Therapeutic vaccination using minimal HPV16 epitopes in a novel MHC-humanized murine HPV tumor model

Development and evaluation of a novel E7 multi-epitopic vaccine for human papillomavirus type 16: design, expression, purification, and immunological characterization

BACKGROUND

Persistent infection with high-risk Human papillomavirus (HPV), specifically HPV-16, is the leading cause of cervical cancer. Although preventative vaccines have shown significant efficacy in preventing HPV infection, cervical cancer is a significant public health issue that affects millions of women worldwide. Modern therapeutic approaches, such as peptide vaccines, could be promising and have potential for the treatment of the HPV-infected population.

METHODS

A HPV16-E7 multi-epitopic vaccine (MEVE7) was designed to comprise potent CD4 + and CD8 + T cell epitopes and optimally expressed in a prokaryotic expression system. Polyclonal antibodies were generated, and their reactivity with immunizing antigen and native protein in E7 expressing cells (TC-1) was assessed by ELISA and immunofluorescent staining, respectively. The efficacy of the vaccine was assessed in a therapeutic animal model of HPV-induced cancer.

RESULTS

Our study revealed that the final construct was successfully expressed in E. coli BL21 (DE3)-gold within 4 h of induction as inclusion bodies. Among the tested solubilization buffers, the buffer with a pH of 12 and containing 2 M urea showed the highest solubilization effect. Polyclonal antibodies directed against the E7 multi-epitope vaccine were able to react strongly with the immunizing antigen and E7-bearing cells (TC-1). Immunization of TC-1 tumor-bearing mice with HPV16-E7, markedly delayed tumor growth and propagation.

CONCLUSION

The poly-epitope vaccine for HPV16-E7, as expressed and purified in this research, is highly immunogenic and capable of triggering E7-specific antibodies, making it a potential therapeutic HPV vaccine. Further research is needed to optimize the vaccination schedule and assess the E7-specific immune cell profile.

Design and evaluation of a multi-epitope DNA vaccine against HPV16

Cervical cancer, among the deadliest cancers affecting women globally, primarily arises from persistent infection with high-risk human papillomavirus (HPV). To effectively combat persistent infection and prevent the progression of precancerous lesions into malignancy, a therapeutic HPV vaccine is under development. This study utilized an immunoinformatics approach to predict epitopes of cytotoxic T lymphocytes (CTLs) and helper T lymphocytes (HTLs) using the E6 and E7 oncoproteins of the HPV16 strain as target antigens. Subsequently, through meticulous selection of T-cell epitopes and other necessary elements, a multi-epitope vaccine was constructed, exhibiting good immunogenic, physicochemical, and structural characteristics. Furthermore, in silico simulations showed that the vaccine not only interacted well with toll-like receptors (TLR2/TLR3/TLR4), but also induced a strong innate and adaptive immune response characterized by elevated Th1-type cytokines, such as interferon-gamma (IFN-γ) and interleukin-2 (IL2). Additionally, our study investigated the effects of different immunization intervals on immune responses, aiming to optimize a time-efficient immunization program. In animal model experiments, the vaccine exhibited robust immunogenic, therapeutic, and prophylactic effects. Administered thrice, it consistently induced the expansion of specific CD4 and CD8 T cells, resulting in substantial cytokines release and increased proliferation of memory T cell subsets in splenic cells. Overall, our findings support the potential of this multi-epitope vaccine in combating HPV16 infection and signify its candidacy for future HPV vaccine development.

Viral Vector-Based Chlamydia trachomatis Vaccines Encoding CTH522 Induce Distinct Immune Responses in C57BL/6J and HLA Transgenic Mice

Chlamydia trachomatis remains a major global health problem with increasing infection rates, requiring innovative vaccine solutions. Modified Vaccinia Virus Ankara (MVA) is a well-established, safe and highly immunogenic vaccine vector, making it a promising candidate for C. trachomatis vaccine development. In this study, we evaluated two novel MVA-based recombinant vaccines expressing spCTH522 and CTH522:B7 antigens. Our results show that while both vaccines induced CD4+ T-cell responses in C57BL/6J mice, they failed to generate antigen-specific systemic CD8+ T cells. Only the membrane-anchored CTH522 elicited strong IgG2b and IgG2c antibody responses. In an HLA transgenic mouse model, both recombinant MVAs induced Th1-directed CD4+ T cell and multifunctional CD8+ T cells, while only the CTH522:B7 vaccine generated antibody responses, underscoring the importance of antigen localization. Collectively, our data indicate that distinct antigen formulations can induce different immune responses depending on the mouse strain used. This research contributes to the development of effective vaccines by highlighting the importance of careful antigen design and the selection of appropriate animal models to study specific vaccine-induced immune responses. Future studies should investigate whether these immune responses provide protection in humans and should explore different routes of immunization, including mucosal and systemic immunization.

A safe and potentiated multi-type HPV L2-E7 nanoparticle vaccine with combined prophylactic and therapeutic activity

Persistent infection with high-risk human papillomavirus (HPV) is widely recognized as the primary cause of cervical and other malignant cancers. There are six licensed prophylactic vaccines available against HPV, but none of them shows any significant therapeutic effect on pre-existing infections or lesions. Thus, a prophylactic vaccine also endowed with therapeutic activity would afford protection regardless of the vaccine recipients HPV-infection status. Here, we describe the refinement and further potentiation of a dual-purpose HPV nanoparticle vaccine (hereafter referred to as cPANHPVAX) relying on eight different HPV L2 peptide epitopes and on the E7 oncoantigens from HPV16 and 18. cPANHPVAX not only induces anti-HPV16 E7 cytotoxic T-cell responses in C57BL/6 mice, but also anti-HPV18 E7 T-cell responses in transgenic mice with the A2.DR1 haplotype. These cytotoxic responses add up to a potent, broad-coverage humoral (HPV-neutralizing) response. cPANHPVAX safety was further improved by deletion of the pRb-binding domains of E7. Our dual-purpose vaccine holds great potential for clinical translation as an immune-treatment capable of targeting active infections as well as established HPV-related malignancies, thus benefiting both uninfected and infected individuals.

Development of an Orthotopic HPV16-Dependent Base of Tongue Tumor Model in MHC-Humanized Mice

Head and neck squamous cell carcinomas (HNSCC) caused by infections with high-risk human papillomaviruses (HPV) are responsible for an increasing number of head and neck cancers, particularly in the oropharynx. Despite the significant biological differences between HPV-driven and HPV-negative HNSCC, treatment strategies are similar and not HPV targeted. HPV-driven HNSCC are known to be more sensitive to treatment, particularly to radiotherapy, which is at least partially due to HPV-induced immunogenicity. The development of novel therapeutic strategies that are specific for HPV-driven cancers requires tumor models that reflect as closely as possible the characteristics and complexity of human tumors and their response to treatment. Current HPV-positive cancer models lack one or more hallmarks of their human counterpart. This study presents the development of a new HPV16 oncoprotein-dependent tumor model in MHC-humanized mice, modeling the major biologic features of HPV-driven tumors and presenting HLA-A2-restricted HPV16 epitopes. Furthermore, this model was developed to be orthotopic (base of tongue). Thus, it also reflects the correct tumor microenvironment of HPV-driven HNSCC. The cancer cells are implanted in a manner that allows the exact control of the anatomical location of the developing tumor, thereby homogenizing tumor growth. In conclusion, the new model is suited to study HPV16-specific therapeutic vaccinations and other immunotherapies, as well as tumor-targeted interventions, such as surgery or radiotherapy, or a combination of all these modalities.

Inducing Immunity Where It Matters: Orthotopic HPV Tumor Models and Therapeutic Vaccinations

Anogenital and oropharyngeal cancers caused by human papillomavirus (HPV) infections account for 4.5% of all cancer cases worldwide. So far, only the initial infection with selected high-risk types can be prevented by prophylactic vaccination. Already existing persistent HPV infections, however, can currently only be treated by surgical removal of resulting lesions. Therapeutic HPV vaccination, promoting cell-based anti-HPV immunity, would be ideal to eliminate and protect against HPV-induced lesions and tumors. A multitude of vaccination approaches has been tested to date, many of which led to high amounts of HPV-specific T cells in vivo. However, growing evidence suggests that not the induction of systemic but of local immunity is paramount for tackling mucosal infections and tumors. Therefore, recent therapeutic vaccination studies have focused on how to induce tissue-resident T cells in the anogenital and oropharyngeal mucosa. These approaches include direct mucosal vaccinations and influencing the migration of systemic T cells toward the mucosa. The efficacy of these new vaccination approaches is best tested in vivo by utilizing orthotopic tumor models, i.e. HPV-positive tumors being located in the animal's mucosa. In line with this, we here review existing HPV tumor models and describe two novel tumorigenic cell lines for the MHC-humanized mouse model A2.DR1. These were used for the establishment of an HPV16 E6/E7-positive vaginal tumor model, suitable for testing therapeutic vaccines containing HLA-A2-restricted HPV16-derived epitopes. The newly developed MHC-humanized orthotopic HPV16-positive tumor model is likely to improve the translatability of in vivo findings to the clinical setting.

Robust anti-tumor T cell response with efficient intratumoral infiltration by nanodisc cancer immunotherapy

Potent anti-tumor T cell response and efficient intratumoral T cell infiltration are the major challenges for therapeutic cancer vaccines. To address these issues, a nano-vaccine system has been designed to promote anti-tumor T cell responses, and intratumoral infiltration was examined in various murine tumor models. Subcutaneous vaccination with nanodiscs carrying human papillomavirus (HPV)-16 E7 antigen elicits as high as ~32% E7-specific CD8 α + T cell responses in circulation, representing a 29-fold improvement over the soluble peptide vaccination. Importantly, nanodisc vaccination also promotes robust intratumoral T cell infiltration and eliminates HPV16 E6/E7-expressing TC-1 tumors at mucosal sites, including lungs, inner lip, and intravaginal tissues. In a benchmark study with a live Listeria vaccine combined with anti-PD-1 IgG, nanodiscs plus anti-PD-1 immune checkpoint blockade elicits comparable levels of T cell responses with anti-tumor efficacy. Furthermore, compared with Complete Freund's Adjuvant combined with tetanus toxoid, nanodisc vaccination in HLA-A02 mice generates >200-fold stronger IFN-γ+ T cell responses against a neoantigen from an HLA-A02 melanoma patient. Overall, these results show that the nanodisc system is a promising cancer vaccine platform for inducing anti-tumor T cell responses.

HPV16-E7 Protein T Cell Epitope Prediction and Global Therapeutic Peptide Vaccine Design Based on Human Leukocyte Antigen Frequency: An In-Silico Study

Cervical cancer is the second most common leading cause of women's death due to cancer worldwide, about 528,000 patients’ cases and 266,000 deaths per year, related to human papillomavirus (HPV). Peptide-based vaccines being safe, stable, and easy to produce have demonstrated great potential to develop therapeutic HPV vaccine. In this study, the major histocompatibility complex (MHC) class I, class II T cell epitopes of HPV16-E7 were predicted. Therefore, we designed a plan to find the most effective peptides to prompt appropriate immune responses. For this purpose, retrieving protein sequences, conserved region identification, phylogenic tree construction, T cell epitope prediction, epitope-predicted population coverage calculation, and molecular docking were performed consecutively and most effective immune response prompting peptides were selected. Based on different tools index, six CD8+ T cells and six CD4+ epitopes were chosen. This combination of 12 epitopes created a putative global vaccine with a 95.06% population coverage. These identified peptides can be employed further for peptide analysis and can be used as a peptide or poly-epitope candidates for therapeutic vaccine studies to treat HPV-associated cancers.

Papillomavirus Immune Evasion Strategies Target the Infected Cell and the Local Immune System

Persistent infection with human papillomavirus (HPV) initiates ~5% of all human cancers, and particularly cervical and oropharyngeal cancers. HPV vaccines prevent HPV infection, but do not eliminate existing HPV infections. Papillomaviruses induce hyperproliferation of epithelial cells. In this review we discuss how hyperproliferation renders epithelial cells less sensitive to immune attack, and impacts upon the efficiency of the local immune system. These observations have significance for the design of therapeutic HPV cancer immunotherapies.

T Lymphocyte Development and Activation in Humanized Mouse Model

Humanized mice, containing engrafted human cells and tissues, are emerging as an important in vivo platform for studying human diseases. Since the development of Nod scid gamma (NSG) mice bearing mutations in the IL-2 receptor gamma chain, many investigators have used NSG mice engrafted with human hematopoietic stem cells (HSCs) to generate functional human immune systems in vivo, results in high efficacy of human cell engraftment. The development of NSG mice has allowed significant advances to be made in studies on several human diseases, including cancer and graft-versus-host-disease (GVHD), and in regenerative medicine. Based on the human HSC transplantation, organ transplantation including thymus and liver in the renal capsule has been performed. Also, immune reconstruction of cells, of the lymphoid as well as myeloid lineages, has been partly accomplished. However, crosstalk between pluripotent stem cell derived therapeutic cells with human leukocyte antigen (HLA) mis/matched types and immune CD3 T cells have not been fully addressed. To overcome this hurdle, human major histocompatibility complex (MHC) molecules, not mouse MHC molecules, are required to generate functional T cells in a humanized mouse model. Here, we briefly summarize characteristics of the humanized mouse model, focusing on development of CD3 T cells with MHC molecules. We also highlight the necessity of the humanized mouse model for the treatment of various human diseases.