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Background: Neoantigen vaccines can induce or enhance highly specific antitumor immune responses with minimal risk of autoimmunity. We have developed a neoantigen DNA vaccine platform capable of efficiently presenting both HLA class I and II epitopes and performed a phase 1 clinical trial in triple-negative breast cancer patients with persistent disease on surgical pathology following neoadjuvant chemotherapy, a patient population at high risk of disease recurrence. Methods: Expressed somatic mutations were identified by tumor/normal exome sequencing and tumor RNA sequencing. The pVACtools software suite of neoantigen prediction algorithms was used to identify and prioritize cancer neoantigens and facilitate vaccine design for manufacture in an academic GMP facility. Neoantigen DNA vaccines were administered via electroporation in the adjuvant setting (i.e., following surgical removal of the primary tumor and completion of standard of care therapy). Vaccines were monitored for safety and immune responses via ELISpot, intracellular cytokine production via flow cytometry, and TCR sequencing. Results: Eighteen subjects received three doses of a neoantigen DNA vaccine encoding on average 11 neoantigens per patient (range 4–20). The vaccinations were well tolerated with relatively few adverse events. Neoantigen-specific T cell responses were induced in 14/18 patients as measured by ELISpot and flow cytometry. At a median follow-up of 36 months, recurrence-free survival was 87.5% (95% CI: 72.7–100%) in the cohort of vaccinated patients. Conclusion: Our study demonstrates neoantigen DNA vaccines are safe, feasible, and capable of inducing neoantigen-specific immune responses. Clinical trial registration number: NCT02348320. [ABSTRACT FROM AUTHOR]

Objective: Somatostatin (SS) plays important regulatory roles in animal growth and reproduction by affecting the synthesis and secretion of growth hormone (GH). However, the mechanism by which SS regulates growth and development in goats is still unclear. Methods: In this study, we randomly selected eight 7monthold Dazu black goats (DBGs) of similar body weight and equally assigned four bucks as the immunised and negative control groups. The immunised group received the Salmonella typhi attenuated vaccine X9241 (ptCS/2SSasd) orally, whilst the negative control group received the empty vector vaccine X9241 (pVAXasd) orally. Results: The SS concentration in the serum of goats in the immunised group was significantly lower than that in the negative control group, and the daily gain was significantly higher (p<0.05). SS14 DNA vaccine immunisation resulted in significantly higher concentrations of growthrelated hormones such as GHreleasing hormone and insulin growth factor 1 (IGF1) in the serum of goats (p<0.05). RNAseq analysis of hypothalamus of oral SS14 DNA vaccine and negative control DBGs identified 31 differentially expressed genes (DEGs). Pituitary gland identified 164 DEGs. A total of 246 DEGs were detected in the liver by RNAseq. Gene ontology of DEGs was enriched in mitochondrial envelope, extracellular region, receptor binding and cell proliferation. The biological metabolic pathways associated with DEGs were explored by Kyoto encyclopedia of genes and genomes analysis. DEGs were associated with metabolic pathways, oxidative phosphorylation, vitamin digestion and absorption and galactose metabolism. These candidate genes (e.g. DGKK, CYTB, DUSP1, and LRAT) may provide references for exploring the molecular mechanisms by which SS promotes growth and development. Conclusion: Overall, these results demonstrated that the SS DNA vaccine enhanced the growth of DBGs by altering growthrelated hormone concentrations and regulating the expression of growthrelated genes in the hypothalamic--pituitary--liver axis. [ABSTRACT FROM AUTHOR]

Globally, streptococcal disease caused by Streptococcus agalactiae is known for its high mortality rate, which severely limits the development of the tilapia breeding industry. As a third‐generation vaccine, DNA vaccines have shown great application prospects in the prevention and control of aquatic diseases, but their low immunogenicity limits their development. The combination of DNA vaccines and molecular adjuvants proved to be an effective method for inducing protective immunity. This study constructed recombinant plasmids encoding tilapia HSP70 and IL‐1β genes (pcHSP70 and pcIL‐1β) to verify their effectiveness as molecular adjuvants for S. agalactiae DNA vaccine (pcSIP) in the immunized tilapia model. The results revealed that serum‐specific IgM production, enzyme activities, and immune‐related gene expression in tilapia immunized with pcSIP plus pcHSP70 or pcIL‐1β were significantly higher than those in tilapia immunized with pcSIP alone. It is worth noting that combination with molecular adjuvants improved the immune protection of DNA vaccines, with a relative percentage survival (RPS) of 51.72% (pcSIP plus pcHSP70) and 44.83% (pcSIP plus pcIL‐1β), respectively, compared with that of pcSIP alone (24.14%). Thus, our study indicated that HSP70 and IL‐1β in tilapia are promising molecular adjuvants of the DNA vaccine in controlling S. agalactiae infection. [ABSTRACT FROM AUTHOR]

In this study, we developed an injectable DNA vaccine targeting the aopB gene of Aeromonas hydrophila, encapsulated within poly(lactic‐co‐glycolic acid) (PLGA) nanoparticles, for use in common carp. Juvenile common carp were divided into six groups with three replicates each. Groups A and B received intramuscular injections of the plasmid containing the target gene (pCDNA3.1‐aopB) with or without encapsulation, respectively. Groups C and D received the plasmid lacking the target gene via the same route. Group E received PLGA, while Group F (control) received phosphate‐buffered saline. Sampling occurred on days 0, 30, and 60, and hematological and immunological indices were compared among the groups. On day 60, all groups were challenged with Aeromonas hydrophila, and cumulative mortality rates were assessed. Our results indicated successful detection of the target gene in various tissues of vaccinated fish. Notably, vaccinated groups exhibited a significant decrease in cumulative mortality (p < 0.05). Immunological indices, such as serum antibody titer and nonspecific immune responses, significantly improved in vaccinated groups, particularly those receiving the DNA vaccine with PLGA encapsulation (p < 0.05). Overall, the DNA vaccine, especially when nanoencapsulated with PLGA, demonstrated efficacy and immunogenicity against A. Hydrophila in common carp, suggesting its potential as a vaccination strategy against this infection. Further research could optimize its effectiveness and applicability. [ABSTRACT FROM AUTHOR]

Background: Human papillomavirus type 16 (HPV-16) infection is strongly associated with considerable parts of cervical, neck, and head cancers. Performed investigations have had moderate clinical success, so research to reach an efficient vaccine has been of great interest. In the present study, the immunization potential of a newly designed HPV-16 construct was evaluated in a mouse model. Results: Initially, a construct containing HPV-16 mutant (m) E6/E7 fusion gene was designed and antigen produced in two platforms (i.e., DNA vaccine and recombinant protein). Subsequently, the immunogenicity of these platforms was investigated in five mice) C57BL/6 (groups based on several administration strategies. Three mice groups were immunized recombinant protein, DNA vaccine, and a combination of them, and two other groups were negative controls. The peripheral blood mononuclear cells (PBMCs) proliferation, Interleukin-5 (IL-5) and interferon-γ (IFN-γ) cytokines, IgG1 and IgG2a antibody levels were measured. After two weeks, TC-1 tumor cells were injected into all mice groups, and subsequently further analysis of tumor growth and metastasis and mice survival were performed according to the schedule. Overall, the results obtained from in vitro immunology and tumor cells challenging assays indicated the potential of the mE6/E7 construct as an HPV16 therapeutic vaccine candidate. The results demonstrated a significant increase in IFN-γ cytokine (P value < 0.05) in the Protein/Protein (D) and DNA/Protein (E) groups. This finding was in agreement with in vivo assays. Control groups show a 10.5-fold increase (P value < 0.001) and (C) DNA/DNA group shows a 2.5-fold increase (P value < 0.01) in tumor growth compared to D and E groups. Also, a significant increase in survival of D and E (P value < 0.001) and C (P value < 0.01) groups were observed. Conclusions: So, according to the findings, the recombinant protein could induce stronger protection compared to the DNA vaccine form. Protein/Protein and DNA/Protein are promising administration strategies for presenting this construct to develop an HPV-16 therapeutic vaccine candidate. [ABSTRACT FROM AUTHOR]

Objectives: Non-viral mediated plasmid DNA transfection by electroporation (EP) is an established method for gene transfection. In this study, the usefulness of direct EP at an intradermal (i.d.) site (DEP) with implanted electrodes to achieve a high protein expression level was investigated. In addition, DEP application with various intervals with a low application voltage was also evaluated to confirm its effect on protein expression. Methods: Green fluorescent protein (GFP)- and luciferase-encoding DNA were administrated, and GFP and luciferase were evaluated. Results: A higher protein expression level was observed after green fluorescent protein (GFP)- and luciferase-encoding DNA were delivered by i.d. injection followed by DEP application. When luciferase expression was observed with an in vivo imaging system, continuous expression was confirmed over 21 days after i.d. injection followed by DEP at 100 V. This approach provided increased gene expression levels compared with conventional EP methods via the stratum corneum layer. In addition, the effect of application voltage on luciferase expression was investigated; two-time applications (repeated DEP) at 20 V with 5 min intervals showed similar luciferase expression level to single DEP application with 100 V. Histological observations showed the skin became thicker after a single DEP at 100 V, whereas no apparent thickness changes were confirmed after repeated DEP at 20 V with 5 min intervals. Conclusions: This study revealed that direct i.d. voltage application achieved high protein expression levels even at low voltages. Skin is a promising administration site for DNA vaccines, so this approach may be effective for DNA vaccine delivery into skin tissue. [ABSTRACT FROM AUTHOR]

Background/Objectives: There is no approved human vaccine for Venezuelan equine encephalitis (VEE), a life-threatening disease caused by the VEE virus (VEEV). In previous studies, plasmid DNA encoding the full-length RNA genome of the VEE V4020 vaccine was used for the preparation of experimental live virus VEE vaccines in the plasmid-transfected cell culture. Methods: Here, we used the high-fidelity polymerase chain reaction (PCR) to prepare synthetic, transcriptionally active PCR (TAP) fragments encoding the V4020 genome. Results: TAP fragment initiated the replication of the V4020 live virus vaccine in TAP fragment-transfected cells. A transfection of less than 1 ug of TAP fragment resulted in the replication of the V4020 vaccine virus in CHO cells. Conclusion: We conclude that not only plasmid DNA but also synthetic PCR-generated DNA fragments can be used for the manufacturing of live vaccines for VEEV and, potentially, other viruses. [ABSTRACT FROM AUTHOR]

Background: Arg‐gingipain A (RgpA) is the primary virulence factor of Porphyromonas gingivalis and contains hemagglutinin adhesin (HA), which helps bacteria adhere to cells and proteins. Hemagglutinin's functional domains include cleaved adhesin (CA), which acts as a hemagglutination and hemoglobin‐binding actor. Here, we confirmed that the HA and CA genes are immunogenic, and using adjuvant chemokine to target dendritic cells (DCs) enhanced protective autoimmunity against P. gingivalis–induced periodontal disease. Methods: C57 mice were immunized prophylactically with pVAX1‐CA, pVAX1‐HA, pVAX1, and phosphate‐buffered saline (PBS) through intramuscular injection every 2 weeks for a total of three administrations before P. gingivalis–induced periodontitis. The DCs were analyzed using flow cytometry and ribonucleic acid sequencing (RNA‐seq) transcriptomic assays following transfection with CA lentivirus. The efficacy of the co‐delivered molecular adjuvant CA DNA vaccine was evaluated in vivo using flow cytometry, immunofluorescence techniques, and micro‐computed tomography. Results: After the immunization, both the pVAX1‐CA and pVAX1‐HA groups exhibited significantly elevated P. gingivalis–specific IgG and IgG1, as well as a reduction in bone loss around periodontitis‐affected teeth, compared to the pVAX1 and PBS groups (p < 0.05). The expression of CA promoted the secretion of HLA, CD86, CD83, and DC‐specific intercellular adhesion molecule‐3‐grabbing non‐integrin (DC‐SIGN) in DCs. Furthermore, the RNA‐seq analysis revealed a significant increase in the chemokine (C–C motif) ligand 19 (p < 0.05). A notable elevation in the quantities of DCs co‐labeled with CD11c and major histocompatibility complex class II, along with an increase in interferon‐gamma (IFN‐γ) cells, was observed in the inguinal lymph nodes of mice subjected to CCL19‐CA immunization. This outcome effectively illustrated the preservation of peri‐implant bone mass in rats afflicted with P. gingivalis–induced peri‐implantitis (p < 0.05). Conclusions: The co‐administration of a CCL19‐conjugated CA DNA vaccine holds promise as an innovative and targeted immunization strategy against P. gingivalis–induced periodontitis and peri‐implantitis. [ABSTRACT FROM AUTHOR]

Background: Tumor-reactive T cells play a crucial role in anti-tumor responses, but T cells induced by DNA vaccination are time-consuming processes and exhibit limited anti-tumor efficacy. Therefore, we evaluated the anti-tumor effectiveness of reactive T cells elicited by electroporation (EP)-mediated DNA vaccine targeting epidermal growth factor receptor variant III (pEGFRvIII plasmid), in conjunction with adoptive cell therapy (ACT), involving the transfer of lymphocytes from a pEGFRvIII EP-vaccinated healthy donor. Methods: The validation of the established pEGFRvIII plasmid and EGFRvIII-positive cell model was confirmed through immunofluorescence and western blot analysis. Flow cytometry and cytotoxicity assays were performed to evaluate the functionality of antigen-specific reactive T cells induced by EP-mediated pEGFRvIII vaccines, ACT, or their combination. The anti-tumor effectiveness of EP-mediated pEGFRvIII vaccines alone or combined with ACT was evaluated in the B16F10-EGFRvIII tumor model. Results: EP-mediated pEGFRvIII vaccines elicited serum antibodies and a robust cellular immune response in both healthy and tumor-bearing mice. However, this response only marginally inhibited early-stage tumor growth in established tumor models. EP-mediated pEGFRvIII vaccination followed by adoptive transfer of lymphocytes from vaccinated healthy donors led to notable anti-tumor efficacy, attributed to the synergistic action of antigen-specific CD4+ Th1 cells supplemented by ACT and antigen-specific CD8+ T cells elicited by the EP-mediated DNA vaccination. Conclusions: Our preclinical studies results demonstrate an enhanced anti-tumor efficacy of EP-mediated DNA vaccination boosted with adoptively transferred, vaccinated healthy donor-derived allogeneic lymphocytes. [ABSTRACT FROM AUTHOR]

Background: Tuberculosis remains the major infectious and contagious disease with respect to morbidity and mortality around the globe. The main etiological agent of TB is Mycobacterium tuberculosis (M. tb). The cure and/or control of this disease is getting difficult day by day especially due to emergence of drug resistant strains, HIV co-infection and unavailability of good vaccines. BCG is the only available and permitted vaccine against TB, which has variable efficacy only limited to childhood. Therefore, new, well defined, antigen specific and state of the art Molecular Biology based DNA vaccines are required. Methods: The current study is designed to develop subunit-based DNA vaccines against tuberculosis by using five different Mycobacterium specific genes, namely Rv1908c/KatG, Rv0350/DnaK, Rv0440/GroEL2, Rv0934/PstS and Rv3418c/GroES. All the selected genes were amplified through PCR and cloned into mammalian expression pVAX1 vector. Results: All the transformed constructs were confirmed through restriction digestion, colony PCR and sequence analysis. These constructs will be used for various in Vivo immunization studies and also for the challenge studies against TB in future experiments. Conclusion: DNA vaccines, alone or in combination with BCG, have enough potential to be a good therapeutic tool for TB and reduce the treatment time in future. [ABSTRACT FROM AUTHOR]

Severe acute respiratory syndrome coronavirus 2 had devastating consequences for human health. Despite the introduction of several vaccines, COVID-19 continues to pose a serious health risk due to emerging variants of concern. DNA vaccines gained importance during the pandemic due to their advantages such as induction of both arms of immune response, rapid development, stability, and safety profiles. Here, we report the immunogenicity and protective efficacy of a DNA vaccine encoding spike protein with D614G mutation (named pcoSpikeD614G) and define a large-scale production process. According to the in vitro studies, pcoSpikeD614G expressed abundant spike protein in HEK293T cells. After the administration of pcoSpikeD614G to BALB/c mice through intramuscular (IM) route and intradermal route using an electroporation device (ID + EP), it induced high level of anti-S1 IgG and neutralizing antibodies (P < 0.0001), strong Th1-biased immune response as shown by IgG2a polarization (P < 0.01), increase in IFN-γ levels (P < 0.01), and increment in the ratio of IFN-γ secreting CD4+ (3.78–10.19%) and CD8+ (5.24–12.51%) T cells. Challenging K18-hACE2 transgenic mice showed that pcoSpikeD614G administered through IM and ID + EP routes conferred 90–100% protection and there was no sign of pneumonia. Subsequently, pcoSpikeD614G was evaluated as a promising DNA vaccine candidate and scale-up studies were performed. Accordingly, a large-scale production process was described, including a 36 h fermentation process of E. coli DH5α cells containing pcoSpikeD614G resulting in a wet cell weight of 242 g/L and a three-step chromatography for purification of the pcoSpikeD614G DNA vaccine. [ABSTRACT FROM AUTHOR]

Severe fever with thrombocytopenia syndrome (SFTS) is an emerging tick-borne viral disease caused by the SFTS virus (Dabie bandavirus), which has become a substantial risk to public health. No specific treatment is available now, that calls for an effective vaccine. Given this, we aimed to develop a multi-epitope DNA vaccine through the help of bioinformatics. The final DNA vaccine was inserted into a special plasmid vector pVAX1, consisting of CD8+ T cell epitopes, CD4+ T cell epitopes and B cell epitopes (six epitopes each) screened from four genome-encoded proteins——nuclear protein (NP), glycoprotein (GP), RNA-dependent RNA polymerase (RdRp), as well as nonstructural protein (NSs). To ascertain if the predicted structure would be stable and successful in preventing infection, an immunological simulation was run on it. In conclusion, we designed a multi-epitope DNA vaccine that is expected to be effective against Dabie bandavirus, but in vivo trials are needed to verify this claim. [ABSTRACT FROM AUTHOR]

Objective To construct a recombinant plasmid pcDNA3.1-ICP27377-513 expressing infected cells protein 27 (ICP27) of herpes simplex virus type 2 (HSV-2) and observe the immune effect of IL-15 DNA vaccine combined with HSV-2-ICP27377-513 DNA vaccine. Methods Molecular cloning technology was used to construct the pcDNA3.1-ICP27377-513 recombinant plasmid. Female BALB/c mice were randomly divided into four groups: pcDNA3.1-ICP27377-513 combined with pcDNA3.1-IL-15 (pIL-15) group, pcDNA3.1-ICP27377-513 group, pcDNA3.1 group, and pIL-15 group. Mice were immunized three times at two-week intervals. Blood was collected 28 days after the final immunization to detect specific neutralizing antibodies in the serum using a micro-neutralization assay, and the levels of IL-4, IL-2, and IFN-γ in serum were measured using ELISA. Mice were challenged with a lethal dose of HSV-2 in the vagina, and vaginal lavage fluid was collected at 3, 7, and 14 days post-inoculation to detect viral load using quantitative fluorescence PCR. Results The neutralizing antibody titers in the pcDNA3.1-ICP27377-513 combined with pIL-15 group (first combined group) and pcDNA3.1-ICP27377-513 group were 40.00±8.16 and 28.67±4.47, respectively, with no statistically significant difference between the two groups (P＞0.05）. The levels of IFN-γ and IL-4 in the first combined group were significantly higher than those in the pcDNA3.1-ICP27377-513 group (P＜0.05）, but there was no significant difference in IL-2 levels between the two groups (P＞0.05）. After vaginal inoculation with a lethal dose of HSV-2, the viral load in vaginal lavage fluid gradually decreased over time in both the first combined group and the pcDNA3.1-ICP27377-513 group, with a statistically significant difference between the two groups (P＜0.05）. Conclusion IL-15 DNA vaccine combined with HSV-2-ICP27377-513 DNA vaccine has a good immune protective effect on mice. [ABSTRACT FROM AUTHOR]

In light of increasing resistance to PD1 antibody therapy among certain patient populations, there is a critical need for in‐depth research. Our study assesses the synergistic effects of a MUC1 DNA vaccine and PD1 antibody for surmounting PD1 resistance, employing a murine CT26/MUC1 colon carcinoma model for this purpose. When given as a standalone treatment, PD1 antibodies showed no impact on tumour growth. Additionally, there was no change observed in the intra‐tumoural T‐cell ratios or in the functionality of T‐cells. In contrast, the sole administration of a MUC1 DNA vaccine markedly boosted the cytotoxicity of CD8+ T cells by elevating IFN‐γ and granzyme B production. Our compelling evidence highlights that combination therapy more effectively inhibited tumour growth and prolonged survival compared to either monotherapy, thus mitigating the limitations intrinsic to single‐agent therapies. This enhanced efficacy was driven by a significant alteration in the tumour microenvironment, skewing it towards pro‐immunogenic conditions. This assertion is backed by a raised CD8+/CD4+ T‐cell ratio and a decrease in immunosuppressive MDSC and Treg cell populations. On the mechanistic front, the synergistic therapy amplified expression levels of CXCL13 in tumours, subsequently facilitating T‐cell ingress into the tumour setting. In summary, our findings advocate for integrated therapy as a potent mechanism for surmounting PD1 antibody resistance, capitalizing on improved T‐cell functionality and infiltration. This investigation affords critical perspectives on enhancing anti‐tumour immunity through the application of innovative therapeutic strategies. [ABSTRACT FROM AUTHOR]

In this study, a DNA vaccine was designed based on the aopB gene of type III secretory system of Aeromonas hydrophila using the eukaryotic pCDNA3.1 expression system. Produced DNA vaccine was encapsulated with synthetic polylactic-co-glycolic acid (PLGA) nanoparticles. After evaluating the efficiency and quality of nanoencapsulation, 270 common carp (18.3 ± 2.4 g) were divided into six equal groups in triplicates. Groups A and B (GA & GB) were orally vaccinated with pCDNA3.1-aopB plasmid with or without nanoencapsulation with PLGA, respectively. Groups C and D (GC & GD) were orally vaccinated with pCDNA3.1 plasmid with or without PLGA nanoencapsulation, respectively. Groups E and F received PLGA and PBS, respectively. The serum samples, head kidney, and intestine tissues were taken on days 0, 30, and 60 of the experiment. Hemato-immunological parameters and tissue distribution of the recombinant plasmid were assayed. All groups were also challenged with virulent A. hydrophila bacteria and the survival rate was recorded to determine the vaccination efficacy. The recombinant plasmid was detected in the anterior kidney and intestine of GA and GB. Anti-A. hydrophila antibody titer and the survival rate were significantly increased after the bacterial challenge in GA and GB compared to the control groups (P < 0.05). Nonspecific immune response markers were significantly increased in GA compared to the control group (P < 0.05). Hematological parameters show no significant difference in all groups and sampling time points (P > 0.05). Consequently, the constructed oral DNA vaccine based on the pCDNA3.1-aopB gene, encapsulated with PLGA, showed either sufficient protection or reliable immunogenicity against A. hydrophila infection in common carp. [ABSTRACT FROM AUTHOR]

The use of attenuated bacteria for oral delivery of DNA vaccines is a recent innovation. We designed and constructed the naked plasmid DNA vaccine pcDNA-CCOL2A1, which effectively prevented and treated a rheumatoid arthritis model by inducing immunotolerance. We aimed to ensure a reliable, controllable dosage of this oral DNA vaccine preparation and establish its stability. We transformed pcDNA-CCOL2A1 via electroporation into attenuated Salmonella typhimurium SL7207. A resistant plate assay confirmed the successful construction of the transformed strain of the SL7207/pcDNA-CCOL2A1 oral DNA vaccine. We verified its identification and stability in vitro and in vivo. Significant differences were observed in the characteristics of the transformed and blank SL7207 strains. No electrophoretic restriction patterns or direct sequencing signals were observed in the original extract of the transformed strain. However, target gene bands and sequence signals were successfully detected after PCR amplification. CCOL2A1 expression was detected in the ilea of BALB/c mice that were orally administered SL7207/pcDNA-CCOL2A1. The pcDNA-CCOL2A1 plasmid of the transformed strain was retained under the resistant condition, and the transformed strain remained stable at 4 °C for 100 days. The concentration of the strain harboring the pcDNA-CCOL2A1 plasmid was stable at 109 CFU/mL after 6–8 h of incubation. The results demonstrated that the transformed strain SL7207/pcDNA-CCOL2A1 can be expressed in vivo, has good stability, and may be used to prepare the oral DNA vaccine pcDNA-CCOL2A1 with a stable, controllable dosage and the capacity to provide oral immunization. This vehicle can effectively combine both oral immunotolerance and DNA vaccination. Key points: Attenuated Salmonella typhimurium SL7207 aids immunization as a DNA vaccine carrier. The transformed strain SL7207/pcDNA-CCOL2A1 was constructed as an oral DNA vaccine. The formulated oral DNA vaccine offers a reliable, stable, and adjustable dosage. [ABSTRACT FROM AUTHOR]

H5 highly pathogenic avian influenza (HPAI) viruses of the Asian lineage (A/goose/Guangdong/1/96) belonging to clade 2.3.4.4 have spread worldwide through wild bird migration in two major waves: in 2014/2015 (clade 2.3.4.4c), and since 2016 up to now (clade 2.3.4.4b). Due to the increasing risk of these H5 HPAI viruses to establish and persist in the wild bird population, implementing vaccination in certain sensitive areas could be a complementary measure to the disease control strategies already applied. In this study, the efficacy of a novel DNA vaccine, encoding a H5 gene (A/gyrfalcon/Washington/41088-6/2014 strain) of clade 2.3.4.4c was evaluated in specific pathogen-free (SPF) white leghorn chickens against a homologous and heterologous H5 HPAI viruses. A single vaccination at 2 weeks of age (1 dose), and a vaccination at 2 weeks of age, boosted at 4 weeks (2 doses), with or without adjuvant were characterized. The groups that received 1 dose with or without adjuvant as well as 2 doses with adjuvant demonstrated full clinical protection and a significant or complete reduction of viral shedding against homologous challenge at 6 and 25 weeks of age. The heterologous clade 2.3.4.4b challenge of 6-week-old chickens vaccinated with 2 doses with or without adjuvant showed similar results, indicating good cross-protection induced by the DNA vaccine. Long lasting humoral immunity was observed in vaccinated chickens up to 18 or 25 weeks of age, depending on the vaccination schedule. The analysis of viral transmission after homologous challenge showed that sentinels vaccinated with 2 doses with adjuvant were fully protected against mortality with no excretion detected. This study of H5 DNA vaccine efficacy confirmed the important role that this type of so-called third-generation vaccine could play in the fight against H5 HPAI viruses. [ABSTRACT FROM AUTHOR]

Single-dose, immunogenic DNA (iDNA) vaccines coding for whole live-attenuated viruses are reviewed. This platform, sometimes called immunization DNA, has been used for vaccine development for flavi- and alphaviruses. An iDNA vaccine uses plasmid DNA to launch live-attenuated virus vaccines in vitro or in vivo. When iDNA is injected into mammalian cells in vitro or in vivo, the RNA genome of an attenuated virus is transcribed, which starts replication of a defined, live-attenuated vaccine virus in cell culture or the cells of a vaccine recipient. In the latter case, an immune response to the live virus vaccine is elicited, which protects against the pathogenic virus. Unlike other nucleic acid vaccines, such as mRNA and standard DNA vaccines, iDNA vaccines elicit protection with a single dose, thus providing major improvement to epidemic preparedness. Still, iDNA vaccines retain the advantages of other nucleic acid vaccines. In summary, the iDNA platform combines the advantages of reverse genetics and DNA immunization with the high immunogenicity of live-attenuated vaccines, resulting in enhanced safety and immunogenicity. This vaccine platform has expanded the field of genetic DNA and RNA vaccines with a novel type of immunogenic DNA vaccines that encode entire live-attenuated viruses. [ABSTRACT FROM AUTHOR]

Physical-based gene delivery via biolistic methods (such as the Helios gene gun) involve precipitation of nucleic acids onto microparticles and direct transfection through cell membranes of exposed tissue (e.g. skin) by high velocity acceleration. The glycosaminoglycan (GAG)-binding enhanced transduction (GET) system exploits novel fusion peptides consisting of cell-binding, nucleic acid condensing, and cell-penetrating domains, which enable enhanced transfection across multiple cell types. In this study, we combined chemical (GET) and physical (gene gun) DNA delivery systems, and hypothesized the combination would generate enhanced distribution and effective uptake in cells not initially transfected by biolistic penetration. Physicochemical characterization, optimization of bullet contents and transfection experiments in vitro in cell monolayers and engineered tissue demonstrated these formulations transfected efficiently, including DC2.4 dendritic cells. We incorporated these formulations into a biolistic format for gene gun by forming fireable dry bullets obtained via lyophilization (freeze drying). This system is simple and with enhanced scalability compared to conventional methods to generate bullets. Flushed GET bullet contents retained their ability to mediate transfection (17-fold greater and 13-fold greater reporter gene expression than standard spermidine bullets in the absence and presence of serum, respectively). Fired GET bullets in vitro (in cells and collagen gels) and in vivo (mice) showed increased reporter gene transfection compared to untreated controls, whilst maintaining cell viability in vitro and having no obvious toxicity in vivo. Lastly, a SARS-CoV-2 plasmid DNA vaccine with spike (S) protein-receptor binding domain (S-RBD) was delivered by gene gun using GET bullets. Specific T cell and antibody responses comparable to the conventional system were generated. The non-physical and physical combination of GET‑gold-DNA carriers using gene gun shows potential as an alternative DNA delivery method that is scalable for mass deployable vaccination and intradermal gene delivery. [Display omitted] [ABSTRACT FROM AUTHOR]

Human noroviruses (HuNoVs) are highly contagious and a leading cause of epidemics of acute gastroenteritis worldwide. Among the various HuNoV genotypes, GII.4 is the most prevalent cause of outbreaks. However, no vaccines have been approved for HuNoVs to date. DNA vaccines are proposed to serve as an ideal platform against HuNoV since they can be easily produced and customized to express target proteins. In this study, we constructed a CMV/R vector expressing a major structural protein, VP1, of GII.4 HuNoV (CMV/R-GII.4 HuNoV VP1). Transfection of CMV/R-GII.4 HuNoV VP1 into human embryonic kidney 293T (HEK293T) cells resulted in successful expression of VP1 proteins in vitro. Intramuscular or intradermal immunization of mice with the CMV/R-GII.4 HuNoV VP1 construct elicited the production of blocking antibodies and activation of T cell responses against GII.4 HuNoV VP1. Our collective data support the utility of CMV/R-GII.4 HuNoV VP1 as a promising DNA vaccine candidate against GII.4 HuNoV. [ABSTRACT FROM AUTHOR]

Background: New treatment options with improved safety and novel mechanisms of actions are needed for patients with peanut allergy. Objectives: To evaluate the safety, tolerability, and immunogenicity of ASP0892, a peanut DNA vaccine, after intradermal (id) or intramuscular (im) administration in adult or adolescent patients with peanut allergy in two phase 1 studies. Methods: ASP0892 or placebo was administered every 2 weeks for a total of 4 doses. The doses were 1 mg or 4 mg id or 4 mg im for adults, and 1 mg or 4 mg id for adolescents. Immunologic parameters were assessed longitudinally. Results: Thirty‐one adults (mean age 24.3 years, 17 males) received ASP0892 (9, 8, 8 patients for 1 mg id, 4 mg id or 4 mg im, respectively) or placebo (2 patients/group). Twenty adolescents (mean age 14.2 years, 11 males) received ASP0892 (8 patients/group) or placebo (2 patients/group). In both studies, the most common treatment‐emergent adverse event (TEAE) was injection site pruritus. No deaths or treatment withdrawal were related to TEAEs. No serious TEAEs related to treatment were observed in adult or adolescent patients. ASP0892 treatment led to modest increases in allergen‐specific IgG and/or IgG4 in adults (1 mg id, 4 mg im) and adolescents (1 mg id, 4 mg id). No improvements in clinical outcomes, including double‐blind placebo‐controlled food challenge, were found after ASP0892 treatment. Conclusions: In two phase 1 studies, ASP0892 was well tolerated with modest but not clinically relevant changes in immune responses. ClinicalTrials.gov Identifiers NCT02851277, NCT03755713. [ABSTRACT FROM AUTHOR]

With the advent of cancer immunotherapy, there is a growing interest in vaccine development as a means to activate the cellular immune system against cancer. Despite the promise of DNA vaccines in this regard, their effectiveness is hindered by poor immunogenicity, leading to modest therapeutic outcomes across various cancers. The role of Type 1 conventional dendritic cells (cDC1), capable of cross-presenting vaccine antigens to activate CD8+T cells, emerges as crucial for the antitumor function of DNA vaccines. To address the limitations of DNA vaccines, a promising approach involves targeting antigens to cDC1 through the fusion of XCL1, a ligand specific to the receptor XCR1 on the surface of cDC1. Here, female C57BL/6 mice were selected for tumor inoculation and immunotherapy. Additionally, recognizing the complexity of cancer, this study explored the use of combination therapies, particularly the combination of cDC1-targeted DNA vaccine with the chemotherapy drug Gemcitabine (Gem) and the anti-PD1 antibody in a mouse lung cancer model. The study's findings indicate that fusion antigens with XCL1 effectively enhance both the immunogenicity and antitumor effects of DNA vaccines. Moreover, the combination of the cDC1-targeted DNA vaccine with Gemcitabine and anti-PD1 antibody in the mouse lung cancer model demonstrates an improved antitumor effect, leading to the prolonged survival of mice. In conclusion, this research provides important support for the clinical investigation of cDC1-targeting DNA vaccines in combination with other therapies. [ABSTRACT FROM AUTHOR]

In this study, novel solid lipid particles containing the adjuvant lipid monophosphoryl lipid A (termed 'SLN-A') were synthesised. The SLN-A particles were able to efficiently bind and form complexes with a DNA vaccine encoding the urease alpha subunit of Helicobacter pylori. The resultant nanoparticles were termed lipoplex-A. In a mouse model of H. pylori infection, the lipoplex-A nanoparticles were used to immunise mice, and the resultant immune responses were analysed. It was found that the lipoplex-A vaccine was able to induce high levels of antigen-specific antibodies and an influx of gastric CD4+ T cells in vaccinated mice. In particular, a prime with lipoplex-A and a boost with soluble UreA protein induced significantly high levels of the IgG1 antibody, whereas two doses of lipoplex-A induced high levels of the IgG2c antibody. In this study, lipoplex-A vaccination did not lead to a significant reduction in H. pylori colonisation in a challenge model; however, these results point to the utility of the system for delivering DNA vaccine-encoded antigens to induce immune responses and suggest the ability to tailor those responses. [ABSTRACT FROM AUTHOR]

Background Andes virus (ANDV), a rodent-borne hantavirus, causes hantavirus pulmonary syndrome (HPS). The safety and immunogenicity of a novel ANDV DNA vaccine was evaluated. Methods Phase 1, double-blind, dose-escalation trial randomly assigned 48 healthy adults to placebo or ANDV DNA vaccine delivered via needle-free jet injection. Cohorts 1 and 2 received 2 mg of DNA or placebo in a 3-dose (days 1, 29, 169) or 4-dose (days 1, 29, 57, 169) schedule, respectively. Cohorts 3 and 4 received 4 mg of DNA or placebo in the 3-dose and 4-dose schedule, respectively. Subjects were monitored for safety and neutralizing antibodies by pseudovirion neutralization assay (PsVNA50) and plaque reduction neutralization test (PRNT50). Results While 98% and 65% of subjects had at least 1 local or systemic solicited adverse event (AE), respectively, most AEs were mild or moderate; no related serious AEs were detected. Cohorts 2, 3, and 4 had higher seroconversion rates than cohort 1 and seropositivity of at least 80% by day 197, sustained through day 337. PsVNA50 geometric mean titers were highest for cohort 4 on and after day 197. Conclusions This first-in-human candidate HPS vaccine trial demonstrated that an ANDV DNA vaccine was safe and induced a robust, durable immune response. Clinical Trials Registration. NCT03682107. [ABSTRACT FROM AUTHOR]

The use of attenuated bacteria for oral delivery of DNA vaccines is a recent innovation. We designed and constructed the naked plasmid DNA vaccine pcDNA-CCOL2A1, which effectively prevented and treated a rheumatoid arthritis model by inducing immunotolerance. We aimed to ensure a reliable, controllable dosage of this oral DNA vaccine preparation and establish its stability. We transformed pcDNA-CCOL2A1 via electroporation into attenuated Salmonella typhimurium SL7207. A resistant plate assay confirmed the successful construction of the transformed strain of the SL7207/pcDNA-CCOL2A1 oral DNA vaccine. We verified its identification and stability in vitro and in vivo. Significant differences were observed in the characteristics of the transformed and blank SL7207 strains. No electrophoretic restriction patterns or direct sequencing signals were observed in the original extract of the transformed strain. However, target gene bands and sequence signals were successfully detected after PCR amplification. CCOL2A1 expression was detected in the ilea of BALB/c mice that were orally administered SL7207/pcDNA-CCOL2A1. The pcDNA-CCOL2A1 plasmid of the transformed strain was retained under the resistant condition, and the transformed strain remained stable at 4 °C for 100 days. The concentration of the strain harboring the pcDNA-CCOL2A1 plasmid was stable at 109 CFU/mL after 6–8 h of incubation. The results demonstrated that the transformed strain SL7207/pcDNA-CCOL2A1 can be expressed in vivo, has good stability, and may be used to prepare the oral DNA vaccine pcDNA-CCOL2A1 with a stable, controllable dosage and the capacity to provide oral immunization. This vehicle can effectively combine both oral immunotolerance and DNA vaccination. Key points: Attenuated Salmonella typhimurium SL7207 aids immunization as a DNA vaccine carrier. The transformed strain SL7207/pcDNA-CCOL2A1 was constructed as an oral DNA vaccine. The formulated oral DNA vaccine offers a reliable, stable, and adjustable dosage. [ABSTRACT FROM AUTHOR]

Background: Animal reproduction performance is crucial in husbandry. Immunocastrated animals serve as an ideal animal model for studying testicular function. During androgen suppression, the testis undergoes dramatic developmental and structural changes, including the inhibition of hormone secretion and spermatogenesis. Methods: To characterize this process, we investigated the effects of castration using a recombinant B2L and KISS1 DNA vaccine, and then identified functional genes in the testes of Yiling goats using RNA-seq and WGS. The experimental animals were divided into three groups: the PVAX-asd group (control), PBK-asd-immunized group, and surgically castrated group. Results: The results demonstrated that the administration of the recombinant PBK-asd vaccine in goats elicited a significant antibody response, and reduced serum follicle-stimulating hormone (FSH) and luteinizing hormone (LH), resulting in smaller scrotal circumferences and decreased sexual desire compared to the control group. In addition, RNA transcriptome sequencing (RNA-seq) analysis of the testes revealed that the biological processes after immunocastration mainly focused on the regulation of cell matrix adhesion, histone acetylation, negative regulation of developmental processes, apoptosis, and activation of the complement system and the thrombin cascade reaction system. Then, we integrated the whole-genome sequencing and testis transcriptome, and identified several candidate genes (FGF9, FST, KIT, TH, TCP1, PLEKHA1, TMEM119, ESR1, TIPARP, LEP) that influence steroidogenesis secretion and spermatogenesis. Conclusions: Multiple pathways and polygenic co-expression participate in the response to castration vaccines, altering hormone secretion and spermatogenesis. Taken together, our atlas of the immunocastration goat testis provides multiple insights into the developmental changes and key factors accompanying androgen suppression, and thus may contribute to understanding the genetic mechanism of testis function. Joint analysis of whole genome sequencing and RNA-seq enables reliable screening of candidate genes, benefiting future genome-assisted breeding of goats. [ABSTRACT FROM AUTHOR]

In clinical practice, the low immunogenicity and low stability of the DNA plasmid vaccine candidates are two significant shortcomings in their application against infectious diseases. To overcome these two disadvantages, the plasmid expressing IL-29 (pIL-29) as a genetic adjuvant and polylactic-co-glycolic acid (PLGA) as a non-viral delivery system were used, respectively. In this study, the pIL-29 encapsulated in PLGA nanoparticles (nanoIL-29) and the pgD1 encapsulated in PLGA nanoparticles (nanoVac) were simultaneously applied to boost immunologic responses against HSV-1. We generated spherical nanoparticles with encapsulation efficiency of 75 ± 5% and sustained the release of plasmids from them. Then, Balb/c mice were subcutaneously immunized twice with nanoVac+nanoIL-29, Vac+IL-29, nanoVac, Vac, nanoIL-29, and/or IL-29 in addition to negative and positive control groups. Cellular immunity was evaluated via lymphocyte proliferation assay, cytotoxicity test, and IFN-γ, IL-4, and IL-2 measurements. Mice were also challenged with 50X LD50 of HSV-1. The nanoVac+nanoIL-29 candidate vaccine efficiently enhances CTL and Th1-immune responses and increases the survival rates by 100% in mice vaccinated by co-administration of nanoVac and nanoIL-29 against the HSV-1 challenge. The newly proposed vaccine is worth studying in further clinical trials, because it could effectively improve cellular immune responses and protected mice against HSV-1. [ABSTRACT FROM AUTHOR]

Currently licensed dengue vaccines do not induce long-term protection in children without prior dengue virus exposure. A better understanding of the mechanism by which the immune system prevents dengue virus infection is urgently needed to improve vaccine efficacy. In this study, the induction of protective antibody responses against dengue virus infection was tested in a non-human primate model using the heterologous prime-boost vaccination approach. Groups of cynomolgus macaques were immunized with a priming dose of attenuated dengue viruses and followed by two booster doses of virus-like particles in four monovalent arms, or in the tetravalent arm (prM + E)-expressing plasmids. At 1 month post-immunization, all macaques had elevated levels of neutralizing antibodies, and live viral challenges revealed an overall protective efficacy of 91% (40/44 macaques protected) against infection with clinical isolates. Breakthrough infections occurred in macaques with distinctive antibody profiles at the time of challenge: two macaques had the lowest neutralizing antibodies against the respective DENV-1 and -4 challenge strains among the respective groups, whereas two other DENV-4-infected macaques exhibited high levels of neutralizing and virus-binding antibodies. The ratio of antibodies recognizing a DENV-4-specific epitope and those that bound viral particles was at the lowest levels in the latter DENV-4-infected macaques, indicating an underrepresentation of antibodies targeting the serotype-specific epitope. Protection among macaques challenged with DENV-2 or -3 coincided with vigorous EDIII-binding antibody responses induced by booster immunization. A combination of attenuated viruses for priming and non-infectious particle-based antigens for boosting may be a more effective means of preventing dengue. [ABSTRACT FROM AUTHOR]

The SARS-CoV-2 pandemic revealed the critical shortfalls of global vaccine availability for emergent pathogens and the need for exploring additional vaccine platforms with rapid update potential in response to new variants. Thus, it remains essential, for the present evolving SARS-CoV-2/Covid-19 and future pandemics, to continuously develop and characterize new and different vaccine platforms. Here, we describe an expression-optimized DNA vaccine candidate based on the SARS-CoV-2 spike protein of the Beta variant (B.1.351), pNTC-Spike.351, and, in animal models, compare its immunogenicity with a similar DNA vaccine encoding the ancestral index strain spike protein, pNTC-Spike. Both DNA vaccines induced neutralizing antibodies and a Th1 biased immune response. In contrast to the index-specific vaccine, the Beta-specific DNA vaccine induced antibodies in mice and rabbits that, even at low levels, efficiently neutralize the otherwise antibody resistant Beta variant. It similarly neutralized unrelated variants bearing the neutralization resistant E484K spike mutation. Intensive priming using two vaccinations with pNTC-Spike and a single booster immunization with the pNTC-Spike.351 induced a more robust neutralizing antibody response with comparable magnitude against different variants of concern. Thus, DNA vaccine technology with heterologous spike protein prime-boost should be explored further using the Beta derived pNTC-Spike.351 to broaden neutralizing antibody responses against emerging variants of concern. [ABSTRACT FROM AUTHOR]

DNA vaccine, melanization, pancreas disease, salmonid alphavirus, side-effect, vaccination (d) Retraction of the dnv to allow entrance of the next fish for vaccination. gl During vaccination with automatic vaccination machines, Clynav® is often administered simultaneously with i.p. administered oil-based vaccines. Keywords: DNA vaccine; melanization; pancreas disease; salmonid alphavirus; side-effect; vaccination EN DNA vaccine melanization pancreas disease salmonid alphavirus side-effect vaccination 1157 1161 5 09/15/23 20231001 NES 231001 Pancreas disease (PD) is a severe infectious disease affecting farmed salmonids in Norway and other European countries, caused by different genotypes of salmonid alphavirus (SAV) (World Organization for Animal Health, [21]). To the authors' knowledge, this is the first description of this phenomenon following vaccination with dual vaccination in Atlantic salmon. [Extracted from the article]

An artificial T-cell immunogen consisting of conserved fragments of different proteins of the SARS-CoV-2 virus and its immunogenic properties were studied in BALB/c mice. To create a T-cell immunogen, we used an approach based on the design of artificial antigens that combine many epitopes from the main proteins of the SARS-CoV-2 virus in the one molecule. The gene of the engineered immunogen protein was cloned as part of the pVAX1 plasmid in two versions: with an N-terminal ubiquitin and without it. The obtained plasmids were analyzed for their ability to provide the synthesis of the immunogen protein in vitro and in vivo. It has been shown that protein product of the created artificial genes is actively processed in HEK293T cells and induces cellular immunity in mice. [ABSTRACT FROM AUTHOR]

The COVID-19 pandemic exerted significant impacts on public health and global economy. Research efforts to develop vaccines at warp speed against SARS-CoV-2 led to novel mRNA, viral vectored, and inactivated vaccines being administered. The current COVID-19 vaccines incorporate the full S protein of the SARS-CoV-2 Wuhan strain but rapidly emerging variants of concern (VOCs) have led to significant reductions in protective efficacies. There is an urgent need to develop next-generation vaccines which could effectively prevent COVID-19. PubMed and Google Scholar were systematically reviewed for peer-reviewed papers up to January 2023. A promising solution to the problem of emerging variants is a DNA vaccine platform since it can be easily modified. Besides expressing whole protein antigens, DNA vaccines can also be constructed to include specific nucleotide genes encoding highly conserved and immunogenic epitopes from the S protein as well as from other structural/non-structural proteins to develop effective vaccines against VOCs. DNA vaccines are associated with low transfection efficiencies which could be enhanced by chemical, genetic, and molecular adjuvants as well as delivery systems. The DNA vaccine platform offers a promising solution to the design of effective vaccines. The challenge of limited immunogenicity in humans might be solved through the use of genetic modifications such as the addition of nuclear localization signal (NLS) peptide gene, strong promoters, MARs, introns, TLR agonists, CD40L, and the development of appropriate delivery systems utilizing nanoparticles to increase uptake by APCs in enhancing the induction of potent immune responses. [ABSTRACT FROM AUTHOR]

Canine distemper (CD), caused by canine distemper virus (CDV), is a highly contagious and lethal disease in domestic and wild carnivores. Although CDV live-attenuated vaccines have reduced the incidence of CD worldwide, low levels of protection are achieved in the presence of maternal antibodies in juvenile animals. Moreover, live-attenuated CDV vaccines may retain residual virulence in highly susceptible species and cause disease. Here, we generated several CDV DNA vaccine candidates based on the biscistronic vector (pIRES) co-expressing virus wild-type or codon-optimized hemagglutinin (H) and nucleocapsid (N) or ferret interferon (IFN)-γ, as a molecular adjuvant, respectively. Apparently, ferret (Mustela putorius furo)-specific codon optimization increased the expression of CDV H and N proteins. A ferret model of CDV was used to evaluate the protective immune response of the DNA vaccines. The results of the vaccinated ferrets showed that the DNA vaccine co-expressing the genes of codon-optimized H and ferret IFN-γ (poptiH-IRES-IFN) elicited the highest anti-CDV serum-neutralizing antibodies titer (1:14) and cytokine responses (upregulated TNF-α, IL-4, IL-2, and IFN-γ expression) after the third immunization. Following vaccination, the animals were challenged with a lethal CDV 5804Pe/H strain with a dose of 105.0 TCID50. Protective immune responses induced by the DNA vaccine alleviated clinical symptoms and pathological changes in CDV-infected ferrets. However, it cannot completely prevent virus replication and viremia in vivo as well as virus shedding due to the limited neutralizing antibody level, which eventually contributed to a survival rate of 75% (3/4) against CDV infection. Therefore, the improved strategies for the present DNA vaccines should be taken into consideration to develop more protective immunity, which includes increasing antigen expression or alternative delivery routes, such as gene gun injection. [ABSTRACT FROM AUTHOR]

The outbreak of COVID-19 started in December 2019 and spread rapidly all over the world. It became clear that the development of an effective vaccine was the only way to stop the pandemic. It was the first time in the history of infectious diseases that the process of the development of a new vaccine was conducted on such a large scale and accelerated so rapidly. At the end of 2020, the first COVID-19 vaccines were approved for marketing. At the end of March 2023, over three years after the outbreak of the COVID-19 pandemic, 199 vaccines were in pre-clinical development and 183 in clinical development. The candidate vaccines in the clinical phase are based on the following platforms: protein subunit, DNA, RNA, non-replication viral vector, replicating viral vector, inactivated virus, virus-like particles, live attenuated virus, replicating viral vector combined with an antigen-presenting cell, non-replication viral vector combined with an antigen-presenting cell, and bacterial antigen-spore expression vector. Some of the new vaccine platforms have been approved for the first time for human application. This review presents COVID-19 vaccines currently available in the world, procedures for assurance of the quality and safety of the vaccines, the vaccinated population, as well as future perspectives for the new vaccine platforms in drug and therapy development for infectious and non-infectious diseases. [ABSTRACT FROM AUTHOR]

Echinococcosis is a highly prevalent global zoonosis, and vaccines are required. The commercial vaccine based on a protein-based subunit (EG95), however, is limited by its insufficient cellular immunity, a short protection period, and limited prevention against novel mutant strains. Herein, we applied bioinformatics to develop a DNA vaccine (pEG95-IL2) expressing both multi-epitope-based antigens (EG95-PT1/2/3) and an IL-2 adjuvant to regulate T cell differentiation and memory cell response. EG95-PT1/2/3 was screened with hierarchical structure prediction from the epitope conformation of B cells with high confidence across various species to guarantee immunogenicity. Importantly, cationic arginine-rich lipid nanoparticles (RNP) were utilized as a delivery vehicle to form lipoplexes that had a transfection efficiency of nearly two orders of magnitude greater than that of commercial reagents (Lipofectamine 2000 and polyethyleneimine) with both immune and nonimmune cells (DC2.4 and L929 cells, respectively). RNP/pEG95-IL2 lipoplexes displayed a robust and long-term antigen expression, as well as adjuvant effects during the immunization. Consequently, intramuscular injection of RNP/pEG95-IL2 elicited similar humoral immune responses and significantly greater cellular responses in mice when compared with those of the commercial vaccine. In addition, the inoculation protocol of RNP/pEG95-IL2 with sequential booster further strengthens cellular immunity in comparison with the homologous booster. Those findings provide a promising strategy for improving plasmid vaccine efficacy. [Display omitted] • Multi-epitope-based DNA vaccine (RNP/pEG95-IL2) was developed by bioinformatics technology. • RNP/pEG95-IL2 elicited stronger cellular immune responses compared to the commercial vaccine. • The SB strategy of DNA vaccine produced greater immune responses than HB. • RNP benefited high and long-lasting expression of DNA antigens. • RNP accelerated BMDCs maturation and cytokine production as an immune adjuvant. [ABSTRACT FROM AUTHOR]

Zoonotic leishmaniases are a worldwide public health problem for which the development of effective vaccines remains a challenge. A vaccine against leishmaniases must be safe and affordable and should induce cross-protection against the different disease-causing species. In this context, the DNA vaccine pHisAK70 has been demonstrated to induce, in a murine model, a resistant phenotype against L. major, L. infantum, and L. amazonensis. Moreover, a chimeric multiepitope peptide, HisDTC, has been obtained by in silico analysis from the histone proteins encoded in the DNA vaccine and has showed its ability to activate a potent CD4+ and CD8+ T-cell protective immune response in mice against L. infantum infection. In the present study, we evaluated the plasmid DNA vaccine pHisAK70 in comparison with the peptide HisDTC (with and without saponin) against L. major and L. infantum infection. Our preliminary results showed that both formulations were able to induce a potent cellular response leading to a decrease in parasite load against L. infantum. In addition, the DNA candidate was able to induce better lesion control in mice against L. major. These preliminary results indicate that both strategies are potentially effective candidates for leishmaniases control. Furthermore, it is important to carry out such comparative studies to elucidate which vaccine candidates are the most appropriate for further development. [ABSTRACT FROM AUTHOR]

Chikungunya virus (CHIKV) has become a significant public health concern due to the increasing number of outbreaks worldwide and the associated comorbidities. Despite substantial efforts, there is no specific treatment or licensed vaccine against CHIKV to date. The E2 glycoprotein of CHIKV is a promising vaccine candidate as it is a major target of neutralizing antibodies during infection. In this study, we evaluated the immunogenicity of two DNA vaccines (a non-targeted and a dendritic cell-targeted vaccine) encoding a consensus sequence of E2CHIKV and a recombinant protein (E2*CHIKV). Mice were immunized with different homologous and heterologous DNAprime-E2* protein boost strategies, and the specific humoral and cellular immune responses were accessed. We found that mice immunized with heterologous non-targeted DNA prime- E2*CHIKV protein boost developed high levels of neutralizing antibodies, as well as specific IFN-γ producing cells and polyfunctional CD4+ and CD8+ T cells. We also identified 14 potential epitopes along the E2CHIKV protein. Furthermore, immunization with recombinant E2*CHIKV combined with the adjuvant AS03 presented the highest humoral response with neutralizing capacity. Finally, we show that the heterologous prime-boost strategy with the non-targeted pVAX-E2 DNA vaccine as the prime followed by E2* protein + AS03 boost is a promising combination to elicit a broad humoral and cellular immune response. Together, our data highlights the importance of E2CHIKV for the development of a CHIKV vaccine. [ABSTRACT FROM AUTHOR]

Waning vaccine-induced immunity, coupled with the emergence of SARS-CoV-2 variants, has inspired the widespread implementation of COVID-19 booster vaccinations. Here, we evaluated the potential of the GX-19N DNA vaccine as a heterologous booster to enhance the protective immune response to SARS-CoV-2 in mice primed with either an inactivated virus particle (VP) or an mRNA vaccine. We found that in the VP-primed condition, GX-19N enhanced the response of both vaccine-specific antibodies and cross-reactive T Cells to the SARS-CoV-2 variant of concern (VOC), compared to the homologous VP vaccine prime-boost. Under the mRNA-primed condition, GX-19N induced higher vaccine-induced T Cell responses but lower antibody responses than the homologous mRNA vaccine prime-boost. Furthermore, the heterologous GX-19N boost induced higher S-specific polyfunctional CD4+ and CD8+ T cell responses than the homologous VP or mRNA prime-boost vaccinations. Our results provide new insights into booster vaccination strategies for the management of novel COVID-19 variants. [ABSTRACT FROM AUTHOR]

Our previous research developed a novel tuberculosis (TB) DNA vaccine ag85a/b that showed a significant therapeutic effect on the mouse tuberculosis model by intramuscular injection (IM) and electroporation (EP). However, the action mechanisms between these two vaccine immunization methods remain unclear. In a previous study, 96 Mycobacterium tuberculosis (MTB) H37Rv‐infected BALB/c mice were treated with phosphate‐buffered saline, 10, 50, 100, and 200 μg ag85a/b DNA vaccine delivered by IM and EP three times at 2‐week intervals, respectively. In this study, peripheral blood mononuclear cells (PBMCs) from three mice in each group were isolated to extract total RNA. The gene expression profiles were analyzed using gene microarray technology to obtain differentially expressed (DE) genes. Finally, DE genes were validated by real‐time reverse transcription‐quantitive polymerase chain reaction and the GEO database. After MTB infection, most of the upregulated DE genes were related to the digestion and absorption of nutrients or neuroendocrine (such as Iapp, Scg2, Chga, Amy2a5), and most of the downregulated DE genes were related to cellular structural and functional proteins, especially the structure and function proteins of the alveolar epithelial cell (such as Sftpc, Sftpd, Pdpn). Most of the abnormally upregulated or downregulated DE genes in the TB model group were recovered in the 100 and 200 μg ag85a/b DNA IM groups and four DNA EP groups. The pancreatic secretion pathway downregulated and the Rap1 signal pathway upregulated had particularly significant changes during the immunotherapy of the ag85a/b DNA vaccine on the mouse TB model. The action targets and mechanisms of IM and EP are highly consistent. Tuberculosis infection causes rapid catabolism and slow anabolism in mice. For the first time, we found that the effective dose of the ag85a/b DNA vaccine immunized whether by IM or EP could significantly up‐regulate immune‐related pathways and recover the metabolic disorder and the injury caused by MTB. [ABSTRACT FROM AUTHOR]

HIV subtypes B and C together account for around 60% of HIV-1 cases worldwide. We evaluated the safety and immunogenicity of a subtype B DNA vaccine prime followed by a subtype C viral vector boost. Fourteen healthy adults received DNA plasmid encoding HIV-1 subtype B nef/tat/vif and env (n = 11) or placebo (n = 3) intramuscularly (IM) via electroporation (EP) at 0, 1, and 3 months, followed by IM injection of recombinant vesicular stomatitis virus encoding subtype C Env or placebo at 6 and 9 months. Participants were assessed for safety, tolerability of EP, and Env-specific T-cell and antibody responses. EP was generally well tolerated, although some device-related adverse events did occur, and vaccine reactogenicity was mild to moderate. The vaccine stimulated Env-specific CD4 + T-cell responses in greater than 80% of recipients, and CD8 + T-cell responses in 30%. Subtype C Env-specific IgG binding antibodies (bAb) were elicited in all vaccine recipients, and antibody-dependent cell-mediated cytotoxicity (ADCC) responses to vaccine-matched subtype C targets in 80%. Negligible V1/V2 and neutralizing antibody (nAb) responses were detected. This prime/boost regimen was safe and tolerable, with some device-related events, and immunogenic. Although immunogenicity missed targets for an HIV vaccine, the DNA/rVSV platform may be useful for other applications. Trial registration. Clinicaltrials.gov : NCT02654080. [ABSTRACT FROM AUTHOR]

RF-amide related peptides (RFRP) have been proposed as critical regulators of gonadotropin secretion in mammals. This study was designed to construct a DNA vaccine and investigate the effect of vaccine encoding RFRP-3 on reproduction physiology in ewe. A recombinant vaccine was constructed using two copies of the RFRP-3 gene and HBsAg-S that generate a fusion protein to induce an immunology response. Results showed this recombinant vaccine could produce a significant antibody titer in the treated animals (P < 0.05). The specific RFRP-3 antibody response induced by the vaccine was detected at week 2 with a peak at week 6 after the initial immunization. Furthermore, we found that ewes inoculated with pVAX-tPA-HBsAg-S-2RFRP-asd vaccine significantly raised the concentration of GnRH, LH and E 2 in serum compared to the control group. LH and E2 concentration in the treated ewes (Group T) was significantly higher than that in control ewes (Group C) at weeks 10, 12 and 14 after the initial immunization, respectively (P < 0.05). Therefore, RFRP-3 can be used as a target for DNA immunization to promote reproductive hormone secretion in ewes and RFRP-3 gene immunization might be a candidate tool to regulate mammal reproduction. • The recombinant HBsAg-S and RFRP-3 DNA bivalent vaccine induces powerful anti-RFRP-3 antibody response. • The vaccine increased the secretion of reproductive hormones in the HPG axis in sheep. • RFRP-3 can be used as a target for DNA immunization to promote the reproductive hormones in ewes. [ABSTRACT FROM AUTHOR]

Chlamydia psittaci (C. psittaci), a zoonotic pathogen, poses a potential threat to public health security and the development of animal husbandry. Vaccine-based preventative measures for infectious diseases have a promising landscape. DNA vaccines, with many advantages, have become one of the dominant candidate strategies in preventing and controlling the chlamydial infection. Our previous study showed that CPSIT_p7 protein is an effective candidate for a vaccine against C. psittaci. Thus, this study evaluated the protective immunity of pcDNA3.1(+)/CPSIT_p7 against C. psittaci infection in BALB/c mice. We found that pcDNA3.1(+)/CPSIT_p7 can induce strong humoral and cellular immune responses. The IFN-γ and IL-6 levels in the infected lungs of mice immunized with pcDNA3.1(+)/CPSIT_p7 reduced substantially. In addition, the pcDNA3.1(+)/CPSIT_p7 vaccine diminished pulmonary pathological lesions and reduced the C. psittaci load in the lungs of infected mice. It is worth noting that pcDNA3.1(+)/CPSIT_p7 suppressed C. psittaci dissemination in BALB/c mice. In a word, these results demonstrate that the pcDNA3.1(+)/CPSIT_p7 DNA vaccine has good immunogenicity and immunity protection effectiveness against C. psittaci infection in BALB/c mice, especially pulmonary infection, and provides essential practical experience and insights for the development of a DNA vaccine against chlamydial infection. [ABSTRACT FROM AUTHOR]

The nervous necrosis virus (NNV) of the BFNNV genotype is the causative agent of viral encephalopathy and retinopathy (VER) in cold water fishes. Similar to the RGNNV genotype, BFNNV is also considered a highly destructive virus. In the present study, the RNA2 of the BFNNV genotype was modified and expressed in the EPC cell line. The subcellular localization results showed that the capsid and N-terminal (1–414) were located in the nucleus, while the C-terminal (415–1014) of the capsid was located in the cytoplasm. Meanwhile, cell mortality obviously increased after expression of the capsid in EPC. EPC cells were transfected with pEGFP-CP and sampled at 12 h, 24 h and 48 h for transcriptome sequencing. There are 254, 2997 and 229 up-regulated genes and 387, 1611, and 649 down-regulated genes post-transfection, respectively. The ubiquitin-activating enzyme and ubiquitin-conjugating enzyme were up-regulated in the DEGs, indicating that cell death evoked by capsid transfection may be related to ubiquitination. The qPCR results showed that heat stock protein 70 (HSP70) is extremely up-regulated after expression of BFNNV capsid in EPC, and N-terminal is the key region to evoke the high expression. For further study, the immunoregulation of the capsid in fish pcDNA-3.1-CP was constructed and injected into the Takifugu rubripes muscle. pcDNA-3.1-CP can be detected in gills, muscle and head kidney, and lasted for more than 70 d post-injection. The transcripts of IgM and interferon inducible gene Mx were up-regulated after being immunized in different tissues, and immune factors, such as IFN-γ and C3, were also up-regulated in serum, while C4 was down-regulated one week after injection. It was suggested that pcDNA-3.1-CP can be a potential DNA vaccine in stimulating the immune system of T. rubripes; however, NNV challenge needs to be conducted in the following experiments. [ABSTRACT FROM AUTHOR]

Grass carp hemorrhagic disease caused by grass carp reovirus (GCRV) results in significant economic losses to the global grass carp aquaculture industry. Oral vaccination is an ideal choice for disease precaution in aquaculture. However, oral vaccine can be degraded in the gut. Therefore, the selection of loading materials is essential. In this study, the S6 and S7 fragments (encoding the outer capsid protein VP4 and fibronectin VP56 of GCRV) and grass carp interferons (IFNs), including IFN1, IFN3, and IFNγ2 were used to create DNA vaccines and adjuvants based on pcDNA3.1, respectively. The oral DNA vaccine was encapsulated in poly(lactic-co-glycolic acid) (PLGA) and polyvinyl alcohol (PVA) with IFNs. The PLGA-PVA (PP) nano-microspheres were prepared by double emulsionsolvent evaporation technique. Using transmission electron microscopy and dynamic light scattering assays, it was determined the vaccines had a spherical structure with uniform particle size (643.5 ± 35.3 nm). The nano-microspheres possessed excellent encapsulation efficiency (81.6 ± 2.6%) and loading rate (0.54 ± 0.02%), and simultaneously exhibited negligible hemolytic activity and cell toxicity. The protection rate and tissue viral loads post-GCRV challenge in grass carp were assessed. The oral PP nano-microsphere with pVP4 þ pIFN1 (PP41) vaccine increased protection rate by 44% compared with the control group and was correlated with relatively low viral loads in the spleen, head kidney, and hindgut. Further, three crucial serum biochemical indexes, total superoxide dismutase (TSOD), complement C3 (C3), and lysozyme (LZM), were also dramatically increased. Furthermore, mRNA expressions of representative immune-related genes (IgM, IFN1, IFNγ2, MHC-I, and CD8α) in the head kidney and spleen were significantly enhanced. In addition, mRNA expression of IgT was significantly boosted in the hindgut. The results indicate that DNA vaccine capsulated with PP is effective against GCRV infection. The present study provides insights into a prospective strategy for oral vaccine development in aquaculture. [ABSTRACT FROM AUTHOR]

DNA and RNA vaccines (nucleic acid-based vaccines) are a promising platform for vaccine development. The first mRNA vaccines (Moderna and Pfizer/BioNTech) were approved in 2020, and a DNA vaccine (Zydus Cadila, India), in 2021. They display unique benefits in the current COVID-19 pandemic. Nucleic acid-based vaccines have a number of advantages, such as safety, efficacy, and low cost. They are potentially faster to develop, cheaper to produce, and easier to store and transport. A crucial step in the technology of DNA or RNA vaccines is choosing an efficient delivery method. Nucleic acid delivery using liposomes is the most popular approach today, but this method has certain disadvantages. Therefore, studies are actively underway to develop various alternative delivery methods, among which synthetic cationic polymers such as dendrimers are very attractive. Dendrimers are three-dimensional nanostructures with a high degree of molecular homogeneity, adjustable size, multivalence, high surface functionality, and high aqueous solubility. The biosafety of some dendrimers has been evaluated in several clinical trials presented in this review. Due to these important and attractive properties, dendrimers are already being used to deliver a number of drugs and are being explored as promising carriers for nucleic acid-based vaccines. This review summarizes the literature data on the development of dendrimer-based delivery systems for DNA and mRNA vaccines. [ABSTRACT FROM AUTHOR]

Objective Bovine ephemeral fever (BEF) is an arthropod-borne viral disease of cattle and water buffalos which causes considerable economic and commercial losses in the cattle industry. The G glycoprotein of bovine ephemeral fever virus (BEFV) has been identified as a plausible candidate to product recombinant vaccines against this disease. The aim of this study was to investigate the immunogenicity of a eukaryotic plasmid expressing the G1 epitope of bovine ephemeral fever virus G glycoprotein as a possible DNA vaccine in mice. Materials and methods At first, a eukaryotic plasmid expressing the G1 epitope of bovine ephemeral fever virus G glycoprotein was constructed and designated as pEGFPN1-G1. After transfection of the pEGFPN1-G1 recombinant construct to human embryonic kidney 293 (HEK 293) cells, the expression of G1 protein was confirmed by indirect immunofluorescent staining (IFA). Immunization experiments were intramuscularly carried out by inoculating 6-8-week-old female mice in four groups with five repeats, including the pEGFPN1-G1 recombinant construct, bovine ephemeral fever-inactivated vaccine, pEGFP-N1 plasmid alone, and phosphate-buffered saline (PBS) (1X) three times with 2-week intervals. Fourteen days after the last immunization, the animals were bled and the resulting sera were tested for anti-G1-specific antibodies by immunoblotting analysis, indirect enzyme-linked immunosorbent assay (ELISA) and virus neutralisation (VN) test. The optical density values of all the serum samples obtained from the ELISA assay were statistically analyzed in the form of a completely randomized design with four treatments and five replications using SAS software. Results Immunoblotting analysis and statistical analysis of serum samples obtained from the ELISA assay showed that the pEGFPN1-G1 recombinant construct was able to elicit specific antibodies against G1 antigen of bovine ephemeral fever virus in mice. However, the serum of mice inoculated with this plasmid could not neutralize the replicating bovine ephemeral fever virus in virus neutralization assay. Conclusions Since the pEGFPN1-G1 recombinant construct had the ability to produce specific antibodies against the G1 antigen of bovine ephemeral fever virus, the results of this study can be a step towards the development of new vaccines for bovine ephemeral fever in the future. [ABSTRACT FROM AUTHOR]

pGO-1002, a non-viral DNA vaccine that expresses both spike and ORF3a antigens of SARS-CoV-2, is undergoing phase 1 and phase 2a clinical trials in Korea and the US. A preclinical repeated-dose toxicity study in New Zealand white rabbits in compliance with Good Laboratory Practice (GLP) was conducted to assess the potential toxicity, local tolerance, and immunogenicity of the vaccine and GeneDerm suction device. The dose rate was 1.2 mg/head pGO-1002, and this was administered intradermally to a group of animals (eight animals/sex/group) three times at 2-week intervals, followed by a 4-week recovery period. After each administration, suction was applied to the injection site using the GeneDerm device. Mortality, clinical signs, body weight, food consumption, skin irritation, ophthalmology, body temperature, urinalysis, and clinical pathology were also monitored. Gross observations and histopathological evaluation were performed. Overall, pGO-1002 administration-related changes were confined to minor damage or changes at the injection site, increased spleen weight and minimal increased cellularity in white pulp. All changes of injection site were considered local inflammatory changes or pharmacological actions due to the vaccine with the changes in spleen considered consistent with vaccine-induced immune activation. All findings showed reversibility during the 4-week recovery period. Animals vaccinated with pGO-1002, administered by intradermal injection and followed by application of suction with GeneDerm, developed humoral and cellular responses against the SARS-CoV-2 antigens consistent with prior studies in rats. Collectively, it was concluded that the pGO-1002 vaccine was safe and effective under these experimental conditions and these data supported future human study of the vaccine, now known as GLS-5310, for clinical trial use. [ABSTRACT FROM AUTHOR]

Generating vaccines is a promising and effective method for stopping the spread of Acinetobacter baumannii (A. baumannii) infections that are becoming more and more drug-resistant (MDR). Developing a DNA vaccine and testing its efficacy and protective effects in BALB/c mice were the goals of this research. We examined the genomes of 35 different strains of A. baumannii using the Vaxign online program, and we selected outer membrane and secreted proteins as potential vaccine candidates. Next, the proteins' immunogenicity, antigenic features, physical and chemical characteristics, and B and MHCI/II cell epitope concentrations were assessed. The DNA vaccine was synthesized. Then, to generate CS-DNA nanoparticles, the DNA vaccine was e encapsulated by chitosan (CS) nanoparticles (NPs). BALB/c mice were used to assess the vaccine's immunogenicity and immunoprotective effectiveness. CS-DNA NPs were nontoxic, positively charged (4.39 mV), and small (mean size of 285–350 nm) with ostensibly spherical shapes. It was possible to establish a continuously slow release profile and a high entrapment efficiency (78.12 %). CS-DNA vaccinated BALB/c mice elicited greater levels of csuC-specific IgG in plasma and IFN-γ in splenocyte lysate compared with non-encapsulated DNA vaccine. In addition, BALB/c mice immunized with CS-DNA nanovaccine showed decreased lung damage and bacterial loads in the lung and blood, as well as significant immunity (87.5 %) versus acute fatal intratracheal A. baumannii challenge. In conclusion, acute fatal intratracheal A. baumannii exposure was prevented by CS-DNA NPs that induced specific IgG antibodies, Th1 cellular immunity, and other protective mechanisms. Our findings show that this nanovaccine is a promising contender for stopping the spread of A. baumannii infection. [ABSTRACT FROM AUTHOR]

Edwardsiella septicemia disease in the cultured Indian major carps is caused by the fish pathogen Edwardsiella tarda and it is preventable by DNA vaccination. Here, we tried to develop a bicistronic DNA vaccine pGPD/IFN expressing the Glyceraldehyde 3-phosphate dehydrogenase (GAPDH) gene of Edwardsiella tarda and Interferon-gamma (IFN-γ) gene of Labeo rohita. The vaccine showed high protective efficiency in our previous studies; however as a limitation of bicistronic construct the expression of gene cloned in second frame (B) is poor. To overcome this limitation we re-engineered the construct and designed a fusion gene co-expressing the GAPDH and IFN-γ genes as one frame with an aim to get the optimum expression of both the genes. For this purpose, a fusion insert comprising GAPDH and IFN-γ coding sequences was cloned in to pcDNA3.1(+) plasmid vector. The fusion genes' in vitro expression was confirmed in the striped snakehead fish cell line (SSN-1). Successful expression of the re-engineered fusion gene DNA vaccine in the cell line was achieved at 48h post-transfection, which was confirmed by amplifying the expression transcripts of GAPDH and IFN-γ genes. Thus, the study concludes that the re-engineered fusion vaccine pcGPD/IFN (pcDNA3.1(+) plasmid having fusion GPD/IFN) is functional and can be effectively utilized to vaccinate rohu (Labeo rohita) as it contains the species-specific immune gene (IFN-γ) as an adjuvant. [ABSTRACT FROM AUTHOR]

• This study reports the safety and immunogenicity of the GLS-5310 DNA vaccine through 48 weeks. • First clinical application of the GeneDerm suction device for DNA vaccine delivery. • GLS-5310 was well tolerated and without vaccine-associated severe adverse effects. • T cell responses of ∼1200 site forming units/106 peripheral blood mononuclear cells were maintained through 48 weeks. • T cell responses were many-fold higher than all other vaccine platforms. • Antibody responses were induced in 95.5% and maintained through 48 weeks. The CoV2-001 phase I randomized trial evaluated the safety and immunogenicity of the GLS-5310 bi-cistronic DNA vaccine through 48 weeks of follow-up. A total of 45 vaccine-naïve participants were recruited between December 31, 2020, and March 30, 2021. GLS-5310, encoding for the SARS-CoV-2 spike and open reading frame 3a (ORF3a) proteins, was administered intradermally at 0.6 mg or 1.2 mg per dose, followed by application of the GeneDerm suction device as part of a two-dose regimen spaced either 8 or 12 weeks between vaccinations. GLS-5310 was well tolerated with no serious adverse events reported. Antibody and T cell responses were dose-independent. Anti-spike antibodies were induced in 95.5% of participants with an average geometric mean titer of ∼480 four weeks after vaccination and declined minimally through 48 weeks. Neutralizing antibodies were induced in 55.5% of participants with post-vaccination geometric mean titer of 28.4. T cell responses were induced in 97.8% of participants, averaging 716 site forming units/106 cells four weeks after vaccination, increasing to 1248 at week 24, and remaining greater than 1000 through 48 weeks. GLS-5310 administered with the GeneDerm suction device was well tolerated and induced high levels of binding antibodies and T-cell responses. Antibody responses were similar to other DNA vaccines, whereas T cell responses were many-fold greater than DNA and non-DNA vaccines. [ABSTRACT FROM AUTHOR]