Meeting report: Considerations for trial design and endpoints in licensing therapeutic HPV16/18 vaccines to prevent cervical cancer.

Cervical cancer is a major cause of morbidity and mortality globally with a disproportionate impact on women in low- and middle-income countries. In 2021, the World Health Organization (WHO) called for increased vaccination, screening, and treatment to eliminate cervical cancer. However, even with widespread rollout of human papillomavirus (HPV) prophylactic vaccines, millions of women who previously acquired HPV infections will remain at risk for progression to cancer for decades to come. The development and licensing of an affordable, accessible therapeutic HPV vaccine, designed to clear or control carcinogenic HPV and/or to induce regression precancer could significantly contribute to the elimination efforts, particularly benefiting those who missed out on the prophylactic vaccine. One barrier to development of such vaccines is clarity around the regulatory pathway for licensure. In Washington, D.C. on September 12-13, 2023, a meeting was convened to provide input and guidance on trial design with associated ethical and regulatory considerations. This report summarizes the discussion and conclusions from the meeting. Expert presentation topics included the current state of research, potential regulatory challenges, WHO preferred product characteristics, modeling results of impact of vaccine implementation, epidemiology and natural history of HPV infection, immune responses related to viral clearance and/or precancer regression including potential biomarkers, and ethical considerations. Panel discussions were held to explore specific trial design recommendations to support the licensure process for two vaccine indications: (1) treatment of prevalent HPV infection or (2) treatment of cervical precancers. Discussion covered inclusion/exclusion criteria, study endpoints, sample size and power, safety, study length, and additional data needed, which are reported here. Further research of HPV natural history is needed to address identified gaps in regulatory guidance, especially for therapeutic vaccines intended to treat existing HPV infections.

Differentiation signals induce APOBEC3A expression via GRHL3 in squamous epithelia and squamous cell carcinoma.

Two APOBEC (apolipoprotein-B mRNA editing enzyme catalytic polypeptide-like) DNA cytosine deaminase enzymes (APOBEC3A and APOBEC3B) generate somatic mutations in cancer, driving tumour development and drug resistance. Here we used single cell RNA sequencing to study APOBEC3A and APOBEC3B expression in healthy and malignant mucosal epithelia, validating key observations with immunohistochemistry, spatial transcriptomics and functional experiments. Whereas APOBEC3B is expressed in keratinocytes entering mitosis, we show that APOBEC3A expression is confined largely to terminally differentiating cells and requires Grainyhead-like transcription factor 3 (GRHL3). Thus, in normal tissue, neither deaminase appears to be expressed at high levels during DNA replication, the cell cycle stage associated with APOBEC-mediated mutagenesis. In contrast, we show that in squamous cell carcinoma tissues, there is expansion of GRHL3 expression and activity to a subset of cells undergoing DNA replication and concomitant extension of APOBEC3A expression to proliferating cells. These findings indicate a mechanism for acquisition of APOBEC3A mutagenic activity in tumours.

Risk factors for human papillomavirus infection and disease: A targeted literature summary.

Adolescents are the primary cohort for routine human papillomavirus (HPV) vaccination, but unvaccinated adults may also benefit. A lack of consensus on which adults to target and the presence of reimbursement barriers likely contribute to the lag in adult vaccinations, highlighting missed prevention opportunities. Understanding factors contributing to risk of HPV infection and disease could help in decision making on vaccination. This review summarizes existing literature on risk factors for HPV infection and disease and includes 153 studies reporting relative risks or odds ratios for factors associated with HPV infection or disease in adults, published between 2009 and 2020. Despite inconsistent design and reporting of risk factors across studies, this review confirmed several risk factors associated with adult infection, including human immunodeficiency virus positivity, number of sex partners, and smoking. These findings can support policymaking, guideline development, and clinical decision making for HPV vaccination and screening of high-risk adult groups.

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.

The human Papillomavirus twilight zone - Latency, immune control and subclinical infection.

The incorporation of HPV DNA testing into cervical screening programs has shown that many HPV-positive women are cytologically normal, with HPV-positivity fluctuating throughout life. Such results suggest that papillomaviruses may persist in a latent state after disease clearance, with sporadic recurrence. It appears that virus latency represents a narrow slot in a wider spectrum of subclinical and possibly productive infections. Clinical studies, and animal model infection studies, suggested a key role for host immune surveillance in maintaining such asymptomatic infections, and although infections may also be cleared, most studies have used the term 'clearance' to describe a situation where the presence of HPV DNA falls below the clinical detection level. Given our knowledge of papillomavirus immune evasion strategies and the restricted pattern of viral gene expression required for 'basal cell' persistence, the term 'apparent clearance' and 'subclinical persistence' of infection may better summarise our understanding. Subclinical infection also encompasses the lag phase, which occurs between infection and lesion development. This is dependent on infection titre, with multifocal infections developing more rapidly to disease. These concepts can usefully influence patient management where HPV-positivity occurs sometime after the onset of sexual activity, and where vertical transmission is suspected despite a lag period.

Mus musculus papillomavirus 1 E8

High-risk human papillomaviruses (PV) account for approximately 600,000 new cancers per year. The early protein E8^E2 is a conserved repressor of PV replication, whereas E4 is a late protein that arrests cells in G2 and collapses keratin filaments to facilitate virion release. While inactivation of the Mus musculus PV1 (MmuPV1) E8 start codon (E8-) increases viral gene expression, surprisingly, it prevents wart formation in FoxN1nu/nu mice. To understand this surprising phenotype, the impact of additional E8^E2 mutations was characterized in tissue culture and mice. MmuPV1 and HPV E8^E2 similarly interact with cellular NCoR/SMRT-HDAC3 co-repressor complexes. Disruption of the splice donor sequence used to generate the E8^E2 transcript or E8^E2 mutants (mt) with impaired binding to NCoR/SMRT-HDAC3 activates MmuPV1 transcription in murine keratinocytes. These MmuPV1 E8^E2 mt genomes also fail to induce warts in mice. The phenotype of E8^E2 mt genomes in undifferentiated cells resembles productive PV replication in differentiated keratinocytes. Consistent with this, E8^E2 mt genomes induced aberrant E4 expression in undifferentiated keratinocytes. In line with observations for HPV, MmuPV1 E4-positive cells displayed a shift to the G2 phase of the cell cycle. In summary, we propose that in order to enable both expansion of infected cells and wart formation in vivo, MmuPV1 E8^E2 inhibits E4 protein expression in the basal keratinocytes that would otherwise undergo E4-mediated cell cycle arrest. IMPORTANCE Human papillomaviruses (PVs) initiate productive replication, which is characterized by genome amplification and expression of E4 protein strictly within suprabasal, differentiated keratinocytes. Mus musculus PV1 mutants that disrupt splicing of the E8^E2 transcript or abolish the interaction of E8^E2 with cellular NCoR/SMRT-HDAC3 co-repressor complexes display increased gene expression in tissue culture but are unable to form warts in vivo. This confirms that the repressor activity of E8^E2 is required for tumor formation and genetically defines a conserved E8 interaction domain. E8^E2 prevents expression of E4 protein in basal-like, undifferentiated keratinocytes and thereby their arrest in G2 phase. Since binding of E8^E2 to NCoR/SMRT-HDAC3 co-repressor is required to enable expansion of infected cells in the basal layer and wart formation in vivo, this interaction represents a novel, conserved, and potentially druggable target.

HPV E6 inhibits E6AP to regulate epithelial homeostasis by modulating keratinocyte differentiation commitment and YAP1 activation.

Human papillomaviruses (HPV) cause persistent infections by modulating epithelial homeostasis in cells of the infected basal layer. Using FUCCI and cell-cell competition assays, we have identifed regulatory roles for E6AP and NHERF1, which are the primary HPV11 E6 cellular targets, as well as being targets of the high-risk E6 proteins, in processes governing epithelial homeostasis (i.e. cell density, cell cycle entry, commitment to differentiation and basal layer delamination). Depletion of E6AP, or expression of HPV11 or 16E6 increased keratinocyte cell density and cell cycle activity, and delayed the onset of differentiation; phenotypes which were conspicuously present in HPV11 and 16 infected patient tissue. In line with proposed E6 functions, in HPV11 condyloma tissue, E6AP and NHERF1 were significantly reduced when compared to uninfected epithelium. In experimental systems, loss of HPV11 E6/E6AP binding abolished 11E6's homeostasis regulatory functions, while loss of E6/NHERF1 binding reduced the cell density threshold at which differentiation was triggered. By contrast, a NHERF1-binding mutant of 16E6 was not compromised in its homeostasis functions, while E6AP appeared essential. RNA sequencing revealed similar transcriptional profiles in both 11 and 16E6-expressing cells and E6AP-/- cells, with YAP target genes induced, and keratinocyte differentiation genes being downregulated. HPV11 E6-mediated Yap activation was observed in 2D and 3D (organotypic raft) cell culture systems and HPV-infected lesions, with both NHERF1, which is a regulator of the Hippo and Wnt pathways, and E6AP, playing an important role. As the conserved binding partner of Alpha group HPV E6 proteins, the precise role of E6AP in modulating keratinocyte phenotype and associated signalling pathways has not previously been defined. Our study suggests a model in which the preserved functions of the low and high-risk Alpha E6 proteins modulate epithelial homeostasis via E6AP activity, and lead to alteration of multiple downstream pathways, including those involving NHERF1 and YAP.

The preference of women living with HIV for the HPV self-sampling of urine at a rural HIV clinic in Uganda.

Background: Women living with HIV have a double risk of acquiring cervical cancer (CC) due to repeated human papilloma virus (HPV) infections resulting from reduced immunity, with CC screening being low at 46.7%. Objectives: To determine the factors associated with the preference for HPV self-sampling using urine as well as establish its feasibility among women living with HIV attending a rural HIV clinic in Uganda. Method: A cross-sectional study design using quantitative data collection methods was used at the HIV clinic, Luweero District Hospital, among 426 women aged between 30 and 65 years. Data were analysed using descriptive statistics and modified Poisson regression. Urine samples were analysed using a Liferiver high-risk HPV genotyping real-time polymerase chain reaction (PCR) kit to determine the prevalence of the 15 HPV subtypes. Cervical intraepithelial neoplasia 2 (CIN2) was determined by visual inspection under acetic acid (VIA) using the nurse-led approach. Results: Most women (296/426, 70%) preferred nurse-led screening. Preference for HPV self-sampling using urine was associated with older age (46-65 years) (adjusted prevalence risk ratios [aPRR] 1.59; 95% confidence interval [CI]: 1.13-2.24), history of sexually transmitted infections (aPRR 0.74: 95% CI: 0.55-0.98) and acquisition of CC information from the television (aPRR 1.48: 95% CI: 1.09-2.02). Approximately 97% (68/70) of women living with HIV tested HPV positive with one or more subtypes. The most prevalent subtype of HPV was HPV 58 (87.1%). Only one woman tested positive with VIA. Conclusion: Nurse-led CC screening is preferred among women living with HIV, and HPV self-sampling using urine is feasible at the HIV clinic. Therefore, educational programmes to reassure the masses about urine HPV self-sampling need to be designed. Contribution: This study's findings provide early insights into the merits and demerits of the current HPV sample collection approaches. Hence, HPV testing should be tailored to routine HIV care in rural communities.

Integrated analysis of cervical squamous cell carcinoma cohorts from three continents reveals conserved subtypes of prognostic significance.

Human papillomavirus (HPV)-associated cervical cancer is a leading cause of cancer deaths in women. Here we present an integrated multi-omic analysis of 643 cervical squamous cell carcinomas (CSCC, the most common histological variant of cervical cancer), representing patient populations from the USA, Europe and Sub-Saharan Africa and identify two CSCC subtypes (C1 and C2) with differing prognosis. C1 and C2 tumours can be driven by either of the two most common HPV types in cervical cancer (16 and 18) and while HPV16 and HPV18 are overrepresented among C1 and C2 tumours respectively, the prognostic difference between groups is not due to HPV type. C2 tumours, which comprise approximately 20% of CSCCs across these cohorts, display distinct genomic alterations, including loss or mutation of the STK11 tumour suppressor gene, increased expression of several immune checkpoint genes and differences in the tumour immune microenvironment that may explain the shorter survival associated with this group. In conclusion, we identify two therapy-relevant CSCC subtypes that share the same defining characteristics across three geographically diverse cohorts.

Cervical cell lift: A novel triage method for the spatial mapping and grading of precancerous cervical lesions.

BACKGROUND: Primary HPV screening, due to its low specificity, requires an additional liquid-based cytology (LBC) triage test. However, even with LBC triage there has been a near doubling in the number of patients referred for colposcopy in recent years, the majority having low-grade disease. METHODS: To counter this, a triage test that generates a spatial map of the cervical surface at a molecular level has been developed which removes the subjectivity associated with LBC by facilitating identification of lesions in their entirety. 50 patients attending colposcopy were recruited to participate in a pilot study to evaluate the test. For each patient, cells were lifted from the cervix onto a membrane (cervical cell lift, CCL) and immunostained with a biomarker of precancerous cells, generating molecular maps of the cervical surface. These maps were analysed to detect high-grade lesions, and the results compared to the final histological diagnosis. FINDINGS: We demonstrated that spatial molecular mapping of the cervix has a sensitivity of 90% (95% CI 69-98) (positive predictive value 81% (95% CI 60-92)) for the detection of high-grade disease, and that AI-based analysis could aid disease detection through automated flagging of biomarker-positive cells. INTERPRETATION: Spatial molecular mapping of the CCL improved the rate of detection of high-grade disease in comparison to LBC, suggesting that this method has the potential to decisively identify patients with clinically relevant disease that requires excisional treatment. FUNDING: CRUK Early Detection Project award, Jordan-Singer BSCCP award, Addenbrooke's Charitable Trust, UK-MRC, Janssen Pharmaceuticals/Advanced Sterilisation Products, and NWO.

Performance of HPV E4 and p16INK4a biomarkers in predicting regression of cervical intraepithelial neoplasia grade 2 (CIN2): protocol for a historical cohort study.

INTRODUCTION: Cervical intraepithelial neoplasia grade 2 (CIN2) represents a spectrum of lesions with variable progression and regression. Pathological diagnosis of CIN2 is subjective and poorly reproducible. Accurate diagnosis and identification of different patterns of CIN2 related to outcome are essential to reduce the risks of overtreatment or undertreatment. It is important to explore novel methods for risk stratification of CIN2 to enable targeted treatment of women at high risk of progression or persistent disease and follow-up of women at low risk. The combination of the novel biomarker human papillomavirus (HPV) E4 with p16INK4a targets steps in the transition from a productive oncogenic HPV infection (CIN1) to a transformed lesion (CIN3) within CIN2. Previous cross-sectional studies suggest that HPV E4 combined with p16INK4a may be valuable for risk assessment of CIN2. However, data on HPV E4/p16INK4a as a predictor for CIN2 regression is lacking. METHODS AND ANALYSIS: We will conduct a historical cohort study including 500 women aged 23-40 years with a first CIN2 diagnosis in Aarhus, Denmark during 2000-2010. Women will be eligible if they have undergone active surveillance and have no previous record of hysterectomy, cone biopsy, and CIN2 or worse. Women will be randomly selected through the Danish Pathology Databank. Tissue samples from women included will be sectioned for p16INK4a and HPV E4 immunohistochemical staining in addition to conventional hematoxylin and eosin (H&E) staining. A positive result will be defined as HPV E4 positive. Through the Danish Pathology Databank, we will collect results on all subsequent cervical biopsies. Regression will be used as the primary outcome. ETHICS AND DISSEMINATION: The study has been approved by the Ethical Committee in Central Denmark Region (1-10-72-60-20) and registered at the Faculty of Health, Aarhus University. Results will be published in a peer-reviewed journal and presented at scientific meetings. TRIAL REGISTRATION NUMBER: NCT05049252.

Evidence of latent HPV infection in older Danish women with a previous history of cervical dysplasia.

INTRODUCTION: Understanding whether human papillomavirus (HPV) may establish latency in the uterine cervix is important. A better understanding of HPV natural history is useful for clinical counseling of women attending screening and to accurately inform health prevention strategies such as screening and HPV vaccination. We evaluated the extent of latent HPV infections in older women with a history of abnormal cytology. MATERIAL AND METHODS: We conducted a cross-sectional study in Aarhus, Denmark, from March 2013 through April 2015. Women were enrolled if they underwent cervical amputation or total hysterectomy because of benign disease. Prior to surgery, women completed a questionnaire and a cervical smear was collected for HPV testing and morphological assessment. For evaluation of latency (i.e., no evidence of active HPV infection, but HPV detected in the tissue), we selected women with a history of abnormal cervical cytology or histology, as these women were considered at increased risk of harboring a latent infection. Cervical tissue underwent extensive HPV testing using the SPF10-DEIA-LipA25 assay. RESULTS: Of 103 women enrolled, 26 were included in this analysis. Median age was 55 years (interquartile range [IQR] 52-65), and most women were postmenopausal and parous. The median number of sexual partners over the lifetime was six (IQR 3-10), and 85% reported no recent new sexual partner. Five women (19.2%) had evidence of active infection at the time of surgery, and 19 underwent latency evaluation. Of these, a latent infection was detected in 11 (57.9%), with HPV16 being the most prevalent type (50%). Nearly 80% (n = 14) of the 18 women with a history of previous low-grade or high-grade cytology with no treatment had an active or latent HPV infection, with latent infections predominating. HPV was detected in two of the six women with a history of high-grade cytology and subsequent excisional treatment, both as latent infections. CONCLUSIONS: HPV can be detected in cervical tissue specimens without any evidence of an active HPV infection, indicative of a latent, immunologically controlled infection. Modeling studies should consider including a latent state in their model when estimating the appropriate age to stop screening and when evaluating the impact of HPV vaccination.

The Reservoir of Persistent Human Papillomavirus Infection; Strategies for Elimination Using Anti-Viral Therapies.

Human Papillomaviruses have co-evolved with their human host, with each of the over 200 known HPV types infecting distinct epithelial niches to cause diverse disease pathologies. Despite the success of prophylactic vaccines in preventing high-risk HPV infection, the development of HPV anti-viral therapies has been hampered by the lack of enzymatic viral functions, and by difficulties in translating the results of in vitro experiments into clinically useful treatment regimes. In this review, we discuss recent advances in anti-HPV drug development, and highlight the importance of understanding persistent HPV infections for future anti-viral design. In the infected epithelial basal layer, HPV genomes are maintained at a very low copy number, with only limited viral gene expression; factors which allow them to hide from the host immune system. However, HPV gene expression confers an elevated proliferative potential, a delayed commitment to differentiation, and preferential persistence of the infected cell in the epithelial basal layer, when compared to their uninfected neighbours. To a large extent, this is driven by the viral E6 protein, which functions in the HPV life cycle as a modulator of epithelial homeostasis. By targeting HPV gene products involved in the maintenance of the viral reservoir, there appears to be new opportunities for the control or elimination of chronic HPV infections.

Role of E6 in Maintaining the Basal Cell Reservoir during Productive Papillomavirus Infection.

Papillomaviruses exclusively infect stratified epithelial tissues and cause chronic infections. To achieve this, infected cells must remain in the epithelial basal layer alongside their uninfected neighbors for years or even decades. To examine how papillomaviruses achieve this, we used the in vivo MmuPV1 (Mus musculus papillomavirus 1) model of lesion formation and persistence. During early lesion formation, an increased cell density in the basal layer, as well as a delay in the infected cells' commitment to differentiation, was apparent in cells expressing MmuPV1 E6/E7 RNA. Using cell culture models, keratinocytes exogenously expressing MmuPV1 E6, but not E7, recapitulated this delay in differentiation postconfluence and also grew to a significantly higher density. Cell competition assays further showed that MmuPV1 E6 expression led to a preferential persistence of the cell in the first layer, with control cells accumulating almost exclusively in the second layer. Interestingly, the disruption of MmuPV1 E6 binding to MAML1 protein abrogated these phenotypes. This suggests that the interaction between MAML1 and E6 is necessary for the lower (basal)-layer persistence of MmuPV1 E6-expressing cells. Our results indicate a role for E6 in lesion establishment by facilitating the persistence of infected cells in the epithelial basal layer, a mechanism that is most likely shared by other papillomavirus types. Interruption of this interaction is predicted to impede persistent papillomavirus infection and consequently provides a novel treatment target. IMPORTANCE Persistent infection with high-risk HPV types can lead to development of HPV-associated cancers, and persistent low-risk HPV infection causes problematic diseases, such as recurrent respiratory papillomatosis. The management and treatment of these conditions pose a considerable economic burden. Maintaining a reservoir of infected cells in the basal layer of the epithelium is critical for the persistence of infection in the host, and our studies using the mouse papillomavirus model suggest that E6 gene expression leads to the preferential persistence of epithelial cells in the lower layers during stratification. The E6 interaction with MAML1, a component of the Notch pathway, is required for this phenotype and is linked to E6 effects on cell density and differentiation. These observations are likely to reflect a common E6 role that is preserved among papillomaviruses and provide us with a novel therapeutic target for the treatment of recalcitrant lesions.

Principles of epithelial homeostasis control during persistent human papillomavirus infection and its deregulation at the cervical transformation zone.

Human papillomaviruses establish a reservoir of infection in the epithelial basal layer. To do this they limit their gene expression to avoid immune detection and modulate epithelial homeostasis pathways to inhibit the timing of basal cell delamination and differentiation to favour persistence. For low-risk Alpha papillomaviruses, which cause benign self-limiting disease in immunocompetent individuals, it appears that cell competition at the lesion edge restricts expansion. These lesions may be considered as self-regulating homeostatic structures, with epithelial cells of the hair follicles and sweat glands, which are proposed targets of the Beta and Mu papillomaviruses, showing similar restrictions to their expansion across the epithelium as a whole. In the absence of immune control, which facilitates deregulated viral gene expression, such lesions can expand, leading to problematic papillomatosis in afflicted individuals. By contrast, he high-risk Alpha HPV types can undergo deregulated viral gene expression in immunocompetent hosts at a number of body sites, including the cervical transformation zone (TZ) where they can drive the formation of neoplasia. Homeostasis at the TZ is poorly understood, but involves two adjacent epithelial cell population, one of which has the potential to stratify and to produce a multilayed squamous epithelium. This process of metaplasia involves a specialised cell type known as the reserve cell, which has for several decades been considered as the cell of origin of cervical cancer. It is becoming clear that during evolution, HPV gene products have acquired functions directly linked to their requirements to modify the normal processes of epithelial homestasis at their various sites of infection. These protein functions are beginning to provide new insight into homeostasis regulation at different body sites, and are likely to be central to our understanding of HPV epithelial tropisms.

Mouse Papillomavirus L1 and L2 Are Dispensable for Viral Infection and Persistence at Both Cutaneous and Mucosal Tissues.

Papillomavirus L1 and L2, the major and minor capsid proteins, play significant roles in viral assembly, entry, and propagation. In the current study, we investigate the impact of L1 and L2 on viral life cycle and tumor growth with a newly established mouse papillomavirus (MmuPV1) infection model. MmuPV1 L1 knockout, L2 knockout, and L1 plus L2 knockout mutant genomes (designated as L1ATGko-4m, L2ATGko, and L1-L2ATGko respectively) were generated. The mutants were examined for their ability to generate lesions in athymic nude mice. Viral activities were examined by qPCR, immunohistochemistry (IHC), in situ hybridization (ISH), and transmission electron microscopy (TEM) analyses. We demonstrated that viral DNA replication and tumor growth occurred at both cutaneous and mucosal sites infected with each of the mutants. Infections involving L1ATGko-4m, L2ATGko, and L1-L2ATGko mutant genomes generally resulted in smaller tumor sizes compared to infection with the wild type. The L1 protein was absent in L1ATGko-4m and L1-L2ATGko mutant-treated tissues, even though viral transcripts and E4 protein expression were robust. Therefore, L1 is not essential for MmuPV1-induced tumor growth, and this finding parallels our previous observations in the rabbit papillomavirus model. Very few viral particles were detected in L2ATGko mutant-infected tissues. Interestingly, the localization of L1 in lesions induced by L2ATGko was primarily cytoplasmic rather than nuclear. The findings support the hypothesis that the L2 gene influences the expression, location, transport, and assembly of the L1 protein in vivo.

Delta-Like Ligand-Notch1 Signaling Is Selectively Modulated by HPV16 E6 to Promote Squamous Cell Proliferation and Correlates with Cervical Cancer Prognosis.

Human papillomavirus (HPV) drives high-grade intraepithelial neoplasia and cancer; for unknown reasons, this occurs most often in the cervical transformation zone. Either mutation or HPV E6-driven inhibition of Notch1 can drive neoplastic development in stratified squamous epithelia. However, the contribution of Notch1 and its Delta-like ligands (DLL) to site susceptibility remains poorly understood. Here, we map DLL1/DLL4 expression in cell populations present in normal cervical biopsies by immunofluorescence. In vitro keratinocyte 2D monolayer models, growth assays, and organotypic raft cultures were used to assess the functional role of DLL-Notch signaling in uninfected cells and its modulation by HPV16 in neoplasia. An RNA sequencing-based gene signature was used to suggest the cell of origin of 279 HPV-positive cervical carcinomas from The Cancer Genome Atlas and to relate this to disease prognosis. Finally, the prognostic impact of DLL4 expression was investigated in three independent cervical cancer patient cohorts. Three molecular cervical carcinoma subtypes were identified, with reserve cell tumors the most common and linked to relatively good prognosis. Reserve cells were characterized as DLL1-/DLL4+, a proliferative phenotype that is temporarily observed during squamous metaplasia and wound healing but appears to be sustained by HPV16 E6 in raft models of low-grade and, more prominently, high-grade neoplasia. High expression of DLL4 was associated with an increased likelihood of cervical cancer-associated death and recurrence. Taken together, DLL4-Notch1 signaling reflects a proliferative cellular state transiently present during physiologic processes but inherent to cervical reserve cells, making them strongly resemble neoplastic tissue even before HPV infection has occurred. SIGNIFICANCE: This study investigates cervical cancer cell-of-origin populations and describes a DLL-Notch1 phenotype that is associated with disease prognosis and that might help identify cells that are susceptible to HPV-induced carcinogenesis.

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.

Summary from an international cancer seminar focused on human papillomavirus (HPV)-positive oropharynx cancer, convened by scientists at IARC and NCI.

Cancer of the oropharynx has attracted considerable attention in recent years given: (1) an increasing incidence in selected populations over the past three decades; (2) the discovery of human papillomavirus (HPV) infection as the driver of the increase, as opposed to the traditional risk factors such as tobacco (smoking and chewing) and alcohol; and (3) the promise of new prevention and treatment strategies. As a result of such developments, the International Agency for Research on Cancer (IARC) and the US National Cancer Institute (NCI), convened the fourth Cancer Seminar meeting in November 2018 to focus on this topic. This report summarizes the proceedings: a review of recent science on the descriptive epidemiology, etiology, biology, genetics, early detection, pathology and treatment of HPV-positive oropharyngeal cancer, and the formulation of key research questions to be addressed.