Phosphatidylinositol 4-Kinase III Alpha Governs Cytoskeletal Organization for Invasiveness of Liver Cancer Cells.

BACKGROUND & AIMS: High expression of phosphatidylinositol 4-kinase III alpha (PI4KIIIα) correlates with poor survival rates in patients with hepatocellular carcinoma. In addition, hepatitis C virus (HCV) infections activate PI4KIIIα and contribute to hepatocellular carcinoma progression. We aimed at mechanistically understanding the impact of PI4KIIIα on the progression of liver cancer and the potential contribution of HCV in this process. METHODS: Several hepatic cell culture and mouse models were used to study the functional importance of PI4KIIIα on liver pathogenesis. Antibody arrays, gene silencing, and PI4KIIIα-specific inhibitor were applied to identify the involved signaling pathways. The contribution of HCV was examined by using HCV infection or overexpression of its nonstructural protein. RESULTS: High PI4KIIIα expression and/or activity induced cytoskeletal rearrangements via increased phosphorylation of paxillin and cofilin. This led to morphologic alterations and higher migratory and invasive properties of liver cancer cells. We further identified the liver-specific lipid kinase phosphatidylinositol 3-kinase C2 domain-containing subunit gamma (PIK3C2γ) working downstream of PI4KIIIα in regulation of the cytoskeleton. PIK3C2γ generates plasma membrane phosphatidylinositol 3,4-bisphosphate-enriched, invadopodia-like structures that regulate cytoskeletal reorganization by promoting Akt2 phosphorylation. CONCLUSIONS: PI4KIIIα regulates cytoskeleton organization via PIK3C2γ/Akt2/paxillin-cofilin to favor migration and invasion of liver cancer cells. These findings provide mechanistic insight into the contribution of PI4KIIIα and HCV to the progression of liver cancer and identify promising targets for therapeutic intervention.

Distinct roles of vaccine-induced SARS-CoV-2-specific neutralizing antibodies and T cells in protection and disease.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-specific neutralizing antibodies (NAbs) lack cross-reactivity between SARS-CoV species and variants and fail to mediate long-term protection against infection. The maintained protection against severe disease and death by vaccination suggests a role for cross-reactive T cells. We generated vaccines containing sequences from the spike or receptor binding domain, the membrane and/or nucleoprotein that induced only T cells, or T cells and NAbs, to understand their individual roles. In three models with homologous or heterologous challenge, high levels of vaccine-induced SARS-CoV-2 NAbs protected against neither infection nor mild histological disease but conferred rapid viral control limiting the histological damage. With no or low levels of NAbs, vaccine-primed T cells, in mice mainly CD8+ T cells, partially controlled viral replication and promoted NAb recall responses. T cells failed to protect against histological damage, presumably because of viral spread and subsequent T cell-mediated killing. Neither vaccine- nor infection-induced NAbs seem to provide long-lasting protective immunity against SARS-CoV-2. Thus, a more realistic approach for universal SARS-CoV-2 vaccines should be to aim for broadly cross-reactive NAbs in combination with long-lasting highly cross-reactive T cells. Long-lived cross-reactive T cells are likely key to prevent severe disease and fatalities during current and future pandemics.

Novel prime-boost immune-based therapy inhibiting both hepatitis B and D virus infections.

OBJECTIVE: Chronic HBV/HDV infections are a major cause of liver cancer. Current treatments can only rarely eliminate HBV and HDV. Our previously developed preS1-HDAg immunotherapy could induce neutralising antibodies to HBV in vivo and raise HBV/HDV-specific T-cells. Here, we further investigate if a heterologous prime-boost strategy can circumvent T-cell tolerance and preclude HDV superinfection in vivo. DESIGN: A DNA prime-protein boost strategy was evaluated for immunogenicity in mice and rabbits. Its ability to circumvent T-cell tolerance was assessed in immunocompetent hepatitis B surface antigen (HBsAg)-transgenic mice. Neutralisation of HBV and HDV was evaluated both in vitro and in immunodeficient human-liver chimeric mice upon adoptive transfer. RESULTS: The prime-boost strategy elicits robust HBV/HDV-specific T-cells and preS1-antibodies that can effectively prevent HBV and HDV (co-)infection in vitro and in vivo. In a mouse model representing the chronic HBsAg carrier state, active immunisation primes high levels of preS1-antibodies and HDAg-specific T-cells. Moreover, transfer of vaccine-induced antibodies completely protects HBV-infected human-liver chimeric mice from HDV superinfection. CONCLUSION: The herein described preS1-HDAg immunotherapy is shown to be immunogenic and vaccine-induced antibodies are highly effective at preventing HBV and HDV (super)infection both in vitro and in vivo. Our vaccine can complement current and future therapies for the control of chronic HBV and HDV infection.

Accelerated DNA vaccine regimen provides protection against Crimean-Congo hemorrhagic fever virus challenge in a macaque model.

Crimean-Congo hemorrhagic fever virus (CCHFV) is widely distributed throughout Africa, the Middle East, Southern Asia, and Southern and Eastern Europe. Spread by Hyalomma ticks or by contact with infected animals, CCHF begins non-specifically but can rapidly progress to severe, sometimes fatal, disease. Due to the non-specific early symptoms and often unrecognized infections, patients often present to healthcare systems exhibiting later stages of disease, when treatment is limited to supportive care. Consequently, simple vaccines are critically needed to protect populations at risk of CCHFV infection. Currently, there are no widely approved vaccines for CCHFV. We have previously reported significant efficacy of a three-dose DNA-based vaccination regimen for CCHFV in cynomolgus macaques (Macaca fasicularis). Here, we show that in cynomolgus macaques, plasmid-expressed CCHFV nucleoprotein (NP) and glycoprotein precursor (GPC) antigens elicit primarily humoral and cellular immunity, respectively. We found that a two-dose vaccination regimen with plasmids expressing the NP and GPC provides significant protection against CCHFV infection. Studies investigating vaccinations with either antigen alone showed that plasmid-expressed NPs could also confer protection. Cumulatively, our data show that this vaccine confers robust protection against CCHFV and suggest that both humoral and cellular immunity contribute to optimal vaccine-mediated protection.

A universal SARS-CoV DNA vaccine inducing highly cross-reactive neutralizing antibodies and T cells.

New variants in the SARS-CoV-2 pandemic are more contagious (Alpha/Delta), evade neutralizing antibodies (Beta), or both (Omicron). This poses a challenge in vaccine development according to WHO. We designed a more universal SARS-CoV-2 DNA vaccine containing receptor-binding domain loops from the huCoV-19/WH01, the Alpha, and the Beta variants, combined with the membrane and nucleoproteins. The vaccine induced spike antibodies crossreactive between huCoV-19/WH01, Beta, and Delta spike proteins that neutralized huCoV-19/WH01, Beta, Delta, and Omicron virus in vitro. The vaccine primed nucleoprotein-specific T cells, unlike spike-specific T cells, recognized Bat-CoV sequences. The vaccine protected mice carrying the human ACE2 receptor against lethal infection with the SARS-CoV-2 Beta variant. Interestingly, priming of cross-reactive nucleoprotein-specific T cells alone was 60% protective, verifying observations from humans that T cells protect against lethal disease. This SARS-CoV vaccine induces a uniquely broad and functional immunity that adds to currently used vaccines.

Nucleoside-Modified mRNA Vaccines Protect IFNAR-/- Mice against Crimean-Congo Hemorrhagic Fever Virus Infection.

Crimean-Congo hemorrhagic fever (CCHF), caused by Crimean-Congo hemorrhagic fever virus (CCHFV), is on the World Health Organizations' list of prioritized diseases and pathogens. With global distribution, high fatality rate, and no approved vaccine or effective treatment, CCHF constitutes a threat against global health. In the current study, we demonstrate that vaccination with nucleoside-modified mRNA-lipid nanoparticles (mRNA-LNP), encoding for the CCHFV nucleoprotein (N) or glycoproteins (GcGn) protect IFNAR-/- mice against lethal CCHFV infection. In addition, we found that both mRNA-LNP induced strong humoral and cellular immune responses in IFNAR-/- and immunocompetent mice and that neutralizing antibodies are not necessary for protection. When evaluating immune responses induced by immunization including CCHFV Gc and Gn antigens, we found the Gc protein to be more immunogenic compared with the Gn protein. Hepatic injury is prevalent in CCHF and contributes to the severity and mortality of the disease in humans. Thus, to understand the immune response in the liver after infection and the potential effect of the vaccine, we performed a proteomic analysis on liver samples from vaccinated and control mice after CCHFV infection. Similar to observations in humans, vaccination affected the metabolic pathways. In conclusion, this study shows that a CCHFV mRNA-LNP vaccine, based on viral nucleo- or glycoproteins, mediate protection against CCHFV induced disease. Consequently, genetic immunization is an attractive approach to prevent disease caused by CCHFV and we believe we have necessary evidence to bring this vaccine platform to the next step in the development of a vaccine against CCHFV infection. IMPORTANCE Crimean-Congo hemorrhagic fever virus (CCHFV) is a zoonotic pathogen causing Crimean-Congo hemorrhagic fever (CCHF), a severe fever disease. CCHFV has a wide distribution and is endemic in several areas around the world. Cases of CCHF are also being reported in new areas, indicating an expansion of the disease, which is of high concern. Dispersion of the disease, high fatality rate, and no approved vaccine makes CCHF a threat to global health. The development of a vaccine is thus of great importance. Here we show 100% protection against lethal CCHFV infection in mice immunized with mRNA-LNP encoding for different CCHFV proteins. The vaccination showed both robust humoral and cellular immunity. mRNA-LNP vaccines combine the ability to induce an effective immune response, the safety of a transient carrier, and the flexibility of genetic vaccines. This and our results from the current study support the development of a mRNA-LNP based vaccine against CCHFV.

Metabolic Perturbation Associated With COVID-19 Disease Severity and SARS-CoV-2 Replication.

Viruses hijack host metabolic pathways for their replicative advantage. In this study, using patient-derived multiomics data and in vitro infection assays, we aimed to understand the role of key metabolic pathways that can regulate severe acute respiratory syndrome coronavirus-2 reproduction and their association with disease severity. We used multiomics platforms (targeted and untargeted proteomics and untargeted metabolomics) on patient samples and cell-line models along with immune phenotyping of metabolite transporters in patient blood cells to understand viral-induced metabolic modulations. We also modulated key metabolic pathways that were identified using multiomics data to regulate the viral reproduction in vitro. Coronavirus disease 2019 disease severity was characterized by increased plasma glucose and mannose levels. Immune phenotyping identified altered expression patterns of carbohydrate transporter, glucose transporter 1, in CD8+ T cells, intermediate and nonclassical monocytes, and amino acid transporter, xCT, in classical, intermediate, and nonclassical monocytes. In in vitro lung epithelial cell (Calu-3) infection model, we found that glycolysis and glutaminolysis are essential for virus replication, and blocking these metabolic pathways caused significant reduction in virus production. Taken together, we therefore hypothesized that severe acute respiratory syndrome coronavirus-2 utilizes and rewires pathways governing central carbon metabolism leading to the efflux of toxic metabolites and associated with disease severity. Thus, the host metabolic perturbation could be an attractive strategy to limit the viral replication and disease severity.

SARS-CoV-2-specific humoral and cellular immunity persists through 9 months irrespective of COVID-19 severity at hospitalisation.

OBJECTIVES: Humoral and cellular immunity to SARS-CoV-2 following COVID-19 will likely contribute to protection from reinfection or severe disease. It is therefore important to characterise the initiation and persistence of adaptive immunity to SARS-CoV-2 amidst the ongoing pandemic. METHODS: Here, we conducted a longitudinal study on hospitalised moderate and severe COVID-19 patients from the acute phase of disease into convalescence at 5 and 9 months post-symptom onset. Utilising flow cytometry, serological assays as well as B cell and T cell FluoroSpot assays, we assessed the magnitude and specificity of humoral and cellular immune responses during and after human SARS-CoV-2 infection. RESULTS: During acute COVID-19, we observed an increase in germinal centre activity, a substantial expansion of antibody-secreting cells and the generation of SARS-CoV-2-neutralising antibodies. Despite gradually decreasing antibody levels, we show persistent, neutralising antibody titres as well as robust specific memory B cell responses and polyfunctional T cell responses at 5 and 9 months after symptom onset in both moderate and severe COVID-19 patients. CONCLUSION: Our findings describe the initiation and, importantly, persistence of cellular and humoral SARS-CoV-2-specific immunological memory in hospitalised COVID-19 patients long after recovery, likely contributing towards protection against reinfection.

Blocking Entry of Hepatitis B and D Viruses to Hepatocytes as a Novel Immunotherapy for Treating Chronic Infections.

BACKGROUND: Chronic hepatitis B and D virus (HBV/HDV) infections can cause cancer. Current HBV therapy using nucleoside analogues (NAs) is life-long and reduces but does not eliminate the risk of cancer. A hallmark of chronic hepatitis B is a dysfunctional HBV-specific T-cell response. We therefore designed an immunotherapy driven by naive healthy T cells specific for the HDV antigen (HDAg) to bypass the need for HBV-specific T cells in order to prime PreS1-specific T cells and PreS1 antibodies blocking HBV entry. METHODS: Ten combinations of PreS1 and/or HDAg sequences were evaluated for induction of PreS1 antibodies and HBV- and HDV-specific T cells in vitro and in vivo. Neutralization of HBV by PreS1-specific murine and rabbit antibodies was evaluated in cell culture, and rabbit anti-PreS1 were tested for neutralization of HBV in mice repopulated with human hepatocytes. RESULTS: The best vaccine candidate induced T cells to PreS1 and HDAg, and PreS1 antibodies blocking HBV entry in vitro. Importantly, adoptive transfer of PreS1 antibodies prevented, or modulated, HBV infection after a subsequent challenge in humanized mice. CONCLUSIONS: We here describe a novel immunotherapy for chronic HBV/HDV that targets viral entry to complement NAs and coming therapies inhibiting viral maturation.

A DNA-based vaccine protects against Crimean-Congo haemorrhagic fever virus disease in a Cynomolgus macaque model.

There is currently no specific prophylaxis or vaccine against Crimean-Congo haemorrhagic fever virus (CCHFV). Crimean-Congo haemorrhagic fever (CCHF) is a severe febrile illness transmitted by Hyalomma ticks in endemic areas, handling of infected livestock or care of infected patients. We report here the successful protection against CCHFV-mediated disease in a non-human primate disease model. Cynomolgus macaques were vaccinated with a DNA-based vaccine using in vivo electroporation-assisted delivery. The vaccine contained two plasmids encoding the glycoprotein precursor (GPC) and the nucleoprotein (NP) of CCHFV. Animals received three vaccinations and we recorded potent antibody and T cell responses after vaccination. While all sham-vaccinated animals developed viraemia, high tissue viral loads and CCHF-induced disease, the NP + GPC vaccinated animals were significantly protected. In conclusion, this is evidence of a vaccine that can protect against CCHFV-induced disease in a non-human primate model. This supports clinical development of the vaccine to protect groups at risk for contracting the infection.

Expansion of SARS-CoV-2-Specific Antibody-Secreting Cells and Generation of Neutralizing Antibodies in Hospitalized COVID-19 Patients.

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), emerged in late 2019 and has since become a global pandemic. Pathogen-specific Abs are typically a major predictor of protective immunity, yet human B cell and Ab responses during COVID-19 are not fully understood. In this study, we analyzed Ab-secreting cell and Ab responses in 20 hospitalized COVID-19 patients. The patients exhibited typical symptoms of COVID-19 and presented with reduced lymphocyte numbers and increased T cell and B cell activation. Importantly, we detected an expansion of SARS-CoV-2 nucleocapsid protein-specific Ab-secreting cells in all 20 COVID-19 patients using a multicolor FluoroSpot Assay. Out of the 20 patients, 16 had developed SARS-CoV-2-neutralizing Abs by the time of inclusion in the study. SARS-CoV-2-specific IgA, IgG, and IgM Ab levels positively correlated with SARS-CoV-2-neutralizing Ab titers, suggesting that SARS-CoV-2-specific Ab levels may reflect the titers of neutralizing Abs in COVID-19 patients during the acute phase of infection. Last, we showed that IL-6 and C-reactive protein serum concentrations were higher in patients who were hospitalized for longer, supporting the recent observations that IL-6 and C-reactive protein could be used as markers for COVID-19 severity. Altogether, this study constitutes a detailed description of clinical and immunological parameters in 20 COVID-19 patients, with a focus on B cell and Ab responses, and describes tools to study immune responses to SARS-CoV-2 infection and vaccination.

Clinical-Grade Oncolytic Adenovirus Purification Using Polysorbate 20 as an Alternative for Cell Lysis.

INTRODUCTION: Oncolytic virus therapy is currently considered as a promising therapeutic approach for cancer treatment. Adenovirus is well-known and extensively characterized as an oncolytic agent. The increasing number of clinical trials using this virus generates the demand for the development of a well-established purification approach. Triton X-100 is commonly used in cell lysis buffer preparations. The addition of this surfactant in the list of substances with the very high concern of the Registration, Evaluation, Authorization and Restriction of Chemicals (REACH) regulation promoted the research for effective alternatives. METHODS: In this work, a purification strategy for oncolytic adenovirus compatible with phase I clinical trials, using an approved surfactant - Polysorbate 20 was developed. The proposed downstream train, composed by clarification, concentration using tangential flow filtration, intermediate purification with anion exchange chromatography, followed by a second concentration and a final polishing step was evaluated for both Triton X-100 and Polysorbate 20 processes. The impact of cell lysis with Polysorbate20 and Triton X-100 for each downstream step was evaluated in terms of product recovery and impurities removal. Overall, 61 ± 4% of infectious viral particles were recovered. Depletion of host cell proteins and ds-DNA was 99.9% and 97.1%, respectively. RESULTS & CONCLUSION: The results indicated that Polysorbate 20 can be used as a replacement for Triton X-100 during cell lysis with no impact on product recovery, potency, and purity. Moreover, the developed process is scalable and able to provide a highly purified product to be used in phase I and II clinical trials.

Immune-mediated effects targeting hepatitis C virus in a syngeneic replicon cell transplantation mouse model.

OBJECTIVE: HCV is characterised by its ability to establish chronic infection in hepatocytes and to replicate in the presence of an inflammation. We mimicked this situation in vivo in immune-competent mice by syngeneic transplantation of HCV replicon-containing mouse hepatoma cells. DESIGN: A total of 5 million H-2b positive Hep56.1D cells, carrying a subgenomic genotype (gt) 2a replicon (HCV replicon cells) or stably expressing comparable levels of the HCV NS3/4A protease/helicase complex (NS3/4A hepatoma cells), were injected subcutaneously into syngeneic H-2b-restricted mice. Kinetics of tumour growth, HCV RNA replication levels and HCV-specific immune responses were monitored. For immune monitoring, new H-2b-restricted cytotoxic T cell epitopes within the gt2a NS3/4A region were mapped. Immune mice were generated by DNA-based vaccination. RESULTS: HCV replicon and NS3/4A hepatoma cells generated solid tumours in vivo. Similar to what is seen in human HCV infection did HCV RNA replicate in the presence of inflammation. NS3/4A-specific CD8+ T cells seemed to transiently reduce HCV RNA levels. Both CD4+ and CD8+ T cells were required for protection against tumour growth. Vaccine-induced NS3/4A(gt2a)-specific T cells protected against HCV replicon tumours in wild-type, but not in HCV NS3/4A(gt1a)-transgenic mice with dysfunctional HCV-specific T cells. Importantly, as in human HCV infection, HCV replicon cells neither primed nor boosted a strong NS3/4A-specific T cell response. CONCLUSION: Syngeneic transplantation of mouse HCV replicon cells into immune-competent animals mirrors many in vivo events in humans. This system is versatile and can be applied to any genetically modified H-2b-restricted mouse strain.

Functional differences in hepatitis C virus nonstructural (NS) 3/4A- and 5A-specific T cell responses.

The hepatitis C virus nonstructural (NS) 3/4A and NS5A proteins are major targets for the new direct-acting antiviral compounds. Both viral proteins have been suggested as modulators of the response to the host cell. We have shown that NS3/4A- and NS5A-specific T cell receptors confer different effector functions, and that killing of NS3/4A-expressing hepatocytes is highly dependent on IFN-γ. We here characterize the functional differences in the T cell responses to NS3/4A and NS5A. NS3/4A- and NS5A-specific T cells could be induced at various frequencies in wild-type-, NS3/4A-, and NS5A-transgenic mice. Priming of NS5A-specific T cells required a high DNA dose, and was unlike NS3/4A dependent on both CD4(+) and CD8(+) T cells, but less influenced by CD25(+)/GITR(+) regulatory T cells. The presence of IL-12 greatly improved specific CD8(+) T cell priming by NS3/4A but not by NS5A, suggesting a less dependence of IFN-γ for NS5A. This notion was supported by the observation that NS5A-specific T cells could eliminate NS5A-expressing hepatocytes also in the absence of IFN-γ-receptor-2. This supports that NS3/4A- and NS5A-specific T cells become activated and eliminate antigen expressing, or infected hepatocytes, by distinct mechanisms, and that NS5A-specific T cells show an overall less dependence of IFN-γ.

A targeted controlled force injection of genetic material in vivo.

A general limitation in gene delivery is the cellular uptake in lager animals including humans. Several approaches have been tested including liposomes, micro-needles, in vivo electro-transfer, ballistic delivery, and needle-free delivery. All these techniques have individual limitations. One approach reproducibly delivering genetic material in muscle tissue in nonhuman primates is hydrodynamic injection, a forced injection of a volume equaling the volume of the tissue to be transfected thereby causing an increased local pressure resulting in an improved uptake of genetic material. We transferred the principle of hydrodynamic injection to a device, where a small injection volume can be delivered to a targeted tissue volume, termed in vivo intracellular injection (IVIN). The device is based on needle(s) with apertures along the needle shafts, where multiple needles can fix the tissue volume to be transfected. The apertures direct the injection from a central needle outward or inward to the centroid of a geometric arrangement thereby targeting the tissue to be transfected. With a controlled force, this results in a targeted injection with increased transfection efficiency. We here show that the IVIN technology reproducibly improved plasmid uptake and expression and the immunogenicity. The IVIN technology can be generally applied to a targeted delivery of genetic materials.

Methods to Evaluate Novel Hepatitis C Virus Vaccines.

The hepatitis C virus (HCV) is a major cause of severe liver disease worldwide. It is estimated that around 130-170 million individuals are chronic carriers of the infection and they are over time at an increased risk of developing severe liver disease. HCV is often referred to as a silent epidemic because the majority of infected individuals do not develop any symptoms. Hence, many individuals are diagnosed at a late stage and thus in need of immediate treatment. Today we have very effective direct-acting antivirals (DAAs), which cure more than 90-95 % of all treated patients. However, this treatment is associated with high-costs and the use is limited to the patients with most advanced liver disease in high-income countries. Notably, a majority of the chronic HCV carriers live in resource-poor countries and do not have access to the new effective DAAs. We therefore need to develop alternative treatments for chronic HCV infection such as therapeutic vaccines. The idea with therapeutic vaccines is to reactivate the infected patient's own immune system. It is well known that patients with chronic HCV infection have dysfunctional immune responses to the virus. Hence, the vaccine should activate HCV-specific T cells that will home to the liver and eradicate the HCV infected hepatocytes. Importantly, one should also consider the combination of a therapeutic vaccine and DAAs as a treatment strategy to equip the resolving patients with post-cure HCV-specific immune responses. This would provide patients with a better protection against reinfection. Numerous genetic vaccine candidates for HCV have been developed and tested in clinical trials with limited effects on viral load and in general inefficient activation of HCV-specific immune responses. In this chapter we describe the rational of developing highly immunogenic vaccines for HCV. Different strategies to improve vaccine immunogenicity and methods to evaluate vaccine efficacy are described. Detailed description of vaccine delivery by intramuscular immunization in combination with in vivo electroporation/electrotransfer (EP/ET) is covered, as well as immunological analysis of primed immune responses by determination of interferon-γ (IFN-γ) production by ELISpot assay and direct ex vivo quantification of HCV NS3/4A-specific CD8+ T cells by pentamer staining. To analyze the in vivo functionality of primed NS3/4A-specific T cells we utilized the in vivo bioluminescence imaging technology. In conclusion, this chapter describes a method to design HCV vaccines and also a protocol to assess their efficacy.

A non-human hepadnaviral adjuvant for hepatitis C virus-based genetic vaccines.

Human hepatitis B virus (HBV) core antigen (HBcAg) can act as an adjuvant in hepatitis C virus (HCV)-based DNA vaccines. Since two billion people are, or have been, in contact with HBV, one may question the use of human HBV sequences as adjuvant. We herein evaluated non-human stork hepatitis B virus core gene-sequences from stork as DNA vaccine adjuvants. Full-length and fragmented stork HBcAg gene-sequences were added to an HCV non-structural (NS) 3/4A gene (NS3/4A-stork-HBcAg). This resulted in an enhanced priming of HCV-specific IFN-γ and IL-2 responses in both wild-type (wt)- and NS3/4A-transgenic (Tg) mice, the latter with dysfunctional NS3/4A-specific T cells. The NS3/4A-stork-HBcAg vaccine primed NS3/4A-specific T cells in hepatitis B e antigen (HBeAg)-Tg mice with dysfunctional T cells to HBcAg and HBeAg. Repeated immunizations boosted expansion of IFN-γ and IL-2-producing NS3/4A-specific T cells in wt- and NS3/4A-Tg mice. Importantly, NS3/4A-stork-HBcAg-DNA induced in vivo long-term functional memory T cell responses, whose maintenance required CD4(+) T cells. Thus, avian HBcAg gene-sequences from stork can effectively act as a DNA vaccine adjuvant. This technology can most likely be universally expanded to other genetic vaccine antigens, as this completely avoids the use of sequences from a human virus where a pre-existing immunity may interfere with its adjuvant effect.

Electroporation for therapeutic DNA vaccination in patients.

DNA vaccination has historically failed to raise strong immune responses in humans. Recent delivery techniques such as the gene gun and in vivo electroporation (EP)/electrotransfer (ET) have completely changed the efficiency of DNA vaccines in humans. In vivo EP exerts multiple effects that contribute to its efficiency. The two central factors are most likely the increased DNA uptake due to the transient membrane destabilization, and the local tissue damage acting as an adjuvant. To date, several studies in humans have used in vivo EP/ET to deliver DNA. Some of these results have been quite promising with strong T cell responses and/or transient effects on the viral replication. This suggests that improved strategies of in vivo EP/ET can be a future way to deliver DNA in humans.