CD4+ and CD8+ T cells can act separately in tumour rejection after immunization with murine pneumotropic virus chimeric Her2/neu virus-like particles

A Recombinant MVA-Based RSV Vaccine Induces T-Cell and Antibody Responses That Cooperate in the Protection Against RSV Infection

Respiratory syncytial virus (RSV) causes a respiratory disease with a potentially fatal outcome especially in infants and elderly individuals. Several vaccines failed in pivotal clinical trials, and to date, no vaccine against RSV has been licensed. We have developed an RSV vaccine based on the recombinant Modified Vaccinia Virus Ankara-BN^® (MVA-RSV), containing five RSV-specific antigens that induced antibody and T-cell responses, which is currently tested in clinical trials. Here, the immunological mechanisms of protection were evaluated to determine viral loads in lungs upon vaccination of mice with MVA-RSV followed by intranasal RSV challenge. Depletion of CD4 or CD8 T cells, serum transfer, and the use of genetically engineered mice lacking the ability to generate either RSV-specific antibodies (T11µMT), the IgA isotype (IgA knockout), or CD8 T cells (β2M knockout) revealed that complete protection from RSV challenge is dependent on CD4 and CD8 T cells as well as antibodies, including IgA. Thus, MVA-RSV vaccination optimally protects against RSV infection by employing multiple arms of the adaptive immune system.

Enhancing immunogenicity of HPV16 E7 DNA vaccine by conjugating codon-optimized GM-CSF to HPV16 E7 DNA

OBJECTIVE

To generate immunity against human papillomavirus (HPV), the use of a recombinant DNA vaccine to carry an appropriate target gene is a promising and cost-effective approach. Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a potent immunomodulatory cytokine that enhances the efficacy of vaccines by promoting the development and prolongation of humoral and cellular immunity. In this study, we linked codon-optimized GM-CSF (cGM-CSF) to the HPV16 E7 sequence as fused protein and evaluated the immunogenic potential of this DNA vaccine.

MATERIALS AND METHODS

We have demonstrated that cGM-CSF enhanced immunity against tumor challenges by generating and promoting the proliferation of HPV16 E7-specific CD8+ T cells, which secrete IFN-γ in the murine model. In this study, we aimed to evaluate the immunogenic potential of DNA vaccine that constructed by linking codon-optimized GM-CSF to HPV16 E7 sequence in the animal model. We study the half-life of RNA decay and cellular location of HPV16 E7 by Q-PCR and Western blot. We also assess immune response in the animal model by flow cytometry and ELISA.

RESULTS

The cGM-CSF-E7 sequence increased and extended the expression of E7 mRNA, in comparison with the E7 sequence alone. Mice vaccinated with the cGM-CSF-E7 DNA vaccine exhibited a slower rate of tumor growth than those vaccinated with the unconjugated E7 DNA vaccine. We also found that the CD4 and CD8+ T cells from these mice showed strong secretion of IFN-γ.

CONCLUSION

Through in vivo antibody depletion experiments, we demonstrated that both CD4+ and CD8+ T cells play an important role in the suppression of tumor growth.

In vivo targeting of DNA vaccines to dendritic cells using functionalized gold nanoparticles

The clinical success of dendritic cell (DC)-based genetic immunization remains critically dependent on the availability of effective and safe nano-carriers for targeting antigen-encoded DNA vaccines to DCs, the most potent antigen-presenting cells in the human body in vivo. Recent studies revealed the efficacies of mannose receptor-mediated in vivo DC-targeted genetic immunization by liposomal DNA vaccine carriers containing both mannose-mimicking shikimoyl and transfection enhancing guanidinyl functionalities. However, to date, the efficacies of this approach have not been examined for metal-based nanoparticle DNA vaccine carriers. Herein, we report for the first time, the design, synthesis, physico-chemical characterization and bioactivities of gold nanoparticles covalently functionalized with a thiol ligand containing both shikimoyl and guanidinyl functionalities (Au-SGSH). We show that Au-SGSH nanoparticles can deliver DNA vaccines to mouse DCs under in vivo conditions. Subcutaneous administration of near infrared (NIR) dye-labeled Au-SGSH showed significant accumulation of the NIR dye in the DCs of the nearby lymph nodes compared to that for the non-targeting NIR-labeled Au-GSH nanoconjugate containing only a covalently tethered guanidinyl group, not the shikimoyl-functionality. Under prophylactic settings, in vivo immunization (s.c.) with the Au-SGSH-pCMV-MART1 nanoplex induced a long-lasting (180 days) immune response against murine melanoma. Notably, mannose receptor-mediated in vivo DC-targeted immunization (s.c.) with the Au-SGSH-MART1 nanoplex significantly inhibited established melanoma growth and increased the overall survivability of melanoma-bearing mice under therapeutic settings. The Au-SGSH nanoparticles reported herein have potential use for in vivo DC-targeted genetic immunization against cancer and infectious diseases.

Microenvironment-derived ADAM28 prevents cancer dissemination

Previous studies have linked cancer cell-associated ADAM28 expression with tumor progression and metastatic dissemination. However, the role of host-derived ADAM28 in cancer dissemination processes remains unclear.

Genetically engineered-mice fully deficient for ADAM28 unexpectedly display increased lung colonization by pulmonary, melanoma or breast tumor cells. In experimental tumor cell dissemination models, host ADAM28 deficiency is further associated with a decreased lung infiltration by CD8⁺ T lymphocytes. Notably, naive ADAM28-deficient mice already display a drastic reduction of CD8⁺ T cells in spleen which is further observed in lungs. Interestingly, ex vivo CD8⁺ T cell characterization revealed that ADAM28-deficiency does not impact proliferation, migration nor activation of CD8⁺ T cells. Our data highlight a functional role of ADAM28 in T cell mobilization and point to an unexpected protective role for host ADAM28 against metastasis.

A simple, clinically relevant therapeutic vaccine shows long-term protection in an aggressive, delayed-treatment B lymphoma model

Despite initial remission after successful treatments, B lymphoma patients often encounter relapses and resistance causing high mortality. Thus, there is a need to develop therapies that prevent relapse by providing long-term protection and, ultimately, lead to functional cure. In this study, our goal was to develop a simple, clinically relevant, and easily translatable therapeutic vaccine that provides durable immune protection against aggressive B cell lymphoma and identify critical immune biomarkers that are predictive of long-term survival. In a delayed-treatment, aggressive, murine model of A20 B lymphoma that mimics human diffuse large B cell lymphoma, we show that therapeutic A20 lysate vaccine adjuvanted with an NKT cell agonist, α-galactosylceramide (α-GalCer), provides long-term immune protection against lethal tumor challenges and the antitumor immunity is primarily CD8 T cell dependent. Using experimental and computational methods, we demonstrate that the initial strength of germinal center reaction and the magnitude of class-switching into a Th1 type humoral response are the best predictors for the long-term immunity of B lymphoma lysate vaccine. Our results not only provide fundamentally insights for successful immunotherapy and long-term protection against B lymphomas, but also present a simple, therapeutic vaccine that can be translated easily due to the facile and inexpensive method of preparation.

Vaccine-elicited CD8+ T cells cure mesothelioma by overcoming tumor-induced immunosuppressive environment

Eradicating malignant tumors by vaccine-elicited host immunity remains a major medical challenge. To date, correlates of immune protection remain unknown for malignant mesothelioma. In this study, we demonstrated that antigen-specific CD8(+) T-cell immune response correlates with the elimination of malignant mesothelioma by a model PD-1-based DNA vaccine. Unlike the nonprotective tumor antigen WT1-based DNA vaccines, the model vaccine showed complete and long-lasting protection against lethal mesothelioma challenge in immunocompetent BALB/c mice. Furthermore, it remained highly immunogenic in tumor-bearing animals and led to therapeutic cure of preexisting mesothelioma. T-cell depletion and adoptive transfer experiments revealed that vaccine-elicited CD8(+) T cells conferred to the protective efficacy in a dose-dependent way. Also, these CD8(+) T cells functioned by releasing inflammatory IFNγ and TNFα in the vicinity of target cells as well as by initiating TRAIL-directed tumor cell apoptosis. Importantly, repeated DNA vaccinations, a major advantage over live-vectored vaccines with issues of preexisting immunity, achieve an active functional state, not only preventing the rise of exhausted PD-1(+) and Tim-3(+) CD8(+) T cells but also suppressing tumor-induced myeloid-derived suppressive cells and Treg cells, with the frequency of antigen-specific CD8(+) T cells inversely correlating with tumor mass. Our results provide new insights into quantitative and qualitative requirements of vaccine-elicited functional CD8(+) T cells in cancer prevention and immunotherapy.

Effective induction of anti-tumor immunity using p5 HER-2/neu derived peptide encapsulated in fusogenic DOTAP cationic liposomes co-administrated with CpG-ODN

Cationic liposomes have been used as efficient antigen delivery systems for cancer vaccination. The current study has investigated whether the incorporation of the helper-fusogenic lipid dioleoylphosphatidylethanolamine (DOPE) in cationic liposomes composed of 1,2-dioleoyl-3-trimethylammonium propane (DOTAP)-cholesterol enhances the cytosolic delivery of p5 HER-2/neu derived peptide (p5) and promotes cytotoxic T lymphocytes (CTL) response. The p5, which is a very hydrophobic peptide, was encapsulated into liposomes by using three different methods and characterized for their colloidal properties. A chaotropic loading method using 7 M urea provided the highest encapsulation yields. Mice were first immunized with encapsulated p5 in liposomes composed of either DOTAP-cholesterol or DOTAP-cholesterol-DOPE, alone or co-administered with CpG-ODN, as an immunoadjuvant, then, inoculated with a subcutaneous injection of TUBO tumor cells. Results obtained from enzyme-linked immunospot, cytotoxicity and intracellular cytokine assays as well as tumor sizes and animal survival analysis demonstrated that p5 encapsulated in DOTAP-cholesterol-DOPE liposomes co-administered with CpG-ODN greatly enhanced the cytotoxic T lymphocytes response and highly inhibited the tumor progression. The outperformance of DOTAP-cholesterol-DOPE liposomes+CpG-ODN was found to be attributed to its capability in induction of both CD8+ and CD4+ responses. This formulation could be a suitable vaccine candidate against Her2 positive cancers and merits further investigations.

The specificity of targeted vaccines for APC surface molecules influences the immune response phenotype

Different diseases require different immune responses for efficient protection. Thus, prophylactic vaccines should prime the immune system for the particular type of response needed for protection against a given infectious agent. We have here tested fusion DNA vaccines which encode proteins that bivalently target influenza hemagglutinins (HA) to different surface molecules on antigen presenting cells (APC). We demonstrate that targeting to MHC class II molecules predominantly induced an antibody/Th2 response, whereas targeting to CCR1/3/5 predominantly induced a CD8⁺/Th1 T cell response. With respect to antibodies, the polarizing effect was even more pronounced upon intramuscular (i.m) delivery as compared to intradermal (i.d.) vaccination. Despite these differences in induced immune responses, both vaccines protected against a viral challenge with influenza H1N1. Substitution of HA with ovalbumin (OVA) demonstrated that polarization of immune responses, as a consequence of APC targeting specificity, could be extended to other antigens. Taken together, the results demonstrate that vaccination can be tailor-made to induce a particular phenotype of adaptive immune responses by specifically targeting different surface molecules on APCs.

Production and biomedical applications of virus-like particles derived from polyomaviruses

Virus-like particles (VLPs), aggregates of capsid proteins devoid of viral genetic material, show great promise in the fields of vaccine development and gene therapy. These particles spontaneously self-assemble after heterologous expression of viral structural proteins. This review will focus on the use of virus-like particles derived from polyomavirus capsid proteins. Since their first recombinant production 27 years ago these particles have been investigated for a myriad of biomedical applications. These virus-like particles are safe, easy to produce, can be loaded with a broad range of diverse cargoes and can be tailored for specific delivery or epitope presentation. We will highlight the structural characteristics of polyomavirus-derived VLPs and give an overview of their applications in diagnostics, vaccine development and gene delivery.

DNA vaccine that targets hemagglutinin to MHC class II molecules rapidly induces antibody-mediated protection against influenza

New influenza A viruses with pandemic potential periodically emerge due to viral genomic reassortment. In the face of pandemic threats, production of conventional egg-based vaccines is time consuming and of limited capacity. We have developed in this study a novel DNA vaccine in which viral hemagglutinin (HA) is bivalently targeted to MHC class II (MHC II) molecules on APCs. Following DNA vaccination, transfected cells secreted vaccine proteins that bound MHC II on APCs and initiated adaptive immune responses. A single DNA immunization induced within 8 d protective levels of strain-specific Abs and also cross-reactive T cells. During the Mexican flu pandemic, a targeted DNA vaccine (HA from A/California/07/2009) was generated within 3 wk after the HA sequences were published online. These results suggest that MHC II-targeted DNA vaccines could play a role in situations of pandemic threats. The vaccine principle should be extendable to other infectious diseases.

Immunotherapy for polyomaviruses: opportunities and challenges

Polyomaviruses are small DNA viruses present in mammals and birds, and in 1953 the first one to be described was murine polyomavirus. It was not until 1971 that the first two human polyomaviruses (HPyVs), BK virus and JC virus, were discovered and found to be common in humans, but only associated with disease in severely immunosuppressed patients. Since 2007, seven new HPyVs have been identified: KI polyomavirus, WU polyomavirus, Merkel cell polyomavirus, HPyV6, HPyV7, trichodyplasia spinulosa polyomavirus and HPyV9. Notably, Merkel cell polyomavirus was detected in Merkel cell cancer, a tumor mainly found in elderly and immunocompromised individuals, while trichodyplasia spinulosa polyomavirus was found in trichodyplasia spinulosa, a skin disorder observed only in immunosuppressed individuals. Consequently, many polyomaviruses cause problems in immunosuppressed individuals. This review deals with these issues, and the potential of the capsid protein VP1 to form virus-like particles for use as vaccines against polyomavirus infections.

Viral Infections of Laboratory Mice

Viral infections of laboratory mice have considerable impact on research results, and prevention of such infections is therefore of crucial importance. This chapter covers infections of mice with the following viruses: herpesviruses, mousepox virus, murine adenoviruses, polyomaviruses, parvoviruses, lactate dehydrogenase-elevating virus, lymphocytic choriomeningitis virus, mammalian orthoreovirus serotype 3, murine hepatitis virus, murine norovirus, murine pneumonia virus, murine rotavirus, Sendai virus, and Theiler’s murine encephalomyelitis virus. For each virus, there is a description of the agent, epizootiology, clinical symptoms, pathology, methods of diagnosis and control, and its impact on research.

Baculovirus capsid display potentiates OVA cytotoxic and innate immune responses

Baculoviruses (BV) are DNA viruses that are pathogenic for insects. Although BV infect a range of mammalian cell types, they do not replicate in these cells. Indeed, the potential effects of these insect viruses on the immune responses of mammals are only just beginning to be studied. We show in this paper that a recombinant Autographa californica multiple nuclear polyhedrosis virus carrying a fragment of ovalbumin (OVA) on the VP39 capsid protein (BV-OVA) has the capacity to act as an adjuvant and vector of antigens in mice, thereby promoting specific CD4 and cytotoxic T cell responses against OVA. BV also induced in vivo maturation of dendritic cells and the production of inflammatory cytokines, thus promoting innate and adaptive immune responses. The OVA-specific response induced by BV-OVA was strong enough to reject a challenge with OVA-expressing melanoma cells (MO5 cells) and effectively prolonged survival of MO5 bearing mice. All these findings, together with the absence of pre-existing immunity to BV in humans and the lack of viral gene expression in mammalian cells, make BV a candidate for vaccination.

Murine polyomavirus virus-like particles carrying full-length human PSA protect BALB/c mice from outgrowth of a PSA expressing tumor

Virus-like particles (VLPs) consist of capsid proteins from viruses and have been shown to be usable as carriers of protein and peptide antigens for immune therapy. In this study, we have produced and assayed murine polyomavirus (MPyV) VLPs carrying the entire human Prostate Specific Antigen (PSA) (PSA-MPyVLPs) for their potential use for immune therapy in a mouse model system. BALB/c mice immunized with PSA-MPyVLPs were only marginally protected against outgrowth of a PSA-expressing tumor. To improve protection, PSA-MPyVLPs were co-injected with adjuvant CpG, either alone or loaded onto murine dendritic cells (DCs). Immunization with PSA-MPyVLPs loaded onto DCs in the presence of CpG was shown to efficiently protect mice from tumor outgrowth. In addition, cellular and humoral immune responses after immunization were examined. PSA-specific CD4⁺ and CD8⁺ cells were demonstrated, but no PSA-specific IgG antibodies. Vaccination with DCs loaded with PSA-MPyVLPs induced an eight-fold lower titre of anti-VLP antibodies than vaccination with PSA-MPyVLPs alone. In conclusion, immunization of BALB/c mice with PSA-MPyVLPs, loaded onto DCs and co-injected with CpG, induces an efficient PSA-specific tumor protective immune response, including both CD4⁺ and CD8⁺ cells with a low induction of anti-VLP antibodies.