E4 antibodies facilitate detection and type-assignment of active HPV infection in cervical disease

Prophylactic HPV vaccines in patients with HPV-associated diseases and cancer

Individuals with human papillomavirus (HPV)-related disease remain at risk for subsequent HPV infection and related disease after treatment of specific lesions. Prophylactic HPV vaccines have shown benefits in preventing subsequent HPV-related disease when administered before or soon after treatment. Based on our understanding of the HPV life cycle and vaccine mechanism of action, prophylactic HPV vaccination is not expected to clear active persistent HPV infection or unresected HPV-associated dysplastic tissue remaining after surgery. However, vaccination may reasonably be expected to prevent new HPV infections caused by a different HPV type as well as re-infection with the same HPV type, whether from a new exposure to an infected partner or through autoinoculation from an adjacent or distant productively infected site. In this review, we describe the evidence for using prophylactic HPV vaccines in patients with HPV-associated disease before, during, or after treatment and discuss potential mechanisms by which individuals with HPV-associated disease may or may not benefit from prophylactic vaccines. We also consider how precise terminology relating to the use of prophylactic vaccines in this population is critical to avoid the incorrect implication that prophylactic vaccines have direct therapeutic potential, which would be counter to the vaccine's mechanism of action, as well as considered off-label. In other words, the observed effects occur through the known mechanism of action of prophylactic HPV vaccines, namely by preventing virus of the same or a different HPV type from infecting the patient after the procedure.

Usefulness of high-risk HPV early oncoprotein (E6 and E7) serological markers in the detection of cervical cancer: A systematic review and meta-analysis

We reviewed the literature on the importance of selected anti-high-risk human papillomavirus (HR-HPV) antibodies (namely, 16/18 and early oncoproteins E6 and E7) as potential serological markers for early detection of individuals at high risk of cervical cancer. We searched for studies in PubMed and Embase databases published from 2010 to 2020 on antibodies against HR-HPV E6 and E7 early proteins and cervical cancer. Pooled sensitivity and specificity for HPV16 and HPV18 antibodies were calculated using a bivariate hierarchical random-effects model. A total of 69 articles were identified; we included three studies with 1550 participants. For the three HPV16/18 E6 and E7 antibody tests, enzyme-linked immunosorbent assay-based assays had a sensitivity of 18% for detecting CIN2+ (95% confidence interval [CI]: 15-21) and a specificity of 96% (95% CI: 92-98), for slot-blot, sensitivity was 28.9% (95% CI: 23.3-35.1) and specificity was 72% (95% CI: 66.6-77.0) for detecting CIN2+, and for multiplex HPV serology assay based on a glutathione S-transferase, sensitivity was 16% (95% CI: 8.45-28.6) and specificity was 98% (95% CI: 97-99) for detecting invasive cervical cancer. HR-HPV16/18 E6 and E7 serological markers showed high specificity, but sensitivity was suboptimal for the detection of cervical cancer in either population screening settings or as point-of-care screening tests.

FAM19A4/miR124-2 Methylation Testing and Human Papillomavirus (HPV) 16/18 Genotyping in HPV-Positive Women Under the Age of 30 Years

BACKGROUND

High-grade squamous intraepithelial lesions (HSIL) or cervical intraepithelial neoplasia (CIN) grade 2/3 lesions in human papillomavirus (HPV)-positive women <30 years of age have high spontaneous regression rates. To reduce overtreatment, biomarkers are needed to delineate advanced CIN lesions that require treatment. We analyzed the FAM19A4/miR124-2 methylation test and HPV16/18 genotyping in HPV-positive women aged <30 years, aiming to identify CIN2/3 lesions in need of treatment.

METHODS

A European multicenter retrospective study was designed evaluating the FAM19A4/miR124-2 methylation test and HPV16/18 genotyping in cervical scrapes of 1061 HPV-positive women aged 15-29 years (690 ≤CIN1, 166 CIN2, and 205 CIN3+). A subset of 62 CIN2 and 103 CIN3 were immunohistochemically characterized by HPV E4 expression, a marker for a productive HPV infection, and p16ink4a and Ki-67, markers indicative for a transforming infection. CIN2/3 lesions with low HPV E4 expression and high p16ink4a/Ki-67 expression were considered as nonproductive, transforming CIN, compatible with advanced CIN2/3 lesions in need of treatment.

RESULTS

FAM19A4/miR124-2 methylation positivity increased significantly with CIN grade and age groups (<25, 25-29, and ≥30 years), while HPV16/18 positivity was comparable across age groups. FAM19A4/miR124-2 methylation positivity was HPV type independent. Methylation-positive CIN2/3 lesions had higher p16ink4a/Ki-67-immunoscores (P = .003) and expressed less HPV E4 (P = .033) compared with methylation-negative CIN2/3 lesions. These differences in HPV E4 and p16ink4a/Ki-67 expression were not found between HPV16/18-positive and non-16/18 HPV-positive lesions.

CONCLUSIONS

Compared with HPV16/18 genotyping, the FAM19A4/miR124-2 methylation test detects nonproductive, transforming CIN2/3 lesions with high specificity in women aged <30 years, providing clinicians supportive information about the need for treatment of CIN2/3 in young HPV-positive women.

Characterisation of anal intraepithelial neoplasia and anal cancer in HIV-positive men by immunohistochemical markers p16, Ki-67, HPV-E4 and DNA methylation markers

Human papillomavirus (HPV)-induced anal intraepithelial neoplasia (AIN, graded 1-3) is highly prevalent in HIV-positive (HIV+) men who have sex with men (MSM), but only a minority of lesions progresses to cancer. Our study aimed to characterise comprehensively anal tissue samples from a cross-sectional series (n = 104) of HIV+ MSM and longitudinal series (n = 40) of AIN2/3 progressing to cancer using different biomarkers. The cross-sectional series consisted of 8 normal, 26 AIN1, 45 AIN2, 15 AIN3 and 10 anal squamous cell carcinoma. Tissue sections were immunohistochemically (IHC) stained for p16 (viral transformation marker), Ki-67 (cellular proliferation marker) and HPV-E4 (viral production marker). We evaluated the expression of IHC markers and compared it with DNA methylation, a marker for malignant transformation. E4 positivity decreased, whereas p16 and Ki-67 scores and methylation marker positivity increased (P values < .001) with increasing severity of anal lesions. Within AIN2, a heterogeneous biomarker pattern was observed concerning E4, p16 and methylation status, reflecting the biological heterogeneity of these lesions. In the longitudinal series, all AIN2/3 and carcinomas showed high p16 and Ki-67 expression, strong methylation positivity and occasional E4 positivity. We earlier showed that high methylation levels are associated with progression to cancer. The observed E4 expression in some AIN2/3 during the course of progression to cancer and absence of E4 in a considerable number of AIN1 lesions make the potential clinical significance of E4 expression difficult to interpret. Our data show that IHC biomarkers can help to characterise AIN; however, their prognostic value for cancer risk stratification, next to objective methylation analysis, appears to be limited.

Classification of high-grade cervical intraepithelial neoplasia by p16ink4a , Ki-67, HPV E4 and FAM19A4/miR124-2 methylation status demonstrates considerable heterogeneity with potential consequences for management

High‐grade cervical intraepithelial neoplasia (CIN2 and CIN3) represents a heterogeneous disease with varying cancer progression risks. Biomarkers indicative for a productive human papillomavirus (HPV) infection (HPV E4) and a transforming HPV infection (p16^ink4a, Ki‐67 and host‐cell DNA methylation) could provide guidance for clinical management in women with high‐grade CIN. This study evaluates the cumulative score of immunohistochemical expression of p16^ink4a (Scores 0‐3) and Ki‐67 (Scores 0‐3), referred to as the “immunoscore” (IS), in 262 CIN2 and 235 CIN3 lesions derived from five European cohorts in relation to immunohistochemical HPV E4 expression and FAM19A4/miR124‐2 methylation in the corresponding cervical scrape. The immunoscore classification resulted in 30 lesions within IS group 0‐2 (6.0%), 151 lesions within IS group 3‐4 (30.4%) and 316 lesions within IS group 5‐6 (63.6%). E4 expression decreased significantly from CIN2 to CIN3 (P < .001) and with increasing immunoscore group (P_trend < .001). Methylation positivity increased significantly from CIN2 to CIN3 (P < .001) and with increasing immunoscore group (P_trend < .001). E4 expression was present in 9.8% of CIN3 (23/235) and in 12.0% of IS group 5‐6 (38/316). Notably, in a minority (43/497, 8.7%) of high‐grade lesions, characteristics of both transforming HPV infection (DNA hypermethylation) and productive HPV infection (E4 expression) were found simultaneously. Next, we stratified all high‐grade CIN lesions, based on the presumed cancer progression risk of the biomarkers used, into biomarker profiles. These biomarker profiles, including immunoscore and methylation status, could help the clinician in the decision for immediate treatment or a “wait and see” policy to reduce overtreatment of high‐grade CIN lesions.

What's new?

Treating all high‐grade cervical intraepithelial neoplasia (CIN2/3) with excisional therapy leads to overtreatment, as these lesions have varying cancer progression risks. Here, the authors evaluated expression patterns of p16^ink4a, Ki‐67 and the HPV E4 protein, and methylation of FAM19A4/miR124‐2 in high‐grade CIN. The biomarker expression patterns revealed the high degree of heterogeneity among CIN2/3 lesions. Biomarker profiles based on the presumed cancer progression risks were established and could guide clinicians in choosing whether to treat immediately or wait and see.

Immunodiagnosis and Immunotherapeutics Based on Human Papillomavirus for HPV-Induced Cancers

Infection with human papillomavirus (HPV) is one of the main causes of malignant neoplasms, especially cervical, anogenital, and oropharyngeal cancers. Although we have developed preventive vaccines that can protect from HPV infection, there are still many new cases of HPV-related cancers worldwide. Early diagnosis and therapy are therefore important for the treatment of these diseases. As HPVs are the major contributors to these cancers, it is reasonable to develop reagents, kits, or devices to detect and eliminate HPVs for early diagnosis and therapeutics. Immunological methods are precise strategies that are promising for the accurate detection and blockade of HPVs. During the last decades, the mechanism of how HPVs induce neoplasms has been extensively elucidated, and several oncogenic HPV early proteins, including E5, E6, and E7, have been shown to be positively related to the oncogenesis and malignancy of HPV-induced cancers. These oncoproteins are promising biomarkers for diagnosis and as targets for the therapeutics of HPV-related cancers. Importantly, many specific monoclonal antibodies (mAbs), or newly designed antibody mimics, as well as new immunological kits, devices, and reagents have been developed for both the immunodiagnosis and immunotherapeutics of HPV-induced cancers. In the current review, we summarize the research progress in the immunodiagnosis and immunotherapeutics based on HPV for HPV-induced cancers. In particular, we depict the most promising serological methods for the detection of HPV infection and several therapeutical immunotherapeutics based on HPV, using immunological tools, including native mAbs, radio-labelled mAbs, affitoxins (affibody-linked toxins), intracellular single-chain antibodies (scFvs), nanobodies, therapeutical vaccines, and T-cell-based therapies. Our review aims to provide new clues for researchers to develop novel strategies and methods for the diagnosis and treatment of HPV-induced tumors.

Dynamics of papillomavirus in vivo disease formation & susceptibility to high-level disinfection-Implications for transmission in clinical settings

BACKGROUND

High-level disinfection protects tens-of-millions of patients from the transmission of viruses on reusable medical devices. The efficacy of high-level disinfectants for preventing human papillomavirus (HPV) transmission has been called into question by recent publications, which if true, would have significant public health implications.

METHODS

Evaluation of the clinical relevance of these published findings required the development of novel methods to quantify and compare: (i) Infectious titres of lab-produced, clinically-sourced, and animal-derived papillomaviruses, (ii) The papillomavirus dose responses in the newly developed in vitro and in vivo models, and the kinetics of in vivo disease formation, and (iii) The efficacy of high-level disinfectants in inactivating papillomaviruses in these systems.

FINDINGS

Clinical virus titres obtained from cervical lesions were comparable to those obtained from tissue (raft-culture) and in vivo models. A mouse tail infection model showed a clear dose-response for disease formation, that papillomaviruses remain stable and infective on fomite surfaces for at least 8 weeks without squames and up to a year with squames, and that there is a 10-fold drop in virus titre with transfer from a fomite surface to a new infection site. Disinfectants such as ortho-phthalaldehyde and hydrogen peroxide, but not ethanol, were highly effective at inactivating multiple HPV types in vitro and in vivo.

INTERPRETATION

Together with comparable results presented in a companion manuscript from an independent laboratory, this work demonstrates that high-level disinfectants inactivate HPV and highlights the need for standardized and well-controlled methods to assess HPV transmission and disinfection.

FUNDING

Advanced Sterilization Products, UK-MRC (MR/S024409/1 and MC-PC-13050) and Addenbrookes Charitable Trust.

Cervical cancer risk profiling: molecular biomarkers predicting the outcome of hrHPV infection

INTRODUCTION

Cervical cancer affects half a million women worldwide annually. Given the association between high-risk human papillomavirus (hrHPV) infection and carcinogenesis, hrHPV DNA testing became an essential diagnostic tool. However, hrHPV alone does not cause the disease, and, most importantly, many cervical lesions regress to normal in a year because of the host immune system. Hence, the low specificity of hrHPV DNA tests and their inability to predict the outcome of infections have triggered a further search for biomarkers.

AREAS COVERED

We evaluated the latest viral and cellular biomarkers validated for clinical use as primary screening or triage for cervical cancer and assessed their promise for prevention as well as potential use in the future. The literature search focused on effective biomarkers for different stages of the disease, aiming to determine their significance in predicting the outcome of hrHPV infections.

EXPERT OPINION

Biomarkers such as p16/Ki-67, hrHPV genotyping, hrHPV transcriptional status, and methylation patterns have demonstrated promising results. Their eventual implementation in the screening programs may support the prompt diagnosis of hrHPV infection and its progression to cancer. These biomarkers will help in making clinical management decisions on time, thus, saving the lives of hrHPV-infected women, particularly in developing countries.

Differential expression of human papillomavirus 16-, 18-, 52-, and 58-derived transcripts in cervical intraepithelial neoplasia

Background

Human papillomavirus (HPV) infection is a primary cause of cervical cancer. Although epidemiologic study revealed that carcinogenic risk differs according to HPV genotypes, the expression patterns of HPV-derived transcripts and their dependence on HPV genotypes have not yet been fully elucidated.

Methods

In this study, 382 patients with abnormal cervical cytology were enrolled to assess the associations between HPV-derived transcripts and cervical intraepithelial neoplasia (CIN) grades and/or HPV genotypes. Specifically, four HPV-derived transcripts, namely, oncogenes E6 and E6*, E1^E4, and viral capsid protein L1 in four major HPV genotypes—HPV 16, 18, 52, and 58—were investigated.

Results

The detection rate of E6/E6* increased with CIN progression, whereas there was no significant change in the detection rate of E1^E4 or L1 among CIN grades. In addition, we found that L1 gene expression was HPV type-dependent. Almost all HPV 52-positive specimens, approximately 50% of HPV 58-positive specimens, around 33% of HPV 16-positive specimens, and only one HPV18-positive specimen expressed L1.

Conclusions

We demonstrated that HPV-derived transcripts are HPV genotype-dependent. Especially, expression patterns of L1 gene expression might reflect HPV genotype-dependent patterns of carcinogenesis.

Human papillomavirus type 16 causes a defined subset of conjunctival in situ squamous cell carcinomas

Squamous cell carcinoma of the conjunctiva is associated with a number of risk factors, including HIV infection, iatrogenic immunosuppression and atopy. In addition, several studies have suggested an involvement of HPV, based on the presence of viral DNA, but did not establish whether there was active infection or evidence of causal disease association. In this manuscript, 31 cases of conjunctival in situ squamous cell carcinoma were classified as HPV DNA-positive or -negative, before being analysed by immunohistochemistry to establish the distribution of viral and cellular biomarkers of HPV gene expression. Our panel included p16INK4a, TP53 and MCM, but also the virally encoded E4 gene product, which is abundantly expressed during productive infection. Subsequent in situ detection of HPV mRNA using an RNAscope approach confirmed that early HPV gene expression was occurring in the majority of cases of HPV DNA-positive conjunctival in situ squamous cell carcinoma, with all of these cases occurring in the atopic group. Viral gene expression correlated with TP53 loss, p16INK4a elevation, and extensive MCM expression, in line with our general understanding of E6 and E7's role during transforming infection at other epithelial sites. A characteristic E4 expression pattern was detected in only one case. HPV mRNA was not detected in lower grades of dysplasia, and was not observed in cases that were HPV DNA-negative. Our study demonstrates an active involvement of HPV in the development of a subset of conjunctival in situ squamous cell carcinoma. No high-risk HPV types were detected other than HPV16. It appears that the conjunctiva is a vulnerable epithelial site for HPV-associated transformation. These cancers are defined by their pattern of viral gene expression, and by the distribution of surrogate markers of HPV infection.

Cervical cancer stem cells and other leading factors associated with cervical cancer development

Cervical cancer (CC) is one of the leading causes of cancer-associated mortalities in women from developing countries. Similar to other types of cancer, CC is considered to be a multifactorial disease, involving socioeconomic, cultural, immunological and epigenetic factors, as well as persistent human papilloma virus (HPV) infection. It has been well established that cancer stem cells (CSCs) play an important role in defining tumor size, the speed of development and the level of regression following treatment; therefore, CSCs are associated with a poor prognosis. CSCs have been detected in many types of cancer, including leukemia, pancreatic, colon, esophagus, liver, prostate, breast, gastric and lung cancer. In cervical cancer, CSCs have been associated with resistance to normally used drugs such as cisplatin. The present review summarizes the strategies that high-risk HPV viruses (HPV-16 and HPV-18) have developed to transform normal epithelial cells into cancer cells, as well as the cellular pathways and studies associated with the identification of cervical cancer stem cell biomarkers. In this sense, the present review provides state of the art information regarding CC development.

Roles for E1-independent replication and E6-mediated p53 degradation during low-risk and high-risk human papillomavirus genome maintenance

Human papillomaviruses (HPV) have genotype-specific disease associations, with high-risk alpha types causing at least 5% of all human cancers. Despite these conspicuous differences, our data show that high- and low- risk HPV types use similar approaches for genome maintenance and persistence. During the maintenance phase, viral episomes and the host cell genome are replicated synchronously, and for both the high- and low-risk HPV types, the E1 viral helicase is non-essential. During virus genome amplification, replication switches from an E1-independent to an E1-dependent mode, which can uncouple viral DNA replication from that of the host cell. It appears that the viral E2 protein, but not E6 and E7, is required for the synchronous maintenance-replication of both the high and the low-risk HPV types. Interestingly, the ability of the high-risk E6 protein to mediate the proteosomal degradation of p53 and to inhibit keratinocyte differentiation, was also seen with low-risk HPV E6, but in this case was regulated by cell density and the level of viral gene expression. This allows low-risk E6 to support genome amplification, while limiting the extent of E6-mediated cell proliferation during synchronous genome maintenance. Both high and low-risk E7s could facilitate cell cycle re-entry in differentiating cells and support E1-dependent replication. Despite the well-established differences in the viral pathogenesis and cancer risk, it appears that low- and high-risk HPV types use fundamentally similar molecular strategies to maintain their genomes, albeit with important differences in their regulatory control. Our results provide new insights into the regulation of high and low-risk HPV genome replication and persistence in the epithelial basal and parabasal cells layers. Understanding the minimum requirement for viral genome persistence will facilitate the development of therapeutic strategies for clearance.

Human papillomaviruses' proteins with clinical utility

Cervical cancer, the fourth leading cause of cancer-associated deaths among women worldwide, is associated with human papilloma virus (HPV) infection. Despite the prophylactic HPV vaccination and the implementation of cervical and HPV-based screening programs, a significant increase in cervical cancer incidence is estimated by the year 2020. Thus, further development of diagnostic tools that allow detection and risk assesment in genital HPV infection is necessary. A special interest is focused on the HPV viral proteins whose expression might be of use either as primary screening tool or in conjunction with other markers (cellular proteins, HPV DNA, PAP test).

HPV E4 expression and DNA hypermethylation of CADM1, MAL, and miR124-2 genes in cervical cancer and precursor lesions

In this study, we evaluate the expression of human papillomavirus E4 protein (marker for the onset of a productive infection) and hypermethylation of host-cell CADM1, MAL, and miR124-2 genes (marker for an advanced, transforming infection) in cervical intraepithelial neoplasia (CIN) and cancer. A total of 115 cervical lesions were categorized by 3 pathologists into no dysplasia, CIN1, CIN2, CIN3, or cancer by classical histomorphological grading criteria, and by an immunoscore (cumulative value: 0-6) grading system based on Ki-67 (score: 0-3) and p16^ink4a (score: 0-3) expression. Lesions were immunostained for E4 protein and analyzed for hypermethylation of CADM1, MAL, or miR124-2 genes. Expression of E4 and hypermethylation levels were related to CIN grade based on both classical and immunoscore grading. Hypermethylation increased with severity of the lesion as defined by both classical histomorphological grading and immunoscore criteria, and was always present in carcinomas (22/22). Extensive E4 expression decreased with increasing CIN grade and immunoscore, being most frequent in classically graded CIN1 or in lesions with cumulative immunoscore 1-3 and absent in carcinomas. High-grade lesions (CIN2/3 or immunoscore: 4-6) showed less E4 expression, which was inversely related to an increasing hypermethylation. Extensive E4 expression, as observed in a small proportion of high-grade lesions (6/49 and 8/43, respectively), was mostly associated with a negative methylation marker status (5/6 and 7/8, respectively). Our results illustrate the gradual transition of productive CIN (reflected by extensive E4 expression), to advanced transforming CIN (reflected by extensive hypermethylation) and cancer. Expression patterns of E4 and hypermethylation status of host-cell genes, may be used to identify cervical lesions at risk for cervical cancer, providing a better guidance for clinicians on treatment decisions.

Risk stratification of cervical disease using detection of human papillomavirus (HPV) E4 protein and cellular MCM protein in clinical liquid based cytology samples

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Cytospinning is a viable method for preparing LBC cells for antibody staining.

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We assessed the performance of a dual biomarker (one viral: HPVE4, one cellular: MCM2) in risk stratification of cervical disease.

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MCM2 was significantly associated with CIN2+ (p = 0.03). HPVE4 was associated with CIN1/normal (p = 0.06).

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The dual biomarker approach may be useful to risk stratify cervical disease especially in resource-poor settings.

Background

While human papillomavirus (HPV) DNA testing offers high sensitivity for the detection of significant cervical disease, its specificity is suboptimal given the high prevalence of transient HPV infections (CIN1 or less). Biomarkers to identify those suffering from low grade disease from those with high grade disease could save healthcare costs and reduce patient anxiety.

Objective

The objective of the present work was to develop and test an immunohistochemistry (IHC)-based dual viral and cellular biomarker strategy which was applicable to liquid based cytology (LBC) samples.

Study design

We developed a novel IHC assay for detection of HPV E4 and cellular minichromosome maintenance (MCM) proteins in routinely taken cervical LBC samples using cytospin-prepared slides. The assay was applied to a prospective cohort of Scottish women referred to a colposcopy clinic due to preceding cytological abnormalities. The performance of the biomarkers for detection of clinically insignificant (CIN1 or less) versus significant disease was determined.

Results

A total of 81 women were recruited representing 64 cases of <=CIN1 and 28 of CIN2 + . Biomarker performance relative to histopathology outcomes showed high levels of MCM detection was significantly associated with CIN2+ (p = 0.03) while E4 was detected more frequently in <=CIN1 (p = 0.06).

Conclusions

Combined detection of a host proliferation marker and a marker of viral gene expression could allow triage of cases of clinically insignificant disease prior to colposcopy. However, there was overlap between distributions of MCM levels in CIN2+ and <=CIN1 suggesting that additional biomarkers would be required for improved specificity. Combined with cytospin-prepared slides this approach could provide a means of risk stratification of disease in low resource settings.

Mutations in HPV18 E1^E4 Impact Virus Capsid Assembly, Infectivity Competence, and Maturation

The most highly expressed protein during the productive phase of the human papillomavirus (HPV) life cycle is E1^E4. Its full role during infection remains to be established. HPV E1^E4 is expressed during both the early and late stages of the virus life cycle and contributes to viral genome amplification. In an attempt to further outline the functions of E1^E4, and determine whether it plays a role in viral capsid assembly and viral infectivity, we examined wild-type E1^E4 as well as four E1^E4 truncation mutants. Our study revealed that HPV18 genomes containing the shortest truncated form of E1^E4, the 17/18 mutant, produced viral titers that were similar to wild-type virus and significantly higher compared to virions containing the three longer E1^E4 mutants. Additionally, the infectivity of virus containing the shortest E1^E4 mutation was equivalent to wild-type and significantly higher than the other three mutants. In contrast, infectivity was completely abrogated for virus containing the longer E1^E4 mutants, regardless of virion maturity. Taken together, our results indicate for the first time that HPV18 E1^E4 impacts capsid assembly and viral infectivity as well as virus maturation.

Serum Immune Profiling for Early Detection of Cervical Disease

Background: The most recent (2012) worldwide estimates from International Agency for Research on Cancer indicate that approximately 528,000 new cases and 270,000 deaths per year are attributed to cervical cancer worldwide. The disease is preventable with HPV vaccination and with early detection and treatment of pre-invasive cervical intraepithelial neoplasia, CIN. Antibodies (Abs) to HPV proteins are under investigation as potential biomarkers for early detection.

Methods: To detect circulating HPV-specific IgG Abs, we developed programmable protein arrays (NAPPA) that display the proteomes of two low-risk HPV types (HPV6 and 11) and ten oncogenic high-risk HPV types (HPV16, 18, 31, 33, 35, 39, 45, 51, 52 and 58). Arrays were probed with sera from women with CIN 0/I (n=78), CIN II/III (n=84), or invasive cervical cancer (ICC, n=83).

Results: Abs to any early (E) HPV protein were detected less frequently in women with CIN 0/I (23.7%) than women with CIN II/III (39.0%) and ICC (46.1%, p<0.04). Of the E Abs, anti-E7 Abs were the most frequently detected (6.6%, 19.5%, and 30.3%, respectively). The least frequently detected Abs were E1 and E2-Abs in CIN 0/I (1.3%) and E1-Abs in CIN II/III (1.2%) and ICC (7.9%). HPV16-specific Abs correlated with HPV16 DNA detected in the cervix in 0% of CIN 0/I, 21.2% of CIN II/III, and 45.5% of ICC. A significant number (29 - 73%) of E4, E7, L1, and L2 Abs had cross-reactivity between HPV types.

Conclusion: HPV protein arrays provide a valuable high-throughput tool for measuring the breadth, specificity, and heterogeneity of the serologic response to HPV in cervical disease.

Human Papillomavirus and Its Testing Assays, Cervical Cancer Screening, and Vaccination

Human papillomavirus (HPV) was found to be the causative agent for cervical cancer in the 1980s with almost 100% of cervical cancer cases testing positive for HPV. Since then, many studies have been conducted to elucidate the molecular basis of HPV, the mechanisms of carcinogenesis of the virus, and the risk factors for HPV infection. Traditionally, the Papanicolaou test was the primary screening method for cervical cancer. Because of the discovery and evolving understanding of the role of HPV in cervical dysplasia, HPV testing has been recommended as a new method for cervical cancer screening by major professional organizations including the American Cancer Society, American Society for Colposcopy and Cervical Pathology, and the American Society for Clinical Pathology. In order to detect HPV infections, many sensitive and specific HPV assays have been developed and used clinically. Different HPV assays with various principles have shown their unique advantages and limitations. In response to a clear causative relationship between high-risk HPV and cervical cancer, HPV vaccines have been developed which utilize virus-like particles to create an antibody response for the prevention of HPV infection. The vaccines have been shown in long-term follow-up studies to be effective for up to 8 years; however, how this may impact screening for vaccinated women remains uncertain. In this chapter, we will review the molecular basis of HPV, its pathogenesis, and the epidemiology of HPV infection and associated cervical cancer, discuss the methods of currently available HPV testing assays as well as recent guidelines for HPV screening, and introduce HPV vaccines as well as their impact on cervical cancer screening and treatments.

HPV16 and 18 genome amplification show different E4-dependence, with 16E4 enhancing E1 nuclear accumulation and replicative efficiency via its cell cycle arrest and kinase activation functions

To clarify E1^E4’s role during high-risk HPV infection, the E4 proteins of HPV16 and 18 were compared side by side using an isogenic keratinocyte differentiation model. While no effect on cell proliferation or viral genome copy number was observed during the early phase of either virus life cycle, time-course experiments showed that viral genome amplification and L1 expression were differently affected upon differentiation, with HPV16 showing a much clearer E4 dependency. Although E4 loss never completely abolished genome amplification, its more obvious contribution in HPV16 focused our efforts on 16E4. As previously suggested, in the context of the virus life cycle, 16E4s G2-arrest capability was found to contribute to both genome amplification success and L1 accumulation. Loss of 16E4 also lead to a reduced maintenance of ERK, JNK and p38MAPK activity throughout the genome amplifying cell layers, with 16E4 (but not 18E4) co-localizing precisely with activated cytoplasmic JNK in both wild type raft tissue, and HPV16-induced patient biopsy tissue. When 16E1 was co-expressed with E4, as occurs during genome amplification in vivo, the E1 replication helicase accumulated preferentially in the nucleus, and in transient replication assays, E4 stimulated viral genome amplification. Interestingly, a 16E1 mutant deficient in its regulatory phosphorylation sites no longer accumulated in the nucleus following E4 co-expression. E4-mediated stabilisation of 16E2 was also apparent, with E2 levels declining in organotypic raft culture when 16E4 was absent. These results suggest that 16E4-mediated enhancement of genome amplification involves its cell cycle inhibition and cellular kinase activation functions, with E4 modifying the activity and function of viral replication proteins including E1. These activities of 16E4, and the different kinase patterns seen here with HPV18, 31 and 45, may reflect natural differences in the biology and tropisms of these viruses, as well as differences in E4 function.

In HPV induced lesions, the most abundant protein expressed in the productive stage of viral life cycle is E1^E4 (E4), with its expression being coincident with viral genome amplification. To clarify the role of E4 in the high-risk HPV life cycle, we carried out a comparative analysis of E4 function in HPV16 and 18 using an isogenic keratinocyte cell-line background. Our results show that E1^E4 contributes to virus genome replication efficiency and life cycle completion rather than being essential. These effects were seen more dramatically with HPV16. The difference between HPV16 and HPV18 in our system suggests important tropism differences between these viruses. HPV16 E4’s contribution to the virus life cycle is mediated by several activities, including its G2 arrest function, as well as its role in activating members of the MAPK pathway, including ERK, p38, and most notably pJNK. These 16 E4 functions facilitated the nuclear localization of the E1 virus helicase and enhanced E1/E2 dependent viral genome amplification as well as stabilising E2. We suspect that the massive accumulation of E4 in the upper epithelial layers may however underlie a more critical role for E4 post-genome amplification.

Potential Role of E4 Protein in Human Papillomavirus Screening: a Review

In 2006, cervical cancer was reported as the second most common cancer in women of Malaysia. This type of cancer has been shown to correlate with persistent high risk human papillomavirus (HPV) infection. Although HPV is well known to induce cervical cancer, knowledge of pathways that link the latent stage of the viral replication cycle to precancerous and cancerous stages remains incomplete. However, it is interesting to note that the virus can be isolated from tissues ranging from normal to low-grade squamous intraepithelial lesions as well as high-grade intraepithelial lesions (HSILs), thus prompting scientists to develop HPV detection methods for screening. Detection of HPV using viral proteins such as L1 and E1 is proposed to be very useful in assisting the management of high risk infection and cervical cancer. These tests however can lead to false positive results, largely due to the exisstence of asymptomatic or transient HPV infections within any given individual. Somes observation indicate that use of HPV proteins such as E6 and E7 might lead to false positive results. However, one particular HPV protein, E4 shows potential as an accurate marker of the tissue state following HPV infection. E4 expression has been shown to correlate with the levels of HPV DNA incorporation by the host. Thus, it is possible that E4 could serve as a useful marker to define stages of viral carcinogenesis.

Functional Roles of E6 and E7 Oncoproteins in HPV-Induced Malignancies at Diverse Anatomical Sites

Approximately 200 human papillomaviruses (HPVs) infect human epithelial cells, of which the alpha and beta types have been the most extensively studied. Alpha HPV types mainly infect mucosal epithelia and a small group of these causes over 600,000 cancers per year worldwide at various anatomical sites, especially anogenital and head-and-neck cancers. Of these the most important is cervical cancer, which is the leading cause of cancer-related death in women in many parts of the world. Beta HPV types infect cutaneous epithelia and may contribute towards the initiation of non-melanoma skin cancers. HPVs encode two oncoproteins, E6 and E7, which are directly responsible for the development of HPV-induced carcinogenesis. They do this cooperatively by targeting diverse cellular pathways involved in the regulation of cell cycle control, of apoptosis and of cell polarity control networks. In this review, the biological consequences of papillomavirus targeting of various cellular substrates at diverse anatomical sites in the development of HPV-induced malignancies are highlighted.

Detection of Papillomavirus Gene Expression Patterns in Tissue Sections

Molecular events during the papillomavirus life cycle can be mapped in infected tissue biopsies using antibodies to viral and cellular gene products, or by in situ hybridization approaches that detect viral DNA or viral transcription products. For proteins, ease of immunodetection depends on antibody specificity and antigen availability. Epitopes in formalin-fixed paraffin-embedded (FFPE) samples are often masked by crosslinking and must be exposed for immunodetection. RNA in FFPE material is often degraded, and such tissue must be handled carefully to optimize detection. Viral proteins and viral genomic DNA are both well preserved in routinely processed FFPE samples, with sensitive detection methodologies allowing the simultaneous detection of multiple markers. The combined visualization of nucleic acid and (viral) protein targets, when coupled with image analysis approaches that allow correlation with standard pathology diagnosis, have allowed us to understand the molecular changes required for normal HPV life-cycle organization as well as deregulation during cancer progression. © 2016 by John Wiley & Sons, Inc.

Validation of Serological Antibody Profiles Against Human Papillomavirus Type 16 Antigens as Markers for Early Detection of Cervical Cancer

Cervical cancer (CC) is the second most frequent neoplasia among women worldwide. Cancer prevention programs around the world have used the Papanicolaou (Pap) smear as the primary diagnostic test to reduce the burden of CC. Nevertheless, such programs have not been effective in developing countries, thus leading to research on alternative tests for CC screening. During the virus life cycle and in the process toward malignancy, different human papillomavirus (HPV) proteins are expressed, and they induce a host humoral immune response that can be used as a potential marker for different stages of the disease. We present a new Slot blot assay to detect serum antibodies against HPV16 E4, E7, and VLPs-L1 antigens. The system was validated with sera from a female population (n = 485) aged 18 to 64 years referred to the dysplasia clinic at the General Hospital in Cuautla, Morelos, Mexico. To evaluate the clinical performance of the serological markers, the sensitivity, specificity, positive, and negative predictive values and receiver-operating characteristic curves (for antibodies alone or in combination) were calculated in groups of lesions of increasing severity. The results showed high prevalence of anti-E4 (73%) and anti-E7 (80%) antibodies in the CC group. Seropositivity to 1, 2, or 3 antigens showed associations of increasing magnitude with CC (odds ratio [OR] = 12.6, 19.9, and 58.5, respectively). The highest association with CC was observed when the analysis was restricted to only anti-E4+E7 antibodies (OR = 187.7). The best clinical performance to discriminate CC from cervical intraepithelial neoplasia 2 to 3 was the one for the combination of anti-E4 and/or anti-E7 antibodies, which displayed high sensitivity (93.3%) and moderate specificity (64.1%), followed by anti-E4 and anti-E7 antibodies (73.3% and 80%; 89.6% and 66%, respectively). In addition, the sensitivity of anti-E4 and/or anti-E7 antibodies is high at any time of sexual activity (TSA), which suggests they can be biomarkers for the early detection of CC. The sensitivity of anti-E4 antibodies was low (<10%) when the TSA was <10 years, and it increased up to 100% in relation to the TSA, suggesting that anti-E4 antibodies can be useful as HPV exposure markers at early stages of the disease.

Investigating Diagnostic Problems of CIN1 and CIN2 Associated With High-risk HPV by Combining the Novel Molecular Biomarker PanHPVE4 With P16INK4a

Grading cervical intraepithelial neoplasia (CIN) determines clinical management of women after abnormal cytology with potential for overdiagnosis and overtreatment. We studied a novel biomarker of human papillomavirus (HPV) life-cycle completion (panHPVE4), in combination with the minichromosome maintenance (MCM) protein cell-cycle marker and the p16INK4a transformation marker, to improve CIN diagnosis and categorization. Scoring these biomarkers alongside CIN grading by 3 pathologists was performed on 114 cervical specimens with high-risk (HR) HPV. Interobserver agreement for histopathology was moderate (κ=0.43 for CIN1/negative, 0.54 for CIN2/≤CIN1, and 0.36 for CIN3). Agreement was good or excellent for biomarker scoring (E4: κ=0.896; 95% confidence interval [CI]: 0.763-0.969; p16INK4a : κ=0.798; 95% CI: 0.712-0.884; MCM: κ=0.894; 95% CI: NC (this quantity cannot be calculated). Biomarker expression was studied by immunofluorescence and immunohistochemistry and was correlated with 104 final CIN diagnoses after histologic review. All 25 histologically negative specimens were p16INK4a and panHPVE4 negative, although 9 were MCM-positive. There were variable extents of p16INK4a positivity in 11/11 CIN1 and extensive panHPVE4 staining in 9/11. Ten CIN2 lesions expressed panHPVE4 and p16INK4a, and 13 CIN2 expressed only p16INK4a. CIN3 showed extensive p16INK4a positivity with no/minimal panHPVE4 staining. PanHPVE4, unlike MCM, distinguished CIN1 from negative. PanHPVE4 with p16INK4a separated CIN2/3 showing only expression of p16INK4a, indicating transforming HR-HPV E7 expression, from CIN1/2 showing completion of HR-HPV life cycle by E4 expression and variable p16INK4a expression. PanHPVE4 and p16INK4a staining are complementary markers that could provide simple, reliable support for diagnosing CIN. Their value in distinguishing CIN1/2 that supports HR-HPV life-cycle completion (and which might ultimately regress) from purely transforming CIN2/3 needing treatment warrants further research.

Humoral Immune Response Against Human Papillomavirus as Source of Biomarkers for the Prediction and Detection of Cervical Cancer

Cervical cancer (CC) is one of the main causes of death among women of reproductive age. Although there are different tests, the disease tends to be diagnosed at late stages. In recent years, the use of complementary tests or sequential diagnostic tests has been implemented. Nevertheless, the results are variable and not conclusive; therefore, more studies for improving the usefulness of these tests in diagnostics are necessary. The human papillomavirus (HPV) infection has been associated with both benign and malignant proliferation of skin and mucosal tissues. Furthermore, some HPV types have been classified as high risk due to their potential to cause cancer, and HPV16 is most frequently associated with this disease. Although between 70% and 80% of precancerous lesions are eliminated by the host's immune system, there is no available test to distinguish between regressive lesions from those that could progress to CC. An HPV infection generates a humoral immune response against L1 and L2 capsid proteins, which can be protective and a response against early proteins. The latter is not a protective response, but these antibodies can be used as markers to determine the stage of the infection and/or the stage of the cervical lesion. Up to now, the humoral immune response resulting from the HPV infection has been used to study the biology of the virus and the efficacy of the HPV vaccines. Although there are no conclusive results regarding the use of these antibodies for diagnosis, we hereby review the actual panorama of the antibody response against the HPV proteins during the development of the disease as well as their possible use as biomarkers for the progression of cervical lesions and of CC.

Stratification of HPV-induced cervical pathology using the virally encoded molecular marker E4 in combination with p16 or MCM

High-risk human papillomavirus (HPV) types cause cervical lesions of varying severity, ranging from transient productive infections to high-grade neoplasia. Disease stratification requires the examination of lesional pathology, and possibly also the detection of biomarkers. P16(INK4a) and MCM are established surrogates of high-risk HPV E6/E7 activity, and can be extensively expressed in high-grade lesions. Here we have combined these two cellular biomarkers with detection of the abundant HPV-encoded E4 protein in order to identify both productive and transforming lesions. This approach has allowed us to distinguish true papillomavirus infections from similar pathologies, and has allowed us to divide the heterogeneous CIN2 category into those that are CIN1-like and express E4, and those that more closely resemble nonproductive CIN3. To achieve this, 530 lesional areas were evaluated according to standard pathology criteria and by using a multiple staining approach that allows us to superimpose biomarker patterns either singly or in combination onto an annotated hematoxylin and eosin (H&E) image. Conventional grading of neoplasia was established by review panel, and compared directly with the composite molecular pathology visualized on the same tissue section. The detection of E4 coincided with the onset of vacuolation, becoming abundant in koilocytes as the MCM marker declined and cells lost their defined nuclear margins as visualized by standard H&E staining. Of the dual marker approaches, p16(INK4a) and E4 appeared most promising, with E4 generally identifying areas of low-grade disease even when p16(INK4a) was present. Extensive p16(INK4a) expression usually coincided with an absence of E4 expression or its focal retention in sporadic cells within the lesion. Our results suggest that a straightforward molecular evaluation of HPV life-cycle deregulation in cervical neoplasia may help improve disease stratification, and that this can be achieved using complementary molecular biomarker pairs such as MCM/E4 or, more promisingly, p16(INK4a)/E4 as an adjunct to conventional pathology.

Improved detection reveals active β-papillomavirus infection in skin lesions from kidney transplant recipients

The aim of this study was to determine whether detection of β-HPV gene products, as defined in epidermodysplasia verruciformis skin cancer, could also be observed in lesions from kidney transplant recipients alongside the viral DNA. A total of 111 samples, corresponding to 79 skin lesions abscised from 17 kidney transplant recipients, have been analyzed. The initial PCR analysis demonstrated that β-HPV-DNA was highly present in our tumor series (85%). Using a combination of antibodies raised against the E4 and L1 proteins of the β-genotypes, we were able to visualize productive infection in 4 out of 19 actinic keratoses, and in the pathological borders of 1 out of 14 squamous cell carcinomas and 1 out of 31 basal cell carcinomas. Increased expression of the cellular proliferation marker minichromosome maintenance protein 7 (MCM7), that extended into the upper epithelial layers, was a common feature of all the E4-positive areas, indicating that cells were driven into the cell cycle in areas of productive viral infections. Although the present study does not directly demonstrate a causal role of these viruses, the detection of E4 and L1 positivity in actinic keratosis and the adjacent pathological epithelium of skin cancer, clearly shows that β-HPV are actively replicating in the intraepidermal precursor lesions of kidney transplant recipients and can therefore cooperate with other carcinogenic agents, such as UVB, favoring skin cancer promotion.

The E4 protein; structure, function and patterns of expression

The papillomavirus E4 open reading frame (ORF) is contained within the E2 ORF, with the primary E4 gene-product (E1^E4) being translated from a spliced mRNA that includes the E1 initiation codon and adjacent sequences. E4 is located centrally within the E2 gene, in a region that encodes the E2 protein's flexible hinge domain. Although a number of minor E4 transcripts have been reported, it is the product of the abundant E1^E4 mRNA that has been most extensively analysed. During the papillomavirus life cycle, the E1^E4 gene products generally become detectable at the onset of vegetative viral genome amplification as the late stages of infection begin. E4 contributes to genome amplification success and virus synthesis, with its high level of expression suggesting additional roles in virus release and/or transmission. In general, E4 is easily visualised in biopsy material by immunostaining, and can be detected in lesions caused by diverse papillomavirus types, including those of dogs, rabbits and cattle as well as humans. The E4 protein can serve as a biomarker of active virus infection, and in the case of high-risk human types also disease severity. In some cutaneous lesions, E4 can be expressed at higher levels than the virion coat proteins, and can account for as much as 30% of total lesional protein content. The E4 proteins of the Beta, Gamma and Mu HPV types assemble into distinctive cytoplasmic, and sometimes nuclear, inclusion granules. In general, the E4 proteins are expressed before L2 and L1, with their structure and function being modified, first by kinases as the infected cell progresses through the S and G2 cell cycle phases, but also by proteases as the cell exits the cell cycle and undergoes true terminal differentiation. The kinases that regulate E4 also affect other viral proteins simultaneously, and include protein kinase A, Cyclin-dependent kinase, members of the MAP Kinase family and protein kinase C. For HPV16 E1^E4, these kinases regulate one of the E1^E4 proteins main functions, the association with the cellular keratin network, and eventually also its cleavage by the protease calpain which allows assembly into amyloid-like fibres and reorganisation of the keratin network. Although the E4 proteins of different HPV types appear divergent at the level of their primary amino acid sequence, they share a recognisable modular organisation and pattern of expression, which may underlie conserved functions and regulation. Assembly into higher-order multimers and suppression of cell proliferation are common to all E4 proteins examined. Although not yet formally demonstrated, a role in virus release and transmission remains a likely function for E4.