The initial steps leading to papillomavirus infection occur on the basement membrane prior to cell surface binding

A comprehensive overview on the crosstalk between microRNAs and viral pathogenesis and infection

Infections caused by viruses as the smallest infectious agents, pose a major threat to global public health. Viral infections utilize different host mechanisms to facilitate their own propagation and pathogenesis. MicroRNAs (miRNAs), as small noncoding RNA molecules, play important regulatory roles in different diseases, including viral infections. They can promote or inhibit viral infection and have a pro-viral or antiviral role. Also, viral infections can modulate the expression of host miRNAs. Furthermore, viruses from different families evade the host immune response by producing their own miRNAs called viral miRNAs (v-miRNAs). Understanding the replication cycle of viruses and their relation with host miRNAs and v-miRNAs can help to find new treatments against viral infections. In this review, we aim to outline the structure, genome, and replication cycle of various viruses including hepatitis B, hepatitis C, influenza A virus, coronavirus, human immunodeficiency virus, human papillomavirus, herpes simplex virus, Epstein-Barr virus, Dengue virus, Zika virus, and Ebola virus. We also discuss the role of different host miRNAs and v-miRNAs and their role in the pathogenesis of these viral infections.

Impact of Annexin A2 on virus life cycles

Due to the limited size of viral genomes, hijacking host machinery by the viruses taking place throughout the virus life cycle is inevitable for the survival and proliferation of the virus in the infected hosts. Recent reports indicated that Annexin A2 (AnxA2), a calcium- and lipid-binding cellular protein, plays an important role as a critical regulator in various steps of the virus life cycle. The multifarious AnxA2 functions in cells, such as adhesion, adsorption, endocytosis, exocytosis, cell proliferation and division, inflammation, cancer metastasis, angiogenesis, etc., are intimately related to the various clinical courses of viral infection. Ubiquitous expression of AnxA2 across multiple cell types indicates the broad range of susceptibility of diverse species of the virus to induce disparate viral disease in various tissues, and intracellular expression of AnxA2 in the cytoplasmic membrane, cytosol, and nucleus suggests the involvement of AnxA2 in the regulation of the different stages of various virus life cycles within host cells. However, it is yet unclear as to the molecular processes on how AnxA2 and the infected virus interplay to regulate virus life cycles and thereby the virus-associated disease courses, and hence elucidation of the molecular mechanisms on AnxA2-mediated virus life cycle will provide essential clues to develop therapeutics deterring viral disease.

A peptide derived from sorting nexin 1 inhibits HPV16 entry, retrograde trafficking, and L2 membrane spanning

High risk human papillomavirus (HPV) infection is responsible for 99 % of cervical cancers and 5 % of all human cancers worldwide. HPV infection requires the viral genome (vDNA) to gain access to nuclei of basal keratinocytes of epithelium. After virion endocytosis, the minor capsid protein L2 dictates the subcellular retrograde trafficking and nuclear localization of the vDNA during mitosis. Prior work identified a cell-permeable peptide termed SNX1.3, derived from the BAR domain of sorting nexin 1 (SNX1), that potently blocks the retrograde and nuclear trafficking of EGFR in triple negative breast cancer cells. Given the importance of EGFR and retrograde trafficking pathways in HPV16 infection, we set forth to study the effects of SNX1.3 within this context. SNX1.3 inhibited HPV16 infection by both delaying virion endocytosis, as well as potently blocking virion retrograde trafficking and Golgi localization. SNX1.3 had no effect on cell proliferation, nor did it affect post-Golgi trafficking of HPV16. Looking more directly at L2 function, SNX1.3 was found to impair membrane spanning of the minor capsid protein. Future work will focus on mechanistic studies of SNX1.3 inhibition, and the role of EGFR signaling and SNX1-mediated endosomal tubulation, cargo sorting, and retrograde trafficking in HPV infection.

Vaccination with a Human Papillomavirus L2 Multimer Provides Broad Protection against 17 Human Papillomavirus Types in the Mouse Cervicovaginal Challenge Model

Human papillomavirus (HPV) is a prevalent cause of mucosal and cutaneous infections and underlying conditions ranging from benign warts to anogenital and oropharyngeal cancers affecting both males and females, notably cervical cancer. Cervical cancer is the fourth leading cause of cancer deaths among women globally and is the most impactful in low- and middle-income countries (LMICs), where the costs of screening and licensed L1-based HPV vaccines pose significant barriers to comprehensive administration. Additionally, the licensed L1-based HPV vaccines fail to protect against all oncogenic HPV types. This study generated three independent lots of an L2-based target antigen (LBTA), which was engineered from conserved linear L2-protective epitopes (aa11-88) from five human alphapapillomavirus genotypes in E. coli under cGMP conditions and adjuvanted with aluminum phosphate. Vaccination of rabbits with LBTA generated high neutralizing antibody titers against all 17 HPV types tested, surpassing the nine types covered by Gardasil®9. Passive transfer of naïve mice with LBTA antiserum revealed its capacity to confer protection against vaginal challenge with all 17 αHPV types tested. LBTA shows stability at room temperature over >1 month. Standard in vitro and in vivo toxicology studies suggest a promising safety profile. These findings suggest LBTA's promise as a next-generation vaccine with comprehensive coverage aimed at reducing the economic and healthcare burden of cervical and other HPV+ cancers in LMICs, and it has received regulatory approval for a first-in-human clinical study (NCT05672966).

A Peptide Derived from Sorting Nexin 1 Inhibits HPV16 Entry, Retrograde Trafficking, and L2 Membrane Spanning

High risk human papillomavirus (HPV) infection is responsible for 99% of cervical cancers and 5% of all human cancers worldwide. HPV infection requires the viral genome (vDNA) to gain access to nuclei of basal keratinocytes of epithelium. After virion endocytosis, the minor capsid protein L2 dictates the subcellular retrograde trafficking and nuclear localization of the vDNA during mitosis. Prior work identified a cell-permeable peptide termed SNX1.3, derived from the BAR domain of sorting nexin 1 (SNX1), that potently blocks the retrograde and nuclear trafficking of EGFR in triple negative breast cancer cells. Given the importance of EGFR and retrograde trafficking pathways in HPV16 infection, we set forth to study the effects of SNX1.3 within this context. SNX1.3 inhibited HPV16 infection by both delaying virion endocytosis, as well as potently blocking virion retrograde trafficking and Golgi localization. SNX1.3 had no effect on cell proliferation, nor did it affect post-Golgi trafficking of HPV16. Looking more directly at L2 function, SNX1.3 was found to impair membrane spanning of the minor capsid protein. Future work will focus on mechanistic studies of SNX1.3 inhibition, and the role of EGFR signaling and SNX1- mediated endosomal tubulation, cargo sorting, and retrograde trafficking in HPV infection.

The BICD2 dynein cargo adaptor binds to the HPV16 L2 capsid protein and promotes HPV infection

During entry, human papillomavirus (HPV) traffics from the endosome to the trans Golgi network (TGN) and Golgi and then the nucleus to cause infection. Although dynein is thought to play a role in HPV infection, how this host motor recruits the virus to support infection and which entry step(s) requires dynein are unclear. Here we show that the dynein cargo adaptor BICD2 binds to the HPV L2 capsid protein during entry, recruiting HPV to dynein for transport of the virus along the endosome-TGN/Golgi axis to promote infection. In the absence of BICD2 function, HPV accumulates in the endosome and TGN and infection is inhibited. Cell-based and in vitro binding studies identified a short segment near the C-terminus of L2 that can directly interact with BICD2. Our results reveal the molecular basis by which the dynein motor captures HPV to promote infection and identify this virus as a novel cargo of the BICD2 dynein adaptor.

Down-regulation of FA-BRCA Pathway in Cervical Carcinoma Gradually Reversed During the Development of Chemo-tolerance: Clinical Implications

Cervical cancer is one of the leading causes of cancer death among females, worldwide. The contributory role of different cellular pathways in the process of carcinogenesis is still poorly understood. Our study was focused here to understand the functional evaluation of key regulatory genes of FA-BRCA pathway in the development of CACX and their role in chemo-tolerance of the disease by analyzing the molecular profile of the genes both in normal and tumour tissue of our sample pool, also validated in in silico datasets. Later on, prognostic importance of the genes was further evaluated in plasma DNA and cisplatin-treated in vitro system. We found that expression profile of FA-BRCA pathway genes was gradually reduced from undifferentiated basal-parabasal layers of normal tissue towards the progression of the disease. Further analysis revealed that frequent promoter methylation [32-55%] and deletion [34-52%] events were the plausible reasons for their reduced expression in CACX. Noticeably, invasion of promoter methylation of the genes [11-17%] in plasma CTCs of CACX patients was positively correlated [p < 0.001] with poor prognosis among patients. On the other hand, functional upregulation of these genes at higher concentrations [IC50-70] of cisplatin was a predictor for the development of drug tolerance, as evaluated in our in vitro study. This finding was supported further by low prevalence of γ-H2X foci formation and reduced expression of DNMT1 at higher concentrations of cisplatin. In totality, we discovered that the FA-BRCA pathway must be inactivated for cancer formation. In contrast, elevated gene expression played a substantial role in building of chemo-tolerance and might be associated with developing increased risk of disease recurrence among patients.

Interaction studies between human papillomavirus virus-like particles and laminin 332 by affinity capillary electrophoresis assisted by bio-layer interferometry

Human papillomavirus (HPV) interacts, in vitro, with laminin 332 (LN332), a key component of the extracellular matrix. In this study, we performed bio-layer interferometry (BLI) and affinity capillary electrophoresis (ACE) to investigate the binding properties of this interaction. Virus-like particles (VLPs), composed of the HPV16 L1 major capsid protein, were used as HPV model and LN332 as the VLPs binding partner. Using BLI, we quantitatively determined the kinetics of the interaction, via the measurement of VLP binding and release from LN332 immobilized onto the surface of aminopropylsilane biosensors. We found an averaged kon of 1.74 x 104 M-1s-1 and an averaged koff of 1.50 x 10-4 s-1. Furthermore, an ACE method was developed to study the interaction under physiological conditions, where the interactants are moving freely in solution, without any fluorescence labeling. Specifically, a constant amount of HPV16-VLPs was preincubated with increasing LN332 concentrations and then the samples were injected in the capillary electrophoresis instrument. A shift in the migration time of the HPV16-VLP/LN332 complexes, carrying an increasing number of LN332 molecules bound per VLP, was observed. The mobility of the complexes was found to decrease with increasing LN332 concentrations in the sample. It was used to quantify stability constant. From BLI and ACE approaches, we reported an apparent equilibrium dissociation constant in the nanomolar range (8.89 nM and 17.7 nM, respectively) for the complex between HPV16-VLPs and LN332.

Inter-epitope spacer variation within polytopic L2-based human papillomavirus antigens affects immunogenicity

The human papillomavirus minor capsid protein L2 is being extensively explored in pre-clinical studies as an attractive vaccine antigen capable of inducing broad-spectrum prophylactic antibody responses. Recently, we have developed two HPV vaccine antigens - PANHPVAX and CUT-PANHPVAX- both based on heptameric nanoparticle antigens displaying polytopes of the L2 major cross-neutralizing epitopes of eight mucosal and twelve cutaneous HPV types, respectively. Prompted by the variable neutralizing antibody responses against some of the HPV types targeted by the antigens observed in previous studies, here we investigated the influence on immunogenicity of six distinct glycine-proline spacers inserted upstream to a specific L2 epitope. We show that spacer variants differentially influence antigen immunogenicity in a mouse model, with the antigen constructs M8merV6 and C12merV6 displaying a superior ability in the induction of neutralizing antibodies as determined by pseudovirus-based neutralization assays (PBNAs). L2-peptide enzyme-linked immunosorbent assay (ELISA) assessments determined the total anti-L2 antibody level for each antigen variant, showing for the majority of sera a correlation with their repective neutralizing antibody level. Surface Plasmon Resonance revealed that L2 epitope-specific, neutralizing monoclonal antibodies (mAbs) display distinct avidities to different antigen spacer variants. Furthermore, mAb affinity toward individual spacer variants was well correlated with their neutralizing antibody induction capacity, indicating that the mAb affinity assay predicts L2-based antigen immunogenicity. These observations provide insights on the development and optimization of L2-based HPV vaccines.

Impact of HPV strains on molecular mechanisms of cervix cancer

PURPOSE

Cervical cancer accounts for a high number of deaths worldwide. Risk factors are extensive for cervix cancer but Human papillomavirus (HPV) plays a prime role in its development. Different strains of HPV are prevalent globally, which show different grades of mortality and morbidity among women. This study is planned to evaluate the molecular mechanism of different strains of HPV infection and progression leading to cervix cancer.

METHODS

This review includes different research articles on cervix cancer progression reported from India and all over the world.

RESULTS

HPV 16 and 18 are prevalent strains using heparan sulfate-independent and dependent pathways for viral replication inside the cell. It also uses transcription mechanisms through NF-kappa B, FOXA-1, and AP-1 genes while strains like HPV-35, 45, and 52 are also predominant in India, which showed a very slow mechanism of progression due to which mortality rate is low after their infection with these strains.

CONCLUSION

HPV uses E6 and E7 proteins which activate NF-kappa B and AP-1 pathway which suppresses the tumor suppressor gene and activates cytokine production, causing inflammation and leading to a decrease in apoptosis due to Caspase-3 activation. In contrast, the E7 protein involves HOXA genes and decreases apoptotic factors due to which mortality and incidence rates are low in viruses that use E7 motifs. Some HPV strains employ the cap-dependent pathway, which is also associated with lower mortality and infection rates.

Impact of age at vaccination and cervical HPV infection status on binding and neutralizing antibody titers at 10 years after receiving single or higher doses of quadrivalent HPV vaccine

Long-term follow-up of a cohort of unmarried girls who received one, two, or three doses of quadrivalent HPV vaccine, between 10 and 18 years of age, in an Indian multi-centric study allowed us to compare antibody responses between the younger and older age cohorts at 10-years post-vaccination, and study the impact of initiation of sexual activity and cervical HPV infections on antibody levels. Among the younger (10-14 years) recipients of a single dose, 97.7% and 98.2% had detectable binding antibody titers against HPV 16 and HPV 18 respectively at ten years post-vaccination. The proportions among those receiving a single dose at age 15-18 years were 92.3% and 94.2% against HPV 16 and HPV 18 respectively. Mean HPV 16 binding antibody titers were 2.1 folds (95%CI 1.4 to 3.3) higher in those vaccinated at ages 10-14 years, and 1.9 folds (95%CI 1.2 to 3.0) higher in those vaccinated at 15-18 years compared to mean titers seen in the unvaccinated women. Compared to previous timepoints of 36 or 48 months, binding antibodies against HPV 16 and neutralizing antibodies against both HPV 16 and HPV 18 were significantly higher at 10 years. This rise was more pronounced in participants vaccinated at 15-18 years. No association of marital status or cervical HPV infections was observed with the rise in titer. Durability of antibody response in single dose recipients correlated well with the high efficacy of a single dose against persistent HPV 16/18 infections irrespective of age at vaccination, as we reported earlier.

Epidemiology, Molecular Pathogenesis, Immuno-Pathogenesis, Immune Escape Mechanisms and Vaccine Evaluation for HPV-Associated Carcinogenesis

Human papillomavirus (HPV) is implicated in over 90% of cervical cancer cases, with factors like regional variability, HPV genotype, the population studied, HPV vaccination status, and anatomical sample collection location influencing the prevalence and pathology of HPV-induced cancer. HPV-16 and -18 are mainly responsible for the progression of several cancers, including cervix, anus, vagina, penis, vulva, and oropharynx. The oncogenic ability of HPV is not only sufficient for the progression of malignancy, but also for other tumor-generating steps required for the production of invasive cancer, such as coinfection with other viruses, lifestyle factors such as high parity, smoking, tobacco chewing, use of contraceptives for a long time, and immune responses such as stimulation of chronic stromal inflammation and immune deviation in the tumor microenvironment. Viral evasion from immunosurveillance also supports viral persistence, and virus-like particle-based prophylactic vaccines have been licensed, which are effective against high-risk HPV types. In addition, vaccination awareness programs and preventive strategies could help reduce the rate and incidence of HPV infection. In this review, we emphasize HPV infection and its role in cancer progression, molecular and immunopathogenesis, host immune response, immune evasion by HPV, vaccination, and preventive schemes battling HPV infection and HPV-related cancers.

Recent Updates on Viral Oncogenesis: Available Preventive and Therapeutic Entities

Human viral oncogenesis is a complex phenomenon and a major contributor to the global cancer burden. Several recent findings revealed cellular and molecular pathways that promote the development and initiation of malignancy when viruses cause an infection. Even, antiviral treatment has become an approach to eliminate the viral infections and prevent the activation of oncogenesis. Therefore, for a better understanding, the molecular pathogenesis of various oncogenic viruses like, hepatitis virus, human immunodeficiency viral (HIV), human papillomavirus (HPV), herpes simplex virus (HSV), and Epstein-Barr virus (EBV), could be explored, especially, to expand many potent antivirals that may escalate the apoptosis of infected malignant cells while sparing normal and healthy ones. Moreover, contemporary therapies, such as engineered antibodies antiviral agents targeting signaling pathways and cell biomarkers, could inhibit viral oncogenesis. This review elaborates the recent advancements in both natural and synthetic antivirals to control viral oncogenesis. The study also highlights the challenges and future perspectives of using antivirals in viral oncogenesis.

HPV is a cargo for the COPI sorting complex during virus entry

During entry, human papillomavirus (HPV) traffics from the cell surface to the endosome and then to the trans-Golgi network (TGN) and Golgi apparatus. HPV must transit across the TGN/Golgi and exit these compartments to reach the nucleus to cause infection, although how these steps are accomplished is unclear. Combining cellular fractionation, unbiased proteomics, and gene knockdown strategies, we identified the coat protein complex I (COPI), a highly conserved protein complex that facilitates retrograde trafficking of cellular cargos, as a host factor required for HPV infection. Upon TGN/Golgi arrival, the cytoplasmic segment of HPV L2 binds directly to COPI. COPI depletion causes the accumulation of HPV in the TGN/Golgi, resembling the fate of a COPI binding-defective L2 mutant. We propose that the L2-COPI interaction drives HPV trafficking through the TGN and Golgi stacks during virus entry. This shows that an incoming virus is a cargo of the COPI complex.

Pseudotyped Virus for Papillomavirus

Papillomavirus is difficult to culture in vitro, which limits its related research. The development of pseudotyped virus technology provides a valuable research tool for virus infectivity research, vaccine evaluation, infection inhibitor evaluation, and so on. Depending on the application fields, different measures have been developed to generate various kinds of pseudotyped papillomavirus. L1-based and L2-based HPV vaccines should be evaluated using different pseudotyped virus system. Pseudotyped papillomavirus animal models need high-titer pseudotyped virus and unique handling procedure to generate robust results. This paper reviewed the development, optimization, standardization, and application of various pseudotyped papillomavirus methods.

Mutation Profile of HPV16 L1 and L2 Genes in Different Geographic Areas

The causal relationship between HPV and cervical cancer in association with the high prevalence of high risk HPV genotypes led to the design of HPV vaccines based on the major capsid L1 protein. In recent years, capsid protein L2 has also become a focal point in the field of vaccine research. The present review focuses on the variability of HPV16 L1 and L2 genes, emphasizing the distribution of specific amino acid changes in the epitopes of capsid proteins. Moreover, a substantial bioinformatics analysis was conducted to describe the worldwide distribution of amino acid substitutions throughout HPV16 L1, L2 proteins. Five amino acid changes (T176N, N181T; EF loop), (T266A; FG loop), (T353P, T389S; HI loop) are frequently observed in the L1 hypervariable surface loops, while two amino acid substitutions (D43E, S122P) are adjacent to L2 specific epitopes. These changes have a high prevalence in certain geographic regions. The present review suggests that the extensive analysis of the amino acid substitutions in the HPV16 L1 immunodominant loops may provide insights concerning the ability of the virus in evading host immune response in certain populations. The genetic variability of the HPV16 L1 and L2 epitopes should be extensively analyzed in a given population.

Bovine Papillomavirus Type 1 or 2 Virion-Infected Primary Fibroblasts Constitute a Near-Natural Equine Sarcoid Model

Equine sarcoids are common, locally aggressive skin tumors induced by bovine papillomavirus types 1, 2, and possibly 13 (BPV1, BPV2, BPV13). Current in vitro models do not mimic de novo infection. We established primary fibroblasts from horse skin and succeeded in infecting these cells with native BPV1 and BPV2 virions. Subsequent cell characterization was carried out by cell culture, immunological, and molecular biological techniques. Infection of fibroblasts with serial 10-fold virion dilutions (2 × 10⁶-20 virions) uniformly led to DNA loads settling at around 150 copies/cell after four passages. Infected cells displayed typical features of equine sarcoid cells, including hyperproliferation, and loss of contact inhibition. Neither multiple passaging nor storage negatively affected cell hyperproliferation, viral DNA replication, and gene transcription, suggestive for infection-mediated cell immortalization. Intriguingly, extracellular vesicles released by BPV1-infected fibroblasts contained viral DNA that was most abundant in the fractions enriched for apoptotic bodies and exosomes. This viral DNA is likely taken up by non-infected fibroblasts. We conclude that equine primary fibroblasts stably infected with BPV1 and BPV2 virions constitute a valuable near-natural model for the study of yet unexplored mechanisms underlying the pathobiology of BPV1/2-induced sarcoids.

The Alterations and Roles of Glycosaminoglycans in Human Diseases

Glycosaminoglycans (GAGs) are a heterogeneous family of linear polysaccharides which are composed of a repeating disaccharide unit. They are also linked to core proteins to form proteoglycans (PGs). GAGs/PGs are major components of the cell surface and the extracellular matrix (ECM), and they display critical roles in development, normal function, and damage response in the body. Some properties (such as expression quantity, molecular weight, and sulfation pattern) of GAGs may be altered under pathological conditions. Due to the close connection between these properties and the function of GAGs/PGs, the alterations are often associated with enormous changes in the physiological/pathological status of cells and organs. Therefore, these GAGs/PGs may serve as marker molecules of disease. This review aimed to investigate the structural alterations and roles of GAGs/PGs in a range of diseases, such as atherosclerosis, cancer, diabetes, neurodegenerative disease, and virus infection. It is hoped to provide a reference for disease diagnosis, monitoring, prognosis, and drug development.

The Activity of Chelidonium majus L. Latex and Its Components on HPV Reveal Insights into the Antiviral Molecular Mechanism

Yellow-orange latex of Chelidonium majus L. has been used in folk medicine as a therapeutic agent against warts and other visible symptoms of human papillomavirus (HPV) infections for centuries. The observed antiviral and antitumor properties of C. majus latex are often attributed to alkaloids contained therein, but recent studies indicate that latex proteins may also play an important role in its pharmacological activities. Therefore, the aim of the study was to investigate the effect of the crude C. majus latex and its protein and alkaloid-rich fractions on different stages of the HPV replication cycle. The results showed that the latex components, such as alkaloids and proteins, decrease HPV infectivity and inhibit the expression of viral oncogenes (E6, E7) on mRNA and protein levels. However, the crude latex and its fractions do not affect the stability of structural proteins in HPV pseudovirions and they do not inhibit the virus from attaching to the cell surface. In addition, the protein fraction causes increased TNFα secretion, which may indicate the induction of an inflammatory response. These findings indicate that the antiviral properties of C. majus latex arise both from alkaloids and proteins contained therein, acting on different stages of the viral replication cycle.

Oral Papillomatosis: Its Relation with Human Papilloma Virus Infection and Local Immunity—An Update

Oral papilloma lesions may appear as a result of HPV infection, or not, and only special molecular methods could differentiate them. Low-risk and high-risk HPV types could induce oral HPV papillomatosis with different natural evolution, clearance and persistence mechanisms. The pathogenic mechanisms are based on the crosstalk between the oral epithelial and immune cells and this very efficient virus. HPV acts as a direct inducer in the process of transforming a benign lesion into a malignant one, the cancerization process being also debated in this paper. According to the degree of malignity, three types of papillomatous lesions can be described in the oral cavity: benign lesions, potential malign disorders and malignant lesions. The precise molecular diagnostic is important to identify the presence of various virus types and also the virus products responsible for its oncogenicity. An accurate diagnostic of oral papilloma can be established through a good knowledge of etiological and epidemiological factors, clinical examination and laboratory tests. This review intends to update the pathogenic mechanisms driving the macroscopic and histological features of oral papillomatosis having HPV infection as the main etiological factor, focusing on its interreference in the local immunity. In the absence of an accurate molecular diagnostic and knowledge of local immunological conditions, the therapeutic strategy could be difficult to decide.

Single-cell analysis of Kaposi's sarcoma-associated herpesvirus infection in three-dimensional air-liquid interface culture model

The oral cavity is the major site for transmission of Kaposi's sarcoma-associated herpesvirus (KSHV), but how KSHV establishes infection and replication in the oral epithelia remains unclear. Here, we report a KSHV spontaneous lytic replication model using fully differentiated, three-dimensional (3D) oral epithelial organoids at an air-liquid interface (ALI). This model revealed that KSHV infected the oral epithelia when the basal epithelial cells were exposed by damage. Unlike two-dimensional (2D) cell culture, 3D oral epithelial organoid ALI culture allowed high levels of spontaneous KSHV lytic replication, where lytically replicating cells were enriched at the superficial layer of epithelial organoid. Single cell RNA sequencing (scRNAseq) showed that KSHV infection induced drastic changes of host gene expression in infected as well as uninfected cells at the different epithelial layers, resulting in altered keratinocyte differentiation and cell death. Moreover, we identified a unique population of infected cells containing lytic gene expression at the KSHV K2-K5 gene locus and distinct host gene expression compared to latent or lytic infected cells. This study demonstrates an in vitro 3D epithelial organoid ALI culture model that recapitulates KSHV infection in the oral cavity, where KSHV undergoes the epithelial differentiation-dependent spontaneous lytic replication with a unique cell population carrying distinct viral gene expression.

Therapeutic Vaccines for HPV-Associated Oropharyngeal and Cervical Cancer: The Next De-Intensification Strategy?

The rise in human papillomavirus (HPV)-associated oropharyngeal squamous cell carcinoma (OPSCC) has prompted a quest for further understanding of the role of high-risk HPV in tumor initiation and progression. Patients with HPV-positive OPSCC (HPV+ OPSCC) have better prognoses than their HPV-negative counterparts; however, current therapeutic strategies for HPV+ OPSCC are overly aggressive and leave patients with life-long sequalae and poor quality of life. This highlights a need for customized treatment. Several clinical trials of treatment de-intensification to reduce acute and late toxicity without compromising efficacy have been conducted. This article reviews the differences and similarities in the pathogenesis and progression of HPV-related OPSCC compared to cervical cancer, with emphasis on the role of prophylactic and therapeutic vaccines as a potential de-intensification treatment strategy. Overall, the future development of novel and effective therapeutic agents for HPV-associated head and neck tumors promises to meet the challenges posed by this growing epidemic.

Harnessing Human Papillomavirus' Natural Tropism to Target Tumors

Human papillomaviruses (HPV) are small non-enveloped DNA tumor viruses established as the primary etiological agent for the development of cervical cancer. Decades of research have elucidated HPV's primary attachment factor to be heparan sulfate proteoglycans (HSPG). Importantly, wounding and exposure of the epithelial basement membrane was found to be pivotal for efficient attachment and infection of HPV in vivo. Sulfation patterns on HSPG's become modified at the site of wounds as they serve an important role promoting tissue healing, cell proliferation and neovascularization and it is these modifications recognized by HPV. Analogous HSPG modification patterns can be found on tumor cells as they too require the aforementioned processes to grow and metastasize. Although targeting tumor associated HSPG is not a novel concept, the use of HPV to target and treat tumors has only been realized in recent years. The work herein describes how decades of basic HPV research has culminated in the rational design of an HPV-based virus-like infrared light activated dye conjugate for the treatment of choroidal melanoma.

RG2-VLP: a Vaccine Designed to Broadly Protect against Anogenital and Skin Human Papillomaviruses Causing Human Cancer

The family of human papillomaviruses (HPV) includes over 400 genotypes. Genus α genotypes generally infect the anogenital mucosa, and a subset of these HPV are a necessary, but not sufficient, cause of cervical cancer. Of the 13 high-risk (HR) and 11 intermediate-risk (IR) HPV associated with cervical cancer, genotypes 16 and 18 cause 50% and 20% of cases, respectively, whereas HPV16 dominates in other anogenital and oropharyngeal cancers. A plethora of βHPVs are associated with cutaneous squamous cell carcinoma (CSCC), especially in sun-exposed skin sites of epidermodysplasia verruciformis (EV), AIDS, and immunosuppressed patients. Licensed L1 virus-like particle (VLP) vaccines, such as Gardasil 9, target a subset of αHPV but no βHPV. To comprehensively target both α- and βHPVs, we developed a two-component VLP vaccine, RG2-VLP, in which L2 protective epitopes derived from a conserved αHPV epitope (amino acids 17 to 36 of HPV16 L2) and a consensus βHPV sequence in the same region are displayed within the DE loop of HPV16 and HPV18 L1 VLP, respectively. Unlike vaccination with Gardasil 9, vaccination of wild-type and EV model mice (Tmc6Δ/Δ or Tmc8Δ/Δ) with RG2-VLP induced robust L2-specific antibody titers and protected against β-type HPV5. RG2-VLP protected rabbits against 17 αHPV, including those not covered by Gardasil 9. HPV16- and HPV18-specific neutralizing antibody responses were similar between RG2-VLP- and Gardasil 9-vaccinated animals. However, only transfer of RG2-VLP antiserum effectively protected naive mice from challenge with all βHPVs tested. Taken together, these observations suggest RG2-VLP's potential as a broad-spectrum vaccine to prevent αHPV-driven anogenital, oropharyngeal, and βHPV-associated cutaneous cancers. IMPORTANCE Licensed preventive HPV vaccines are composed of VLPs derived by expression of major capsid protein L1. They confer protection generally restricted to infection by the αHPVs targeted by the up-to-9-valent vaccine, and their associated anogenital cancers and genital warts, but do not target βHPV that are associated with CSCC in EV and immunocompromised patients. We describe the development of a two-antigen vaccine protective in animal models against known oncogenic αHPVs as well as diverse βHPVs by incorporation into HPV16 and HPV18 L1 VLP of 20-amino-acid conserved protective epitopes derived from minor capsid protein L2.

Proteases and HPV-Induced Carcinogenesis

Simple Summary

Human papillomavirus (HPV) infection is a sexually transmitted disease with high prevalence worldwide. Although most HPV infections do not lead to cancer, some HPV types are correlated with the majority of cervical cancers, and with some anogenital and oropharyngeal cancers. Moreover, enzymes known as proteases play an essential role in the pathogenic process in HPV-induced carcinogenesis. This review highlights the role of proteases and recent epidemiological data regarding HPV-dependent carcinogenesis.

Abstract

Persistent infection with Human papillomavirus (HPV) is the main etiologic factor for pre-malignant and malignant cervical lesions. Moreover, HPV is also associated with oropharynx and other anogenital carcinomas. Cancer-causing HPV viruses classified as group 1 carcinogens include 12 HPV types, with HPV 16 and 18 being the most prevalent. High-risk HPVs express two oncoproteins, E6 and E7, the products of which are responsible for the inhibition of p53 and pRB proteins, respectively, in human keratinocytes and cellular immortalization. p53 and pRB are pleiotropic proteins that regulate the activity of several signaling pathways and gene expression. Among the important factors that are augmented in HPV-mediated carcinogenesis, proteases not only control processes involved in cellular carcinogenesis but also control the microenvironment. For instance, genetic polymorphisms of matrix metalloproteinase 1 (MMP-1) are associated with carcinoma invasiveness. Similarly, the serine protease inhibitors hepatocyte growth factor activator inhibitor-1 (HAI-1) and -2 (HAI-2) have been identified as prognostic markers for HPV-dependent cervical carcinomas. This review highlights the most crucial mechanisms involved in HPV-dependent carcinogenesis, and includes a section on the proteolytic cascades that are important for the progression of this disease and their impact on patient health, treatment, and survival.

HIV-1-Mediated Acceleration of Oncovirus-Related Non-AIDS-Defining Cancers

With the advent of combination antiretroviral therapy (cART), overall survival has been improved, and the incidence of acquired immunodeficiency syndrome (AIDS)-defining cancers has also been remarkably reduced. However, non-AIDS-defining cancers among human immunodeficiency virus-1 (HIV-1)-associated malignancies have increased significantly so that cancer is the leading cause of death in people living with HIV in certain highly developed countries, such as France. However, it is currently unknown how HIV-1 infection raises oncogenic virus-mediated cancer risks in the HIV-1 and oncogenic virus co-infected patients, and thus elucidation of the molecular mechanisms for how HIV-1 expedites the oncogenic viruses-triggered tumorigenesis in the co-infected hosts is imperative for developing therapeutics to cure or impede the carcinogenesis. Hence, this review is focused on HIV-1 and oncogenic virus co-infection-mediated molecular processes in the acceleration of non-AIDS-defining cancers.

Chondroitin Sulfate Proteoglycans Are De Facto Cellular Receptors for Human Papillomavirus 16 under High Serum Conditions

Heparan sulfate proteoglycans (HSPGs) have previously been identified as primary attachment factors for the initial binding of human papillomaviruses (HPVs) prior to infection. Here, we demonstrate that in vitro , HPV binding to HSPGs is strongly dependent on the surrounding experimental conditions, including the concentration of fetal bovine serum (FBS).

HPV16 Entry into Epithelial Cells: Running a Gauntlet

During initial infection, human papillomaviruses (HPV) take an unusual trafficking pathway through their host cell. It begins with a long period on the cell surface, during which the capsid is primed and a virus entry platform is formed. A specific type of clathrin-independent endocytosis and subsequent retrograde trafficking to the trans-Golgi network follow this. Cellular reorganization processes, which take place during mitosis, enable further virus transport and the establishment of infection while evading intrinsic cellular immune defenses. First, the fragmentation of the Golgi allows the release of membrane-encased virions, which are partially protected from cytoplasmic restriction factors. Second, the nuclear envelope breakdown opens the gate for these virus–vesicles to the cell nucleus. Third, the dis- and re-assembly of the PML nuclear bodies leads to the formation of modified virus-associated PML subnuclear structures, enabling viral transcription and replication. While remnants of the major capsid protein L1 and the viral DNA remain in a transport vesicle, the viral capsid protein L2 plays a crucial role during virus entry, as it adopts a membrane-spanning conformation for interaction with various cellular proteins to establish a successful infection. In this review, we follow the oncogenic HPV type 16 during its long journey into the nucleus, and contrast pro- and antiviral processes.

If prophylactic HPV vaccination is considered in a woman with CIN2+, what is the value and should it be given before or after the surgical treatment?

Since the introduction of human papilloma virus (HPV) vaccination, the number of precancerous lesions has decreased in countries with a high HPV vaccination coverage. Currently women who present with a precancerous cervical lesions (CIN2 + ), are often not vaccinated or not vaccinated with the latest vaccine. Although resection of the precancerous lesion is the standard approach, the guidelines regarding vaccination are not clear. Vaccination will be valuable in reducing the risk of recurrence. Therefore, it is beneficial to understand the importance of vaccination or revaccination with the nonavalent vaccine in these cases. Furthermore, the timing of vaccination, either before or after surgery, should be determined. To answer these questions, twelve studies regarding vaccination and conization were reviewed. The inconsistency of study designs and inclusion criteria between the different studies introduced a considerable risk of bias. Nevertheless, the analysis showed that 43 women needed to be vaccinated and treated for CIN2 + lesions to prevent a recurrence. The ideal timing could not be established, but theoretically vaccination before the start of treatment was most logic. Although the data is not level 1 evidence, these recommendations should be used during counseling in the clinical setting until results of ongoing randomized controlled trials become available.

Recent Advances in Our Understanding of the Infectious Entry Pathway of Human Papillomavirus Type 16

Papillomaviruses are a diverse viral species, but several types such as HPV16 are given special attention due to their contribution towards the pathogenesis of several major cancers. In this review, we will summarize how the knowledge of HPV16 entry has expanded since the last comprehensive HPV16 entry review our lab published in 2017.

Photodynamic therapy using methylene blue and intense pulsed light versus intense pulsed light alone in treatment of verruca: A randomized controlled study

BACKGROUND

Many therapeutic modalities are available for treatment of warts, but no single therapy is universally effective. Photodynamic therapy (PDT) using intralesional methylene blue (MB) followed by intense pulsed light (IPL) could be a successful option for treatment by several mechanisms.

METHODS

This prospective randomized controlled trial was carried out on eighty patients with verrucae. Patients were randomized into three groups; group A (30 patients) received MB/IPL/PDT sessions, group B (30 Patients) received IPL sessions, and group C (control). Response was assessed by clinical and dermoscopy score (0,1, 2, or 3 according to extent of clinical and dermoscopic resolution), cure rate (percent of verrucae clinically and dermoscopy cleared), and imageJ analysis (surface area of wart and haemorrhagic structures or vessels).

RESULTS

Clinical and dermoscopic clearance was achieved in 43.3% and 20% of patients in groups A and B respectively. Cure rate was 40.9% for group A compared to 23.4% for group B. ImageJ analysis revealed more reduction of surface area in group A being 80.05 ± 27.12% for verrucae and 89.28 ± 19.19% for vessels and haemorrhagic dots compared to 48.16 ± 34.21% and 65.99 ± 30.58% in group B.

CONCLUSIONS

MB/IPL/PDT is an effective option for treatment of warts with a success rate of around 40%, based on clinical and dermoscopic assessment. The efficacy was found to be higher on using imageJ utilizing both the surface area of the wart and surface area of vessels and haemorrhagic dots with the latter being more effected by treatment.

Kallikreins emerge as new regulators of viral infections

Kallikrein-related peptidases (KLKs) or kallikreins have been linked to diverse (patho) physiological processes, such as the epidermal desquamation and inflammation, seminal clot liquefaction, neurodegeneration, and cancer. Recent mounting evidence suggests that KLKs also represent important regulators of viral infections. It is well-established that certain enveloped viruses, including influenza and coronaviruses, require proteolytic processing of their hemagglutinin or spike proteins, respectively, to infect host cells. Similarly, the capsid protein of the non-enveloped papillomavirus L1 should be proteolytically cleaved for viral uncoating. Consequently, extracellular or membrane-bound proteases of the host cells are instrumental for viral infections and represent potential targets for drug development. Here, we summarize how extracellular proteolysis mediated by the kallikreins is implicated in the process of influenza (and potentially coronavirus and papillomavirus) entry into host cells. Besides direct proteolytic activation of viruses, KLK5 and 12 promote viral entry indirectly through proteolytic cascade events, like the activation of thrombolytic enzymes that also can process hemagglutinin, while additional functions of KLKs in infection cannot be excluded. In the light of recent evidence, KLKs represent potential host targets for the development of new antivirals. Humanized animal models to validate their key functions in viral infections will be valuable.

Mixed Bacteriophage MS2-L2 VLPs Elicit Long-Lasting Protective Antibodies against HPV Pseudovirus 51

Three prophylactic vaccines are approved to protect against HPV infections. These vaccines are highly immunogenic. The most recent HPV vaccine, Gardasil-9, protects against HPV types associated with ~90% of cervical cancer (worldwide). Thus, ~10% of HPV-associated cancers are not protected by Gardasil-9. Although this is not a large percentage overall, the HPV types associated with 10% of cervical cancer not protected by the current vaccine are significantly important, especially in HIV/AIDS patients who are infected with multiple HPV types. To broaden the spectrum of protection against HPV infections, we developed mixed MS2-L2 VLPs (MS2-31L2/16L2 VLPs and MS2-consL2 (69-86) VLPs) in a previous study. Immunization with the VLPs neutralized/protected mice against infection with eleven high-risk HPV types associated with ~95% of cervical cancer and against one low-risk HPV type associated with ~36% of genital warts & up to 32% of recurrent respiratory papillomatosis. Here, we report that the mixed MS2-L2 VLPs can protect mice from three additional HPV types: HPV51, which is associated with ~0.8% of cervical cancer; HPV6, which is associated with up to 60% of genital warts; HPV5, which is associated with skin cancers in patients with epidermodysplasia verruciformis (EV). Overall, mixed MS2-L2 VLPs can protect against twelve HPV types associated with ~95.8% of cervical cancers and against two HPV types associated with ~90% of genital warts and >90% recurrent respiratory papillomatosis. Additionally, the VLPs protect against one of two HPV types associated with ~90% of HPV-associated skin cancers in patients with EV. More importantly, we observed that mixed MS2-L2 VLPs elicit protective antibodies that last over 9 months. Furthermore, a spray-freeze-dried formulation of the VLPs is stable, immunogenic, and protective at room temperature and 37 °C.

Lineage analysis of human papillomavirus types 31 and 45 in cervical samples of Iranian women

Knowing the regional lineages/sublineages of human papillomavirus 31 (HPV 31) and 45 would be of great importance for further evolutionary, epidemiological, and biological analysis. In this regard, to characterize more common lineages and sublineages of HPV 31 and 45, the sequence variations of E6 gene were investigated in normal, premalignant, and malignant samples collected from the cervix in Iran. In total, 54 HPV 31- and 24 HPV 45-positive samples were analyzed by hemi-nested polymerase chain reaction (PCR) and nested-PCR, respectively. All PCR products were subjected to direct sequencing analysis. The results indicated that all three lineages A, B, and C were detected in HPV 31-positive samples; among which HPV 31 lineage A was dominant as it was found in 66.7% of all samples. HPV 31 lineages B and C were identified in 5.5% and 27.8% of samples, respectively. In HPV 45-infected samples, lineage B comprised of 62.5% of all samples and the remaining 37.5%  belonged to lineage A. In conclusion, our findings showed that lineage A of HPV 31 was predominant in Iran. Lineage B of HPV 45 was also dominant among Iranian women. However, further studies with larger sample size should be addressed to estimate the pathogenicity risk of HPV 31 or HPV 45 lineages/sublineages in the development of cervical cancer among Iranian women.

Viruses and Skin Cancer

Advances in virology and skin cancer over recent decades have produced achievements that have been recognized not only in the field of dermatology, but also in other areas of medicine. They have modified the therapeutic and preventive solutions that can be offered to some patients and represent a significant step forward in our knowledge of the biology of skin cancer. In this paper, we review the viral agents responsible for different types of skin cancer, especially for solid skin tumors. We focus on human papillomavirus and squamous cell cancers, Merkel cell polyomavirus and Merkel cell carcinoma, and human herpesvirus 8 and Kaposi’s sarcoma.

Genetic instability and anti-HPV immune response as drivers of infertility associated with HPV infection

Human papillomavirus (HPV) is a sexually transmitted infection common among men and women of reproductive age worldwide. HPV viruses are associated with epithelial lesions and cancers. HPV infections have been shown to be significantly associated with many adverse effects in reproductive function. Infection with HPVs, specifically of high-oncogenic risk types (HR HPVs), affects different stages of human reproduction, resulting in a series of adverse outcomes: 1) reduction of male fertility (male infertility), characterized by qualitative and quantitative semen alterations; 2) impairment of couple fertility with increase of blastocyst apoptosis and reduction of endometrial implantation of trophoblastic cells; 3) defects of embryos and fetal development, with increase of spontaneous abortion and spontaneous preterm birth. The actual molecular mechanism(s) by which HPV infection is involved remain unclear. HPV-associated infertility as Janus, has two faces: one reflecting anti-HPV immunity, and the other, direct pathogenic effects of HPVs, specifically, of HR HPVs on the infected/HPV-replicating cells. Adverse effects observed for HR HPVs differ depending on the genotype of infecting virus, reflecting differential response of the host immune system as well as functional differences between HPVs and their individual proteins/antigens, including their ability to induce genetic instability/DNA damage. Review summarizes HPV involvement in all reproductive stages, evaluate the adverse role(s) played by HPVs, and identifies mechanisms of viral pathogenicity, common as well as specific for each stage of the reproduction process.

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.

Emerging Roles of Heparan Sulfate Proteoglycans in Viral Pathogenesis

Heparan sulfate is a glycosaminoglycan present in nearly all mammalian tissues. Heparan sulfate moieties are attached to the cell surface via heparan sulfate proteoglycans (HSPGs) which are composed of a protein core bound to multiple heparan sulfate chains. HSPGs contribute to the structural integrity of the extracellular matrix and participate in cell signaling by releasing bound cytokines and chemokines once cleaved by an enzyme, heparanase. HSPGs are often exploited by viruses during infection, particularly during attachment and egress. Loss or inhibition of HSPGs initially during infection can yield significant decreases in viral entry and infectivity. In this review, we provide an overview of HSPGs in the lifecycle of multiple viruses, including herpesviruses, human immunodeficiency virus, dengue virus, human papillomavirus, and coronaviruses.

How Enhancing Immunity to Low-Risk HPV Could Cure Recurrent Respiratory Papillomatosis

Recurrent respiratory papillomatosis (RRP) is currently treated with repeat surgical resection of papillomatous disease that does not address the fundamental underlying issue of chronic infection with low-risk human papillomavirus. Here, we review the biology and immunology of low-risk human papillomavirus (HPV) infections. Antiviral or antiangiogenic adjuvant treatments similarly address the papillomatous disease itself but do not activate HPV immunity. It is likely that only through immune-mediated clearance of low-risk HPV infection can patients with RRP be cured. In some patients, this occurs spontaneously. In others with more aggressive disease, adjuvant immunotherapy to activate immunity may be needed. Based on current understanding of antiviral immune responses, the only rational strategy to clear HPV-infected epithelial cells is through activation of the T-lymphocyte arm of the adaptive immune response. Translation of immunotherapies that are Food and Drug Administration-approved or under clinical study for cancer, such as immune checkpoint blockade or engineered therapeutic vaccines, may provide a path toward tolerable and efficacious adjuvant immunotherapy for RRP. LEVEL OF EVIDENCE: NA Laryngoscope, 131:2041-2047, 2021.

Glycosaminoglycan-Protein Interactions and Their Roles in Human Disease

Glycosaminoglycans (GAGs) are a family of linear and negatively charged polysaccharides that exist ubiquitously on the human cell surface as well as in the extracellular matrix. GAGs interact with a wide range of proteins, including proteases, growth factors, cytokines, chemokines and adhesion molecules, enabling them to mediate many physiological processes, such as protein function, cellular adhesion and signaling. GAG-protein interactions participate in and intervene in a variety of human diseases, including cardiovascular disease, infectious disease, neurodegenerative diseases and tumors. The breakthrough in analytical tools and approaches during the last two decades has facilitated a greater understanding of the importance of GAG-protein interactions and their roles in human diseases. This review focuses on aspects of the molecular basis and mechanisms of GAG-protein interactions involved in human disease. The most recent advances in analytical tools, especially mass spectrometry-based GAG sequencing and binding motif characterization methods, are introduced. An update of selected families of GAG binding proteins is presented. Perspectives on development of novel therapeutics targeting specific GAG-protein interactions are also covered in this review.

RG1-VLP and Other L2-Based, Broad-Spectrum HPV Vaccine Candidates

Licensed human papillomavirus (HPV) vaccines contain virus-like particles (VLPs) self-assembled from L1 major-capsid proteins that are remarkably effective prophylactic immunogens. However, the induced type-restricted immune response limits coverage to the included vaccine types, and costly multiplex formulations, restrictive storage and distribution conditions drive the need for next generation HPV vaccines. Vaccine candidates based upon the minor structural protein L2 are particularly promising because conserved N-terminal epitopes induce broadly cross-type neutralizing and protective antibodies. Several strategies to increase the immunological potency of such epitopes are being investigated, including concatemeric multimers, fusion to toll-like receptors ligands or T cell epitopes, as well as immunodominant presentation by different nanoparticle or VLP structures. Several promising L2-based vaccine candidates have reached or will soon enter first-in-man clinical studies. RG1-VLP present the HPV16L2 amino-acid 17–36 conserved neutralization epitope “RG1” repetitively and closely spaced on an immunodominant surface loop of HPV16 L1-VLP and small animal immunizations provide cross-protection against challenge with all medically-significant high-risk and several low-risk HPV types. With a successful current good manufacturing practice (cGMP) campaign and this promising breadth of activity, even encompassing cross-neutralization of several cutaneous HPV types, RG1-VLP are ready for a first-in-human clinical study. This review aims to provide a general overview of these candidates with a special focus on the RG1-VLP vaccine and its road to the clinic.

Human Papillomavirus-Associated Cancers

Human Papillomavirus (HPV) is the causative agent in the majority of anal, head and neck, oral, oropharyngeal, penile, vaginal, vulvar, and cervical cancers. Cervical cancer is the fourth most common cancer among women worldwide. Of all diagnosed human malignant neoplasms, approximately 4.5% are attributable to HPV, including cervical, anal cancers, vaginal, vulvar, penile, and oropharyngeal cancers. Over 182 HPV types have been identified and sequenced to date however, only certain types of HPV are more frequent in malignant lesions and considered to be a major risk factor in the development of some cancers. Because most HPV infections are transient, and an individual's immunocompetent may clear the infection, HPV infection has received little attention from clinicians, the general public, or policy makers. This lack of attention may underpin a deadly and increasing problem because each newly acquired infection has the potential to persist and become an incurable, lifelong affliction. In addition, no successful treatment of HPV infection currently exists despite the great strides toward understanding the mechanisms underlying HPV pathogenesis. Moreover, ample research has proven that the use of prophylactic vaccines, such as Gardasil and Cervarix, have led to documented progress in decreasing the burden of HPV infection, however not all countries introduced a government-funded National HPV Vaccination Program to protect young men and women. This chapter summarizes the HPV infection, detection and prevention. We also shed light on non-cervical HPV-related cancers, which is rapidly increasing in more developed countries toward cervical cancer.

Theta-Defensins Inhibit High-Risk Human Papillomavirus Infection Through Charge-Driven Capsid Clustering

Persistent infection with high-risk human papillomavirus (hrHPV) genotypes results in a large number of anogenital and head and neck cancers worldwide. Although prophylactic vaccination coverage has improved, there remains a need to develop methods that inhibit viral transmission toward preventing the spread of HPV-driven disease. Defensins are a class of innate immune effector peptides that function to protect hosts from infection by pathogens such as viruses and bacteria. Previous work utilizing α and β defensins from humans has demonstrated that the α-defensin HD5 is effective at inhibiting the most common high-risk genotype, HPV16. A third class of defensin that has yet to be explored are θ-defensins: small, 18-amino acid cyclic peptides found in old-world monkeys whose unique structure makes them both highly cationic and resistant to degradation. Here we show that the prototype θ-defensin, rhesus theta defensin 1, inhibits hrHPV infection through a mechanism involving capsid clustering that inhibits virions from binding to cell surface receptor complexes.

p120 catenin recruits HPV to γ-secretase to promote virus infection

During internalization and trafficking, human papillomavirus (HPV) moves from the cell surface to the endosome where the transmembrane protease γ-secretase promotes insertion of the viral L2 capsid protein into the endosome membrane. Protrusion of L2 through the endosome membrane into the cytosol allows the recruitment of cytosolic host factors that target the virus to the Golgi en route for productive infection. How endosome-localized HPV is delivered to γ-secretase, a decisive infection step, is unclear. Here we demonstrate that cytosolic p120 catenin, likely via an unidentified transmembrane protein, interacts with HPV at early time-points during viral internalization and trafficking. In the endosome, p120 is not required for low pH-dependent disassembly of the HPV L1 capsid protein from the incoming virion. Rather, p120 is required for HPV to interact with γ-secretase-an interaction that ensures the virus is transported along a productive route. Our findings clarify an enigmatic HPV infection step and provide critical insights into HPV infection that may lead to new therapeutic strategies against HPV-induced diseases.

Possible Oncogenic Viruses Associated with Lung Cancer

Lung cancer is the most common cause of cancer death worldwide. Tobacco smoking is the most predominant etiology for lung cancer. However, only a small percentage of heavy smokers develop lung cancer, which suggests that other cofactors are required for lung carcinogenesis. Viruses have been central to modern cancer research and provide profound insights into cancer causes. Nevertheless, the role of virus in lung cancer is still unclear. In this article, we reviewed the possible oncogenic viruses associated with lung cancer.

Progress in L2-Based Prophylactic Vaccine Development for Protection against Diverse Human Papillomavirus Genotypes and Associated Diseases

The human papillomaviruses (HPVs) are a family of small DNA tumor viruses including over 200 genotypes classified by phylogeny into several genera. Different genera of HPVs cause ano-genital and oropharyngeal cancers, skin cancers, as well as benign diseases including skin and genital warts. Licensed vaccines composed of L1 virus-like particles (VLPs) confer protection generally restricted to the ≤9 HPV types targeted. Here, we examine approaches aimed at broadening the protection against diverse HPV types by targeting conserved epitopes of the minor capsid protein, L2. Compared to L1 VLP, L2 is less immunogenic. However, with appropriate presentation to the immune system, L2 can elicit durable, broadly cross-neutralizing antibody responses and protection against skin and genital challenge with diverse HPV types. Such approaches to enhance the strength and breadth of the humoral response include the display of L2 peptides on VLPs or viral capsids, bacteria, thioredoxin and other platforms for multimerization. Neither L2 nor L1 vaccinations elicit a therapeutic response. However, fusion of L2 with early viral antigens has the potential to elicit both prophylactic and therapeutic immunity. This review of cross-protective HPV vaccines based on L2 is timely as several candidates have recently entered early-phase clinical trials.

Antiviral therapy for the sexually transmitted viruses: recent updates on vaccine development

INTRODUCTION

The sexually transmitted infections (STIs) caused by viruses including human T cell leukemia virus type-1 (HTLV-1), human immunodeficiency virus-1 (HIV-1), human simplex virus-2 (HSV-2), hepatitis C virus (HCV), hepatitis B virus (HBV), and human papillomavirus (HPV) are major public health issues. These infections can cause cancer or result in long-term health problems. Due to high prevalence of STIs, a safe and effective vaccine is required to overcome these fatal viruses.

AREAS COVERED

This review includes a comprehensive overview of the literatures relevant to vaccine development against the sexually transmitted viruses (STVs) using PubMed and Sciencedirect electronic search engines. Herein, we discuss the efforts directed toward development of effective vaccines using different laboratory animal models including mice, guinea pig or non-human primates in preclinical trials, and human in clinical trials with different phases.

EXPERT OPINION

There is no effective FDA approved vaccine against the sexually transmitted viruses (STVs) except for HBV and HPV as prophylactic vaccines. Many attempts are underway to develop vaccines against these viruses. There are several approaches for improving prophylactic or therapeutic vaccines such as heterologous prime/boost immunization, delivery system, administration route, adjuvants, etc. In this line, further studies can be helpful for understanding the immunobiology of STVs in human. Moreover, development of more relevant animal models is a worthy goal to induce effective immune responses in humans.

Virus-like Particle-Based L2 Vaccines against HPVs: Where Are We Today?

Human papillomaviruses (HPVs) are the most common sexually transmitted infections worldwide. Ninety percent of infected individuals clear the infection within two years; however, in the remaining 10% of infected individuals, the infection(s) persists and ultimately leads to cancers (anogenital cancers and head and neck cancers) and genital warts. Fortunately, three prophylactic vaccines have been approved to protect against HPV infections. The most recent HPV vaccine, Gardasil-9 (a nonavalent vaccine), protects against seven HPV types associated with ~90% of cervical cancer and against two HPV types associated with ~90% genital warts with little cross-protection against non-vaccine HPV types. The current vaccines are based on virus-like particles (VLPs) derived from the major capsid protein, L1. The L1 protein is not conserved among HPV types. The minor capsid protein, L2, on the other hand, is highly conserved among HPV types and has been an alternative target antigen, for over two decades, to develop a broadly protective HPV vaccine. The L2 protein, unlike the L1, cannot form VLPs and as such, it is less immunogenic. This review summarizes current studies aimed at developing HPV L2 vaccines by multivalently displaying L2 peptides on VLPs derived from bacteriophages and eukaryotic viruses. Recent data show that a monovalent HPV L1 VLP as well as bivalent MS2 VLPs displaying HPV L2 peptides (representing amino acids 17–36 and/or consensus amino acids 69–86) elicit robust broadly protective antibodies against diverse HPV types (6/11/16/18/26/31/33/34/35/39/43/44/45/51/52/53/56/58/59/66/68/73) associated with cancers and genital warts. Thus, VLP-based L2 vaccines look promising and may be favorable, in the near future, over current L1-based HPV vaccines and should be explored further.

The Underlying Mechanism of 3-Hydroxyphthalic Anhydride-Modified Bovine Beta-Lactoglobulin to Block Human Papillomavirus Entry Into the Host Cell

We have previously demonstrated that 3-hydroxyphthalic anhydride (3HP)-modified bovine beta-lactoglobulin (3HP-β-LG) is highly effective in inhibiting entry of pseudovirus (PsV) of high- and low-risk human papillomavirus (HPV) into the target cell. Intravaginally applied 3HP-β-LG-containing vaginal gel could significantly inhibit HPV infection and reduce viral load in the cervical region. However, we still do not understand the underlying molecular mechanism by which 3HP-β-LG is able to inhibit HPV infection. Here, though, we showed that 3HP-β-LG did not inactivate HPV PsV, but rather blocked entry of HPV PsV into the target cell via its interaction with virus, not cell. It bound to the positively charged region in the HPV L1 protein, suggesting that 3HP-β-LG binds to HPV L1 protein through the interaction between the negatively charged region in 3HP-β-LG and the positively charged region in HPV L1 protein, thus competitively blocking the binding of HPV to the receptor on the basement membrane in vaginal mucosa. Although 3HP-modified chicken ovalbumin (3HP-OVA) also carries high net negative charges, it exhibited no anti-HPV activity, suggesting that the interaction between 3HP-modified protein and HPV L1 protein relies on both electrostatic and matchable conformation of the binding sites in both proteins. When topically applied, 3HP-β-LG did not enter the host cell or blood circulation. These findings suggest that 3HP-β-LG targets HPV L1 protein and blocks HPV entry into the host cell, thus being safe and effective for topical application in the treatment of HPV infection.