Deoxyribonucleic Acid Vaccine Research Articles

A Review of Clinical Trials of Cancer and Its Treatment as a Vaccine.

Cancer and infectious diseases are one of the greatest challenges of modern medicine. An unhealthy lifestyle, poor drug use, or drug misuse contribute to the rise in morbidity and mortality brought on by these illnesses. The inadequacies of the medications now being used to treat these disorders, along with the growing issue of drug resistance, have compelled researchers to look for novel compounds with therapeutic promise. The number of infections and diseases has significantly abated due to vaccine development and use over time, which is described in detail. Several novel vaccines can now be produced by manipulating Deoxyribonucleic acid (DNA), Ribonucleic acid (RNA), Messenger Ribonucleic acid (mRNA), proteins, viral vector Recombinant, and other molecules due to advances in genetic engineering and our understanding of the immune defense. The main topic of discussion is cancer-based vaccinations, which were developed less than a decade ago but have already been used to treat a wide range of both life-threatening and deadly diseases. It contains clinical studies for cancer vaccines against kidney, liver, prostate, cervix, and certain RNA-based cancer vaccines against breast and bladder cancer. Numerous studies using various DNA and RNA-based methods have been conducted on the basis of cancer, with 9-10 diseases related to DNA and 8-9 diseases associated with RNA. Some of these studies have been completed, while others have been eliminated due to a lack of research; further studies are ongoing regarding the same. This brief discussion of vaccines and their varieties with examples also discusses vaccine clinical trials in relation to cancer diseases in this DNA and RNA-based cancer vaccine that has had successful clinical trials like the cervical cancer drug VGX-3100, the kidney cancer drug Pembrolizumab, MGN-1601, the prostate cancer drug pTVG-HP with rhGM-CSF, the melanoma cancer drug proteasome siRNA, and the lung cancer drug FRAME-001.

Coronavirus disease 2019 vaccines: challenges of using global mass vaccination to achieve herd immunity.

Coronavirus disease 2019 vaccines: challenges of using global mass vaccination to achieve herd immunity.

Protection of SARS-CoV-2 trial vaccines in human is a functnion of the viral genomes

Abstract Objectives Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has devastated mankind with complaints that many vaccines developed against the disease could not offer protection and guarantee safety, hence many vaccinated individuals either came down with the infection and died or transmitted the infection. Therefore permanent immunization may become difficult due to interplay between the viral and human genomes. Methods In view of this, literatures were searched on the trial vaccines against SARS-CoV-2.Concentration log10 (copies/ml) of the virus, log10 viral copies, populations of human vaccinated, protection indices of the vaccines, population of Tcells, lethal concentration 1 (LC1) of the virus, doses of the trial vaccines and vaccine regimens of the SARS-CoV-2 obtained from membrane ribonucleic acid (MRNA), replication defective viral vector (RDVV), inactivated pathogen vaccine (IPV), and protein subunit vaccine (PSV),virus like particle (VLP) and deoxyribonucleic acid vaccine (DNAV) were used with an intent to assessing the pathogenicity and virulence of the vaccines. Key findings Findings have shown that virion of 3.3 x10 8-9 could kill human over a period of ≥20 days, and 10 9-11virions have killed three in every 100 humans. However, viral load of detection (3.22 x 10 3), positivity threshold (3.3 x 10 3) and index patient value (6.6 x 10 6) respectively have been established. The protection index is between 11-99%. Conclusion The viral load of coronavirus found in the affected patients was relatively high and could be fatal. However DNAV based vaccine (2 mg) administered twice 4 weeks apart provided the best protection index that lasted for 40 – 60.

Th1 and Th2 epitopes of Cowdria polymorphic gene 1 of Ehrlichia ruminantium.

Cowdriapolymorphic gene 1 (cpg1, Erum2510, ERUM_RS01380) has been shown to induce 30% and 100% protection in sheep immunised by deoxyribonucleic acid (DNA) prime combined with DNA boost and DNA prime combined with protein boost, respectively, against heartwater infection via needle challenge. To localise its antigenic regions for inclusion in a multi-epitope DNA vaccine against heartwater, Erum2510 was cleaved into five overlapping subfragments. These subfragments were expressed individually in anEscherichia colihost expression system and evaluated for their ability to induce proliferative responses, Th1 and Th2 cytokines (interferon gamma [IFN-γ] and interleukin 4 [IL-4]) via enzyme-linked immunospot (ELISpot), quantitative real time polymerase chain reaction (qRT-PCR) and flow cytometry. Recombinant (r)proteins 3 and 4 were shown to induce immunodominant Th1 and Th2 immune responses characterised by the secretion of effector cytokines IFN-γ and IL-4 in addition to differential messenger ribonucleic acid (mRNA) expression of tumour necrosis factor (TNF), IL-2, IL-1, IL-18, IL-10, transforming growth factor (TGF), granulocyte-macrophage colony-stimulating factor (GM-CSF) and inducible nitric oxide synthase (iNOS). Thirty-seven overlapping synthetic peptides (16 mer) spanning the lengths of these immunodominantrproteins were synthesised and assayed. A peptide pool comprising p9 and p10 derived fromrprotein 3 induced a Th1-biased immune response. A peptide pool comprising p28 and p29 derived from rprotein 4 induced a mixed Th1 and Th2 immune response characterised by secretion of IFN-γ and differential mRNA expression of IL-1, IL-2, IL-10, IL-12, iNOS, TGF, TNF and GM-CSF. Only one of the peptides (p29) induced secretion of IL-4. Phenotypic analysis showed significant activation of cluster of differentiation 8+ (CD8+), cluster of differentiation 4+ (CD4+) and B+ lymphocyte populations. Findings suggest that Erum2510rproteins and synthetic peptides can induce both cellular and humoral immune responses, thereby implicating their importance in protection against heartwater.Contribution:This study will facilitate the design of an effective multi-epitope DNA vaccine against heartwater that will contribute to control this economically important disease in sub-Saharan Africa and beyond.

Diagnosis and control of cryptosporidiosis in farm animals.

Cryptosporidium is a pathogenic protozoan parasite infecting the gastrointestinal epithelium of human and animal hosts. In farm animals, cryptosporidiosis causes significant economic losses including deaths in newborn animals, retarded growth, increased labor involved and high cost of drugs. The detection of Cryptosporidium oocysts in fecal samples is traditionally dependent on examination of stained slides by light microscope or by advanced microscopical tools such as: electron microscopy and phase contrast microscopy. Immunological diagnosis using either antibody or antigen detection could offer high sensitivity and specificity. Examples for these tests are Enzyme Linked Immunosorbent Assay (ELISA), Immunochromatographic tests, Immunochromatographic lateral flow (ICLF), Immunofluorescence assays (IFA) and Flow cytometry coupled with cell sorting. Molecular methods could differentiate species and genotypes of Cryptosporidium and help in studying the epidemiological features of this parasite with rapid, simple and sensitive procedures. Nanotechnology-based platforms could improve the sensitivity and specificity of other detection methods like: ELISA, ICLF, IFA and polymerase chain reaction. As the available prophylactic and therapeutic drugs or natural products treatments are insufficient and no approved vaccines are available, the best approach to control this parasite is by following firm hygienic measures. Many vaccine attempts were performed using hyperimmune colostrum, live or attenuated vaccines, recombinant and Deoxyribonucleic acid vaccines. Also, Clustered Regularly Interspaced Short Palindromic Repeats/Cas9 technology could help in Cryptosporidium genome editing to improve drug and vaccine discovery. Another approach that could be useful for assigning drug targets is metabolomics. Probiotics were also used successfully in the treatment of acute diarrhea and they proved a limiting effect on cryptosporidiosis in animal models. In addition, nanotherapy-based approaches could provide a good strategy for improving the potency of any type of drugs against Cryptosporidium and give good anti-cryptosporidial effects. In conclusion, accurate diagnosis using advanced techniques is the key to the control and prevention of cryptosporidiosis.

An Outline of Contributing Vaccine Technologies for SARS CoV2 Advancing in Clinical and Preclinical Phase-Trials.

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS CoV2) is an RNA virus involving 4 structural and 16 non-structural proteins, and exhibiting high transmission potential and fatality. The emergence of this newly encountered beta coronavirus-SARS CoV2 has brought over 2 million people to death, and more than 10 billion people got infected across the globe as yet. Consequently, the global scientific community has contributed to the synthesis and design of effective immunization technologies to combat this virus. This literature review was intended to gather an update on published reports of the vaccines advancing in the clinical trial phases or preclinical trials, to summarize the foundations and implications of contributing vaccine candidates inferring their impact in the pandemic repression. In addition, this literature review distinctly facilitates an outline of the overall vaccine effectiveness at current doses. The reported data in this review was extracted from research articles, review articles and patents published from January 2020 to July 2021, available on Google Scholar, Pubmed, Pubmed Central, Research Gate, Science direct, and Free Patent Online Database by using combination of keywords. Moreover, some information is retrieved from native web pages of vaccine manufacturing companies' due to progressing research and unavailability of published research papers. Contributing vaccine technologies include: RNA (Ribonucleic acid) vaccines, DNA (Deoxyribonucleic acid) vaccines, viral vector vaccines, protein-based vaccines, inactivated vaccines, viruses-like particles, protein superglue, and live-attenuated vaccines. Some vaccines are prepared by establishing bacterial and yeast cell lines and as self-assembling adenovirus- derived multimeric protein-based self-assembling nanoparticle (ADDOmer). On May 19, WHO has issued an emergency use sanction of Moderna, Pfizer, Sinopharm, AstraZeneca, and Covishield vaccine candidates on account of clinical credibility from experimental data.

The Efficacy of Therapeutic DNA Vaccines Expressing the Human Papillomavirus E6 and E7 Oncoproteins for Treatment of Cervical Cancer: Systematic Review.

Cervical cancer is recognized as a serious public health problem since it remains one of the most common cancers with a high mortality rate among women despite existing preventative, screening, and treatment approaches. Since Human Papillomavirus (HPV) was recognized as the causative agent, the preventative HPV vaccines have made great progress over the last few years. However, people already infected with the virus require an effective treatment that would ensure long-term survival and a cure. Currently, clinical trials investigating HPV therapeutic vaccines show a promising vaccine-induced T-cell mediated immune response, resulting in cervical lesion regression and viral eradication. Among existing vaccine types (live vector, protein-based, nucleic acid-based, etc.), deoxyribonucleic acid (DNA) therapeutic vaccines are the focus of the study, since they are safe, cost-efficient, thermostable, easily produced in high purity and distributed. The aim of this study is to assess and compare existing DNA therapeutic vaccines in phase I and II trials, expressing HPV E6 and E7 oncoproteins for the prospective treatment of cervical cancer based on clinical efficacy, immunogenicity, viral clearance, and side effects. Five different DNA therapeutic vaccines (GX-188E, VGX-3100, pNGVL4a-CRT/E7(detox), pNGVL4a-Sig/E7(detox)/HSP70, MEDI0457) were well-tolerated and clinically effective. Clinical implementation of DNA therapeutic vaccines into treatment regimen as a sole approach or in combination with conservative treatment holds great potential for effective cancer treatment.

Limited Flavivirus Cross-Reactive Antibody Responses Elicited by a Zika Virus Deoxyribonucleic Acid Vaccine Candidate in Humans.

Zika virus (ZIKV) deoxyribonucleic acid vaccine VRC5283 encoding viral structural genes has been shown to be immunogenic in humans. Recognizing that antigenically related flaviviruses cocirculate in regions with ZIKV activity, we explored the degree of antibody cross-reactivity elicited by this vaccine candidate using genetically diverse flaviviruses. The antibody response of vaccinated individuals with no evidence of prior flavivirus infection or vaccine experience had a limited capacity to bind heterologous viruses. In contrast, vaccine-elicited antibodies from individuals with prior flavivirus experience had a greater capacity to bind, but not neutralize, distantly related flaviviruses. These findings suggest that prior flavivirus exposure shapes the humoral immune response to vaccination.

DNA vaccines and recombinant allergens with reduced allergenic activity treat allergies

This review is intended to familiarize readers with major novel directions of developing allergy vaccines, their structure, as well as the mechanisms of forming a new immunological response in the course of the treating immunoglobulin E (IgE)-mediated allergic diseases. Currently, science offers a huge variety of new experimental forms of recombinant allergens with reduced allergenic activity and increased immunogenicity, or vice-versa, immune tolerance. Often, the mechanisms of their effect on the immune system are not fully understood. Scientific publications, including reviews covering this topic, allowed us identifying top priority areas in the development of allergy vaccines: recombinant hypoallergenic allergen derivatives, T cell epitope-based allergy vaccines, and B cell epitope-based allergy vaccines. In addition, the review discusses use of deoxyribonucleic acid (DNA) vaccines. Immunotherapy with DNA vaccines is the newest and least studied method of treating allergic diseases.

Enhanced Cancer DNA Vaccine via Direct Transfection to Host Dendritic Cells Recruited in Injectable Scaffolds.

Deoxyribonucleic acid (DNA) vaccines are a promising cancer immunotherapy approach. However, effective delivery of DNA to antigen-presenting cells (e.g., dendritic cells (DCs)) for the induction of an adaptive immune response is limited. Conventional DNA delivery via intramuscular, intradermal, and subcutaneous injection by hypodermal needles shows a low potency and immunogenicity. Here, we propose the enhanced cancer DNA vaccine by direct transfection to the high number of DCs recruited into the chemoattractant-loaded injectable mesoporous silica microrods (MSRs). Subcutaneous administration of the MSRs mixed with tumor-antigen coding DNA polyplexes resulted in DC recruitment in the macroporous space of the scaffold formed by the spontaneous assembly of high-aspect-ratio MSRs, thereby allowing for enhanced cellular uptake of antigen-coded DNA by host DCs. The MSR scaffolds delivering the DNA vaccine trigger a more robust DC activation, antigen-specific CD8+ T cell response, and Th1 immune response compared to the bolus DNA vaccine. Additionally, the immunological memory can be induced with a single administration of the vaccine. The combination of the vaccination and antiprogrammed cell death-1 antibody significantly eliminates established lung metastasis. These results indicate that MSRs serve as a powerful platform for DNA vaccine delivery to DCs for effective cancer immunotherapy.

A Novel DNA Vaccine Coding For H5 and N1 Genes of Highly Pathogenic Avian Influenza H5N1 Subtype

Control of avian influenza infection requires a good vaccine that could induce both humoral and cell-mediated immune response, specifically IFN-ɣ production, to maintain a high level of protection along with the minimal level of viral shedding after the infection to prevent secondary epidemics. In the current study, deoxyribonucleic Acid (DNA) vaccine coding for full-length H5 and N1 genes have been produced and evaluated in SPF-chicken. Humoral immune response estimated by haemagglutination inhibition (HI) assay revealed that the DNA vaccine gave a high titer of antibodies at the day 28-post vaccination and 14 days post-challenge. However, the shedding level was minimal with the DNA vaccine (0.1 Log 10 EID50). The IFN-ɣ transcript was upregulated at a higher level in the DNA vaccinated group. The results revealed that the DNA vaccine could induce a high level of humoral and IFN-ɣ level that maintains a high level of protection (92%) with the advantage of limiting the shedding level and thus, prevent secondary epidemics.

Immunogenicity of a plasmid DNA vaccine encoding G1 epitope of bovine ephemeral fever virus G glycoprotein in mice.

The aim of this study was to investigate the immunogenicity of a plasmid deoxyribonucleic acid (DNA) vaccine encoding the G1 epitope of bovine ephemeral fever virus (BEFV) G glycoprotein in mice. A plasmid DNA carrying the G1 gene was constructed and designated as pcDNA3.1-G1. The expression of the target gene was confirmed in human embryonic kidney 293 (HEK 293) cells transfected with pcDNA3.1-G1 by indirect immunofluorescent staining. Immunisation experiments were intramuscularly carried out by vaccinating 6-week-old female mice in four groups, including the pcDNA3.1-G1 construct, pcDNA3.1 (+) plasmid alone, BEF-inactivated vaccine and phosphate-buffered saline (PBS) (1X) three times with 2-week intervals. Fourteen days after the last immunisation, 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. Serological assays showed that the pcDNA3.1-G1 construct expressing G1 protein was able to elicit specific antibodies against this antigen. Virus neutralisation test showed that pcDNA3.1-G1 could induce anti-BEFV-neutralising antibodies in mice. Our findings indicated that a new dimension can be added to vaccine studies for bovine ephemeral fever (BEF) using eukaryotic expression plasmids encoding the G1 antigen in the future.

Evaluation of therapeutic potency of human papillomavirus-16 E7 DNA vaccine alone and with interleukin-18 as a genetic adjuvant

AIMS: Despite the existence of effective preventive vaccines for human papillomavirus (HPV), therapeutic vaccines that trigger cell-mediated immune responses are required to treat established infections and malignancies. The aim of this study was to evaluate the therapeutic potency of HPV-16 E7 deoxyribonucleic acid (DNA) vaccine alone and with interleukin (IL)-18. METHODS: In vitro expressions of IL-18 were performed on human embryonic kidney 293 cells and confirmed it by Western blotting methods. DNA vaccine was available from a previous study. A total of 45 female C57BL/6 mice divided into five groups (DNA vaccine, DNA vaccine adjuvanted with IL-18, pcDNA3.1, and phosphate buffer saline) were inoculated with murine tissue culture-1 cell line of HPV related carcinoma, expressing HPV-16 E6/E7 antigens. They were then immunized subcutaneously twice at a seven-day interval. The antitumor and antigen specific-cellular immunity were assessed by lymphocyte proliferation (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide: MTT) assay, lactate dehydrogenase release assay, IL-4 assay and interferon-gamma (IFN-γ) assay. Tumor size was followed for 62 days.RESULTS: MTT assay, which measures the lymphocyte proliferation in response to the specific antigen, increased in the co-administration and the DNA vaccine groups as compared to control and genetic adjuvant groups (p<0.001). The mice immunized with the co-administration generated significantly more IFN-γ and IL-4 than other immunized mice (p<0.001). Reduction of the tumor size in the co-administration and the DNA vaccine groups was significantly more pronounced than in the control and genetic adjuvant groups (p<0.001), but no statistically significant difference between DNA vaccine and co-administration groups (p=0.15) occurred.CONCLUSIONS: IL-18 as a genetic adjuvant and E7 DNA vaccine alone enhanced immune responses in mouse model systems against cervical cancer. However, using of IL-18 as a genetic adjuvant with E7 DNA vaccine had no significant synergistic effect on the immune responses in vivo.

The Genetic Adjuvants Interleukin-12 and Granulocyte-Macrophage Colony Stimulating Factor Enhance the Immunogenicity of an Ebola Virus Deoxyribonucleic Acid Vaccine in Mice.

In previous studies, we showed that deoxyribonucleic acid (DNA) vaccines expressing codon-optimized filovirus envelope glycoprotein genes protect mice and nonhuman primates from viral challenge when delivered by intramuscular (IM) electroporation (EP). To determine whether we could achieve equivalent immunogenicity and protective efficacy by a simplified delivery method, we generated DNA vaccine plasmids expressing genetic adjuvants to potentiate immune responses. We tested the Th1-inducing cytokine interleukin-12 and the granulocyte growth factor granulocyte-macrophage colony stimulating factor, both of which have demonstrated significant adjuvant effect when included in clinical DNA vaccine formulations. In addition, because interferon (IFN)-αβ is required for DNA vaccine-induced immunity, we tested inclusion of a potent stimulator of the IFN-αβ pathway. Our data suggest that IM vaccination of mice with plasmid DNA encoding genetic adjuvants enhances vaccine immunogenicity, resulting in increased anti-Ebola virus (EBOV) immunoglobulin G and T-cell responses. Codelivery of genetic adjuvants also improved EBOV neutralizing capability compared with vaccine alone. Finally, IM vaccination with plasmid EBOV and genetic adjuvants provided complete protection against EBOV challenge. Overall, our data suggest that codelivery of genetic adjuvants with filovirus DNA vaccines using IM delivery can provide comparable efficacy to the same DNA vaccines when delivered using IM-EP devices.

Antibody Repertoire of Human Polyclonal Antibodies Against Ebola Virus Glycoprotein Generated After Deoxyribonucleic Acid and Protein Vaccination of Transchromosomal Bovines.

Several Ebola vaccines and therapeutics are under clinical development. However, limited knowledge exists on the quality of antibody response generated by different Ebola vaccines. In this study, antibody repertoire induced by vaccination of transchromosomal bovine (TcB) with Ebola virus (EBOV) glycoprotein ([GP]; recombinant GP [rGP]) encoded by either deoxyribonucleic acid (DNA) or nanoparticle-based vaccine platform was analyzed using EBOV genome fragment phage display library and surface plasmon resonance (SPR)-based real-time kinetics assay to measure antibody affinity maturation to both native and partially denatured Ebola GP as well as GP containing the receptor binding domain but lacking the mucin-like domain. Immunoglobulin (IgG) obtained from rGP nanoparticle-vaccinated TcB demonstrated ~4-fold higher binding affinity compared with DNA-vaccinated TcB-induced IgG against the native rGP’s. The rGP nanoparticle vaccine generated a more robust and diverse antibody immune response to the native EBOV-GP compared with the DNA vaccine, which may explain the protective efficacy observed for these antibody preparations.

Evaluation of a Leishmania hypothetical protein administered as DNA vaccine or recombinant protein against Leishmania infantum infection and its immunogenicity in humans

Visceral leishmaniasis (VL) is a fatal disease when acute and untreated. The treatment against this disease is long and presents toxicity and/or high costs. Moreover, parasite resistance has been increasing. Therefore, alternative control measures to avoid the spread of disease should be considered. It is accepted that the development of the T helper (Th)1 immune response, based on the production of pro-inflammatory cytokines, is required for the control of parasites. Although recombinant protein-based vaccines have been tested against VL, they require supplementation with immune adjuvants. In addition, there is a scarcity of studies that comparatively evaluate the efficacy of the immunogens when administered by different delivery systems in mammalian hosts. In the present study, a Leishmania hypothetical protein, LiHyR, was cloned and evaluated by immunization as a plasmid deoxyribonucleic acid (DNA) vaccine or in a recombinant format plus saponin against Leishmania infantum infection. Results showed that both vaccination regimens induced a Th1 cell-based immunity, since high levels of interferon-gamma (IFN-γ), interleukin (IL)-2, IL-12, granulocyte-macrophage colony-stimulating factor (GM-CSF), and tumor necrosis factor alpha (TNF-α) were found, and were associated with the low production of IL-4, IL-10, and anti-parasite immunoglobulin (IgG)1 isotype. In addition, significant reductions in the parasite load were found in the evaluated organs of the DNA LiHyR or rLiHyR/saponin-vaccinated animals. No significant difference was achieved between groups vaccinated with DNA or the recombinant protein. The antigen proved to be also immunogenic in human peripheral blood mononuclear cells (PBMCs) collected from healthy subjects and from untreated and treated VL patients. A higher IgG2 isotype was also found in sera samples of these subjects, thus demonstrating its possible use as a human vaccine. This study demonstrates the protective efficacy of a new Leishmania protein against VL, when it is administered as a DNA vaccine or a recombinant protein plus saponin, and points out its use as a human vaccine against disease.

Induction of a robust immune response against avian influenza virus following transdermal inoculation with H5-DNA vaccine formulated in modified dendrimer-based delivery system in mouse model.

This study was aimed to evaluate the immunogenicity of recombinant plasmid deoxyribonucleic acid (DNA), pBud-H5-green fluorescent protein (GFP)-interferon-regulatory factor (IRF)3 following delivery using polyamidoamine (PAMAM) dendrimer and transactivator of transcription (TAT)-conjugated PAMAM dendrimer as well as the effect of IRF3 as the genetic adjuvant. BALB/c mice were vaccinated transdermally with pBud-H5-GFP, PAMAM/pBud-H5-GFP, TAT-PAMAM/pBud-H5-GFP, and TAT-PAMAM/pBud-H5-GFP-IRF3. The expression analysis of H5 gene from the blood by using quantitative real-time reverse transcriptase polymerase chain reaction confirmed the ability of PAMAM dendrimer as a carrier for gene delivery, as well as the ability of TAT peptide to enhance the delivery efficiency of PAMAM dendrimer. Mice immunized with modified PAMAM by TAT peptide showed higher hemagglutination inhibition titer, and larger CD3+/CD4+ T cells and CD3+/CD8+ T cells population, as well as the production of cytokines, namely, interferon (IFN)-γ, interleukin (IL)-2, IL-15, IL-12, IL-6, and tumor necrosis factor-α compared with those immunized with native PAMAM. These results suggest that the function of TAT peptide as a cell-penetrating peptide is able to enhance the gene delivery, which results in rapid distribution of H5 in the tissues of the immunized mice. Furthermore, pBud-H5-GFP co-expressing IRF3 as a genetic adjuvant demonstrated the highest hemagglutination inhibition titer besides larger CD3+/CD4+ and CD3+/CD8+ T cells population, and strong Th1-like cytokine responses among all the systems tested. In conclusion, TAT-PAMAM dendrimer-based delivery system with IRF3 as a genetic adjuvant is an attractive transdermal DNA vaccine delivery system utilized to evaluate the efficacy of the developed DNA vaccine in inducing protection during challenge with virulent H5N1 virus.

Evaluation of the Protective Effect of Deoxyribonucleic Acid Vaccines Encoding Granule Antigen 2 and 5 Against Acute Toxoplasmosis in BALB/c Mice.

AbstractToxoplasma gondii infects a broad range of warm-blooded hosts, including humans. Important clinical manifestations include encephalitis in immunocompromised patients as well as miscarriage and fetal damage during early pregnancy. Toxoplasma gondii dense granule antigen 2 and 5 (GRA2 and GRA5) are essential for parasitophorous vacuole development of the parasite. To evaluate the potential of GRA2 and GRA5 as recombinant DNA vaccine candidates, these antigens were cloned into eukaryotic expression vector (pcDNA 3.1C) and evaluated in vaccination experiments. Recombinant DNA vaccines constructed with genes encoding GRAs were validated in Chinese hamster ovary cells before evaluation using lethal challenge of the virulent T. gondii RH strain in BALB/c mice. The DNA vaccines of pcGRA2 and pcGRA5 elicited cellular-mediated immune response with significantly higher levels of interferon-gamma, interleukin-2 (IL-2), IL-4, and IL-10 (P < 0.05) compared with controls. A mixed T-helper cell 1 (Th1)/Th2 response was associated with slightly prolonged survival. These findings provide evidence that DNA vaccination with GRA2 and GRA5 is associated with Th1-like cell-mediated immune responses. It will be worthwhile to construct recombinant multiantigen combining full-length GRA2 or/and GRA5 with various antigenic proteins such as the surface antigens and rhoptry antigens to improve vaccination efficacy.

Cancer Vaccines: Past, Present, and Future.

Cancer is a common and potentially deadly disease. Some of the cancers may be difficult to treat by conventional means such as surgery, radiation, and chemotherapy, but may be controlled by the stimulation of the immune response of the body with the help of cancer vaccines. The use of vaccines for preventing infections by oncogenic viruses such as hepatitis B virus and human papilloma virus has been extremely successful in reducing the incidence of cancers resulting from these infections. The use of vaccines for treating cancers that are not due to viral infections and that are already established is currently the object of numerous clinical trials. Several types of cancer vaccines are being tried. These include antigen vaccines, tumor cell vaccines, dendritic vaccines, deoxyribonucleic acid vaccines, and viral vector vaccines. The development of these therapeutic vaccines is proving difficult with only 1 recent success. However, there is significant enthusiasm and optimism regarding the development of effective therapeutic vaccines stemming from the fact that our understanding regarding the cancer immunology is considerably enhanced in recent years. This expanded knowledge regarding the mechanisms that cancers use to escape the immune system is likely to open new avenues in modulating the immune response to cancer, thus enhancing the effectiveness of therapeutic cancer vaccines.

Wilms’ tumour antigen 1 Immunity via DNA fusion gene vaccination in haematological malignancies by intramuscular injection followed by intramuscular electroporation: a Phase II non-randomised clinical trial (WIN)

BackgroundIn the UK almost 7000 people are diagnosed with leukaemia each year, but despite continuing advances in diagnosis and treatment with new drugs, such as the tyrosine kinase inhibitors, the majority of these patients will eventually die from their disease. Until quite recently, the only treatment to offer the possibility of long-term disease-free survival was allogeneic stem cell transplantation. However, this carries a substantial risk of mortality and is available to only a minority of patients.ObjectivesThe aim of the study was to test the hypothesis that molecular and clinical responses, induced by T lymphocytes (T cells), can be predicted by increases in the number of CD8+ (cluster of differentiation 8-positive) T cells specific for the vaccine-encoded T-cell epitopes. This project also aimed to build on the established programme of deoxyribonucleic acid (DNA) fusion-gene vaccination delivered by intramuscular injection, exploiting a unique experience with electroporation, to induce durable immune responses with the aim of controlling disease by precision attack of the tumour by CD8+ T cells.MethodA non-randomised, open-label, single-dose-level Phase II clinical trial in two patient groups [chronic myeloid leukaemia (CML) and acute myeloid leukaemia (AML)] on stable doses of imatinib. Human leucocyte antigen A2-positive (HLA A2+) patients were vaccinated with two DNA vaccines: (1) p.DOM–WT1-37 (epitope sequence: VLDFAPPGA); and (2) p.DOM–WT1-126 (epitope sequence: RMFPNAPYL). The HLA A2-negative patients formed an unvaccinated control group. The sample size for the HLA A2+ group was originally determined following Simon’s optimal Phase II trial design (Simon R. Optimal two-stage designs for phase II clinical trials.Control Clin Trials1989;10:1–10). This was changed to A’Hern’s single-stage design during the course of the trial (A’Hern RP. Sample size tables for single-stage phase II designs.Stat Med2001;20:859–66), which was endorsed by the trial’s independent oversight committees.ResultsThe study included 12 patients with CML who were vaccinated and nine patients with CML who were unvaccinated as the control group. Both the vaccines and the electroporation were safe, with no new or unexpected toxicities. The evaluation adverse events of special interest (heart, bone marrow, renal) did not reveal safety concerns. TwoBCR–ABL(breakpoint cluster region–Abelson murine leukaemia viral oncogene homolog 1) responses were observed, both of which were defined as a major response, with one in each group. Two Wilms’ tumour antigen 1 (WT1) molecular responses were observed in the vaccinated group and one was observed in the control group. At an immunological level, the vaccine performed as expected.ConclusionsThe study met its primary decision-making target with one major molecular response inBCR–ABLtranscript levels. Overall, the data showed, in this clinical setting, the immunogenicity and safety of the vaccine.LimitationsThe study did not complete recruitment and there were multiple hurdles that contributed to this failure. This is disappointing given the robust induction immune responses againstWT1T-cell responses in 7 out of 10 evaluable patients.Future workEvaluation of the p.DOM–WT1 vaccines in AML remains attractive clinically, but it is unlikely to be feasible at this time. Combination of the DNA vaccine approach with strategies to expand T-cell responses with immunomodulatory antibodies is in development.Funding detailsThis project was funded by the Efficacy and Mechanism Evaluation (EME) programme, a Medical Research Council (MRC) and National Institute for Health Research (NIHR) partnership, and Bloodwise.