Two repeated motifs enriched within some enhancers and origins of replication are bound by SETMAR isoforms in human colon cells.

Setmar is a gene specific to simian genomes. The function(s) of its isoforms are poorly understood and their existence in healthy tissues remains to be validated. Here we profiled SETMAR expression and its genome-wide binding landscape in colon tissue. We found isoforms V3 and V6 in healthy and tumour colon tissues as well as incell lines. In two colorectal cell lines SETMAR binds to several thousand Hsmar1 and MADE1 terminal ends, transposons mostly located in non-genic regions of active chromatin including in enhancers. It also binds to a 12-bp motifs similar to an inner motif in Hsmar1 and MADE1 terminal ends. This motif is interspersed throughout the genome and is enriched in GC-rich regions as well as in CpG islands that contain constitutive replication origins. It is also found in enhancers other than those associated with Hsmar1 and MADE1. The role of SETMAR in the expression of genes, DNA replication and in DNA repair are discussed.

Oral Delivery of miR-320-3p with Lipidic Aminoglycoside Derivatives at Mid-Lactation Alters miR-320-3p Endogenous Levels in the Gut and Brain of Adult Rats According to Early or Regular Weaning.

To investigate if the artificial delivery of microRNAs naturally present in the breastmilk can impact the gut and brain of young rats according to weaning. Animals from a new transgenic rat line expressing the green-fluorescent protein in the endocrine lineage (cholecystokinin expressing cells) received a single oral bolus of miR-320-3p or miR-375-3p embedded in DiOleyl-Succinyl-Paromomycin (DOSP) on D-12. The pups were weaned early (D-15), or regularly (D-30). The expression of relevant miRNA, mRNAs, chromatin complexes, and duodenal cell density were assessed at 8 h post-inoculation and on D-45. The miR-320-3p/DOSP induced immediate effects on H3K4me3 chromatin complexes with polr3d promoter (p < 0.05). On regular weaning, on D-45, miR-320-3p and 375-3p were found to be downregulated in the stomach and upregulated in the hypothalamus (p < 0.001), whereas miR-320-3p was upregulated in the duodenum. After early weaning, miR-320-3p and miR-375-3p were downregulated in the stomach and the duodenum, but upregulated in the hypothalamus and the hippocampus. Combination of miR-320-3p/DOSP with early weaning enhanced miR-320-3p and chromogranin A expression in the duodenum. In the female brain stem, miR-320-3p, miR-504, and miR-16-5p levels were all upregulated. Investigating the oral miRNA-320-3p loads in the duodenal cell lineage paved the way for designing new therapeutics to avoid unexpected long-term impacts on the brain.

Single lipoaminoglycoside promotes efficient intracellular antibody delivery: A comprehensive insight into the mechanism of action.

Delivery of biologically active proteins into cells is emerging as important strategy for many applications. Previous experiments have shown that lipoaminoglycosides were capable of delivery of the anti-cytokeratin8 antibody (anti-K8) but only when formulated with lipid helpers potentially leading to toxicity from excess lipids. Here, we optimized anti-K8 delivery with various lipoaminoglycosides in the absence of a lipid helper. Results led to the identification of the aminoglycoside lipid dioleyl phosphoramido ribostamycin (DOPRI) as a potent intracellular delivery system for anti-K8. Electron microscopy revealed that delivered anti-K8 molecules were bound to intermediate filaments in cells. Anti-K8 was bound to the surface of DOPRI vesicles without perturbing lipid organization. Macropinocytosis and caveolin mediated endocytosis contributed to anti-K8 internalization and to filament labeling with a major contribution being made by the caveolin pathway. The results showed that the unique properties of DOPRI were sufficient for efficient intracellular protein delivery without requiring lipid helpers.

MgtC as a Host-Induced Factor and Vaccine Candidate against Mycobacterium abscessus Infection.

Mycobacterium abscessus is an emerging pathogenic mycobacterium involved in pulmonary and mucocutaneous infections, presenting a serious threat for patients with cystic fibrosis (CF). The lack of an efficient treatment regimen and the emergence of multidrug resistance in clinical isolates require the development of new therapeutic strategies against this pathogen. Reverse genetics has revealed genes that are present in M. abscessus but absent from saprophytic mycobacteria and that are potentially involved in pathogenicity. Among them, MAB_3593 encodes MgtC, a known virulence factor involved in intramacrophage survival and adaptation to Mg(2+) deprivation in several major bacterial pathogens. Here, we demonstrated a strong induction of M. abscessus MgtC at both the transcriptional and translational levels when bacteria reside inside macrophages or upon Mg(2+) deprivation. Moreover, we showed that M. abscessus MgtC was recognized by sera from M. abscessus-infected CF patients. The intramacrophage growth (J774 or THP1 cells) of a M. abscessus knockout mgtC mutant was, however, not significantly impeded. Importantly, our results indicated that inhibition of MgtC in vivo through immunization with M. abscessus mgtC DNA, formulated with a tetrafunctional amphiphilic block copolymer, exerted a protective effect against an aerosolized M. abscessus challenge in CF (ΔF508 FVB) mice. The formulated DNA immunization was likely associated with the production of specific MgtC antibodies, which may stimulate a protective effect by counteracting MgtC activity during M. abscessus infection. These results emphasize the importance of M. abscessus MgtC in vivo and provide a basis for the development of novel therapeutic tools against pulmonary M. abscessus infections in CF patients.

Important role of phosphoramido linkage in imidazole-based dioleyl helper lipids for liposome stability and primary cell transfection.

BACKGROUND: To optimize synthetic gene delivery systems, there is a need to develop more efficient lipid formulations. Most cationic lipid formulations contain 'helper' neutral lipids because of their ability to increase DNA delivery, in particular by improving endosomal escape of DNA molecules via the pH-buffering effect of protonatable groups and/or fusion with the lipid bilayer of endosomes. METHODS: We evaluated the influence of the linker structure between the two oleyl chains in the helper lipid on transfection efficiency in cell lines, as well as in primary cells (hepatocytes/cardiomyocytes). We reported the synthesis of two new pH-buffering imidazole helper lipids characterized by a polar headgroup containing one (compound 6) or two (compound 5) imidazole groups and two oleyl chains linked by an amide group. We studied their association with the aminoglycoside lipidic derivative dioleylsuccinylparomomycin (DOSP), which contains two oleyl chains linked to the aminoglycoside polar headgroup via an amide function. We compared the morphology and transfection properties of such binary liposomes of DOSP/5 and DOSP/6 with those of liposomes combining DOSP with another imidazole-based dioleyl helper lipid (MM27) in which a phosphoramido group acts as a linker between the two oleyl chains and imidazole function. RESULTS: The phosphoramido linker in the helper lipid induces a major difference in terms of morphology and resistance to decomplexation at physical pH for DOSP/helper lipid complexes. CONCLUSIONS: This hybrid dioleyl linker composition of DOSP/MM27 led to higher transfection efficiency in cell lines and in primary cells compared to complexes with homogeneous dioleyl linker.

RILES, a novel method for temporal analysis of the in vivo regulation of miRNA expression.

Novel methods are required to investigate the complexity of microRNA (miRNA) biology and particularly their dynamic regulation under physiopathological conditions. Herein, a novel plasmid-based RNAi-Inducible Luciferase Expression System (RILES) was engineered to monitor the activity of endogenous RNAi machinery. When RILES is transfected in a target cell, the miRNA of interest suppresses the expression of a transcriptional repressor and consequently switch-ON the expression of the luciferase reporter gene. Hence, miRNA expression in cells is signed by the emission of bioluminescence signals that can be monitored using standard bioluminescence equipment. We validated this approach by monitoring in mice the expression of myomiRs-133, -206 and -1 in skeletal muscles and miRNA-122 in liver. Bioluminescence experiments demonstrated robust qualitative and quantitative data that correlate with the miRNA expression pattern detected by quantitative RT-PCR (qPCR). We further demonstrated that the regulation of miRNA-206 expression during the development of muscular atrophy is individual-dependent, time-regulated and more complex than the information generated by qPCR. As RILES is simple and versatile, we believe that this methodology will contribute to a better understanding of miRNA biology and could serve as a rationale for the development of a novel generation of regulatable gene expression systems with potential therapeutic applications.

Reliability of the nanopheres-DNA immunization technology to produce polyclonal antibodies directed against human neogenic proteins.

The molecular domestication of several DNA transposons that occurred during the evolution of the mammalian lineage, has led to the emergence of at least 43 genes, known as neogenes. To date, the limited availability of efficient commercial antibodies directed against most of their protein isoforms hampers investigation of their expression in vitro and in situ. Since immunization protocols using peptides or recombinant proteins have revealed that it is difficult to recover antibodies, we planned to produce antisera in mice using a new technique of nanopheres/DNA immunization, the ICANtibodies™ technology. Here, we investigate the possibilities of obtaining polyclonal antibodies for 24 proteins or protein domains using this immunization strategy. We successfully obtained 13 antisera that were able to detect neogenic proteins by Western blotting and ELISA in protein extracts of transiently-transfected cells and various cancer cell lines, plus another two that only detected the in ELISA and in in situ hybridizations. The features required for the production of these antibodies are analyzed and discussed, and examples are given of the advantages they offer for the study of neogenic proteins.

Probing the in vitro mechanism of action of cationic lipid/DNA lipoplexes at a nanometric scale.

Cationic lipids are used for delivering nucleic acids (lipoplexes) into cells for both therapeutic and biological applications. A better understanding of the identified key-steps, including endocytosis, endosomal escape and nuclear delivery is required for further developments to improve their efficacy. Here, we developed a labelling protocol using aminated nanoparticles as markers for plasmid DNA to examine the intracellular route of lipoplexes in cell lines using transmission electron microscopy. Morphological changes of lipoplexes, membrane reorganizations and endosomal membrane ruptures were observed allowing the understanding of the lipoplex mechanism until the endosomal escape mediated by cationic lipids. The study carried out on two cationic lipids, bis(guanidinium)-tris(2-aminoethyl)amine-cholesterol (BGTC) and dioleyl succinyl paramomycin (DOSP), showed two pathways of endosomal escape that could explain their different transfection efficiencies. For BGTC, a partial or complete dissociation of DNA from cationic lipids occurred before endosomal escape while for DOSP, lipoplexes remained visible within ruptured vesicles suggesting a more direct pathway for DNA release and endosome escape. In addition, the formation of new multilamellar lipid assemblies was noted, which could result from the interaction between cationic lipids and cellular compounds. These results provide new insights into DNA transfer pathways and possible implications of cationic lipids in lipid metabolism.

Amphiphilic block copolymers enhance the cellular uptake of DNA molecules through a facilitated plasma membrane transport.

Amphiphilic block copolymers have been developed recently for their efficient, in vivo transfection activities in various tissues. Surprisingly, we observed that amphiphilic block copolymers such as Lutrol® do not allow the transfection of cultured cells in vitro, suggesting that the cell environment is strongly involved in their mechanism of action. In an in vitro model mimicking the in vivo situation we showed that pre-treatment of cells with Lutrol®, prior to their incubation with DNA molecules in the presence of cationic lipid, resulted in higher levels of reporter gene expression. We also showed that this improvement in transfection efficiency associated with the presence of Lutrol® was observed irrespective of the plasmid promoter. Considering the various steps that could be improved by Lutrol®, we concluded that the nucleic acids molecule internalization step is the most important barrier affected by Lutrol®. Microscopic examination of transfected cells pre-treated with Lutrol® confirmed that more plasmid DNA copies were internalized. Absence of cationic lipid did not impair Lutrol®-mediated DNA internalization, but critically impaired endosomal escape. Our results strongly suggest that in vivo, Lutrol® improves transfection by a physicochemical mechanism, leading to cellular uptake enhancement through a direct delivery into the cytoplasm, and not via endosomal pathways.

704/DNA vaccines leverage cytoplasmic DNA stimulation to promote anti-HIV neutralizing antibody production in mice and strong immune response against alpha-fetoprotein in non-human primates.

Genetic immunization is an attractive approach for prophylactic and therapeutic vaccination using synthetic vectors to deliver antigen-encoding nucleic acids. Recently, DNA delivered by a physical means or RNA by liposomes consisting of four different lipids demonstrated good protection in human phase III clinical trials and received Drugs Controller General of India and US FDA approval to protect against COVID-19, respectively. However, the development of a system allowing for efficient and simple delivery of nucleic acids while improving immune response priming has the potential to unleash the full therapeutic potential of genetic immunization. DNA-based gene therapies and vaccines have the potential for rapid development, as exemplified by the recent approval of Collategene, a gene therapy to treat human critical limb ischemia, and ZyCoV, a DNA vaccine delivered by spring-powered jet injector to protect against SARS-CoV2 infection. Recently, we reported amphiphilic block copolymer 704 as a promising synthetic vector for DNA vaccination in various models of human diseases. This vector allows dose sparing of antigen-encoding plasmid DNA. Here, we report the capacity of 704-mediated HIV and anti-hepatocellular carcinoma DNA vaccines to induce the production of specific antibodies against gp120 HIV envelope proteins in mice and against alpha-fetoprotein antigen in non-human primates, respectively. An investigation of the underlying mechanisms showed that 704-mediated vaccination did trigger a strong immune response by (1) allowing a direct DNA delivery into the cytosol, (2) promoting an intracytoplasmic DNA sensing leading to both interferon and NF-κB cascade stimulation, and (3) inducing antigen expression by muscle cells and presentation by antigen-presenting cells, leading to the induction of a robust adaptive response. Overall, our findings suggest that the 704-mediated DNA vaccination platform is an attractive method to develop both prophylactic and therapeutic vaccines.

Tocilizumab-treated convalescent COVID-19 patients retain the cross-neutralization potential against SARS-CoV-2 variants.

Although tocilizumab treatment in severe and critical coronavirus disease 2019 (COVID-19) patients has proven its efficacy at the clinical level, there is little evidence supporting the effect of short-term use of interleukin-6 receptor blocking therapy on the B cell sub-populations and the cross-neutralization of SARS-CoV-2 variants in convalescent COVID-19 patients. We performed immunological profiling of 69 tocilizumab-treated and non-treated convalescent COVID-19 patients in total. We observed that SARS-CoV-2-specific IgG1 titers depended on disease severity but not on tocilizumab treatment. The plasma of both treated and non-treated patients infected with the ancestral variant exhibit strong neutralizing activity against the ancestral virus and the Alpha, Beta, and Delta variants of SARS-CoV-2, whereas the Gamma and Omicron viruses were less sensitive to seroneutralization. Overall, we observed that, despite the clinical benefits of short-term tocilizumab therapy in modifying the cytokine storm associated with COVID-19 infections, there were no modifications in the robustness of B cell and IgG responses to Spike antigens.

Respiratory mucosal vaccination of peptide-poloxamine-DNA nanoparticles provides complete protection against lethal SARS-CoV-2 challenge.

The ongoing SARS-CoV-2 pandemic represents a brutal reminder of the continual threat of mucosal infectious diseases. Mucosal immunity may provide robust protection at the predominant sites of SARS-CoV-2 infection. However, it remains unclear whether respiratory mucosal administration of DNA vaccines could confer protective immune responses against SARS-CoV-2 challenge due to insurmountable barriers posed by the airway. Here, we applied self-assembled peptide-poloxamine nanoparticles with mucus-penetrating properties for pulmonary inoculation of a COVID-19 DNA vaccine (pSpike/PP-sNp). The pSpike/PP-sNp not only displays superior gene transfection and favorable biocompatibility in the mouse airway, but also promotes a tripartite immunity consisting of systemic, cellular, and mucosal immune responses that are characterized by mucosal IgA secretion, high levels of neutralizing antibodies, and resident memory phenotype T-cell responses in the lungs of mice. Most importantly, immunization with pSpike/PP-sNp completely eliminates SARS-CoV-2 infection in both upper and lower respiratory tracts and enables 100% survival rate of mice following lethal SARS-CoV-2 challenge. Our findings indicate PP-sNp is a promising platform in mediating DNA vaccines to elicit all-around mucosal immunity against SARS-CoV-2.

Treatment efficacy of DNA lipid nanocapsules and DNA multimodular systems after systemic administration in a human glioma model.

BACKGROUND: We previously developed different types of DNA nanocarriers for systemic administration. Recently, the biodistribution profiles of these intravenously administered nanocarriers, DNA lipid nanocapsules (LNCs) and different multimodular systems (MMS), were analysed in healthy mice using in vivo biofluorescence imaging. METHODS: In the present study, the experiments were performed in an ectopic human U87MG glioma model in nude mice. First, the biodistribution profiles of intravenously administered multimodular systems delivering a plasmid DNA with a luciferase cassette were analysed using in vivo biofluorescence imaging. Afterwards, a systemic treatment with two long circulating DNA nanocarriers, poly(ethylene glycol) (PEG) DNA LNCs and galactose (GAL) DNA MMS dioleylamin-succinyl paromomycin (DOSP) was performed on this glioma model using a plasmid encoding the herpes simplex virus thymidine kinase (HSV-tk) and subsequent ganciclovir (GCV) treatment. RESULTS: The biodistribution profiles of the different DNA nanocarriers on this glioma model were similar to those observed on healthy animals and varied in function of their cationic lipid composition and their surface characteristics. Furthermore, PEG DNA LNCs and GAL DNA MMS DOSP showed a specific accumulation and some luciferase expression in the tumour tissue. The systemic treatment using the HSV-tk/GCV approach showed a tumour growth reduction compared to the nontreated mice cohort. CONCLUSIONS: These results are in good accordance with those obtained previously with PEG DNA LNCs in a human melanoma mouse model and highlight the potential use of GAL DNA MMS DOSP and PEG DNA LNCs as future therapeutics in glioma and other cancers.

AFP-specific immunotherapy impairs growth of autochthonous hepatocellular carcinoma in mice.

BACKGROUND AND AIMS: In this study, we have assessed the potential of antigen-specific immunotherapy against hepatocellular carcinoma (HCC) in conditions of low tumour burden, in an autochthonous HCC model. METHODS: Diethylnitrosamine (DEN) injected into infant mice results in the development of multi-nodular HCC in which alpha-fetoprotein (AFP) is re-expressed. DEN-injected animals received an antigen-specific immunization with a synthetic vector consisting of a low dose of AFP-encoding plasmid formulated with the amphiphilic block copolymer 704 (DNAmAFP/704). Animals were treated at 4 and 5 months, before macroscopic nodules were detected, and were sacrificed at 8 months. The tumour burden, as well as liver histology, was assessed. AFP and MHC class I molecule expression in the nodules were monitored by qRT-PCR. RESULTS: The AFP-specific immunotherapy led to a significant (65%) reduction in tumour size. The reduced expression of AFP and MHC class I molecules was measured in the remaining nodules taken from the DNAmAFP/704-treated group. CONCLUSIONS: This is the first study demonstrating the relevance of antigen-specific immunotherapy in an autochthonous HCC model. In this context, we validated the use of an anti-tumour immunotherapy based on vaccination with nanoparticles consisting of low dose antigen-encoding DNA formulated with a block copolymer. Our results demonstrate the potential of this strategy as adjuvant immunotherapy to reduce the recurrence risk after local treatment of HCC patients.

Evidence of DNA transfer across a model membrane by a neutral amphiphilic block copolymer.

BACKGROUND: Neutral amphiphilic triblock copolymers have been shown to be efficient for gene transfection in vivo, especially by direct injection into the muscle. To contribute to a better understanding of the underlying mechanisms, in the present study, we investigated the properties of a poly(ethylene oxide-b-4-vinylpyridine) diblock copolymer as vector for nucleic acid transfer, with the particular aim of shedding some light on a possible mechanism explaining the internalization of DNA by the transfected cells. METHODS: Complexation of plasmid DNA with the PEO-b-P4VP diblock copolymer was investigated by ethidium bromide exclusion and gel electrophoresis assays. Interaction of the copolymer with a lipid model membrane was evaluated by electrophysiological assays and quantification of plasmid DNA was performed by quantitative polymerase chain reaction. In vivo luciferase transfection assays were finally performed. RESULTS: The diblock copolymer was found to poorly interact with DNA up to a mass ratio (copolymer/DNA) as high as 150. At a concentration of 36 µg/ml, it induced the formation of mainly transient (but sometimes permanent) pores and the formation of those pores allowed the translocation of plasmid DNA across the model membrane. However, only low transgene expression was obtained; the luciferase levels observed with the diblock being of the same order of magnitude as those observed with the corresponding PEO and P4VP homopolymers. CONCLUSIONS: These results strongly suggest that gene transfection by neutral block copolymers may involve the formation of cellular pores; in addition, they also highlight that in vivo gene transfection requires the use of adequately soluble block copolymers.

Aerosol-Mediated Non-Viral Lung Gene Therapy: The Potential of Aminoglycoside-Based Cationic Liposomes.

Aerosol lung gene therapy using non-viral delivery systems represents a credible therapeutic strategy for chronic respiratory diseases, such as cystic fibrosis (CF). Progress in CF clinical setting using the lipidic formulation GL67A has demonstrated the relevance of such a strategy while emphasizing the need for more potent gene transfer agents. In recent years, many novel non-viral gene delivery vehicles were proposed as potential alternatives to GL67 cationic lipid. However, they were usually evaluated using procedures difficult or even impossible to implement in clinical practice. In this study, a clinically-relevant administration protocol via aerosol in murine lungs was used to conduct a comparative study with GL67A. Diverse lipidic compounds were used to prepare a series of formulations inspired by the composition of GL67A. While some of these formulations were ineffective at transfecting murine lungs, others demonstrated modest-to-very-efficient activities and a series of structure-activity relationships were unveiled. Lipidic aminoglycoside derivative-based formulations were found to be at least as efficient as GL67A following aerosol delivery of a luciferase-encoding plasmid DNA. A single aerosol treatment with one such formulation was found to mediate long-term lung transgene expression, exceeding half the animal's lifetime. This study clearly supports the potential of aminoglycoside-based cationic lipids as potent GL67-alternative scaffolds for further enhanced aerosol non-viral lung gene therapy for diseases such as CF.

Nature as a source of inspiration for cationic lipid synthesis.

Synthetic gene delivery systems represent an attractive alternative to viral vectors for DNA transfection. Cationic lipids are one of the most widely used non-viral vectors for the delivery of DNA into cultured cells and are easily synthesized, leading to a large variety of well-characterized molecules. This review discusses strategies for the design of efficient cationic lipids that overcome the critical barriers of in vitro transfection. A particular focus is placed on natural hydrophilic headgroups and lipophilic tails that have been used to synthesize biocompatible and non-toxic cationic lipids. We also present chemical features that have been investigated to enhance the transfection efficiency of cationic lipids by promoting the escape of lipoplexes from the endosomal compartment and DNA release from DNA-liposome complexes. Transfection efficiency studies using these strategies are likely to improve the understanding of the mechanism of cationic lipid-mediated gene delivery and to help the rational design of novel cationic lipids.

Non-viral nanosystems for systemic siRNA delivery.

To use siRNA (small interfering ribonucleic acids) for systemic administration, a delivery system is often necessary to overcome barriers between administration and the target sites. These delivery systems require different properties to be efficient. On the one hand, they have to protect siRNA from degradation and/or inactivation and, on the other hand, they have themselves to be stable in blood and possess stealth properties to avoid elimination and degradation. Active and/or passive targeting should help the delivery system to reach the desired cell type or tissue, to be internalised, and to deliver siRNA to the cytoplasm so that siRNA can act by RNA interference and inhibit protein synthesis. This review presents an overview of different non-viral delivery systems, which have been evaluated in vivo or entered in clinical trials, with a focus on their physicochemical properties in order to help the development of new and efficient siRNA delivery systems, as the therapeutic solutions of tomorrow.

DNA/amphiphilic block copolymer nanospheres promote low-dose DNA vaccination.

Intramuscular (i.m.) DNA vaccination induces strong cellular immune responses in the mouse, but only at DNA doses that cannot be achieved in humans. Because antigen expression is weak after naked DNA injection, we screened five nonionic block copolymers of poly(ethyleneoxide)-poly(propyleneoxide) (PEO-PPO) for their ability to enhance DNA vaccination using a beta-galactosidase (betaGal) encoding plasmid, pCMV-betaGal, as immunogen. At a high DNA dose, formulation with the tetrafunctional block copolymers 304 (molecular weight [MW] 1,650) and 704 (MW 5,500) and the triblock copolymer Lutrol (MW 8,600) increased betaGal-specific interferon-gamma enzyme-linked immunosorbent spot (ELISPOT) responses 2-2.5-fold. More importantly, 704 allowed significant reductions in the dose of antigen-encoding plasmid. A single injection of 2 microg pCMV-betaGal with 704 gave humoral and ELISPOT responses equivalent to those obtained with 100 microg naked DNA and conferred protection in tumor vaccination models. However, 704 had no adjuvant properties for betaGal protein, and immune responses were only elicited by low doses of pCMV-betaGal formulated with 704 if noncoding carrier DNA was added to maintain total DNA dose at 20 microg. Overall, these results show that formulation with 704 and carrier DNA can reduce the dose of antigen-encoding plasmid by at least 50-fold.