DNA Vaccinated Research Articles

Efficacy of DNA Vaccines in Protecting Rainbow Trout against VHS and IHN under Intensive Farming Conditions.

Despite the negative impact of viral hemorrhagic septicemia (VHS) and infectious hematopoietic necrosis (IHN) on European rainbow trout farming, no vaccines are commercially available in Europe. DNA vaccines are protective under experimental conditions, but testing under intensive farming conditions remains uninvestigated. Two DNA vaccines encoding the glycoproteins (G) of recent Italian VHSV and IHNV isolates were developed and tested for potency and safety under experimental conditions. Subsequently, a field vaccination trial was initiated at a disease-free hatchery. The fish were injected intramuscularly with either the VHS DNA vaccine or with a mix of VHS and IHN DNA vaccines at a dose of 1 µg/vaccine/fish, or with PBS. At 60 days post-vaccination, fish were moved to a VHSV and IHNV infected facility. Mortality started 7 days later, initially due to VHS. After 3 months, IHN became the dominant cause of disease. Accordingly, both DNA vaccinated groups displayed lower losses compared to the PBS group during the first three months, while the VHS/IHN vaccinated group subsequently had the lowest mortality. A later outbreak of ERM caused equal disease in all groups. The trial confirmed the DNA vaccines to be safe and efficient in reducing the impact of VHS and IHN in farmed rainbow trout.

Protective immunity induced by ankyrin repeat-containing protein-based DNA vaccine against rock bream iridovirus (RBIV) in rock bream (Oplegnathus fasciatus)

Rock bream iridovirus (RBIV) causes severe mass mortalities in rock bream (Oplegnathus fasciatus) and remains an unsolved problem in Korea aquaculture industry. In this study, we assessed the potential of ankyrin repeat (ANK)-containing proteins to induce protective immunity in RBIV-infected rock bream. Rock bream administered with ankyrin repeat-containing protein-based DNA vaccine (200 ng/fish) exhibited significant protection against at 4 and 8 weeks post vaccination to infected with 6.7 × 105 RBIV at 23°C; relative percent survival (RPS) of 60.04% and 40.1%, respectively. Furthermore, survivors from the first infection were strongly protected from RBIV (1.1 × 107) re-infection at 70 days post infection, as 100% RPS was observed and without clinical signs of RBIV diseases. Moreover, TLR3 (9.5-fold), TLR9 (5.2-fold), MyD88 (15.9-fold), Mx (55.5-fold), ISG15 (19.0-fold), PKR (24.2-fold), MHC class I (5.1-fold), perforin (6.5-fold), Fas (6.4-fold), Fas ligand (7.1-fold), caspase8 (5.0-fold), caspase9 (12.5-fold), and caspase3 (6.3-fold) responses were significantly elevated in the muscle (vaccine injection site) of ANK-based DNA vaccinated fish at 7 days post vaccination. However, inflammatory cytokines (IL1β, IL8, and TNFα) were not enhanced in the vaccinated rock bream. Moreover, ANK gene may be a good candidate to detect RBIV infection or in revealing specific information to elucidate the pathogenic mechanisms underlying RBIV infection. In summary, ANK-based DNA vaccination in rock bream induced TLR- and IFN-mediated or apoptosis-related immune responses and suggest efficient preventive measures against RBIV.

Recombinant Glycoprotein B of Equine herpesvirus Type 1 Elicits Protective Immune Response against Challenge in BALB/c Mouse Model

Background: Equine herpesvirus type 1 (EHV-1) is the most important viral pathogen of equines, causing respiratory illness, abortion, neonatal foal mortality and neurologic disorders. Large numbers of commercial EHV-1 vaccines are available to protect equines from the disease, but they provide only partial protection. Despite immunization with inactivated and modified live virus vaccine, mares show abortions. Present study was aimed to investigate the immunogenicity and protective efficacy of EHV-1 recombinant glycoprotein B (rgB) and gB expressing plasmid DNA against EHV-1 infection in BALB/c mice model.Methods: About 3-4 weeks old 225 female BALB/c mice were selected for the comparative study of immunization followed by challenged with EHV-1/India/Tohana/96-2 strain virus in 5 different groups of 45 animals each.Result: Following immunization, rgB vaccinated mice showed optimal stimulation of EHV-1 gB specific cell mediated and humoral mediated immunity (HMI and CMI). The gB expressing plasmid DNA vaccinated mice developed only CMI while inactivated whole virus vaccinated mice had only HMI. Upon EHV-1 challenge, all infected mice displayed variable levels of clinical signs with changes in body weight, however, vaccinated mice showed very rapid recovery with optimal protection. Positive control group mice showed severe pulmonary lesions along with persistence virus infection till 5 days post challenge (dpc) whereas vaccinated mice had less pulmonary lesion only up to 3dpc. Minimal lung lesions and early virus clearance was observed in the rgB immunized mice in comparison to the gB plasmid DNA and inactivated EHV-1 vaccine immunized mice. It has been concluded that immunization with rgB elicits optimum protective immune response against EHV-1 infection in mice model. The rgB could be a potential vaccine candidate against EHV-1 infection in equine in the future.

Intranasal delivery of plasmids expressing bovine herpesvirus 1 gB/gC/gD proteins by polyethyleneimine magnetic beads activates long-term immune responses in mice

BackgroundDNA vaccine is one of the research hotspots in veterinary vaccine development. Several advantages, such as cost-effectiveness, ease of design and production, good biocompatibility of plasmid DNA, attractive biosafety, and DNA stability, are found in DNA vaccines.MethodsIn this study, the plasmids expressing bovine herpesvirus 1 (BoHV-1) gB, gC, and gD proteins were mixed at the same mass ratio and adsorbed polyethyleneimine (PEI) magnetic beads with a diameter of 50 nm. Further, the plasmid and PEI magnetic bead polymers were packaged into double carboxyl polyethylene glycol (PEG) 600 to use as a DNA vaccine. The prepared DNA vaccine was employed to vaccinate mice via the intranasal route. The immune responses were evaluated in mice after vaccination.ResultsThe expression of viral proteins could be largely detected in the lung and rarely in the spleen of mice subjected to a vaccination. The examination of biochemical indicators, anal temperature, and histology indicated that the DNA vaccine was safe in vivo. However, short-time toxicity was observed. The total antibody detected with ELISA in vaccinated mice showed a higher level than PBS, DNA, PEI + DNA, and PBS groups. The antibody level was significantly elevated at the 15th week and started to decrease since the 17th week. The neutralizing antibody titer was significantly higher in DNA vaccine than naked DNA vaccinated animals. The total IgA level was much greater in the DNA vaccine group compared to other component vaccinated groups. The examination of cellular cytokines and the percentage of CD4/CD8 indicated that the prepared DNA vaccine induced a strong cellular immunity.ConclusionThe mixed application of plasmids expressing BoHV-1 gB/gC/gD proteins by nano-carrier through intranasal route could effectively activate long-term humoral, cellular, and mucosal immune responses at high levels in mice. These data indicate PEI magnetic beads combining with PEG600 are an efficient vector for plasmid DNA to deliver intranasally as a DNA vaccine candidate.

Gonad Development and Blood Profile of Anti-KHV DNA Vaccinated Common Carp

Koi herpesvirus (KHV) is one of pathogen that infect common carp. Alternative to prevent KHV infection is vaccination. This study aimed to observe gonad development and blood profile on the common carp was vaccinated DNA anti-KHV GP25. Vaccination was conducted on common carp broodstock at 60 days before spawning. Blood collection for profile analysis was 15 days before pre-vaccination and 30, 45, 60 days post-vaccination. Egg diameter was observed during vaccination and, when spawning was performed. Gonad somatic index was measured in spawning time. Fish were injected phosphate buffer saline as control. Three fish were used for each treatments. The results showed that development of gonads were abdomen still hard, not rounded and the genital papilla was still closed. While spawning time that were abdomen appears rounded, enlarge and soft, papilla genital expands, anal was protrudes and widened. The gonad somatic index in broodstock vaccinated was 13.75±1.57% and broodstock control was 12.15±0.65%. Egg diameters were 0.57±0.06 – 0.97±013 mm at vaccination and 1.47±0.23 – 1.53±0.12 mm at spawning. Erythrocyte was decreased significantly on 30 days post-vaccination ie 1.05±0.34 (x106 cells / mm3). Hemoglobin was decreased on the 45 days ie 5.84±0.72 g/dL and hematocrite was decreased on 30 days ie 41.48±10.90% post-vaccination. This study showed that anti-KHV GP25 DNA vaccine could reduce erythrocytes, hemoglobin and hematocrite but not affected in gonad development of common carp.

The Immunogenicity And Protective Efficacy Of Dna Vaccine Coding For Na1 Gene Of Highly Pathogenic Avian Influenza H5n1 Subtype

Control of avian influenza infection depends mainly on biosafety measures and vaccination, DNA vaccination is a novel method to generate antigen-specific antibody and cell-mediated immunity. In the current study, a DNA vaccine for a full-length N1 gene was developed in a trial to decrease the severity of the avian influenza virus spread and shedding. THE full-length N1 gene was cloned in entry clone p ENTER SD/TOPO, followed by homologous recombination with the destination mammalian expression vector (PDEST 40). The PDEST 40-N1 was used in the immunization of SPF chickens. Potency was evaluated through the survival rate that reaches 65%, which was far less than the commercially available inactivated vaccine. Meanwhile, the shedding of the virus from dead birds was 0.46 Log 10 EID50. At the same time, the most surprising result was the shedding level of the vaccinated live birds that were zero sheddings;on the other hand, the inactivated vaccine could not reduce the shedding level which remains very high (3.2 Log 10 EID50 ). IFN-γ transcript level in the DNA vaccinated group was detected by the 3rd-day post-vaccination and remained upregulated till the 28th post-vaccination. After the challenge, the level of IFN-γ was much higher until 14 days post-challenge. The inactivated vaccine could not stimulate any detectable level post-vaccination. These data suggested the ability of DNA vaccine coding for N1 gene of avian influenza to combat the virus shedding from live birds and could be used in combination with DNA vaccine coding for H5 to produce maximum protection with zero sheddings.

DNA vaccination using recombinant Schistosoma mansoni fatty acid binding protein (smFABP) gene

Schistosomiasis is a fatal disease that has a negative impact on health and economics. Praziquantel (PZQ) is the drug of choice for schistosomiasis treatment, but it has no prophylactic effect; therefore, vaccination is an essential requirement in schistosomiasis control. This work was carried out to investigate the possible effect of DNA vaccination against Schistosoma mansoni infection using recombinant S. mansoni fatty acid binding protein (rsmFABP). The smFABP gene was cloned into the eukaryotic expression vector pcDNAI/Amp in order to obtain an smFABP-pcDNAI recombinant plasmid (DNA vaccine) and was used for the intramuscular DNA vaccination of out-bread Swiss albino mice prior to infection with S. mansoni cercariae. Infected groups, either DNA vaccinated or unvaccinated, were treated with PZQ at week 6 post-infection. After 8 weeks post-infection, all mouse groups were sacrificed and parasitological, immunological and histopathological parameters were studied. DNA vaccinated mice showed a high titer of anti-smFABP-IgG antibodies and acquired significant protection (74.2%, p < 0.01) against S. mansoni infection, with a reduction in ova and granuloma counts. DNA vaccinated and PZQ treated animals had higher titers of anti-smFABP-IgG antibodies and decreased (87%, P < 0.001) parenchymal granulomas compared to the DNA vaccinated PZQ untreated group. Infected mice, either non DNA vaccinated or vaccinated, had very high collagen content and fibrous granulomas (74%) compared to the PZQ treated group (10.3% fibrous granuloma) and PZQ treated + DNA vaccinated group (0% fibrous granuloma). In conclusion, DNA vaccination had protective and anti-pathological effects in naive mice and greatly improved the pathological status in PZQ-treated animals, suggesting an immunological and pathological modulating effect of PZQ treatment.

Gag and env conserved element CE DNA vaccines elicit broad cytotoxic T cell responses targeting subdominant epitopes of HIV and SIV Able to recognize virus-infected cells in macaques

ABSTRACTHIV sequence diversity and the propensity of eliciting immunodominant responses targeting inessential variable regions are hurdles in the development of an effective AIDS vaccine. We developed a DNA vaccine comprising conserved elements (CE) of SIV p27Gag and HIV-1 Env and found that priming vaccination with CE DNA is critical to efficiently overcome the dominance imposed by Gag and Env variable regions. Here, we show that DNA vaccinated macaques receiving the CE prime/CE+full-length DNA co-delivery booster vaccine regimens developed broad, potent and durable cytotoxic T cell responses targeting conserved protein segments of SIV Gag and HIV Env. Gag CE-specific T cells showed robust anamnestic responses upon infection with SIVmac239 which led to the identification of CE-specific cytotoxic lymphocytes able to recognize epitopes covering distinct CE on the surface of SIV infected cells in vivo. Though not controlling infection overall, we found an inverse correlation between Gag CE-specific CD8+ T cell responses and peak viremia. The T cell responses induced by the HIV Env CE immunogen were recalled in some animals upon SIV infection, leading to the identification of two cross-reactive epitopes between HIV and SIV Env based in sequence homology. These data demonstrate that a vaccine combining Gag and Env CE DNA subverted the normal immunodominance patterns, eliciting immune responses that included subdominant, highly conserved epitopes. These vaccine regimens augment cytotoxic T cell responses to highly conserved epitopes in the viral proteome and maximize response breadth. The vaccine-induced CE-specific T cells were expanded upon SIV infection, indicating that the predicted CE epitopes incorporated in the DNA vaccine are processed and exposed by infected cells in their natural context within the viral proteome.

DNA vaccination for finfish aquaculture

In fish, DNA vaccines have been shown to give very high protection in experimental facilities against a number of viral diseases, particularly diseases caused by rhabdoviruses. However, their efficacy in generating protection against other families of fish viral pathogens is less clear. One DNA vaccine is currently in use commercially in fish farms in Canada and the commercialisation of another was authorised in Europe in 2017. The mechanism of action of DNA vaccines, including the role of the innate immune responses induced shortly after DNA vaccination in the activation of the adaptive immunity providing longer term specific protection, is still not fully understood. In Europe the procedure for the commercialisation of a veterinary DNA vaccine requires the resolution of certain concerns particularly about safety for the host vaccinated fish, the consumer and the environment. Relating to consumer acceptance and particularly environmental safety, a key question is whether a DNA vaccinated fish is considered a Genetically Modified Organism (GMO). In the present opinion paper these key aspects relating to the mechanisms of action, and to the development and the use of DNA vaccines in farmed fish are reviewed and discussed.

DNA vaccine encoding myristoylated membrane protein (MMP) of rock bream iridovirus (RBIV) induces protective immunity in rock bream (Oplegnathus fasciatus)

Rock bream iridovirus (RBIV) causes severe mass mortalities in rock bream (Oplegnathus fasciatus) in Korea. In this study, we investigated the potential of viral membrane protein to induce antiviral status protecting rock bream against RBIV infection. We found that fish administered with ORF008L (myristoylated membrane protein, MMP) vaccine exhibited significantly higher levels of survival compared to ORF007L (major capsid protein, MCP). Moreover, ORF008L-based DNA vaccinated fish showed significant protection at 4 and 8 weeks post vaccination (wpv) than non-vaccinated fish after infected with RBIV (6.7 × 105) at 23 °C, with relative percent survival (RPS) of 73.36% and 46.72%, respectively. All of the survivors from the first RBIV infection were strongly protected (100% RPS) from re-infected with RBIV (1.1 × 107) at 100 dpi. In addition, the MMP (ORF008L)-based DNA vaccine significantly induced the gene expression of TLR3 (14.2-fold), MyD88 (11.6-fold), Mx (84.7-fold), ISG15 (8.7-fold), PKR (25.6-fold), MHC class I (13.3-fold), Fas (6.7-fold), Fas ligand (6.7-fold), caspase9 (17.0-fold) and caspase3 (15.3-fold) at 7 days post vaccination in the muscle (vaccine injection site). Our results showed the induction of immune responses and suggest the possibility of developing preventive measures against RBIV using myristoylated membrane protein-based DNA vaccine.

Effect of DNA Vaccination with Retroviral Vector Expressing nfa1 Gene in Naegleria fowleri Infection

Naegleria fowleri is pathogenic free-living amoeba leading to primary amoebic meningoencephalitis(PAM) in human and animals. The nfa1 gene cloned from N. fowleri is located on food-cup structure called pseudopodia and function an adherence of host target cells. To evaluate the effect of nfa1 vaccination against N. fowleri infection, we constructed retroviral vector(pQCXIN) expressing nfa1 gene. To determine the effect of vaccination and protective immunity in in vivo models, we measured the immunoglobulin levels, cytokine induction, and survival rate in mice infected with N. fowleri. Both levels of IgG and IgG subclass in DNA vaccinated mice were significantly elevated. The cytokine analysis show that DNA vaccinated mice induces production of IL-4 and IFN-γcytokines suggesting a Th1/Th2 mixed type immune response. The levels of nfa1 specific IgG antibody were maintained highly until 12 weeks post-vaccination in vaccinted mice. The nfa1 vaccinated mice using retroviral vector increased significantly survival rate(60%) after N. fowleri infection. Consequently, the nfa1 vaccination effectively induces protective immunity by upregulation of immune response in mice infected with N. fowleri. These results suggest that DNA vaccination using retroviral vector may be proper trial for treatment and prevention of PAM.

Transcription of adaptive-immune genes upon challenge with infectious pancreatic necrosis virus (IPNV) in DNA vaccinated rainbow trout

In the present study, rainbow trout weighting 3±0.3 g were vaccinated with an oral DNA vaccine encoding VP2 gene of a prevalent isolate of IPNV in Iranian trout farms encapsulated in sodium alginate microspheres and Chitosan tripolyphosphate (CS/TPP) nanoparticles. The vaccinated fish were then challenged with a virulent isolate of IPNV at 30 days post-vaccination. The transcriptional changes of adaptive- immune genes (IgM and IgT), as well as the VP4 gene of IPNV, as an indicators of viral replication were studied 45 days post-challenge. Analysis of RT-qPCR data showed lower levels of VP4 gene expression in the oral DNA vaccinated trout after IPNV challenge compared with the control one. Moreover, the constructed DNA vaccine did not enhance the expression of IgM and IgT genes above the levels observed in the carrier control group but it showed a mimic of viral activity and contributes to maintaining them at appreciable levels in vaccinated group.

Immunogenicity and Therapeutic Effects of pVAX1-rv1419 DNA from Mycobacterium tuberculosis

Background The situation of tuberculosis (TB) is very severe in China. New therapeutic agents and regimens to treat TB are urgently needed. Objective In this study, a DNA vaccine expressing Mycobacterium tuberculosis (MTB) Rv1419 antigen was constructed and its immunogenicity and therapeutic effects were evaluated. Method Normal mice and TB model mice were immunized intramuscularly three times at two-week intervals with saline, plasmid vector pVAX1, M. vaccae vaccine, pVAX1- ag85a (rv3804c) DNA or pVAX1-rv1419 DNA, respectively. Results At three weeks after the last immunization, flow cytometry showed a higher proportion of CD4+ T cells expressing IFN-y (Th1) in response to Rv1419 protein in blood from the pVAX1- rv1419 DNA group compared with the saline and vector groups (P<0.05), suggesting a predominant Th1 immune response. Live bacterial loads in lungs and spleens were lower by 0.41 log10 in the pVAX1- rv1419 DNA group than in the saline controls. In addition, pathological changes in the lungs of the DNA vaccinated groups were less. These results suggest that pVAX1- rv1419 DNA could be effective for the treatment of TB, significantly increasing the Th1-type cellular immune response, and inhibiting the growth of MTB. Conclusion Therefore pVAX1- rv1419 DNA is a candidate for inclusion in a therapeutic combination DNA vaccine against TB.

Costimulatory Effects of an Immunodominant Parasite Antigen Paradoxically Prevent Induction of Optimal CD8 T Cell Protective Immunity.

Trypanosoma cruzi infection is controlled but not eliminated by host immunity. The T. cruzi trans-sialidase (TS) gene superfamily encodes immunodominant protective antigens, but expression of altered peptide ligands by different TS genes has been hypothesized to promote immunoevasion. We molecularly defined TS epitopes to determine their importance for protection versus parasite persistence. Peptide-pulsed dendritic cell vaccination experiments demonstrated that one pair of immunodominant CD4+ and CD8+ TS peptides alone can induce protective immunity (100% survival post-lethal parasite challenge). TS DNA vaccines have been shown by us (and others) to protect BALB/c mice against T. cruzi challenge. We generated a new TS vaccine in which the immunodominant TS CD8+ epitope MHC anchoring positions were mutated, rendering the mutant TS vaccine incapable of inducing immunity to the immunodominant CD8 epitope. Immunization of mice with wild type (WT) and mutant TS vaccines demonstrated that vaccines encoding enzymatically active protein and the immunodominant CD8+ T cell epitope enhance subdominant pathogen-specific CD8+ T cell responses. More specifically, CD8+ T cells from WT TS DNA vaccinated mice were responsive to 14 predicted CD8+ TS epitopes, while T cells from mutant TS DNA vaccinated mice were responsive to just one of these 14 predicted TS epitopes. Molecular and structural biology studies revealed that this novel costimulatory mechanism involves CD45 signaling triggered by enzymatically active TS. This enhancing effect on subdominant T cells negatively regulates protective immunity. Using peptide-pulsed DC vaccination experiments, we have shown that vaccines inducing both immunodominant and subdominant epitope responses were significantly less protective than vaccines inducing only immunodominant-specific responses. These results have important implications for T. cruzi vaccine development. Of broader significance, we demonstrate that increasing breadth of T cell epitope responses induced by vaccination is not always advantageous for host immunity.

Canine distemper virus DNA vaccination of mink can overcome interference by maternal antibodies

Canine distemper virus (CDV) is highly contagious and can cause severe disease against which conventional live vaccines are ineffective in the presence of maternal antibodies. Vaccination in the presences of maternal antibodies was challenged by vaccination of 5 days old and 3 weeks old mink kits with CDV DNA vaccines. Virus neutralising (VN) antibody responses were induced in mink kits vaccinated with a plasmid encoding the haemaglutinin protein (H) of CDV (n=5, pCDV-H) or a combination of the H, fusion (F) and nucleoprotein (N) of CDV (n=5, pCDV-HFN). These DNA vaccinated kits were protected against virulent experimental infection with field strains of CDV. The pCDV-H was more efficient in inducing protective immunity in the presence of maternal antibodies compared to the pCDV-HFN. The results show that DNA vaccination with the pCDV-H or pCDV-HFN (n=4) only given once at 5 days of age induces virus specific immune response in neonatal mink and protection against virulent CDV exposure later in life.

Alpha-galactosylceramide enhances protective immunity induced by DNA vaccine of the SAG5D gene of Toxoplasma gondii.

BackgroundToxoplasmosis caused by the intracellular parasite Toxoplasma gondii (T. gondii) is a global epidemic parasitic disease. DNA vaccines play an important role in preventing the spread of toxoplasmosis. SAG family genes encoding particular surface proteins of T. gondii are the best candidates of DNA vaccine. As a member of SAG family genes, SAG5 gene has been proved to have better antigenic than SAG1. In addition, alpha-Galactosylceramide (α-GalCer) was used to be an adjuvant in malaria vaccine and received positive results. In this study, the effect of the DNA vaccine enhanced by α-GalCer was evaluated by immunizing BALB/c mice.MethodsIn the present study, SAG5D gene of T. gondii was cloned, sequenced, and biologically characterized. BALB/c mice were randomly divided into five groups, including three experimental groups (pEGFP-C1-SAG5D, α-GalCer and α-GalCer/pEGFP-C1-SAG5D) and two control groups (PBS and pEGFP-C1), and were immunized intramuscularly three times. The levels of IgG antibodies and cytokine productions in mouse sera were determined by enzyme-linked immunosorbent assays (ELISA). Two weeks after the last immunization, all mice were challenged intraperitoneally with 1 × 104 tachyzoites of T. gondii and the survival time of mice was recorded.ResultsA significant level of increase of IgG response against the soluble tachyzoite antigens (STAg) was detected by ELISA in experimental group. It revealed relatively high level of IFN-γ production by the spleen cells. There were higher productions of interleukin-4 (IL-4) in α-GalCer treated groups compared to control groups. Challenge experiment showed a longer survival period (11 days compared with 5 days in control) in SAG5D DNA vaccinated mice was found after a lethal challenge with T. gondii RH strain.ConclusionsThe present study suggested that T. gondii SAG5D was a novel and positive DNA vaccine candidate against toxoplasmosis. In addition, the adjuvant (α-GalCer) enhanced the body’s cellular immune response and prolonged the survival time of mice after challenge.Electronic supplementary materialThe online version of this article (doi:10.1186/s12879-014-0706-x) contains supplementary material, which is available to authorized users.

Vaccines against human HER2 prevent mammary carcinoma in mice transgenic for human HER2

IntroductionThe availability of mice transgenic for the human HER2 gene (huHER2) and prone to the development of HER2-driven mammary carcinogenesis (referred to as FVB-huHER2 mice) prompted us to study active immunopreventive strategies targeting the human HER2 molecule in a tolerant host.MethodsFVB-huHER2 mice were vaccinated with either IL-12-adjuvanted human HER2-positive cancer cells or DNA vaccine carrying chimeric human-rat HER2 sequences. Onset and number of mammary tumors were recorded to evaluate vaccine potency. Mice sera were collected and passively transferred to xenograft-bearing mice to assess their antitumor efficacy.ResultsBoth cell and DNA vaccines significantly delayed tumor onset, leading to about 65% tumor-free mice at 70 weeks, whereas mock-vaccinated FVB-huHER2 controls developed mammary tumors at a median age of 45 weeks. In the DNA vaccinated group, 65% of mice were still tumor-free at about 90 weeks of age. The number of mammary tumors per mouse was also significantly reduced in vaccinated mice. Vaccines broke the immunological tolerance to the huHER2 transgene, inducing both humoral and cytokine responses. The DNA vaccine mainly induced a high and sustained level of anti-huHER2 antibodies, the cell vaccine also elicited interferon (IFN)-γ production. Sera of DNA-vaccinated mice transferred to xenograft-carrying mice significantly inhibited the growth of human HER2-positive cancer cells.ConclusionsAnti-huHER2 antibodies elicited in the tolerant host exert antitumor activity.

DNA vaccination against a fish rhabdovirus promotes an early chemokine-related recruitment of B cells to the muscle

In fish, intramuscular (i.m) injection of plasmid DNA encoding viral proteins has proved a highly effective vaccination strategy against some viral pathogens. The efficacy of DNA vaccination in teleost fish is based on the high level of viral antigen expression in muscle cells inducing a strong and long-lasting protection. However, the mechanisms through which this protection is established and effectuated in fish are still not fully understood. Moreover, similarities to mammalian models cannot be established since DNA vaccination in mammals usually induces much weaker responses. In this work, we have focused on the characterization of the immune cells that infiltrate the muscle at the site of DNA injection in vaccinated fish and the chemokines and chemokine receptors that may be involved in their infiltration. We have demonstrated through diverse techniques that B lymphocytes, both IgM+ and IgT+ cells, represented a major infiltrating cell type in fish vaccinated with a viral haemorrhagic septicaemia virus (VHSV) glycoprotein-encoding DNA vaccine, whereas in control fish injected with an oil adjuvant mainly granulocyte/monocyte-type cells were attracted. Among twelve chemokine genes studied, only CXCL11_L1, CK5B and CK6 mRNA levels were up-regulated in DNA vaccinated fish compared to fish injected with the corresponding vector backbone. Furthermore, the transcription of CXCR3B, a possible receptor for CXCL11_L1 was also significantly up-regulated in vaccinated fish. Finally, experiments performed with recombinant trout CK5B and CK6 and chemokine expression plasmids revealed that these chemokines have chemotactic capacities which might explain the recruitment of B cells to the site of DNA injection. Altogether, our results reveal that there is an early chemokine-related B cell recruitment triggered by i.m. DNA vaccination against VHSV which might play an important role in the initial phase of the immune response.

An adult zebrafish model for preclinical tuberculosis vaccine development

Tuberculosis remains a major global health challenge despite extensive vaccination schemes with the current live vaccine, Bacillus Calmette–Guérin. Tuberculosis vaccine research has been hampered by a scarcity of animal models which replicate human disease and are suitable for large-scale studies. We have shown recently that Mycobacterium marinum, a close relative of Mycobacterium tuberculosis, causes an infection resembling human tuberculosis in adult zebrafish (Danio rerio). In the present study we use this model to show that BCG vaccination as well as DNA vaccination with selected mycobacterial antigens (Ag85B, CFP-10 and ESAT-6) protects adult zebrafish from mycobacterial infection. Using a low-dose (∼20–30 bacteria) intraperitoneal M. marinum infection, both the number of granulomas and the amount of infected organs were reduced in the DNA vaccinated fish. Likewise, when infecting with a lethal infection dose (∼20,000–27,000 bacteria), vaccination significantly reduced both mortality and bacterial counts in a manner dependent on the adaptive immune response. Protective effects of vaccination were associated with enhanced expression of interferon gamma. Our results indicate that the zebrafish is a promising new model for preclinical tuberculosis vaccine research.

Optimization of HIV-1 Envelope DNA Vaccine Candidates within Three Different Animal Models, Guinea Pigs, Rabbits and Cynomolgus Macaques.

HIV-1 DNA vaccines have many advantageous features. Evaluation of HIV-1 vaccine candidates often starts in small animal models before macaque and human trials. Here, we selected and optimized DNA vaccine candidates through systematic testing in rabbits for the induction of broadly neutralizing antibodies (bNAb). We compared three different animal models: guinea pigs, rabbits and cynomolgus macaques. Envelope genes from the prototype isolate HIV-1 Bx08 and two elite neutralizers were included. Codon-optimized genes, encoded secreted gp140 or membrane bound gp150, were modified for expression of stabilized soluble trimer gene products, and delivered individually or mixed. Specific IgG after repeated i.d. inoculations with electroporation confirmed in vivo expression and immunogenicity. Evaluations of rabbits and guinea pigs displayed similar results. The superior DNA construct in rabbits was a trivalent mix of non-modified codon-optimized gp140 envelope genes. Despite NAb responses with some potency and breadth in guinea pigs and rabbits, the DNA vaccinated macaques displayed less bNAb activity. It was concluded that a trivalent mix of non-modified gp140 genes from rationally selected clinical isolates was, in this study, the best option to induce high and broad NAb in the rabbit model, but this optimization does not directly translate into similar responses in cynomolgus macaques.