Papillomavirus L1 major capsid protein self-assembles into virus-like particles that are highly immunogenic

Genetic variability of human papillomavirus type 18 based on E6, E7 and L1 genes in central China

BACKGROUND

High-risk human papillomavirus (HR-HPV) infection is an important factor for the development of cervical cancer. HPV18 is the second most common HR-HPV after HPV16.

METHODS

In this study, MEGA11 software was used to analyze the variation and phylogenetic tree of HPV18 E6-E7 and L1 genes. The selective pressure to E6, E7 and L1 genes was estimated using pamlX. In addition, the B cell epitopes of L1 amino acid sequences and T cell epitopes of E6-E7 amino acid sequences in HPV18 were predicted by ABCpred server and IEDB website, respectively.

RESULTS

A total of 9 single nucleotide variants were found in E6-E7 sequences, of which 2 were nonsynonymous variants and 7 were synonymous variants. Twenty single nucleotide variants were identified in L1 sequence, including 11 nonsynonymous variants and 9 synonymous variants. Phylogenetic analysis showed that E6-E7 and L1 sequences were all distributed in A lineage. In HPV18 E6, E7 and L1 sequences, no positively selected site was found. The nonconservative substitution R545C in L1 affected hypothetical B cell epitope. Two nonconservative substitutions, S82A in E6, and R53Q in E7, impacted multiple hypothetical T cell epitopes.

CONCLUSION

The sequence variation data of HPV18 may lay a foundation for the virus diagnosis, further study of cervical cancer and vaccine design in central China.

Immunogenicity of novel vB_EcoS_NBD2 bacteriophage-originated nanotubes as a carrier for peptide-based vaccines

Non-infectious virus-like nanoparticles mimic native virus structures and can be modified by inserting foreign protein fragments, making them immunogenic tools for antigen presentation. This study investigated, for the first time, the immunogenicity of long and flexible polytubes formed by yeast-expressed tail tube protein gp39 of bacteriophage vB_EcoS_NBD2 and evaluated their ability to elicit an immune response against the inserted protein fragments. Protein gp39-based polytubes induced humoral immune response in mice, even without the use of adjuvant. Bioinformatics analysis guided the selection of protein fragments from Acinetobacter baumannii for insertion into the C-terminus of gp39. Chimeric polytubes, displaying 28-amino acid long OmpA protein fragment, induced IgG response against OmpA protein fragment in immunized mice. These polytubes demonstrated their effectiveness both as antigen carrier and an adjuvant, when the OmpA fragments were either displayed on chimeric polytubes or used alongside with the unmodified polytubes. Our findings expand the potential applications of long and flexible polytubes, contributing to the development of novel antigen carriers with improved immunogenicity and antigen presentation capabilities.

Current status and future directions for the development of human papillomavirus vaccines

The development of human papillomavirus (HPV) vaccines has made substantive progress, as represented by the approval of five prophylactic vaccines since 2006. Generally, the deployment of prophylactic HPV vaccines is effective in preventing newly acquired infections and incidences of HPV-related malignancies. However, there is still a long way to go regarding the prevention of all HPV infections and the eradication of established HPV infections, as well as the subsequent progression to cancer. Optimizing prophylactic HPV vaccines by incorporating L1 proteins from more HPV subtypes, exploring adjuvants that reinforce cellular immune responses to eradicate HPV-infected cells, and developing therapeutic HPV vaccines used either alone or in combination with other cancer therapeutic modalities might bring about a new era getting closer to the vision to get rid of HPV infection and related diseases. Herein, we summarize strategies for the development of HPV vaccines, both prophylactic and therapeutic, with an emphasis on the selection of antigens and adjuvants, as well as implications for vaccine efficacy based on preclinical studies and clinical trials. Additionally, we outline current cutting-edge insights on formulation strategies, dosing schedules, and age expansion among HPV vaccine recipients, which might play important roles in addressing barriers to vaccine uptake, such as vaccine hesitancy and vaccine availability.

Ovine papillomavirus type 3 virus-like particle-based tools for diagnosis and detection of infection

The design of prophylactic and diagnostic tools specific to animal papillomaviruses is hampered by the difficulties of viral in vitro manipulation and by the scarce availability of dedicated biotechnological tools. This paper reports the production of Ovine Papillomavirus 3 (OaPV3)-based virus-like particles (OaPV3-VLPs) in the baculovirus system and their use to investigate host humoral immune response through the establishment of an indirect ELISA test., Polyclonal sera and monoclonal antibodies were generated against OaPV3-VLPs, and their isotype and reactivity were determined. Additionally, antibodies allowed OaPV3 detection in ovine squamous cell carcinoma (SCC) samples by immunohistochemistry. Results encourage the standardization of OaPV3-specific prophylactic and serological diagnostic tools, and open new perspectives for the study of host-viral interaction and SCC development.

CHO cells for virus-like particle and subunit vaccine manufacturing

Chinese Hamster Ovary (CHO) cells, employed primarily for manufacturing monoclonal antibodies and other recombinant protein (r-protein) therapeutics, are emerging as a promising host for vaccine antigen production. This is exemplified by the recently approved CHO cell-derived subunit vaccines (SUV) against respiratory syncytial virus (RSV) and varicella-zoster virus (VZV), as well as the enveloped virus-like particle (eVLP) vaccine against hepatitis B virus (HBV). Here, we summarize the design, production, and immunogenicity features of these vaccine and review the most recent progress of other CHO-derived vaccines in pre-clinical and clinical development. We also discuss the challenges associated with vaccine production in CHO cells, with a focus on ensuring viral clearance for eVLP products.

The Micro-Immunotherapy Medicine 2LPAPI® Displays Immune-Modulatory Effects in a Model of Human Papillomavirus Type-16 L1-Protein Capsid-Treated Human Peripheral Blood Mononuclear Cells and Antiproliferative Effects in a Model of Cervical Cancer Cells

Human papillomavirus (HPV) is the second most common infectious agent causing cancer. Persistent infection with high-risk (HR)-HPV can lead to cervical intra-epithelial neoplasia and cervical carcinomas (CC). While host immune response is necessary for viral clearance, chronic immune activation contributes to a low-grade inflammation that can ultimately lead to carcinogenesis. The micro-immunotherapy medicine (MIM) 2LPAPI® could be a valuable tool to manage the clearance of the virus and reduce the risk of developing CC. In this in vitro study, we aimed to investigate its mode of action. We showed that actives from the MIM increased the IL-6, IFN-γ, and IP-10 secretion in human peripheral blood mononuclear cells (PBMCs) exposed to peptides derived from the HPV-16 capsid (HPV16(L1)). This could reflect an increase in the immune activity toward HPV-16. At the same time, some active substances reduced the lympho-proliferation and the expression of T-cell activation markers. Finally, some of the MIM actives displayed antiproliferative effects in CC-derived HeLa cells under serum-starvation conditions. Altogether, this body of data highlighted for the first time the dual effect of MIM in the framework of HR-HPV infections as a potential (i) immune modulator of HPV16(L1)-treated PBMCs and (ii) antiproliferative agent of HPV-positive CC cells.

Human papilloma virus vaccines: A comprehensive narrative review

Cervical cancer is one of the most common cancers in women aged 15-44 years in the world, with more than three-quarters of cases diagnosed at a locally advanced clinical stage with minor prospects of survival. Although only a small percentage of women with Human Papilloma Virus (HPV) develop cervical cancer and most of the HPV infections are cleared subsequently at primary stage itself, but seroconversion not always guarantees that the individual is immune to HPV. The advent of the cervical carcinoma vaccine has raised the expectations that eradication of cervical carcinoma might be possible in the near future as it exhibited remarkably high efficacy against the vaccine-specific types in naive women with no serious vaccine-related adverse events. Few prophylactic HPV vaccines are currently licensed in over 100 countries. It has also been suggested that vaccinating both men and women is more beneficial than vaccinating only females. Vaccination is a cost-effective strategy to reduce the incidence of cervical cancer and mortality compared to no vaccination based on the cost of cancer treatment. Well-coordinated vaccination strategy with focus on adolescent girls and if possible, boys can lead to dramatic impact on disease reduction around the world.

Recent advance in the development of tuberculosis vaccines in clinical trials and virus-like particle-based vaccine candidates

Tuberculosis (TB) remains a serious public health threat around the world. An effective vaccine is urgently required for cost-effective, long-term control of TB. However, the only licensed vaccine Bacillus Calmette-Guerin (BCG) is limited to prevent TB for its highly variable efficacy. Substantial progress has been made in research and development (R&D) of TB vaccines in the past decades, and a dozen vaccine candidates, including live attenuated mycobacterial vaccines, killed mycobacterial vaccines, adjuvanted subunit vaccines, viral vector vaccines, and messenger RNA (mRNA) vaccines were developed in clinical trials to date. Nevertheless, many challenges to the successful authorization for the use and deployment of an effective tuberculosis vaccine remain. Therefore, it is still necessary and urgent to continue exploring new vaccine construction approaches. Virus-like particles (VLPs) present excellent prospects in the field of vaccine development because of their helpful immunological features such as being safe templates without containing viral nucleic acid, repetitive surface geometry, conformational epitopes similar to natural viruses, and enhancing both innate and adaptive immune responses. The marketization process of VLP vaccines has never stopped despite VLP vaccines face several shortcomings such as their complex and slow development process and high production cost, and several VLP-based vaccines, including vaccines against Human papillomavirus (HPV), Hepatitis B Virus (HBV) and malaria, are successfully licensed for use at the market. In this review, we provide an update on the current progress regarding the development of TB vaccines in clinical trials and seek to give an overview of VLP-based TB vaccine candidates.

Can prophylactic HPV vaccination reduce the recurrence of cervical lesions after surgery? Review and prospect

Women with HSIL typically undergo conization/LEEP to remove cervical lesions, but the risk of HSIL lesions returning after surgical treatment remains higher than in the general population. HPV vaccination is essential to prevent cervical cancer. However, the effect of prophylactic HPV vaccination on reducing the risk of recurrent cervical lesions after surgical treatment remains unclear. This review aims to analyze and summarize the latest literature on the role of prophylactic HPV vaccine in reducing the recurrence of cervical lesions after surgery in patients with HSIL, and to review and update the history, efficacy, effectiveness and safety of HPV vaccine, focusing on the current status of global HPV vaccine implementation and obstacles.

A Therapeutic DNA Vaccine Targeting HPV16 E7 in Combination with Anti-PD-1/PD-L1 Enhanced Tumor Regression and Cytotoxic Immune Responses

Persistent infection of high-risk human papillomavirus (HPV) and the expression of E6 and E7 oncoproteins are the main causes of cervical cancer. Several prophylactic HPV vaccines are used in the clinic, but these vaccines have limited efficacy in patients already infected with HPV. Since HPV E7 is vital for tumor-specific immunity, developing a vaccine against HPV E7 is an attractive strategy for cervical cancer treatment. Here, we constructed an HPV16 E7 mutant that loses the ability to bind pRb while still eliciting a robust immune response. In order to build a therapeutic DNA vaccine, the E7 mutant was packaged in an adenovirus vector (Ad-E7) for efficient expression and enhanced immunogenicity of the vaccine. Our results showed that the Ad-E7 vaccine effectively inhibited tumor growth and increased the proportion of interferon-gamma (IFN-γ)-secreting CD8+ T cells in the spleen, and tumor-infiltrating lymphocytes in a mouse cervical cancer model was achieved by injecting with HPV16-E6/E7-expressing TC-1 cells subcutaneously. Combining the Ad-E7 vaccine with the PD-1/PD-L1 antibody blockade significantly improved the control of TC-1 tumors. Combination therapy elicited stronger cytotoxic T lymphocyte (CTL) responses, and IFN-γ secretion downregulated the proportion of Tregs and MDSCs significantly. The expressions of cancer-promoting factors, such as TNF-α, were also significantly down-regulated in the case of combination therapy. In addition, combination therapy inhibited the number of capillaries in tumor tissues and increased the thickness of the tumor capsule. Thus, Ad-E7 vaccination, in combination with an immune checkpoint blockade, may benefit patients with HPV16-associated cervical cancer.

Nano-Sized Chimeric Human Papillomavirus-16 L1 Virus-like Particles Displaying Mycobacterium tuberculosis Antigen Ag85B Enhance Ag85B-Specific Immune Responses in Female C57BL/c Mice

Bacillus Calmette-Guerin (BCG), the only current vaccine against tuberculosis (TB) that is licensed in clinics, successfully protects infants and young children against several TB types, such as TB meningitis and miliary TB, but it is ineffective in protecting adolescents and adults against pulmonary TB. Thus, it is a matter of the utmost urgency to develop an improved and efficient TB vaccine. In this milieu, virus-like particles (VLPs) exhibit excellent characteristics in the field of vaccine development due to their numerous characteristics, including but not limited to their good safety without the risk of infection, their ability to mimic the size and structure of original viruses, and their ability to display foreign antigens on their surface to enhance the immune response. In this study, the HPV16 L1 capsid protein (HPV16L1) acted as a structural vaccine scaffold, and the extracellular domain of Ag85B was selected as the M. tb immunogen and inserted into the FG loop of the HPV16 L1 protein to construct chimeric HPV16L1/Ag85B VLPs. The chimeric HPV16L1/Ag85B VLPs were produced via the Pichia pastoris expression system and purified via discontinuous Optiprep density gradient centrifugation. The humoral and T cell-mediated immune response induced by the chimeric HPV16L1/Ag85B VLP was studied in female C57BL/c mice. We demonstrated that the insertion of the extracellular domain of Ag85B into the FG loop of HPV16L1 did not affect the in vitro stability and self-assembly of the chimeric HPV16L1/Ag85B VLPs. Importantly, it did not interfere with the immunogenicity of Ag85B. We observed that the chimeric HPV16L1/Ag85B VLPs induced higher Ag85B-specific antibody responses and elicited significant Ag85B-specific T cell immune responses in female C57BL/c mice compared with recombinant Ag85B. Our findings provide new insights into the development of novel chimeric HPV16L1/TB VLP-based vaccine platforms for controlling TB infection, which are urgently required in low-income and developing countries.

Bacterial Outer Membrane Vesicles as a Platform for the Development of a Broadly Protective Human Papillomavirus Vaccine Based on the Minor Capsid Protein L2

Human papillomaviruses (HPVs) are a large family of viruses with a capsid composed of the L1 and L2 proteins, which bind to receptors of the basal epithelial cells and promote virus entry. The majority of sexually active people become exposed to HPV and the virus is the most common cause of cervical cancer. Vaccines are available based on the L1 protein, which self-assembles and forms virus-like particles (VLPs) when expressed in yeast and insect cells. Although very effective, these vaccines are HPV type-restricted and their costs limit broad vaccination campaigns. Recently, vaccine candidates based on the conserved L2 epitope from serotypes 16, 18, 31, 33, 35, 6, 51, and 59 were shown to elicit broadly neutralizing anti-HPV antibodies. In this study, we tested whether E. coli outer membrane vesicles (OMVs) could be successfully decorated with L2 polytopes and whether the engineered OMVs could induce neutralizing antibodies. OMVs represent an attractive vaccine platform owing to their intrinsic adjuvanticity and their low production costs. We show that strings of L2 epitopes could be efficiently expressed on the surface of the OMVs and a polypeptide composed of the L2 epitopes from serotypes 18, 33, 35, and 59 provided a broad cross-protective activity against a large panel of HPV serotypes as determined using pseudovirus neutralization assay. Considering the simplicity of the OMV production process, our work provides a highly effective and inexpensive solution to produce universal anti-HPV vaccines.

Human Papillomavirus Vaccines

Human papillomavirus (HPV) vaccines are highly effective in preventing the transmission of HPV and thus downstream HPV-related lower genital tract neoplasias. First introduced in 2006, the HPV vaccine has demonstrated clinical efficacy in both men and women. Several commercially available vaccines now exist, but only one is available in the United States. Both prelicensure and postlicensure studies demonstrate robust safety profiles. HPV vaccines should be made available to everyone between the ages of 9 and 26 years of age. Newer vaccination recommendations in expanded populations rely on patient-provider shared decision making. Currently, available HPV vaccines offer little therapeutic benefit. Recent research has identified several new DNA vaccines and delivery modifications with early demonstrated success at eliminating prevalent HPV infections and precancerous lesions. Despite the success of the HPV vaccine, vaccination hesitancy and disinformation continue to threaten our ability to eliminate these deadly cancers. Informational, behavioral, and environmental interventions have mixed success in increasing vaccination rates, but several strategies do exist to increase rates of vaccination.

Heterologous Expression of Recombinant Proteins and Their Derivatives Used as Carriers for Conjugate Vaccines

Carrier proteins that provide an effective and long-term immune response to weak antigens has become a real breakthrough in the disease prevention, making it available to a wider range of patients and making it possible to obtain reliable vaccines against a variety of pathogens. Currently, research is continuing both to identify new peptides, proteins, and their complexes potentially suitable for use as carriers, and to develop new methods for isolation, purification, and conjugation of already known and well-established proteins. The use of recombinant proteins has a number of advantages over isolation from natural sources, such as simpler cultivation of the host organism, the possibility of modifying genetic constructs, use of numerous promoter variants, signal sequences, and other regulatory elements. This review is devoted to the methods of obtaining both traditional and new recombinant proteins and their derivatives already being used or potentially suitable for use as carrier proteins in conjugate vaccines.

Cancer Vaccine Therapeutics: Limitations and Effectiveness-A Literature Review

In recent years, there has been a surge of interest in tumor microenvironment-associated cancer vaccine therapies. These innovative treatments aim to activate and enhance the body's natural immune response against cancer cells by utilizing specific antigens present in the tumor microenvironment. The goal is to achieve a complete clinical response, where all measurable cancer cells are either eliminated or greatly reduced in size. With their potential to revolutionize cancer treatment, these therapies represent a promising avenue for researchers and clinicians alike. Despite over 100 years of research, the success of therapeutic cancer vaccines has been variable, particularly in advanced cancer patients, with various limitations, including the heterogeneity of the tumor microenvironment, the presence of immunosuppressive cells, and the potential for tumor escape mechanisms. Additionally, the effectiveness of these therapies may be limited by the variability of the patient's immune system response and the difficulty in identifying appropriate antigens for each patient. Despite these challenges, tumor microenvironment-targeted vaccine cancer therapies have shown promising results in preclinical and clinical studies and have the potential to become a valuable addition to current cancer treatment and "curative" options. While chemotherapeutic and monoclonal antibody treatments remain popular, ongoing research is needed to optimize the design and delivery of these therapies and to identify biomarkers that can predict response and guide patient selection. This comprehensive review explores the mechanisms of cancer vaccines, various delivery methods, and the role of adjuvants in improving treatment outcomes. It also discusses the historical background of cancer vaccine research and examines the current state of major cancer vaccination immunotherapies. Furthermore, the limitations and effectiveness of each vaccine type are analyzed, providing insights into the future of cancer vaccine development.

Virus-like Particle (VLP) Vaccines for Cancer Immunotherapy

Cancer vaccines are increasingly being studied as a possible strategy to prevent and treat cancers. While several prophylactic vaccines for virus-caused cancers are approved and efficiently used worldwide, the development of therapeutic cancer vaccines needs to be further implemented. Virus-like particles (VLPs) are self-assembled protein structures that mimic native viruses or bacteriophages but lack the replicative material. VLP platforms are designed to display single or multiple antigens with a high-density pattern, which can trigger both cellular and humoral responses. The aim of this review is to provide a comprehensive overview of preventive VLP-based vaccines currently approved worldwide against HBV and HPV infections or under evaluation to prevent virus-caused cancers. Furthermore, preclinical and early clinical data on prophylactic and therapeutic VLP-based cancer vaccines were summarized with a focus on HER-2-positive breast cancer.

Microorganisms-derived antigens for preventive anti-cancer vaccines

Cancer prevention is one of the aim with the highest priority in order to reduce the burden of cancer diagnosis and treatment on individuals as well as on healthcare systems. To this aim, vaccines represent the most efficient primary cancer prevention strategy. Indeed, anti-cancer immunological memory elicited by preventive vaccines might promptly expand and prevent tumor from progressing. Antigens derived from microorganisms (MoAs), represent the obvious target for developing highly effective preventive vaccines for virus-induced cancers. In this respect, the drastic reduction in cancer incidence following HBV and HPV preventive vaccines are the paradigmatic example of such evidence. More recently, experimental evidences suggest that MoAs may represent a "natural" anti-cancer preventive vaccination or can be exploited for developing vaccines to prevent cancers presenting highly homologous tumor-associated antigens (TAAs) (e.g. molecular mimicry). The present review describes the different preventive anti-cancer vaccines based on antigens derived from pathogens at the different stages of development.

Peptide Vaccines as Therapeutic and Prophylactic Agents for Female-Specific Cancers: The Current Landscape

Breast and gynecologic cancers are significant global threats to women's health and those living with the disease require lifelong physical, financial, and social support from their families, healthcare providers, and society as a whole. Cancer vaccines offer a promising means of inducing long-lasting immune response against the disease. Among various types of cancer vaccines available, peptide vaccines offer an effective strategy to elicit specific anti-tumor immune responses. Peptide vaccines have been developed based on tumor associated antigens (TAAs) and tumor specific neoantigens which can also be of viral origin. Molecular alterations in HER2 and non-HER2 genes are established to be involved in the pathogenesis of female-specific cancers and hence were exploited for the development of peptide vaccines against these diseases, most of which are in the latter stages of clinical trials. However, prophylactic vaccines for viral induced cancers, especially those against Human Papillomavirus (HPV) infection are well established. This review discusses therapeutic and prophylactic approaches for various types of female-specific cancers such as breast cancer and gynecologic cancers with special emphasis on peptide vaccines. We also present a pipeline for the design and evaluation of a multiepitope peptide vaccine that can be active against female-specific cancers.

Herpes Simplex Virus, Human Papillomavirus, and Cervical Cancer: Overview, Relationship, and Treatment Implications

There is a significant body of research examining the role of human papillomavirus (HPV) in the pathogenesis of cervical cancer, with a particular emphasis on the oncogenic proteins E5, E6, and E7. What is less well explored, however, is the relationship between cervical cancer and herpes simplex virus (HSV). To date, studies examining the role of HSV in cervical cancer pathogenesis have yielded mixed results. While several experiments have determined that HPV/HSV-2 coinfection results in a higher risk of developing cervical cancer, others have questioned the validity of this association. However, clarifying the potential role of HSV in the pathogenesis of cervical cancer may have significant implications for both the prevention and treatment of this disease. Should this relationship be clarified, treating and preventing HSV could open another avenue with which to prevent cervical cancer. The importance of this is highlighted by the fact that, despite the creation of an effective vaccine against HPV, cervical cancer still impacts 604,000 women and is responsible for 342,000 deaths annually. This review provides an overview of HSV and HPV infections and then delves into the possible links between HPV, HSV, and cervical cancer. It concludes with a summary of preventive measures against and recent treatment advances in cervical cancer.

The Tumor-Specific Immune Landscape in HPV+ Head and Neck Cancer

Human papillomaviruses (HPVs) are the causative agent of several anogenital cancers as well as head and neck cancers, with HPV+ head and neck squamous cell carcinoma (HNSCC) becoming a rapidly growing public health issue in the Western world. Due its viral etiology and potentially its subanatomical location, HPV+ HNSCC exhibits an immune microenvironment which is more inflamed and thus distinct from HPV-negative HNSCC. Notably, the antigenic landscape in most HPV+ HNSCC tumors extends beyond the classical HPV oncoproteins E6/7 and is extensively targeted by both the humoral and cellular arms of the adaptive immune system. Here, we provide a comprehensive overview of HPV-specific immune responses in patients with HPV+ HNSCC. We highlight the localization, antigen specificity, and differentiation states of humoral and cellular immune responses, and discuss their similarities and differences. Finally, we review currently pursued immunotherapeutic treatment modalities that attempt to harness HPV-specific immune responses for improving clinical outcomes in patients with HPV+ HNSCC.

Hapten-Decorated DNA Nanostructures Decipher the Antigen-Mediated Spatial Organization of Antibodies Involved in Mast Cell Activation

The immunological response of mast cells is controlled by the multivalent binding of antigens to immunoglobulin E (IgE) antibodies bound to the high-affinity receptor FcεRI on the cell membrane surface. However, the spatial organization of antigen-antibody-receptor complexes at the nanometer scale and the structural constraints involved in the initial events at the cell surface are not yet fully understood. For example, it is unclear what influence the affinity and nanoscale distance between the binding partners involved have on the activation of mast cells to degranulate inflammatory mediators from storage granules. We report the use of DNA origami nanostructures (DON) functionalized with different arrangements of the haptenic 2,4-dinitrophenyl (DNP) ligand to generate multivalent artificial antigens with full control over valency and nanoscale ligand architecture. To investigate the spatial requirements for mast cell activation, the DNP-DON complexes were initially used in surface plasmon resonance (SPR) analysis to study the binding kinetics of isolated IgE under physiological conditions. The most stable binding was observed in a narrow window of approximately 16 nm spacing between haptens. In contrast, affinity studies with FcεRI-linked IgE antibodies on the surface of rat basophilic leukemia cells (RBL-2H3) indicated virtually no distance-dependent variations in the binding of the differently structured DNP-DON complexes but suggested a supramolecular oligovalent nature of the interaction. Finally, the use of DNP-DON complexes for mast cell activation revealed that antigen-directed tight assembly of antibody-receptor complexes is the critical factor for triggering degranulation, even more critical than ligand valence. Our study emphasizes the significance of DNA nanostructures for the study of fundamental biological processes.

Development of modern immunization agent against bovine papillomavirus type 1 infection based on BPV1 L1 recombinant protein

Bovine papillomavirus type 1 L1 protein was produced in a baculovirus expression system and purified as virus-like particles (VLPs) by affinity chromatography using lectins. The morphological integrity of VLPs was confirmed by electron microscopy. Differences between the two detected variants were deciphered by mass spectrometry of peptides (MALDI-TOF). Mice were immunized with purified VLPs in doses of 10, 25, or 50 μg in combination with 1% saponin and 15% alhydrogel per dose as adjuvants. Analysis of the humoral immune response revealed increased levels of specific antibodies detected 3 weeks after the first immunization in all groups of animals. This was further significantly increased by the booster applied 3 weeks after the first dose, with the best immune response in a group of mice immunized by the largest dose of antigen. BPV1 L1 VLPs purified by affinity chromatography using lectins could be used for prophylactic immunization in veterinary medicine.

Differentiated Oral Epithelial Cells Support the HPV Life Cycle

Human Papillomavirus (HPV) associated oral disease continues to increase, both in the context of immune competence and of immune suppression. There are few models of oral HPV infection and current models are laborious. We hypothesized that differentiated oral epithelial cells could support the HPV life cycle. Clinical HPV16 cloned episomes were introduced into differentiated oral epithelial cells (OKF6tert1). Viral and cellular gene expression was assessed in the presence or absence of sodium butyrate, a differentiating agent that moved the cells to full terminal differentiation. Detection of keratin 10, cross-linked involucrin, and loricrin in the presence and absence of sodium butyrate confirmed terminal differentiation. Increasing sodium butyrate concentrations in the absence of HPV, were associated with decreased suprabasal markers and increased terminal differentiation markers. However, in the presence of HPV and of increasing sodium butyrate concentrations, both mitotic and suprabasal markers were increased and the terminal differentiation marker, loricrin, decreased. In this unique differentiated state, early and late viral gene products were detected including spliced mRNAs for E6*, E1^E4, and L1. E7 and L1 proteins were detected. The ratio of late (E1^E4) to early (E6/E7) transcripts in HPV16+ OKF6tert1 cells was distinct compared to HPV16+ C33a cells. Consistent with permissive HPV replication, DNA damage responses (phospho-chk2, gamma-H2AX), HPV E2-dependent LCR transactivation, and DNase-resistant particles were detected and visualized by transmission electron microscopy. In sum, monolayers of differentiated immortalized oral epithelial cells supported the full HPV life cycle. HPV may optimize the differentiation state of oral epithelial cells to facilitate its replication.

Optimal size of DNA encapsidated by plant produced human papillomavirus pseudovirions

Human papillomaviruses (HPVs) are known to be the cause of anogenital and oropharyngeal cancers as well as genital and common warts. HPV pseudovirions (PsVs) are synthetic viral particles that are made up of the L1 major and L2 minor HPV capsid proteins and up to 8 Kb of encapsidated pseudogenome dsDNA. HPV PsVs are used to test novel neutralising antibodies elicited by vaccines, for studying the virus life cycle, and potentially for the delivery of therapeutic DNA vaccines. HPV PsVs are typically produced in mammalian cells, however, it has recently been shown that Papillomavirus PsVs can be produced in plants, a potentially safer, cheaper and more easily scalable means of production. We analysed the encapsidation frequencies of pseudogenomes expressing EGFP, ranging in size from 4.8 Kb to 7.8 Kb, by plant-made HPV-35 L1/L2 particles. The smaller pseudogenomes were found to be packaged more efficiently into PsVs as higher concentrations of encapsidated DNA and higher levels of EGFP expression were obtained with the 4.8 Kb pseudogenome, compared to the larger 5.8-7.8 Kb pseudogenomes. Thus, smaller pseudogenomes, of 4.8 Kb, should be used for efficient plant production of HPV-35 PsVs.

Human papillomavirus genomics: Understanding carcinogenicity

Human papillomavirus (HPV) causes virtually all cervical cancers and many cancers at other anatomical sites in both men and women. However, only 12 of 448 known HPV types are currently classified as carcinogens, and even the most carcinogenic type - HPV16 - only rarely leads to cancer. HPV is therefore necessary but insufficient for cervical cancer, with other contributing factors including host and viral genetics. Over the last decade, HPV whole genome sequencing has established that even fine-scale within-type HPV variation influences precancer/cancer risks, and that these risks vary by histology and host race/ethnicity. In this review, we place these findings in the context of the HPV life cycle and evolution at various levels of viral diversity: between-type, within-type, and within-host. We also discuss key concepts necessary for interpreting HPV genomic data, including features of the viral genome; events leading to carcinogenesis; the role of APOBEC3 in HPV infection and evolution; and methodologies that use deep (high-coverage) sequencing to characterize within-host variation, as opposed to relying on a single representative (consensus) sequence. Given the continued high burden of HPV-associated cancers, understanding HPV carcinogenicity remains important for better understanding, preventing, and treating cancers attributable to infection.

HPV and Cervical Cancer: A Review of Epidemiology and Screening Uptake in the UK

Cervical cancer is the fourth most common malignancy in females worldwide, and a leading cause of death in the United Kingdom (UK). The human papillomavirus (HPV) is the strongest risk factor for developing cervical intraepithelial neoplasia and cancer. Across the UK, the national HPV immunisation programme, introduced in 2008, has been successful in protecting against HPV-related infections. Furthermore, the National Health Service (NHS) implemented the cytology-based cervical cancer screening service to all females aged 25 to 64, which has observed a decline in cervical cancer incidence. In the UK, there has been an overall decline in age-appropriate coverage since April 2010. In 2019, the COVID-19 pandemic disrupted NHS cancer screening and immunisation programmes, leading to a 6.8% decreased uptake of cervical cancer screening from the previous year. Engagement with screening has also been associated with social deprivation. In England, incidence rates of cervical cancer were reported to be 65% higher in the most deprived areas compared to the least, with lifestyle factors such as cigarette consumption contributing to 21% of cervical cancer cases. In this article, we provide an update on the epidemiology of cervical cancer, and HPV pathogenesis and transmission, along with the current prevention programmes within the NHS.

Papillomavirus-like Particles in Equine Medicine

Papillomaviruses (PVs) are a family of small DNA tumor viruses that can induce benign lesions or cancer in vertebrates. The observation that animal PV capsid-proteins spontaneously self-assemble to empty, highly immunogenic virus-like particles (VLPs) has led to the establishment of vaccines that efficiently protect humans from specific PV infections and associated diseases. We provide an overview of PV-induced tumors in horses and other equids, discuss possible routes of PV transmission in equid species, and present recent developments aiming at introducing the PV VLP-based vaccine technology into equine medicine.

Research progress on substitution of in vivo method(s) by in vitro method(s) for human vaccine potency assays

INTRODUCTION

Potency is a critical quality attribute for controlling quality consistency and relevant biological properties of vaccines. Owing to the high demand for animals, lengthy operations and high variability of in vivo methods, in vitro alternatives for human vaccine potency assays are extensively developed.

AREAS COVERED

Herein, in vivo and in vitro methods for potency assays of previously licensed human vaccines were sorted, followed by a brief description of the background for substituting in vivo methods with in vitro alternatives. Based on the analysis of current research on the substitution of vaccine potency assays, barriers and suggestions for substituting were proposed.

EXPERT OPINION

Owing to the variability of in vivo methods, the correlation between in vivo and in vitro methods may be low. One or more in vitro method(s) that determine the vaccine antigen content and functions, should be established. Since the substitution involves with the change of critical quality attributes and specifications, the specifications of in vitro methods should be appropriately set to maintain the efficacy of vaccines. For novel vaccines in research and development, in vitro methods for monitoring the consistency and relevant biological properties, should be established based on reflecting the immunogenicity of vaccines.

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.

Nanotechnology-Based Nucleic Acid Vaccines for Treatment of Ovarian Cancer

Anticancer vaccines represent a promising approach for effective treatment of cancer and along with recent advantages of nucleic acid-based vaccines for other diseases form a prospective and potentially efficacious direction of the research, development and clinical applications. Despite the ongoing several clinical trials of mRNA vaccines for the treatment of various types of cancer, to-date no cancer vaccines were approved by the US Food and Drug Administration. The present review analyzes and summarizes major approaches for treating of different forms of ovarian cancer including mRNA-based vaccines as well as nanotechnology-based approaches for their delivery.

Therapeutic Vaccination for HPV-Mediated Cancers

Purpose of Review

The goal of this narrative review is to educate clinicians regarding the foundational concepts, efficacy, and future directions of therapeutic vaccines for human papillomavirus (HPV)-mediated cancers.

Recent Findings

Therapeutic HPV vaccines deliver tumor antigens to stimulate an immune response to eliminate tumor cells. Vaccine antigen delivery platforms are diverse and include DNA, RNA, peptides, proteins, viral vectors, microbial vectors, and antigen-presenting cells. Randomized, controlled trials have demonstrated that therapeutic HPV vaccines are efficacious in patients with cervical intraepithelial neoplasia. In patients with HPV-mediated malignancies, evidence of efficacy is limited. However, numerous ongoing studies evaluating updated therapeutic HPV vaccines in combination with immune checkpoint inhibition and other therapies exhibit significant promise.

Summary

Therapeutic vaccines for HPV-mediated malignancies retain a strong biological rationale, despite their limited efficacy to date. Investigators anticipate they will be most effectively used in combination with other regimens, such as immune checkpoint inhibition.

Towards Novel Gene and Cell Therapy Approaches for Cervical Cancer

Cervical cancer is one of the most common malignancies in women, and the majority of cases are caused by infection with high-risk human papilloma virus (HPV) subtypes. Despite effective preventative measures, such as vaccinations against HPV, over 300,000 women die world-wide from cervical cancer each year. Once cervical cancer is diagnosed, treatment may consist of radial hysterectomy, or chemotherapy and radiotherapy, or a combination of therapies dependent upon the disease stage. Unfortunately, overall prognosis for patients with metastatic or recurrent disease remains poor. In these cases, immunotherapies may be useful based on promising preclinical work, some of which has been successfully translated to the clinic. For example, approaches using monoclonal antibodies directed against surface proteins important for control of immune checkpoints (i.e., immune checkpoint inhibitors) were shown to improve outcome in many cancer settings, including cervical cancer. Additionally, initial clinical studies showed that application of cytotoxic immune cells modified to express chimeric antigen receptors (CAR) or T cell receptors (TCR) for better recognition and elimination of tumor cells may be useful to control cervical cancer. This review explores these important topics, including strengths and limitations of standard and developing approaches, and how some novel treatment strategies may be optimally used to offer the best possible treatment for cervical cancer patients.

Chimeric Human Papillomavirus-16 Virus-like Particles Presenting P18I10 and T20 Peptides from HIV-1 Envelope Induce HPV16 and HIV-1-Specific Humoral and T Cell-Mediated Immunity in BALB/c Mice

In this study, the HIV-1 P18I10 CTL peptide derived from the V3 loop of HIV-1 gp120 and the T20 anti-fusion peptide of HIV-1 gp41 were inserted into the HPV16 L1 capsid protein to construct chimeric HPV:HIV (L1:P18I10 and L1:T20) VLPs by using the mammalian cell expression system. The HPV:HIV VLPs were purified by chromatography. We demonstrated that the insertion of P18I10 or T20 peptides into the DE loop of HPV16 L1 capsid proteins did not affect in vitro stability, self-assembly and morphology of chimeric HPV:HIV VLPs. Importantly, it did not interfere either with the HIV-1 antibody reactivity targeting sequential and conformational P18I10 and T20 peptides presented on chimeric HPV:HIV VLPs or with the induction of HPV16 L1-specific antibodies in vivo. We observed that chimeric L1:P18I10/L1:T20 VLPs vaccines could induce HPV16- but weak HIV-1-specific antibody responses and elicited HPV16- and HIV-1-specific T-cell responses in BALB/c mice. Moreover, could be a potential booster to increase HIV-specific cellular responses in the heterologous immunization after priming with rBCG.HIVA vaccine. This research work would contribute a step towards the development of the novel chimeric HPV:HIV VLP-based vaccine platform for controlling HPV16 and HIV-1 infection, which is urgently needed in developing and industrialized countries.

Implications and Emerging Therapeutic Avenues of Inflammatory Response in HPV+ Head and Neck Squamous Cell Carcinoma

Head and neck squamous cell carcinomas (HNSCC) are a heterogeneous group of malignancies which have shown exponential incidence in the last two decades especially due to human papillomavirus (HPV) infection. The HPV family comprises more than 100 types of viruses with HPV16 and HPV18 being the most prevalent strains in HNSCC. Literature data reveal that the mutation profile as well as the response to chemotherapy and radiotherapy are distinct among HPV+ versus HPV-negative tumors. Furthermore, the presence of the virus induces activation of an immune response, in particular the recruitment of specific antiviral T lymphocytes to tumor sites. These T cells when activated produce soluble factors including cytokines and chemokines capable of modifying the local immune tumor microenvironment and impact on tumor response to the treatment. In this comprehensive review we investigated current knowledge on how the presence of an HPV can modify the inflammatory response systemically and within the tumor microenvironment's immunological responses, thereby impacting on disease prognosis and survival. We highlighted the research gaps and emerging approaches necessary to discover novel immunotherapeutic targets for HPV-associated HNSCC.

Characterization of an Escherichia coli-derived triple-type chimeric vaccine against human papillomavirus types 39, 68 and 70

In vaccinology, a potent immunogen has two prerequisite attributes-antigenicity and immunogenicity. We have rational designed a triple-type HPV vaccine against HPV58, -33 and -52 covered in Gardasil 9 based on the sequence homology and similar surface loop structure of L1 protein, which is related to cross-type antigenicity. Here, we design another triple-type vaccine against non-vaccine types HPV39, -68 and -70 by immunogenicity optimization considering type specific immunodominant epitopes located in separate region for different types. First, we optimized the expression of wild-type HPV39, -68 and -70 L1-only virus-like particles (VLPs) in E. coli through N-terminal truncation of HPV L1 proteins and non-fusion soluble expression. Second, based on genetic relationships and an L1 homologous loop-swapping rationale, we constructed several triple-type chimeric VLPs for HPV39, -68 and -70, and obtained the lead candidate named H39-68FG-70DE by the immunogenicity optimization using reactivity profile of a panel type-specific monoclonal antibodies. Through comprehensive characterization using various biochemical, VLP-based analyses and immune assays, we show that H39-68FG-70DE assumes similar particulate properties as that of its parental VLPs, along with comparable neutralization immunogenicity for all three HPV types. Overall, this study shows the promise and translatability of an HPV39/68/70 triple-type vaccine, and the possibility of expanding the type-coverage of current HPV vaccines. Our study further expanded the essential criteria on the rational design of a cross-type vaccine, i.e. separate sites with inter-type similar sequence and structure as well as type-specific immunodominant epitope to be clustered together.

How promising are HIV-1-based virus-like particles for medical applications

New approaches aimed at identifying patient-specific drug targets and addressing unmet clinical needs in the framework of precision medicine are a strong motivation for researchers worldwide. As scientists learn more about proteins that drive known diseases, they are better able to design promising therapeutic approaches to target those proteins. The field of nanotechnology has been extensively explored in the past years, and nanoparticles (NPs) have emerged as promising systems for target-specific delivery of drugs. Virus-like particles (VLPs) arise as auspicious NPs due to their intrinsic properties. The lack of viral genetic material and the inability to replicate, together with tropism conservation and antigenicity characteristic of the native virus prompted extensive interest in their use as vaccines or as delivery systems for therapeutic and/or imaging agents. Owing to its simplicity and non-complex structure, one of the viruses currently under study for the construction of VLPs is the human immunodeficiency virus type 1 (HIV-1). Typically, HIV-1-based VLPs are used for antibody discovery, vaccines, diagnostic reagent development and protein-based assays. This review will be centered on the use of HIV-1-based VLPs and their potential biomedical applications.

Current In Vitro and In Vivo Models to Study MCPyV-Associated MCC

Merkel cell polyomavirus (MCPyV) is the only human polyomavirus currently known to cause human cancer. MCPyV is believed to be an etiological factor in at least 80% of cases of the rare but aggressive skin malignancy Merkel cell carcinoma (MCC). In these MCPyV+ MCC tumors, clonal integration of the viral genome results in the continued expression of two viral proteins: the viral small T antigen (ST) and a truncated form of the viral large T antigen. The oncogenic potential of MCPyV and the functional properties of the viral T antigens that contribute to neoplasia are becoming increasingly well-characterized with the recent development of model systems that recapitulate the biology of MCPyV+ MCC. In this review, we summarize our understanding of MCPyV and its role in MCC, followed by the current state of both in vitro and in vivo model systems used to study MCPyV and its contribution to carcinogenesis. We also highlight the remaining challenges within the field and the major considerations related to the ongoing development of in vitro and in vivo models of MCPyV+ MCC.

Next generation L2-based HPV vaccines cross-protect against cutaneous papillomavirus infection and tumor development

Licensed L1-VLP-based immunizations against high-risk mucosal human papillomavirus (HPV) types have been a great success in reducing anogenital cancers, although they are limited in their cross-protection against HPV types not covered by the vaccine. Further, their utility in protection against cutaneous HPV types, of which some contribute to non-melanoma skin cancer (NMSC) development, is rather low. Next generation vaccines achieve broadly cross-protective immunity against highly conserved sequences of L2. In this exploratory study, we tested two novel HPV vaccine candidates, HPV16 RG1-VLP and CUT-PANHPVAX, in the preclinical natural infection model Mastomys coucha. After immunization with either vaccines, a mock control or MnPV L1-VLPs, the animals were experimentally infected and monitored. Besides vaccine-specific seroconversion against HPV L2 peptides, the animals also developed cross-reactive antibodies against the cutaneous Mastomys natalensis papillomavirus (MnPV) L2, which were cross-neutralizing MnPV pseudovirions in vitro. Further, both L2-based vaccines also conferred in vivo protection as the viral loads in plucked hair after experimental infection were lower compared to mock-vaccinated control animals. Importantly, the formation of neutralizing antibodies, whether directed against L1-VLPs or L2, was able to prevent skin tumor formation and even microscopical signs of MnPV infection in the skin. For the first time, our study shows the proof-of-principle of next generation L2-based vaccines even across different PV genera in an infection animal model with its genuine PV. It provides fundamental insights into the humoral immunity elicited by L2-based vaccines against PV-induced skin tumors, with important implications to the design of next generation HPV vaccines.

Governing HPV-related carcinoma using vaccines: Bottlenecks and breakthroughs

Human papillomavirus (HPV) contributes to sexually transmitted infection, which is primarily associated with pre-cancerous and cancerous lesions in both men and women and is among the neglected cancerous infections in the world. At global level, two-, four-, and nine-valent pure L1 protein encompassed vaccines in targeting high-risk HPV strains using recombinant DNA technology are available. Therapeutic vaccines are produced by early and late oncoproteins that impart superior cell immunity to preventive vaccines that are under investigation. In the current review, we have not only discussed the clinical significance and importance of both preventive and therapeutic vaccines but also highlighted their dosage and mode of administration. This review is novel in its way and will pave the way for researchers to address the challenges posed by HPV-based vaccines at the present time.

Single-dose HPV vaccine immunity: is there a role for non-neutralizing antibodies?

A single dose of human papillomavirus (HPV) vaccine against HPV infection (prerequisite for cervical cancer) appears to be as efficacious as two or three doses, despite inducing lower antibody titers. Neutralizing antibodies are thought to be the primary mediator of protection, but the threshold for protection is unknown. Antibody functions beyond neutralization have not been explored for HPV vaccines. Here, we discuss the immune mechanisms of HPV vaccines, with a focus on non-neutralizing antibody effector functions. In the context of single-dose HPV vaccination where antibody is limiting, we propose that non-neutralizing antibody functions may contribute to preventing HPV infection. Understanding the immunological basis of protection for single-dose HPV vaccination will provide a rationale for implementing single-dose HPV vaccine regimens.

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.

Small DNA tumor viruses and human cancer: Preclinical models of virus infection and disease

Human tumor viruses cause various human cancers that account for at least 15% of the global cancer burden. Among the currently identified human tumor viruses, two are small DNA tumor viruses: human papillomaviruses (HPVs) and Merkel cell polyomavirus (MCPyV). The study of small DNA tumor viruses (adenoviruses, polyomaviruses, and papillomaviruses) has facilitated several significant biological discoveries and established some of the first animal models of virus-associated cancers. The development and use of preclinical in vivo models to study HPVs and MCPyV and their role in human cancer is the focus of this review. Important considerations in the design of animal models of small DNA tumor virus infection and disease, including host range, cell tropism, choice of virus isolates, and the ability to recapitulate human disease, are presented. The types of infection-based and transgenic model strategies that are used to study HPVs and MCPyV, including their strengths and limitations, are also discussed. An overview of the current models that exist to study HPV and MCPyV infection and neoplastic disease are highlighted. These comparative models provide valuable platforms to study various aspects of virus-associated human disease and will continue to expand knowledge of human tumor viruses and their relationship with their hosts.

Peroxisomal Membrane Protein PMP34 Is Involved in the Human Papillomavirus Infection Pathway

Infection with high-risk human papillomavirus (HPV) types is linked to the onset of several cancers. The mechanism of HPV infection, however, has not yet been fully elucidated. Here, using the newly developed HPV infectious pseudovirion (HPV PsV) and a genome-wide clustered regularly interspaced short palindromic repeat (CRISPR) screening system, we established an experimental system and searched for genes involved in HPV infection. The HPV PsV has the truncated herpes simplex virus thymidine kinase (dTK) to kill PsV-infected cells when combined with ganciclovir. The five rounds of selection of 293FT cells by infection with HPV PsVs identified two candidate genes involved in the HPV infection pathway. The validation experiments showed that SLC25A17, which encodes the peroxisomal membrane protein PMP34, was involved in the HPV infection pathway. The gRNAs against SLC25A17 attenuated the efficiency of HPV PsV infection in 293FT and HeLa cells. Although further experiments are required to determine whether PMP34 acts as the HPV infection pathway, these results indicate that our screening system is useful for identification of the genes involved in the HPV infection pathway.

Production of codon-optimized Human papillomavirus type 52 L1 virus-like particles in Pichia pastoris BG10 expression system

Cervical cancer caused by Human papillomavirus (HPV) is one of the most common causes of cancer death in women worldwide. Even though the disease can be avoided by immunization, the expensive price of HPV vaccines makes it hard to be accessed by women in middle-low-income countries. Thus, the development of generic HPV vaccines is needed to address inequalities in life-saving access. This study aimed to develop the HPV52 L1 VLP-based recombinant vaccine using Pichia pastoris expression system. The l1 gene was codon-optimized based on P. pastoris codon usage resulting CAI value of 0.804. The gene was inserted into the pD902 plasmid under the regulation of the AOX1 promoter. The linear plasmid was transformed into P. pastoris BG10 genome and screened in YPD medium containing zeocin antibiotic. Colony of transformant that grown on highest zeocin concentration was characterized by genomic PCR and sequencing. The positive clone was selected and expressed using BMGY/BMMY medium induced with various methanol concentrations. The SDS-PAGE and Western blot analyses showed that 55 kDa L1 protein was successfully expressed using an optimum concentration of 1% methanol. The self-assembly of HPV52 L1 protein was also proven using TEM analysis. Moreover, we also analyzed the B-cell epitope of HPV52 L1 protein based on several criteria, including antigenicity, surface accessibility, flexibility, and hydrophilicity. We assumed that epitope ₄₇₆GLQARPKLKRPASSAPRTSTKKKKV₅₀₀ could be developed as an epitope-based vaccine with a neutralizing antibody response toward HPV52 infection. Finally, our study provided the alternative for developing low-cost HPV vaccines, either VLP or epitope-based.

Virus-Like Particles as Preventive and Therapeutic Cancer Vaccines

Virus-like particles (VLPs) are self-assembled viral protein complexes that mimic the native virus structure without being infectious. VLPs, similarly to wild type viruses, are able to efficiently target and activate dendritic cells (DCs) triggering the B and T cell immunities. Therefore, VLPs hold great promise for the development of effective and affordable vaccines in infectious diseases and cancers. Vaccine formulations based on VLPs, compared to other nanoparticles, have the advantage of incorporating multiple antigens derived from different proteins. Moreover, such antigens can be functionalized by chemical modifications without affecting the structural conformation or the antigenicity. This review summarizes the current status of preventive and therapeutic VLP-based vaccines developed against human oncoviruses as well as cancers.