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Hepatitis B Virus (HBV) is a small DNA virus that replicates via an episomal covalently closed circular DNA (cccDNA) that serves as the transcriptional template for viral mRNAs. The host protein, CCCTC-binding factor (CTCF), is a key regulator of cellular transcription by maintaining epigenetic boundaries, nucleosome phasing, stabilisation of long-range chromatin loops and directing alternative exon splicing. We previously reported that CTCF binds two conserved motifs within Enhancer I of the HBV genome and represses viral transcription, however, the underlying mechanisms were not identified. We show that CTCF depletion in cells harbouring cccDNA-like HBV molecules and in de novo infected cells resulted in an increase in spliced transcripts, which was most notable in the abundant SP1 spliced transcript. In contrast, depletion of CTCF in cell lines with integrated HBV DNA had no effect on the abundance of viral transcripts and in line with this observation there was limited evidence for CTCF binding to viral integrants, suggesting that CTCF-regulation of HBV transcription is specific to episomal cccDNA. Analysis of HBV chromatin topology by Assay for Transposase Accessible Chromatin Sequencing (ATAC-Seq) revealed an accessible region spanning Enhancers I and II and the basal core promoter (BCP). Mutating the CTCF binding sites within Enhancer I resulted in a dramatic rearrangement of chromatin accessibility where the open chromatin region was no longer detected, indicating loss of the phased nucleosome up- and down-stream of the HBV enhancer/BCP. These data demonstrate that CTCF functions to regulate HBV chromatin conformation and nucleosomal positioning in episomal maintained cccDNA, which has important consequences for HBV transcription regulation.

Persistent virus infections are achieved when the intricate balance of virus replication, host-cell division and successful immune evasion is met. The genomes of persistent DNA viruses are either maintained as extrachromosomal episomes or can integrate into the host genome. Common to both these strategies of persistence is the chromatinisation of viral DNA by cellular histones which, like host DNA, are subject to epigenetic modification. Epigenetic repression of viral genes required for lytic replication occurs, while genes required for latent or persistent infection are maintained in an active chromatin state. Viruses utilise host-cell chromatin insulators, which function to maintain epigenetic boundaries and enforce this strict transcriptional programme. Here, we review insulator protein function in virus transcription control, focussing on CCCTC-binding factor (CTCF) and cofactors. We describe CTCF-dependent activities in virus transcription regulation through epigenetic and promoter-enhancer insulation, three-dimensional chromatin looping and manipulation of transcript splicing., (Copyright © 2022 The Author(s). Published by Elsevier B.V. All rights reserved.)

The ubiquitous host protein, CCCTC-binding factor (CTCF), is an essential regulator of cellular transcription and functions to maintain epigenetic boundaries, stabilise chromatin loops and regulate splicing of alternative exons. We have previously demonstrated that CTCF binds to the E2 open reading frame (ORF) of human papillomavirus (HPV) 18 and functions to repress viral oncogene expression in undifferentiated keratinocytes by co-ordinating an epigenetically repressed chromatin loop within HPV episomes. Keratinocyte differentiation disrupts CTCF-dependent chromatin looping of HPV18 episomes promoting induction of enhanced viral oncogene expression. To further characterise CTCF function in HPV transcription control we utilised direct, long-read Nanopore RNA-sequencing which provides information on the structure and abundance of full-length transcripts. Nanopore analysis of primary human keratinocytes containing HPV18 episomes before and after synchronous differentiation allowed quantification of viral transcript species, including the identification of low abundance novel transcripts. Comparison of transcripts produced in wild type HPV18 genome-containing cells to those identified in CTCF-binding deficient genome-containing cells identifies CTCF as a key regulator of differentiation-dependent late promoter activation, required for efficient E1^E4 and L1 protein expression. Furthermore, our data show that CTCF binding at the E2 ORF promotes usage of the downstream weak splice donor (SD) sites SD3165 and SD3284, to the dominant E4 splice acceptor site at nucleotide 3434. These findings demonstrate that in the HPV life cycle both early and late virus transcription programmes are facilitated by recruitment of CTCF to the E2 ORF., Competing Interests: The authors have declared that no competing interests exist.

The DNA demethylating agent 5-aza-2'-deoxycytidine (DAC, decitabine) has anti-cancer therapeutic potential, but its clinical efficacy is hindered by DNA damage-related side effects and its use in solid tumours is debated. Here we describe how paracetamol augments the effects of DAC on cancer cell proliferation and differentiation, without enhancing DNA damage. Firstly, DAC specifically upregulates cyclooxygenase-2-prostaglandin E 2 pathway, inadvertently providing cancer cells with survival potential, while the addition of paracetamol offsets this effect. Secondly, in the presence of paracetamol, DAC treatment leads to glutathione depletion and finally to accumulation of ROS and/or mitochondrial superoxide, both of which have the potential to restrict tumour growth. The benefits of combined treatment are demonstrated here in head and neck squamous cell carcinoma (HNSCC) and acute myeloid leukaemia cell lines, further corroborated in a HNSCC xenograft mouse model and through mining of publicly available DAC and paracetamol responses. The sensitizing effect of paracetamol supplementation is specific to DAC but not its analogue 5-azacitidine. In summary, the addition of paracetamol could allow for DAC dose reduction, widening its clinical usability and providing a strong rationale for consideration in cancer therapy., (Copyright © 2021 The Authors. Published by Elsevier B.V. All rights reserved.)

Infections cause 13% of all cancers globally, and DNA tumour viruses account for almost 60% of these cancers. All viruses are obligate intracellular parasites and hijack host cell functions to replicate and complete their life cycles to produce progeny virions. While many aspects of viral manipulation of host cells have been studied, how DNA tumour viruses manipulate host cell metabolism and whether metabolic alterations in the virus life cycle contribute to carcinogenesis are not well understood. In this review, we compare the differences in central carbon and fatty acid metabolism in host cells following infection, oncogenic transformation, and virus-driven cancer of DNA tumour viruses including: Epstein-Barr virus, hepatitis B virus, human papillomavirus, Kaposi's sarcoma-associated herpesvirus and Merkel cell polyomavirus.

Hepatitis B virus (HBV) infection is of global importance with over 2 billion people exposed to the virus during their lifetime and at risk of progressive liver disease, cirrhosis and hepatocellular carcinoma. HBV is a member of the Hepadnaviridae family that replicates via episomal copies of a covalently closed circular DNA (cccDNA) genome. The chromatinization of this small viral genome, with overlapping open reading frames and regulatory elements, suggests an important role for epigenetic pathways to regulate viral transcription. The chromatin-organising transcriptional insulator protein, CCCTC-binding factor (CTCF), has been reported to regulate transcription in a diverse range of viruses. We identified two conserved CTCF binding sites in the HBV genome within enhancer I and chromatin immunoprecipitation (ChIP) analysis demonstrated an enrichment of CTCF binding to integrated or episomal copies of the viral genome. siRNA knock-down of CTCF results in a significant increase in pre-genomic RNA levels in de novo infected HepG2 cells and those supporting episomal HBV DNA replication. Furthermore, mutation of these sites in HBV DNA minicircles abrogated CTCF binding and increased pre-genomic RNA levels, providing evidence of a direct role for CTCF in repressing HBV transcription., (© 2020 The Authors. Cellular Microbiology published by John Wiley & Sons Ltd.)

Warsaw Breakage Syndrome (WABS) is a rare disorder related to cohesinopathies and Fanconi anemia, caused by bi-allelic mutations in DDX11. Here, we report multiple compound heterozygous WABS cases, each displaying destabilized DDX11 protein and residual DDX11 function at the cellular level. Patient-derived cell lines exhibit sensitivity to topoisomerase and PARP inhibitors, defective sister chromatid cohesion and reduced DNA replication fork speed. Deleting DDX11 in RPE1-TERT cells inhibits proliferation and survival in a TP53-dependent manner and causes chromosome breaks and cohesion defects, independent of the expressed pseudogene DDX12p. Importantly, G-quadruplex (G4) stabilizing compounds induce chromosome breaks and cohesion defects which are strongly aggravated by inactivation of DDX11 but not FANCJ. The DNA helicase domain of DDX11 is essential for sister chromatid cohesion and resistance to G4 stabilizers. We propose that DDX11 is a DNA helicase protecting against G4 induced double-stranded breaks and concomitant loss of cohesion, possibly at DNA replication forks.

Human papillomaviruses (HPV) are a large family of viruses which contain a circular, double-stranded DNA genome of approximately 8000 base pairs. The viral DNA is chromatinized by the recruitment of cellular histones which are subject to host cell-mediated post-translational epigenetic modification recognized as an important mechanism of virus transcription regulation. The HPV life cycle is dependent on the terminal differentiation of the target cell within epithelia-the keratinocyte. The virus life cycle begins in the undifferentiated basal compartment of epithelia where the viral chromatin is maintained in an epigenetically repressed state, stabilized by distal chromatin interactions between the viral enhancer and early gene region. Migration of the infected keratinocyte towards the surface of the epithelium induces cellular differentiation which disrupts chromatin looping and stimulates epigenetic remodelling of the viral chromatin. These epigenetic changes result in enhanced virus transcription and activation of the virus late promoter facilitating transcription of the viral capsid proteins. In this review article, we discuss the complexity of virus- and host-cell-mediated epigenetic regulation of virus transcription with a specific focus on differentiation-dependent remodelling of viral chromatin during the HPV life cycle.

Most human papillomavirus (HPV) positive head and neck cancers arise in the tonsil crypts; deep invaginations at the tonsil surface that are lined with reticulated epithelium infiltrated by immune cells. As in cervical HPV infections, HPV16 is the most prevalent high-risk type in the oropharyngeal cancers, and a genital-oral route of infection is most likely. However, the natural history of HPV-driven oropharyngeal pathogenesis is an enigma, although there is evidence that it is different to that of cervical disease. It is not known if the virus establishes a productive or abortive infection in keratinocytes of the tonsil crypt, or if viral infections progress to cancer via a neoplastic phase, as in cervical HPV infection. The HPV DNA is more frequently found unintegrated in the cancers of the oropharynx compared to those that arise in the cervix, and may include novel HPV-human DNA hybrids episomes. Here, we review current understanding of HPV biology in the oropharynx and discuss the cell-based systems being used to model the HPV life cycle in tonsil keratinocytes and how they can be used to inform on HPV-driven neoplastic progression in the oropharynx. This article is part of the theme issue 'Silent cancer agents: multi-disciplinary modelling of human DNA oncoviruses'.

Chronic hepatitis B is one of the world's unconquered diseases with more than 240 million infected subjects at risk of developing liver disease and hepatocellular carcinoma. Hepatitis B virus reverse transcribes pre-genomic RNA to relaxed circular DNA (rcDNA) that comprises the infectious particle. To establish infection of a naïve target cell, the newly imported rcDNA is repaired by host enzymes to generate covalently closed circular DNA (cccDNA), which forms the transcriptional template for viral replication. SAMHD1 is a component of the innate immune system that regulates deoxyribonucleoside triphosphate levels required for host and viral DNA synthesis. Here, we show a positive role for SAMHD1 in regulating cccDNA formation, where KO of SAMHD1 significantly reduces cccDNA levels that was reversed by expressing wild-type but not a mutated SAMHD1 lacking the nuclear localization signal. The limited pool of cccDNA in infected Samhd1 KO cells is transcriptionally active, and we observed a 10-fold increase in newly synthesized rcDNA-containing particles, demonstrating a dual role for SAMHD1 to both facilitate cccDNA genesis and to restrict reverse transcriptase-dependent particle genesis., (© 2019 Wing et al.)

We have explored the rash that appears as target lesions, with the central and dominant diseases belonging to the Stevens-Johnson syndrome/toxic epidermal necrolysis group. After presenting the clinical patterns of an individual target lesion and classifying them into different types of lesions, the contribution has been organized with groups characterized by such specific findings according to the type of lesion: flat or raised, typical or atypical, presence or absence of fever, presence or absence of mucosal ulcerations, presence or absence of arthralgias, and/or internal organ involvement. Other specific features, such as histologic appearance, immunofluorescence findings, and laboratory changes, are considered. We provide clinicians with an algorithmic, systematic, and logical approach to diagnose the condition of the patients who present with targetoid lesions, and enable them to differentiate between those with serious systemic and life-threatening diseases from others with ordinary skin ailments., (Copyright © 2018 Elsevier Inc. All rights reserved.)

The complex life cycle of oncogenic human papillomavirus (HPV) initiates in undifferentiated basal epithelial keratinocytes where expression of the E6 and E7 oncogenes is restricted. Upon epithelial differentiation, E6/E7 transcription is increased through unknown mechanisms to drive cellular proliferation required to support virus replication. We report that the chromatin-organising CCCTC-binding factor (CTCF) promotes the formation of a chromatin loop in the HPV genome that epigenetically represses viral enhancer activity controlling E6/E7 expression. CTCF-dependent looping is dependent on the expression of the CTCF-associated Yin Yang 1 (YY1) transcription factor and polycomb repressor complex (PRC) recruitment, resulting in trimethylation of histone H3 at lysine 27. We show that viral oncogene up-regulation during cellular differentiation results from YY1 down-regulation, disruption of viral genome looping, and a loss of epigenetic repression of viral enhancer activity. Our data therefore reveal a key role for CTCF-YY1-dependent looping in the HPV life cycle and identify a regulatory mechanism that could be disrupted in HPV carcinogenesis., Competing Interests: The authors have declared that no competing interests exist.

Background: Side effects may limit the use of current tetracycline-class antibiotics for acne., Objective: Evaluate the efficacy and safety of once-daily sarecycline, a novel, narrow-spectrum tetracycline-class antibiotic, in moderate to severe acne., Methods: Patients 9-45 years with moderate to severe facial acne (Investigator's Global Assessment [IGA] score ≥ 3, 20-50 inflammatory and ≤ 100 noninflammatory lesions, and ≤ 2 nodules) were randomized 1:1 to sarecycline 1.5 mg/kg/day or placebo for 12 weeks in identically designed phase 3 studies (SC1401 and SC1402)., Results: In SC1401 (sarecycline n=483, placebo n=485) and SC1402 (sarecycline n=519, placebo n=515), at week 12, IGA success (≥ 2-grade improvement and score 0 [clear] or 1 [almost clear]) rates were 21.9% and 22.6% (sarecycline), respectively, versus 10.5% and 15.3% (placebo; P less than 0.0001 and P equals 0.0038). Onset of efficacy in inflammatory lesions occurred by the first visit (week 3), with mean percentage reduction in inflammatory lesions at week 12 in SC1401 and SC1402 of -51.8% and -49.9% (sarecycline), respectively, versus -35.1% and -35.4% (placebo; P less than 0.0001). Onset of efficacy for absolute reduction of noninflammatory lesion count occurred at week 6 in SC1401 (P less than 0.05) and week 9 in SC1402 (P less than 0.01). In SC1401, the most common TEAEs (in ≥ 2% of either sarecycline or placebo group) were nausea (4.6% [sarecycline]; 2.5% [placebo]), nasopharyngitis (3.1%; 1.7%), headache (2.7%; 2.7%), and vomiting (2.1%; 1.4%) and, in SC1402, nasopharyngitis (2.5%; 2.9%) and headache (2.9%; 4.9%). Most were not considered treatment-related. Vestibular (dizziness, tinnitus, vertigo) and phototoxic (sunburn, photosensitivity) TEAEs both occurred in ≤ 1% of sarecycline patients. Gastrointestinal TEAE rates for sarecycline were low. Among females, vulvovaginal candidiasis (SC1401: 1.1% [sarecycline] and 0 [placebo]; SC1402: 0.3% and 0) and mycotic infection (0.7% and 0; 1.0% and 0) rates were low., Conclusion: The narrow-spectrum antibiotic sarecycline was safe, well tolerated, and effective for moderate to severe acne, with low rates of side effects common with tetracycline antibiotics. J Drugs Dermatol. 2018;17(9):987-996.

Given the contradictory nature of the literature regarding the role of human papillomaviruses and polyomaviruses in the pathogenesis of urothelial bladder cancer (UBC), we sought to investigate the frequency of their involvement in a large cohort of primary UBCs. DNA was extracted from 689 fresh-frozen UBC tissues and screened for the presence of high-risk human papillomavirus (HPV) types 16 and 18 and BKV/JCV genomic DNA by qPCR. In positive cases, viral identity was confirmed by Sanger sequencing and viral gene expression was analysed by RT-PCR or immunohistochemistry. All 689 UBCs were negative for HPV18. One UBC from a female patient with areas of squamous differentiation was positive for HPV16. The qPCR data indicated variable levels of polyomavirus in 49 UBCs. In the UBCs with low C t s we were able to confirm that 23 were BKV and 6 were JCV by Sanger sequencing. Polyomavirus large T antigen expression was low but detectable in 70% of the sequencing-confirmed polyomavirus positive samples. Thus, in United Kingdom patients, the presence of HPV DNA sequences is extremely rare in UBC (<1% of cases). Polyomavirus DNA (predominantly BKV) is more common in UBC, but still only detectable in 7% of cases and in many of these cases at low copy number. We have performed the largest virus screening to date in UBC, finding that HPV16, HPV18 and HPyV are unlikely to be common causative agents in UBC.

To assess the relationship of E2 gene disruption with viral gene expression and clinical outcome in human papillomavirus (HPV) positive head and neck squamous cell carcinoma, we evaluated 31 oropharyngeal and 17 non-oropharyngeal HPV16 positive carcinomas using two PCR-based methods to test for disruption of E2, followed by Sanger sequencing. Expression of HPV16 E6, E7 and E2 transcripts, along with cellular ARF and INK4A, were also assessed by RT-qPCR. Associations between E2 disruption, E2/E6/E7 expression, and clinical outcome were evaluated by Kaplan-Meier analysis for loco-regional recurrence and disease-specific survival. The majority (n = 21, 68%) of HPV16 positive oropharyngeal carcinomas had an intact E2 gene, whereas the majority of HPV16 positive non-oropharyngeal carcinomas (n = 10, 59%) had a disrupted E2 gene. Three of the oropharyngeal tumors and two of the non-oropharyngeal tumors had deletions within E2. Detection of an intact E2 gene was associated with a higher DNA viral load and increased E2/E6/E7, ARF and INK4A expression in oropharyngeal tumors. Oropharyngeal carcinomas with an intact E2 had a lower risk of loco-regional recurrence (log-rank p = 0.04) and improved disease-specific survival (p = 0.03) compared to tumors with disrupted E2. In addition, high E7 expression was associated with lower risk of loco-regional recurrence (p = 0.004) as was high E6 expression (p = 0.006). In summary, an intact E2 gene is more common in HPV16 positive oropharyngeal than non-oropharyngeal carcinomas; the presence of an intact E2 gene is associated with higher HPV viral load, higher viral oncogene expression, and improved clinical outcome compared to patients with a disrupted E2 gene in oropharyngeal cancer.

The function of a conserved PDS95/DLG1/ZO1 (PDZ) binding motif (E6 PBM) at the C-termini of E6 oncoproteins of high-risk human papillomavirus (HPV) types contributes to the development of HPV-associated malignancies. Here, using a primary human keratinocyte-based model of the high-risk HPV18 life cycle, we identify a novel link between the E6 PBM and mitotic stability. In cultures containing a mutant genome in which the E6 PBM was deleted there was an increase in the frequency of abnormal mitoses, including multinucleation, compared to cells harboring the wild type HPV18 genome. The loss of the E6 PBM was associated with a significant increase in the frequency of mitotic spindle defects associated with anaphase and telophase. Furthermore, cells carrying this mutant genome had increased chromosome segregation defects and they also exhibited greater levels of genomic instability, as shown by an elevated level of centromere-positive micronuclei. In wild type HPV18 genome-containing organotypic cultures, the majority of mitotic cells reside in the suprabasal layers, in keeping with the hyperplastic morphology of the structures. However, in mutant genome-containing structures a greater proportion of mitotic cells were retained in the basal layer, which were often of undefined polarity, thus correlating with their reduced thickness. We conclude that the ability of E6 to target cellular PDZ proteins plays a critical role in maintaining mitotic stability of HPV infected cells, ensuring stable episome persistence and vegetative amplification.

Rad50-interacting protein 1 (Rint1) associates with the DNA damage response protein Rad50 during the transition from the S phase to the G 2 /M phase and functions in radiation-induced G 2 checkpoint control. It has also been demonstrated that Rint1 is essential in vesicle trafficking from the Golgi apparatus to the endoplasmic reticulum (ER) through an interaction with Zeste-White 10 (ZW10). We have isolated a novel interaction between Rint1 and the human papillomavirus 16 (HPV16) transcription and replication factor E2. E2 binds to Rint1 within its ZW10 interaction domain, and we show that in the absence of E2, Rint1 is localized to the ER and associates with ZW10. E2 expression results in a disruption of the Rint1-ZW10 interaction and an accumulation of nuclear Rint1, coincident with a significant reduction in vesicle movement from the ER to the Golgi apparatus. Interestingly, nuclear Rint1 and members of the Mre11/Rad50/Nbs1 (MRN) complex were found in distinct E2 nuclear foci, which peaked during mid-S phase, indicating that the recruitment of Rint1 to E2 foci within the nucleus may also result in the recruitment of this DNA damage-sensing protein complex. We show that exogenous Rint1 expression enhances E2-dependent virus replication. Conversely, the overexpression of a truncated Rint1 protein that retains the E2 binding domain but not the Rad50 binding domain acts as a dominant negative inhibitor of E2-dependent HPV replication. Put together, these experiments demonstrate that the interaction between Rint1 and E2 has an important function in HPV replication. IMPORTANCE HPV infections are an important driver of many epithelial cancers, including those within the anogenital and oropharyngeal tracts. The HPV life cycle is tightly regulated and intimately linked to the differentiation of the epithelial cells that it infects. HPV replication factories formed in the nucleus are locations where viral DNA is copied to support virus persistence and amplification of infection. The recruitment of specific cellular protein complexes to these factories aids efficient and controlled viral replication. We have identified a novel HPV-host interaction that functions in the cellular response to DNA damage and cell cycle control. We show that the HPV E2 protein targets Rad50-interacting protein 1 (Rint1) to facilitate virus genome replication. These findings add to our understanding of how HPV replicates and the host cell pathways that are targeted by HPV to support virus replication. Understanding these pathways will allow further research into novel inhibitors of HPV genome replication., (Copyright © 2017 Campos-León et al.)

In papillomavirus infections, the viral genome is established as a double-stranded DNA episome. To segregate the episomes into daughter cells during mitosis, they are tethered to cellular chromatin by the viral E2 protein. We previously demonstrated that the E2 proteins of diverse papillomavirus types, including bovine papillomavirus (BPV) and human papillomavirus 16 (HPV16), associate with the cellular DNA helicase ChlR1. This virus-host interaction is important for the tethering of BPV E2 to mitotic chromatin and the stable maintenance of BPV episomes. The role of the association between E2 and ChlR1 in the HPV16 life cycle is unresolved. Here we show that an HPV16 E2 Y131A mutant (E2 Y131A ) had significantly reduced binding to ChlR1 but retained transcriptional activation and viral origin-dependent replication functions. Subcellular fractionation of keratinocytes expressing E2 Y131A showed a marked change in the localization of the protein. Compared to that of wild-type E2 (E2 WT ), the chromatin-bound pool of E2 Y131A was decreased, concomitant with an increase in nuclear matrix-associated protein. Cell cycle synchronization indicated that the shift in subcellular localization of E2 Y131A occurred in mid-S phase. A similar alteration between the subcellular pools of the E2 WT protein occurred upon ChlR1 silencing. Notably, in an HPV16 life cycle model in primary human keratinocytes, mutant E2 Y131A genomes were established as episomes, but at a markedly lower copy number than that of wild-type HPV16 genomes, and they were not maintained upon cell passage. Our studies indicate that ChlR1 is an important regulator of the chromatin association of E2 and of the establishment and maintenance of HPV16 episomes., Importance: Infections with high-risk human papillomaviruses (HPVs) are a major cause of anogenital and oropharyngeal cancers. During infection, the circular DNA genome of HPV persists within the nucleus, independently of the host cell chromatin. Persistence of infection is a risk factor for cancer development and is partly achieved by the attachment of viral DNA to cellular chromatin during cell division. The HPV E2 protein plays a critical role in this tethering by binding simultaneously to the viral genome and to chromatin during mitosis. We previously showed that the cellular DNA helicase ChlR1 is required for loading of the bovine papillomavirus E2 protein onto chromatin during DNA synthesis. Here we identify a mutation in HPV16 E2 that abrogates interaction with ChlR1, and we show that ChlR1 regulates the chromatin association of HPV16 E2 and that this virus-host interaction is essential for viral episome maintenance., (Copyright © 2016 Harris et al.)

The human papillomavirus (HPV) E2 protein is a multifunctional protein essential for the control of virus gene expression, genome replication and persistence. E2 is expressed throughout the differentiation-dependent virus life cycle and is functionally regulated by association with multiple viral and cellular proteins. Here, we show for the first time to our knowledge that HPV16 E2 directly associates with the major capsid protein L1, independently of other viral or cellular proteins. We have mapped the L1 binding region within E2 and show that the α-2 helices within the E2 DNA-binding domain mediate L1 interaction. Using cell-based assays, we show that co-expression of L1 and E2 results in enhanced transcription and virus origin-dependent DNA replication. Upon co-expression in keratinocytes, L1 reduces nucleolar association of E2 protein, and when co-expressed with E1 and E2, L1 is partially recruited to viral replication factories. Furthermore, co-distribution of E2 and L1 was detected in the nuclei of upper suprabasal cells in stratified epithelia of HPV16 genome-containing primary human keratinocytes. Taken together, our findings suggest that the interaction between E2 and L1 is important for the regulation of E2 function during the late events of the HPV life cycle.

All viruses target host cell factors for successful life cycle completion. Transcriptional control of DNA viruses by host cell factors is important in the temporal and spatial regulation of virus gene expression. Many of these factors are recruited to enhance virus gene expression and thereby increase virus production, but host cell factors can also restrict virus gene expression and productivity of infection. CCCTC binding factor (CTCF) is a host cell DNA binding protein important for the regulation of genomic chromatin boundaries, transcriptional control and enhancer element usage. CTCF also functions in RNA polymerase II regulation and in doing so can influence co-transcriptional splicing events. Several DNA viruses, including Kaposi's sarcoma-associated herpesvirus (KSHV), Epstein-Barr virus (EBV) and human papillomavirus (HPV) utilize CTCF to control virus gene expression and many studies have highlighted a role for CTCF in the persistence of these diverse oncogenic viruses. CTCF can both enhance and repress virus gene expression and in some cases CTCF increases the complexity of alternatively spliced transcripts. This review article will discuss the function of CTCF in the life cycle of DNA viruses in the context of known host cell CTCF functions.

Unlabelled: Host cell differentiation-dependent regulation of human papillomavirus (HPV) gene expression is required for productive infection. The host cell CCCTC-binding factor (CTCF) functions in genome-wide chromatin organization and gene regulation. We have identified a conserved CTCF binding site in the E2 open reading frame of high-risk HPV types. Using organotypic raft cultures of primary human keratinocytes containing high-risk HPV18 genomes, we show that CTCF recruitment to this conserved site regulates viral gene expression in differentiating epithelia. Mutation of the CTCF binding site increases the expression of the viral oncoproteins E6 and E7 and promotes host cell proliferation. Loss of CTCF binding results in a reduction of a specific alternatively spliced transcript expressed from the early gene region concomitant with an increase in the abundance of unspliced early transcripts. We conclude that high-risk HPV types have evolved to recruit CTCF to the early gene region to control the balance and complexity of splicing events that regulate viral oncoprotein expression., Importance: The establishment and maintenance of HPV infection in undifferentiated basal cells of the squamous epithelia requires the activation of a subset of viral genes, termed early genes. The differentiation of infected cells initiates the expression of the late viral transcripts, allowing completion of the virus life cycle. This tightly controlled balance of differentiation-dependent viral gene expression allows the virus to stimulate cellular proliferation to support viral genome replication with minimal activation of the host immune response, promoting virus productivity. Alternative splicing of viral mRNAs further increases the complexity of viral gene expression. In this study, we show that the essential host cell protein CTCF, which functions in genome-wide chromatin organization and gene regulation, is recruited to the HPV genome and plays an essential role in the regulation of early viral gene expression and transcript processing. These data highlight a novel virus-host interaction important for HPV pathogenicity., (Copyright © 2015, American Society for Microbiology. All Rights Reserved.)

Cervical cancer is the third most common cause of cancer-related death in women worldwide. Infection with high-risk human papillomavirus (HPV) is established as the cause of cervical carcinoma, therefore, high risk HPV detection may have prognostic significance for the women who are at increased risk of disease progression. The paucity of data on the incidence of cervical cancer in Pakistan makes it difficult to determine disease burden. Even less information is available regarding the prevalent HPV strains in cervical specimens collected from this region. Cervical cancer is a neglected disease in Pakistan in terms of screening, prevention, and vaccination. Identification and accurate genotyping of the virus burden in cancer specimens is important to inform intervention policies for future management of HPV associated disease and to potentially stratify patients dependent on HPV status. In this study, detection and genotyping of HPV types 16 and 18 from 77 cervical specimens were carried out. Consensus primers GP5+/GP6+, which detect 44 genital HPV types, and type specific primers (TS16 and TS18) were used in conjunction with newly designed type specific primers. Using a combination of these methods of detection, a total of 94.81% (95% CI ±4.95) of cervical lesions were positive for HPV. Single infections of HPV16 were detected in 24.68% (95% CI ±9.63) of total samples and HPV18 was found in 25.97% (95% CI ±9.79) samples. Interestingly, a high proportion of samples (40.26%, 95% CI ±10.95) was positive for both HPV16 and 18, indicating a higher incidence of co-infection than previously reported for similar ethnic regions. The HPV genotype of 3.90% of HPV positive samples remained undetected, although these samples were positive with the GP5+/GP6+ primer set indicating infection with an HPV type other than 16 or 18. These data indicate that the overall incidence of high risk HPV infection in cervical cancer and intraepithelial neoplasia specimens in Punjab, Pakistan is in line with the worldwide prevalence, but that the incidence of HPV16 and 18 co-infections in our cohort is higher than that previously reported.

The metaphase chromosome spread technique and subsequent analysis of sister chromatid cohesion is used for (clinical) diagnosis of genetic abnormalities that can cause aberrant sister chromatid cohesion. In addition, the technique can be used to assess the contribution of novel genes to the cohesion establishment and maintenance pathways. Cells are swelled in a hypotonic solution and fixed in Carnoy's solution. Samples are then dropped onto glass slides, and the spread chromosomes are stained and visualized by microscopy. Defects in sister chromatid cohesion can be easily assessed using this method, examples of which are given.

Objective: Naftifine HCl 2% cream (NAFT-2) is a topical allylamine antifungal agent under development in the United States. This randomized, double-blind, vehicle-controlled, phase 3 trial evaluated the efficacy and safety of two weeks of NAFT-2 treatment in subjects with tinea pedis. Naftifine 1% cream (NAFT-1) treatment for four weeks and vehicle were also evaluated as a positive control., Methods: 709 subjects were randomly assigned 2:1:2:1 to one of four treatment groups: (i) NAFT-2 (n= 235), (ii) two-week vehicle (n=118), (iii) NAFT-1 (n=237), or (iv) four-week vehicle (n=119). Efficacy was evaluated at baseline, week 2, week 4, and week 6 and consisted of mycology determination (KOH and dermatophyte culture) and scoring of clinical symptom severity (erythema, scaling, and pruritus). Efficacy was only analyzed in 425 subjects with positive baseline dermatophyte culture. Safety was evaluated by adverse events (AE) and laboratory values in 707 subjects., Results: At week 6, NAFT-2 subjects achieved 18 percent complete cure rate, 67 percent mycological cure rate, 57 percent treatment effectiveness, 22 percent clinical cure rate, and 78 percent clinical success rate compared to respective vehicle rates of seven percent (one-sided, P<0.01), 21 percent (P<0.001), 20 percent (P<0.001), 11 percent (P=0.04) and 49 percent (P<0.001). Week 6 efficacy responses in NAFT-1-treated subjects were significantly higher than vehicle subjects and almost identical to NAFT-2 subjects. Mycological cure and clinical response rates in both NAFT-2 and NAFT-1 increased from week 2 to week 6. Treatment-related AEs occurred in five percent of NAFT-2 subjects, seven percent of vehicle subjects, four percent of NAFT-1 subjects and eight percent of vehicle subjects. The most common AEs for all groups were application site pruritus and skin irritation., Conclusion: Topical NAFT-2 for two weeks is safe and provides significantly superior antifungal treatment than vehicle in tinea pedis subjects. NAFT-2 produces equivalent efficacy responses to four weeks of NAFT-1 treatment. The fungicidal activity of naftifine continues to increase for at least one month after treatment is completed. (Clinical Trials Identification Numbe=NCT00750139). J Drugs Dermatol. 2011;10(11):1282-1288.

Objective: Naftifine HCl 2% cream (NAFT-2%) is a topical allylamine antifungal preparation under development in the U.S. The objective of this randomized, double-blind, vehicle-controlled study was to evaluate the efficacy and safety of a two-week course of once-daily NAFT-2% vs. vehicle in the treatment of Tinea cruris ("jock itch")., Methods: A total of 334 subjects with T. cruris were enrolled and randomly assigned to NAFT-2% (n=166) or vehicle (n=168), which was applied once daily for 14 days. Efficacy and safety were evaluated at week 2 (end of treatment) and week 4. Efficacy measures included complete cure, treatment effectiveness, mycological cure, clinical cure, and clinical success and were analyzed only in subjects with a positive potassium hydroxide (KOH) and dermatophyte culture at baseline (n=75, naftifine; n=71, vehicle). Safety was assessed by adverse events and changes from baseline in clinical status and laboratory studies., Results: At week 4, 25 percent of naftifine-treated subjects achieved complete cure vs. three percent of vehicle subjects and 72 percent achieved mycological cure vs. 16 percent of vehicle treated subjects (one-sided, P<0.001). Treatment effectiveness was achieved in 60 percent of NAFT-2% subjects vs. 10 percent of vehicle subjects (one-sided, P<0.001). Clinical cure rate and clinical success rate were 33 percent and 84 percent in NAFT-2% subjects, respectively vs. 10 percent and 46 percent in vehicle subjects (both P is less than 0.001, 2-sided). Week 2 efficacy response rates in NAFT-2% subjects were all lower than at week 4 but were significantly higher than week 2 vehicle-treated counterparts (P<0.025). Treatment-related AE occurred in 11 subjects (7 NAFT-2%, 4 vehicle) during the study. The most common AE in both groups were contact dermatitis (2 NAFT-2%), pruritus (2 vehicle), and application site reaction (1 per group)., Conclusion: NAFT-2% applied once daily for two weeks (one-half the treatment duration for naftifine 1% cream) is efficacious and safe for the treatment of T. cruris.