Skip to content
Login Register

#DNA vaccines

3 public questions tagged with this topic.

Vaccine

DNA vaccines deliver genes in the form of:

DNA vaccines deliver genetic instructions as circular plasmid DNA rather than protein antigen or RNA. Plasmid constructs typically contain bacterial origin pUC, antibiotic resistance for selection during manufacturing, and eukaryotic expression cassette comprising strong promoter cytomegalovirus CMV immediate early with intron A enhancing transcription, codon optimized antigen gene, polyadenylation signal bovine growth hormone BGH or SV40 preventing mRNA degradation. Plasmids produced in Escherichia coli fermentation high copy number, purified supercoiled isoform removing endotoxin via chromatography. Upon intramuscular delivery with electroporation needles delivering brief electrical pulses increasing membrane permeability or needle free jet injector, plasmid enters myocytes and antigen presenting cells, translocates nucleus independently of cell division, transcribed by RNA polymerase II into mRNA exported then translated. Resulting antigen triggers both humoral and cellular immunity. Advantages include exceptional thermostability stable at room temperature months facilitating transport without stringent cold chain, simple large scale manufacturing, lack of anti-vector immunity permitting homologous boosting, ability to encode multiple antigens single plasmid. Limitations include relatively low transfection efficiency in humans requiring devices, theoretical rare integration at frequencies less than 10^-7 per plasmid. World's first approved ZyCoV-D COVID DNA vaccine India uses three dose regimen.

Ref: Wolff et al. Science 1990 DNA vaccines plasmid; Plotkin DNA vaccines; WHO DNA plasmid.

View Details
Immunological Applications

DNA vaccines work by:

DNA vaccination concept bypasses conventional protein purification manufacturing by delivering genetic blueprint encoding protective antigen allowing host cells to synthesize immunogen in situ mimicking viral infection while noninfectious. Plasmid vector engineered with strong eukaryotic promoter typically human cytomegalovirus immediate early enhancer promoter driving high transcription, chimeric intron improving mRNA stability and export, Kozak consensus GCCACCATGG for efficient translation initiation, antigen coding sequence codon optimized for human usage bias replacing rare codons to increase expression tenfold, and bovine growth hormone polyadenylation signal specifying cleavage and poly-A adding 200 adenines. After intramuscular injection with needle or gene gun gold particles, myocytes and keratinocytes internalize negatively charged plasmid via macropinocytosis, plasmid enters nucleus through nuclear pore complex during mitosis when nuclear envelope breaks down or via active import mediated by importin. This mechanistic insight supports diagnostic and therapeutic applications while reinforcing core immunological and cell biology principles taught in advanced curricula. This mechanistic detail underpins practical applications in diagnostics, vaccine design, and biopharmaceutical manufacturing.

Ref: Ulmer et al Science 1993 DNA vaccine CMV promoter MHC I II; NIH Vaccine plasmid CpG TLR9 adjuvant mechanism.

View Details
Immunological Applications

DNA vaccines work by:

DNA vaccines third-generation platform delivering plasmid DNA encoding microbial antigen rather live attenuated organism purified protein circumventing biosafety level concerns anti-vector immunity. Plasmid constructed E. coli DH5 alpha containing bacterial origin ColE1 antibiotic resistance beta-lactamase ampicillin selection strong eukaryotic expression cassette CMV immediate early enhancer promoter high constitutive transcription Pol II chimeric intron A human beta-globin improving mRNA stability splicing removing premature terminator target gene viral spike bacterial protective antigen tumor neoantigen optimized human codon usage removing rare codons increasing translation bovine GH polyA terminating transcription adding polyA tail aiding nuclear export. Additional unmethylated CpG immunostimulatory motifs GTCGTT enriched activating TLR9 plasmacytoid dendritic MyD88 IRF7 type I interferon alpha endogenous adjuvant stimulating Th1. Intramuscular injection 1 mg plasmid saline followed electroporation needle electrodes 100V 50ms pulses increasing myocyte membrane permeability transient pores enhancing uptake 100-fold plasmid enters nucleus nucleopore remains episomal circular monomer not integrating

Ref: Wolff et al Science 1990 DNA Plasmid Expression Landmark; NIH NIAID DNA Vaccine Mechanism Overview Summary; Nature Reviews Immunology DNA Vaccines Principles 2021 Adjuvant.

View Details