Preclinical evaluation of a candidate naked plasmid DNA vaccine against SARS-CoV-2.

New generation plasmid DNA vaccines may be a safe, fast and simple emergency vaccine platform for preparedness against emerging viral pathogens. Applying platform optimization strategies, we tested the pre-clinical immunogenicity and protective effect of a candidate DNA plasmid vaccine specific for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The DNA vaccine induced spike-specific binding IgG and neutralizing antibodies in mice, rabbits, and rhesus macaques together with robust Th1 dominant cellular responses in small animals. Intradermal and intramuscular needle-free administration of the DNA vaccine yielded comparable immune responses. In a vaccination-challenge study of rhesus macaques, the vaccine demonstrated protection from viral replication in the lungs following intranasal and intratracheal inoculation with SARS-CoV-2. In conclusion, the candidate plasmid DNA vaccine encoding the SARS-CoV-2 spike protein is immunogenic in different models and confers protection against lung infection in nonhuman primates. Further evaluation of this DNA vaccine candidate in clinical trials is warranted.

Polymorphisms in the ABCB1 gene and effect on outcome and toxicity in childhood acute lymphoblastic leukemia.

The membrane transporter P-glycoprotein, encoded by the ABCB1 gene, influences the pharmacokinetics of anti-cancer drugs. We hypothesized that variants of ABCB1 affect outcome and toxicity in childhood acute lymphoblastic leukemia (ALL). We studied 522 Danish children with ALL, 93% of all those eligible. Risk of relapse was increased 2.9-fold for patients with the 1199GA variant versus 1199GG (P=0.001), and reduced 61% and 40%, respectively, for patients with the 3435CT or 3435TT variants versus 3435CC (overall P=0.02). The degree of bone marrow toxicity during doxorubicin, vincristine and prednisolone induction therapy was more prominent in patients with 3435TT variant versus 3435CT/3435CC (P=0.01/P<0.0001). We observed more liver toxicity after high-dose methotrexate in patients with 3435CC variant versus 3435CT/TT (P=0.03). In conclusion, there is a statistically significant association between ABCB1 polymorphisms, efficacy and toxicity in the treatment of ALL, and ABCB1 1199G>A may be a new possible predictive marker for outcome in childhood ALL.

Sequence analysis of HIV-1 isolates from Guinea-Bissau: selection of vaccine epitopes relevant in both West African and European countries.

For a CD8 epitope-based vaccine to match different geographic locations, the targeted epitopes for cytotoxic T-lymphocytes (CTLs) must be present in the local circulating HIV-1 strains. Secondly, the vaccine epitopes should match the host population HLA types. We characterized two new HIV-1 isolates from Guinea-Bissau. Also, we have identified 15 subdominant CD8 epitopes representing common HLA super-types theoretically covering most HLA alleles in any population. Herein we demonstrate that the selected vaccine epitopes are well conserved and simultaneously present in sequences from West Africa and Denmark. Use of the selected epitopes will likely ensure ≥10 immune targets in the majority of candidates for experimental therapeutic vaccination in both geographic regions. Our results warrant testing of the selected vaccine epitopes in both geographic locations.

Reduced folate carrier polymorphism determines methotrexate uptake by B cells and CD4+ T cells.

OBJECTIVE: To examine if polymorphism 80G --> A in the Reduced Folate Carrier (RFC) affects uptake of MTX in B- and CD4+ T-cells. METHODS: Mononuclear cells were isolated from peripheral blood of healthy persons. Real-time PCR was used to detect the RFC80 variants. FITC-labelled MTX was added to cells stimulated with Candida albicans or tetanus toxoid, and the uptake of MTX was measured by flow cytometry. A FITC-conjugated monoclonal antibody against RFC was used to detect the cellular RFC expression. RESULTS: Antigen-stimulated CD4+ T cells and B cells from individuals with the GG variant (n = 9) exhibited lower uptake of MTX than individuals expressing the AA variant (n = 8), or the GA variant (n = 8). No difference could be demonstrated between the three groups with respect to the expression of RFC by CD4+ T cells and B cells, and CD4+ T cells from individuals homozygous for the G allele exhibited lower uptake of MTX per receptor than CD4+ T cells from individuals homozygous for the A allele. CONCLUSION: MTX is taken up more efficiently via the A allele than via the G allele. This difference between the variant forms of RFC suggests that genotyping could be relevant for determining the relevant dosage of MTX in the treatment of neoplastic and autoimmune disease.

Immunological analysis of a Lactococcus lactis-based DNA vaccine expressing HIV gp120.

For reasons of efficiency Escherichia coli is used today as the microbial factory for production of plasmid DNA vaccines. To avoid hazardous antibiotic resistance genes and endotoxins from plasmid systems used nowadays, we have developed a system based on the food-grade Lactococcus lactis and a plasmid without antibiotic resistance genes. We compared the L. lactis system to a traditional one in E. coli using identical vaccine constructs encoding the gp120 of HIV-1. Transfection studies showed comparable gp120 expression levels using both vector systems. Intramuscular immunization of mice with L. lactis vectors developed comparable gp120 antibody titers as mice receiving E. coli vectors. In contrast, the induction of the cytolytic response was lower using the L. lactis vector. Inclusion of CpG motifs in the plasmids increased T-cell activation more when the E. coli rather than the L. lactis vector was used. This could be due to the different DNA content of the vector backbones. Interestingly, stimulation of splenocytes showed higher adjuvant effect of the L. lactis plasmid. The study suggests the developed L. lactis plasmid system as new alternative DNA vaccine system with improved safety features. The different immune inducing properties using similar gene expression units, but different vector backbones and production hosts give information of the adjuvant role of the silent plasmid backbone. The results also show that correlation between the in vitro adjuvanticity of plasmid DNA and its capacity to induce cellular and humoral immune responses in mice is not straight forward.

[Viral vectors for clinical gene therapy]. / Virale vektorer til klinisk genterapi.

The first positive clinical results of gene therapy trials have now become evident. The relatively few positive results and the numerous negative trials make it possible to identify both problems and potential for new development. The biggest problems have come from the viral vectors used for gene transfer. Most of the successful gene therapy trials have involved monogenetic diseases, where the relevant tissue has been isolated ex vivo, and where a retroviral vector has been inserted into the therapeutic gene in the nuclear DNA. Gene therapy seems to have a definite therapeutic potential in several rare, inherited diseases and also in certain acquired diseases, such as ischaemic heart disease.