A novel synthetic DNA vaccine elicits protective immune responses against Powassan virus.

Powassan virus (POWV) infection is a tick-borne emerging infectious disease in the United States and North America. Like Zika virus, POWV is a member of the family Flaviviridae. POWV causes severe neurological sequalae, meningitis, encephalitis, and can cause death. Although the risk of human POWV infection is low, its incidence in the U.S. in the past 16 years has increased over 300%, urging immediate attention. Despite the disease severity and its growing potential for threatening larger populations, currently there are no licensed vaccines which provide protection against POWV. We developed a novel synthetic DNA vaccine termed POWV-SEV by focusing on the conserved portions of POWV pre-membrane and envelope (prMEnv) genes. A single immunization of POWV-SEV elicited broad T and B cell immunity in mice with minimal cross-reactivity against other flaviviruses. Antibody epitope mapping demonstrated a similarity between POWV-SEV-induced immune responses and those elicited naturally in POWV-infected patients. Finally, POWV-SEV induced immunity provided protection against POWV disease in lethal challenge experiments.

A Synthetic DNA, Multi-Neoantigen Vaccine Drives Predominately MHC Class I CD8+ T-cell Responses, Impacting Tumor Challenge.

T-cell recognition of cancer neoantigens is important for effective immune-checkpoint blockade therapy, and an increasing interest exists in developing personalized tumor neoantigen vaccines. Previous studies utilizing RNA and long-peptide neoantigen vaccines in preclinical and early-phase clinical studies have shown immune responses predominantly driven by MHC class II CD4+ T cells. Here, we report on a preclinical study utilizing a DNA vaccine platform to target tumor neoantigens. We showed that optimized strings of tumor neoantigens, when delivered by potent electroporation-mediated DNA delivery, were immunogenic and generated predominantly MHC class I-restricted, CD8+ T-cell responses. High MHC class I affinity was associated specifically with immunogenic CD8+ T-cell epitopes. These DNA neoantigen vaccines induced a therapeutic antitumor response in vivo, and neoantigen-specific T cells expanded from immunized mice directly killed tumor cells ex vivo These data illustrate a unique advantage of this DNA platform to drive CD8+ T-cell immunity for neoantigen immunotherapy.

A Rapid and Improved Method to Generate Recombinant Dengue Virus Vaccine Candidates.

Dengue is one of the most important mosquito-borne infections accounting for severe morbidity and mortality worldwide. Recently, the tetravalent chimeric live attenuated Dengue vaccine Dengvaxia® was approved for use in several dengue endemic countries. In general, live attenuated vaccines (LAV) are very efficacious and offer long-lasting immunity against virus-induced disease. Rationally designed LAVs can be generated through reverse genetics technology, a method of generating infectious recombinant viruses from full length cDNA contained in bacterial plasmids. In vitro transcribed (IVT) viral RNA from these infectious clones is transfected into susceptible cells to generate recombinant virus. However, the generation of full-length dengue virus cDNA clones can be difficult due to the genetic instability of viral sequences in bacterial plasmids. To circumvent the need for a single plasmid containing a full length cDNA, in vitro ligation of two or three cDNA fragments contained in separate plasmids can be used to generate a full-length dengue viral cDNA template. However, in vitro ligation of multiple fragments often yields low quality template for IVT reactions, resulting in inconsistent low yield RNA. These technical difficulties make recombinant virus recovery less efficient. In this study, we describe a simple, rapid and efficient method of using LONG-PCR to recover recombinant chimeric Yellow fever dengue (CYD) viruses as potential dengue vaccine candidates. Using this method, we were able to efficiently generate several viable recombinant viruses without introducing any artificial mutations into the viral genomes. We believe that the techniques reported here will enable rapid and efficient recovery of recombinant flaviviruses for evaluation as vaccine candidates and, be applicable to the recovery of other RNA viruses.

Synthesis, characterization, and immune efficacy of layered double hydroxide@SiO2 nanoparticles with shell-core structure as a delivery carrier for Newcastle disease virus DNA vaccine.

Layered double hydroxide (LDH)@SiO2 nanoparticles were developed as a delivery carrier for the plasmid DNA expressing the Newcastle disease virus F gene. The LDH was hydrotalcite-like materials. The plasmid DNA encapsulated in the LDH@SiO2 nanoparticles (pFDNA-LDH@SiO2-NPs) was prepared by the coprecipitation method, and the properties of pFDNA-LDH@SiO2-NPs were characterized by transmission electron microscopy, zeta potential analyzer, Fourier transform infrared spectroscopy, and X-ray diffraction analysis. The results demonstrated that the pFDNA-LDH@SiO2-NPs had a regular morphology and high stability with a mean diameter of 371.93 nm, loading capacity of 39.66%±0.45%, and a zeta potential of +31.63 mV. A release assay in vitro showed that up to 91.36% of the total plasmid DNA could be sustainably released from the pFDNA-LDH@SiO2-NPs within 288 hours. The LDH@SiO2 nanoparticles had very low toxicity. Additionally, their high transfection efficiency in vitro was detected by fluorescent microscopy. Intranasal immunization of specific pathogen-free chickens with pFDNA-LDH@SiO2-NPs induced stronger cellular, humoral, and mucosal immune responses and achieved a greater sustained release effect than intramuscular naked plasmid DNA, and the protective efficacy after challenge with the strain F48E9 with highly virulent (mean death time of chicken embryos ≤60 hours, intracerebral pathogenicity index in 1 -day-old chickens >1.6) was 100%. Based on the results, LDH@SiO2 nanoparticles can be used as a delivery carrier for mucosal immunity of Newcastle disease DNA vaccine, and have great application potential in the future.

Preparation and characterization of novel PBAE/PLGA polymer blend microparticles for DNA vaccine delivery.

CONTEXT: Poly(beta-amino ester) (PBAE) with its pH sensitiveness and Poly(lactic-co-glycolic acid) (PLGA) with huge DNA cargo capacity in combination prove to be highly efficient as DNA delivery system. OBJECTIVE: To study the effectiveness of novel synthesized PBAE polymer with PLGA blend at different ratios in DNA vaccine delivery. METHODS: In the present study, multifunctional polymer blend microparticles using a combination of PLGA and novel PBAE polymers A1 (bis(3-(propionyloxy)propyl)3,3'-(propane-1,3-diyl-bis(methylazanediyl))dipropanoate) and A2 (bis(4-(propionyloxy)butyl)3,3'-(ethane-1,2-diyl-bis(isopropylazanediyl))dipropanoate) at different ratios (85:15, 75:25, and 50:50) were prepared by double emulsion solvent removal method. The microparticles were characterized for cytotoxicity, transfection efficiency, and DNA encapsulation efficiency. RESULT: It was evident from results that among the microparticles prepared with PLGA/PBAE blend the PLGA:PBAE at 85:15 ratio was found to be more effective combination than the microparticles prepared with PLGA alone in terms of transfection efficiency and better DNA integrity. Microparticles made of PLGA and PBAE A1 at 85:15 ratio, respectively, were found to be less toxic when compared with microparticles prepared with A2 polymer. CONCLUSION: The results encourage the use of the synthesized PBAE polymer in combination with PLGA as an effective gene delivery system.

Development of nucleic acid vaccines: use of self-amplifying RNA in lipid nanoparticles.

Self-amplifying RNA or RNA replicon is a form of nucleic acid-based vaccine derived from either positive-strand or negative-strand RNA viruses. The gene sequences encoding structural proteins in these RNA viruses are replaced by mRNA encoding antigens of interest as well as by RNA polymerase for replication and transcription. This kind of vaccine has been successfully assayed with many different antigens as vaccines candidates, and has been shown to be potent in several animal species, including mice, nonhuman primates, and humans. A key challenge to realizing the broad potential of self-amplifying vaccines is the need for safe and effective delivery methods. Ideally, an RNA nanocarrier should provide protection from blood nucleases and extended blood circulation, which ultimately would increase the possibility of reaching the target tissue. The delivery system must then be internalized by the target cell and, upon receptor-mediated endocytosis, must be able to escape from the endosomal compartment into the cell cytoplasm, where the RNA machinery is located, while avoiding degradation by lysosomal enzymes. Further, delivery systems for systemic administration ought to be well tolerated upon administration. They should be safe, enabling the multiadministration treatment modalities required for improved clinical outcomes and, from a developmental point of view, production of large batches with reproducible specifications is also desirable. In this review, the concept of self-amplifying RNA vaccines and the most promising lipid-based delivery systems are discussed.

Ultrasonic synthetic technique to manufacture a pHEMA nanopolymeric-based vaccine against the H6N2 avian influenza virus: a preliminary investigation.

This preliminary study investigated the use of poly (2-hydroxyethyl methacrylate) (pHEMA) nanoparticles for the delivery of the deoxyribonucleic acid (DNA) vaccine pCAG-HAk, which expresses the full length hemagglutinin (HA) gene of the avian influenza A/Eurasian coot/Western Australian/2727/1979 (H6N2) virus with a Kozak sequence which is in the form of a pCAGGS vector. The loaded and unloaded nanoparticles were characterized using field-emission scanning electron microscopy. Further characterizations of the nanoparticles were made using atomic force microscopy and dynamic light scattering, which was used to investigate particle size distributions. This preliminary study suggests that using 100 µg of pHEMA nanoparticles as a nanocarrier/adjuvant produced a reduction in virus shedding and improved the immune response to the DNA vaccine pCAG-HAk.

Induction of endoplasmic reticulum-endosome fusion for antigen cross-presentation induced by poly (γ-glutamic acid) nanoparticles.

We previously reported that poly (γ-glutamic acid)-based nanoparticles (γ-PGA NPs) are excellent vaccine carriers for inducing efficient cross-presentation in dendritic cells, thereby producing strong antitumor immunity in vivo. Analyzing the mechanism of cross-presentation induced by γ-PGA NPs will be useful toward designing novel vaccine carriers. In this study, we show an intracellular mechanism of efficient cross-presentation induced by OVA-loaded γ-PGA NPs. Cross-presentation induced by γ-PGA NPs depended on cytoplasmic proteasomes and TAP, similar to the classical MHC class I presentation pathway for endogenous Ags. Intracellular behavior analyzed by confocal laser scanning microscopy revealed that encapsulated OVA and γ-PGA accumulated in both the endoplasmic reticulum (ER) and endosome compartments within 2 h. At the same time, electron microscopy analysis clearly showed that intracellular γ-PGA NPs and encapsulated Au NPs were enveloped in endosome-like vesicles, not in the ER. These findings strongly suggest that γ-PGA NPs enhance ER-endosome fusion for cross-presentation. Moreover, inhibition of ER translocon sec61 significantly decreased the γ-PGA NP/OVA-mediated cross-presentation efficiency, indicating that sec61 is important for transporting Ags from the fused ER-endosome to the cytoplasm. These findings imply that the ER-endosome complex is key for the efficient cross-presentation of Ags encapsulated in γ-PGA NPs.

Confronting the barriers to develop novel vaccines against brucellosis.

Brucellosis is an important zoonotic disease of nearly worldwide distribution. This pathogen causes abortion in domestic animals and undulant fever, arthritis, endocarditis and meningitis in humans. Currently, there is no vaccine licensed for brucellosis in humans. Furthermore, control of brucellosis in the human population relies on the control of animal disease. Available animal vaccines may cause disease and in some cases have limited efficacy. This article discusses recent studies in the development of recombinant protein, DNA and live-attenuated vaccines against brucellosis. Furthermore, we call the attention of the scientific community, government and industry professionals to the fact that for these novel vaccine initiatives to become licensed products they need to be effective in natural hosts and bypass the regulatory barriers present in several countries.

Targeting antigen to mouse dendritic cells via Clec9A induces potent CD4 T cell responses biased toward a follicular helper phenotype.

Three surface molecules of mouse CD8(+) dendritic cells (DCs), also found on the equivalent human DC subpopulation, were compared as targets for Ab-mediated delivery of Ags, a developing strategy for vaccination. For the production of cytotoxic T cells, DEC-205 and Clec9A, but not Clec12A, were effective targets, although only in the presence of adjuvants. For Ab production, however, Clec9A excelled as a target, even in the absence of adjuvant. Potent humoral immunity was a result of the highly specific expression of Clec9A on DCs, which allowed longer residence of targeting Abs in the bloodstream, prolonged DC Ag presentation, and extended CD4 T cell proliferation, all of which drove highly efficient development of follicular helper T cells. Because Clec9A shows a similar expression pattern on human DCs, it has particular promise as a target for vaccines of human application.

Construction of a new fusion anti-caries DNA vaccine.

Mutans streptococci (MS) are generally considered to be the principal etiological agent of dental caries. MS have two important virulence factors: cell- surface protein PAc and glucosyltransferases (GTFs). GTFs have two functional domains: an N-terminal catalytic sucrose-binding domain (CAT) and a C-terminal glucan-binding domain (GLU). A fusion anti-caries DNA vaccine, pGJA-P/VAX, encoding two important antigenic domains, PAc and GLU, of S. mutans, was successful in reducing the levels of dental caries caused by S. mutans in gnotobiotic animals. However, its protective effect against S. sobrinus infection proved to be weak. Does the DNA vaccine need an antigen of S. sobrinus to enhance its ability to inhibit infection? To answer this question, in this study, we cloned the catalytic (cat) fragment of S. sobrinus gtf-I, which demonstrated its ability to inhibit water-insoluble glucan synthesis by S. sobrinus, into pGJA-P/VAX to produce a new anti-caries DNA vaccine.

Upstream processing of plasmid DNA for vaccine and gene therapy applications.

The demand for plasmid DNA has increased vastly in response to rapid advances in its use in gene therapy and vaccines. These therapies are based on the same principle, i.e. the introduction of nucleic acids in human/non-human cells receptor to restore, cancel, enhance or introduce a biochemical function. Naked plasmid DNA as a vector has attracted a lot of interest since it offers several advantages over a viral vector, especially weak immunogenicity, better safety and easy to manufacture, but low transfection efficacy. Non-viral gene therapy may require considerable amounts (milligram scale) of pharmaceutical-grade pDNA per patient since the efficacy and duration of gene expression is presently relatively low. Reliance on fermentation, which generates large lysate volumes, for producing the needed quantities of pDNA is becoming more widespread. Through optimization of the biological system, growth environment and the growth mode, improvements can be achieved in biomass productivity, plasmid yield, plasmid quality and production costs. The information on large-scale plasmid production is scarce and usually not available to the scientific community. This review summarizes recent patents and patent applications relating to plasmid upstream processing manufacturing, ranging from plasmid design to growth strategies to produce plasmid-bearing E. coli.

Vaccine adjuvant formulation: a relatively neglected field that is crucial to vaccine success.

This 3-day conference, with a focus on formulation, is part of a series of conferences organized by Meetings Management on different aspects of vaccine adjuvants. The previous Modern Vaccine/Adjuvants Formulation took place in Prague in 2004 and it was interesting to observe what has changed and what since then remains the same.

Novel linear DNA vaccines induce protective immune responses against lethal infection with influenza virus type A/H5N1.

Vaccine development for possible influenza pandemics has been challenging. Conventional vaccines such as inactivated and live attenuated virus preparations are limited in terms of production speed and capacity. DNA vaccination has emerged as a potential alternative to conventional vaccines against influenza pandemics. In this study, we use a novel, cell-free DNA manufacturing process (synDNA) to produce prototype linear DNA vaccines against the influenza virus type A/H5N1. This synDNA process does not require bacterial fermentation, so it avoids the use of antibiotic resistance genes and other nucleic acid sequences unrelated to the antigen gene expression in the actual therapeutic DNA construct. The efficacy of various vaccines expressing the hemagglutinin and neuraminidase proteins (H5N1 synDNA), hemagglutinin alone (H5 synDNA) or neuraminidase alone (N1 synDNA) was evaluated in mice. Two of the constructs (H5 synDNA and H5N1 synDNA) induced a robust protective immune response with up to 93% of treated mice surviving a lethal challenge of a virulent influenza A/Vietnam/1203/04 H5N1 isolate. In combination with a potent biological activity and simplified production footprint, these characteristics make DNA vaccines prepared with our synDNA process highly suitable as alternatives to other vaccine preparations.

[Elaboration and evaluation of a candidate to the DNA vaccine using synthetic genes derived from the peptídeo SBm7462 against the carrapato Rhiphicephalus (Boophilus) microplus]. / Elaboração E avaliação de um candidato à vacina de DNA, utilizando-se genes sintéticos derivados do peptídeo SBm7462contra o carrapato Rhiphicephalus (Boophilus) microplus.

Rhiphicephalus (Boophilus) microplus is one of the most important arthropods in veterinary medicine due economic losses and health problems caused in cattle production. The vaccination represents optimum method evaluated with effective cost to prevent economic losses and to increase the duration and quality of life of the production animals. A synthetic peptide, SBm 7462, derived from Bm86, has been shown great results in control of ticks. The construction and synthesis of one nucleotide sequence based on this peptide might be useful for design a DNA vaccine that has many advances than peptide vaccine. A gene, called seq1, was constructed with a three repetition of nucleotide sequence of SBm 7462. It was cloned into a pCIneo vector expression in mammals and injected in BALB/c mouse. When mice were inoculated with the expression cassette they did not response in ELISA. They elevated antibody titles only when vaccinated with the synthetic peptide SBm7462®. And, the best titles of immunoglobulins were seen when the SBm7462® was administered subcutaneously.

The opposing effects of lipopolysaccharide on the antitumor therapeutic efficacy of DNA vaccine.

DNA vaccine represents a novel method to elicit immunity against infectious disease. Lipopolysaccharide (LPS) copurified with plasmid DNA may affect therapeutic efficacy and immunological response. We aimed to study the effect of LPS on the therapeutic efficacy of HER-2/neu DNA vaccine in a mouse tumor animal model. Plasmid DNA purified from commercial EndoFree plasmid purification kits functioned as a better therapeutic DNA vaccine than that purified from Non-EndoFree purification kit, which contains >or=0.5 microg LPS per 100 mg DNA plasmid. To further investigate the effect of LPS on the therapeutic efficacy of DNA vaccine, increasing amount of LPS was added to endotoxin-free plasmid DNA, and inoculated on mice with established tumors. One mug of LPS significantly attenuated the therapeutic effect of neu DNA vaccine and increased Th2 immune responses bias with interleukin-4 cytokine production. In contrast, high amount (100 microg) of LPS enhanced the therapeutic efficacy of neu DNA vaccine with an increase of cytotoxic T lymphocyte response and Th1 immune response. The effect of LPS on DNA vaccine was diminished when the tumor was grown in toll-like receptor 4 (TLR4)-mutant C3H/HeJ mice. Our results indicate that variation in the LPS doses exerts opposing effects on the therapeutic efficacy of DNA vaccine, and the observed effect is TLR4 dependent.

Heterologous prime-boost strategy to immunize very young infants against measles: pre-clinical studies in rhesus macaques.

Infants in developing countries are at high risk of developing severe clinical measles if they become infected during the "window of vulnerability" (age 4-9 months), when declining maternal antibodies do not protect against wild virus, yet impede successful immunization by attenuated measles vaccine. We developed two Sindbis replicon-based DNA vaccines expressing measles virus hemagglutinin and fusion protein with the goal of priming young infants to respond safely and effectively to subsequent boosting with attenuated measles vaccine. Intradermal prime with DNA vaccines by needle-free injection followed by aerosol or parenteral boost with licensed measles vaccine was well tolerated by juvenile and young infant rhesus macaques, and protected against clinical measles and viremia on wild-type virus challenge. A proteosome-measles vaccine administered alone (three doses) or as a boost following DNA vaccine priming was also safe and protective. These promising results pave the way for clinical trials to assess this prime-boost strategy.

Allergenicity and antigenicity of wild-type and mutant, monomeric, and dimeric carrot major allergen Dau c 1: destruction of conformation, not oligomerization, is the roadmap to save allergen vaccines.

BACKGROUND: Carrot allergy is caused by primary sensitization to birch pollen. Continuous carrot exposure results in additional Dau c 1-specific allergic responses. Thus, immunotherapy with birch pollen may not improve the food allergy. OBJECTIVE: Evaluation of mutation and oligomerization of the major carrot allergen, Dau c 1, in regard to alteration of antibody binding capacities, structure, and the ability to induce blocking IgG antibodies. METHODS: Measurement of IgE reactivities to monomers, dimers of wild-type and mutant Dau c 1.0104 and Dau c 1.0201, and Dau c 1.0104 trimer, their ability to induce blocking antibodies in mice, and their allergenic potency by histamine release. RESULTS: The reactivity of human IgE to the mutant dimer was reduced on average by 81%. Sera of immunized Balb/c mice showed specific IgG similar to the human IgE antibody response; Dau c 1.01 was more antigenic than Dau c 1.02. Both wild-type and mutant Dau c 1 variants induced cross-reacting IgG, which blocked binding of human IgE. The mutants were more antigenic than the wild-type forms, and the dimers induced higher IgG responses in mice than the monomers. The results of the histamine release experiments corroborated the findings of the antibody binding studies. CONCLUSION: Destruction of native conformation rather than oligomerization is the appropriate strategy to reduce the allergenicity of Bet v 1-homologous food allergens. CLINICAL IMPLICATIONS: The dimer composed of mutants of Dau c 1.0104 and Dau c 1.0201 is a promising candidate vaccine for treatment of carrot allergy because of its high immunogenicity and drastically reduced allergenicity.

Adjuvant properties of listeriolysin O protein in a DNA vaccination strategy.

The use of infectious agents as vaccine adjuvants has shown utility in both prophylactic and therapeutic vaccinations. Listeria monocytogenes has been used extensively as a vaccine vehicle due to its ability to initiate both CD4(+) and CD8(+) immune responses. Previous work from this laboratory has used transgenic Listeria to deliver vaccine constructs. A chimeric protein composed of tumor antigen and a non-hemolytic variant of the Listeria protein, listeriolysin O (LLO), has demonstrated effective tumor protection beyond that of antigen alone expressed in the same system. To address the question of how fusion with LLO improves vaccine efficacy, we constructed a number of DNA plasmid vaccines to isolate this effect in the absence of other endogenous Listeria effects. Here we have analyzed the ability of these vaccines to induce the regression of previously established tumors. A vaccine strategy using DNA vaccines bearing the tumor antigen either alone or in combination with LLO in addition to plasmids encoding MIP-1alpha and GM-CSF was examined. Further, LLO was used either as a chimera or in a bicistronic construct to address the importance of fusion between these elements. Notably, the strategies employing both chimeric and bicistronic vaccines were effective in reducing tumor burden suggesting that LLO can act as an adjuvant that does not require fusion with the tumor antigen to mediate its effect.

Prime-boost with alternating DNA vaccines designed to engage different antigen presentation pathways generates high frequencies of peptide-specific CD8+ T cells.

The route for presentation of Ag to CD8+ or CD4+ T cells following DNA vaccination is critical for determining outcome, but the pathways involved are unclear. In this study, we compare two different DNA vaccine designs aimed to elicit CD8+ T cell responses against a specific peptide-epitope either by direct- or cross-presentation. Each carries sequences from tetanus toxin (TT) to provide essential CD4+ T cell help. In the first already proven design, the peptide-epitope is fused to the N-terminal domain of fragment C from TT. This appears to act mainly by cross-presentation. In the second design, the peptide-epitope is encoded by a minigene, with induction of Th responses mediated by coexpression of a hybrid invariant chain molecule, incorporating a single determinant from TT (p30) in exchange for class II-associated invariant chain peptide. This design appears to act mainly via direct presentation from transfected APCs. Both vaccines mediated Th-dependent priming of CD8+ T cells in mice, but the kinetics and level of the responses differed markedly, consistent with engagement of distinct pathways of Ag presentation. Importantly, the vaccines could be combined in an alternating prime-boost regime, in either order, generating substantially expanded memory CD8+ T cells, with potent effector function. Taken together, these results demonstrate that vaccination protocols involving different modes of Ag presentation at prime and boost can significantly improve the effectiveness of immunization.