes were observed with 26/64 being non-synonymous mutations (three in the alpha helix and one in the beta sheet) and 38/64 being synonymous. Selective pressure analysis showed that most of these mutations did not reflect positive selection. The maximal divergence between any two variants within each gene of these two HPV types ranging from 0.94%(HPV-16 L1 gene)to 2.80%(HPV-53 E6 gene). Identifying new variants of HPV-16 and -53 from women in Southwest China may be helpful to design vaccines specifically for women in Southwest China and testing methods specifically for this region. The results of our study may contribute to future researches in diagnostic probes, vaccines improvement, or screening methods for a particular population.

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.

High-resolution melting analysis of HPV-16L1 gene methylation: A promising method for prognosing cervical cancer

OBJECTIVE

Methylation-sensitive high-resolution melting (MS-HRM) is a new technique for DNA methylation analysis, but it is rarely used for the detection of viral DNA methylation. In this study, we investigated the HPV-16L1 gene methylation that is detected by MS-HRM as a potential biomarker for prognosing cervical dysplasia and cancer.

DESIGN AND METHODS

A total of 114 HPV-16 infected patients (normal (17), CIN1 (25), CIN2 (29), CIN3 (32), SCC (11)) who underwent liquid-based cytology test and biopsy were included in this study. 17 cases with HPV-16 infection and negative cytologic and histologic results served as the control group. The HPV-16L1 gene methylation statuses of these samples were investigated using a methylation-sensitive high-resolution melting (MS-HRM) assay after bisulfite modification.

RESULTS

The HPV-16L1 gene methylation statuses of all the 114 specimens were successfully detected by MS-HRM, and we observed increasing methylation levels in severe lesions, as determined using histologic assays. In addition, the methylation levels of CIN2+ (CIN2, CIN3 and SCC) were significantly higher than that of CIN2- (normal and CIN1, P<0.001). When taking CIN2+ as the reference, our HPV-16L1 DNA methylation assay achieved 91.7% sensitivity and 59.5% specificity, respectively.

CONCLUSIONS

The results of the present work demonstrated that HPV-16L1 gene methylation was closely associated with cervical precancerosis and cancer. Moreover, using MS-HRM to detect HPV-16L1 gene methylation may be a powerful assay for the triage of HPV-16-positive females, which could identify patients with high risk of invasive cancer.

Duplex Real-time PCR assay and SYBR green I melting curve analysis for molecular identification of HPV genotypes 16, 18, 31, 35, 51 and 66

Long-term infection with high-risk HPV genotypes is the leading cause of cervical cancer. In the present study a Duplex Real-time PCR assay was developed in order to identify HPV types 16, 18, 31, 35, 51 and 66 in three reactions, through SYBR green I melting curve analysis. The method utilizes type-specific primer sets that allowed the amplification of highly conserved regions of L1 gene. Reconstitution experiments were conducted by using HPV DNA plasmids in order to determine the sensitivity of the assay. The newly designed assay has a limit of detection of 10 copies per reaction. The most prevalent HPV genotype in single and in multiple HPV infections was HPV16 followed by HPV18, HPV51, HPV31, HPV35 and HPV66. The proposed method is a simple, specific, sensitive and cost-effective assay that can be easily incorporated in small and medium size laboratories for the rapid identification of the most clinically important HPV genotypes.

Phylogenetic position of an uncharacterized Brazilian strain of bovine papillomavirus in the genus Xipapillomavirus based on sequencing of the L1 open reading frame

The use of PCR assays with degenerate primers has suggested the existence of numerous as yet uncharacterized bovine papillomaviruses (BPV). Despite the endemic nature of BPV infections, the identification of BPV types in Brazilian cattle is still only sporadic. However, in a recent analysis of a partial segment of the L1 gene, we observed notable diversity among the BPV types detected. The aim of this study was to determine the phylogenetic position of the previously identified wild strain BPV/BR-UEL2 detected in the state of Paraná in Brazil. Since previous analysis of the partial L1 sequence had shown that this strain was most closely related to BPV type 4, genus-specific primers were designed. Phylogenetic analysis using complete L1 ORF sequences revealed that BPV/BR-UEL2 was related to BPV types classified in the genus Xipapillomavirus and shared the highest L1 nucleotide sequence similarity with BPV type 4 (78%). This finding suggests that BPV/BR-UEL2 should be classified as a potential new type of BPV in the genus Xipapillomavirus.

Comparison between L and E gene amplification analytical methods for human papillomavirus typing

OBJECTIVE

L and E6/E7 gene amplification analyses were compared to identify human papillomavirus (HPV) infection and verify the HPV type, with the intent to minimize HPV typing errors.

METHODS

L1 gene verified HPV typing was accomplished via polymerase chain reaction (PCR) and membrane assays. Verification of HPV typing via E6/E7 genes was accomplished through nested multiplexed PCR. The results from 104 samples were compared.

RESULTS

The rates of accordance and difference were 35% and 65%, respectively. For 29% of the analyses, nested multiplexed PCR was more diversified than the membrane assay.

CONCLUSION

HPV can be classified into low-risk HPV and high-risk HPV groups. In parallel amplifications of the L and E genes is more efficient for accurate diagnosis in light of the different symptoms and attendant precautions of the risk groups.