Vaccination is the most effective and least expensive technique used for human diseases prevention and eradication. The need for more vaccine doses and the rapid establishment of facilities for the development of new vaccines are stimulating significate changes in the vaccine industry, which is gradually moving towards cell culture production. One approach is the third generation of vaccines, which are based on the use of plasmid DNA (pDNA) containing transgenes that encode an antigen capable of mimicking intracellular pathogenic infection and triggering both humoral and cellular immune responses. Plasmid DNA vaccination has distinct advantages over other vaccine technologies in terms of safety, ease of fabrication and stability. The effectiveness of pDNA vaccines against viruses, bacteria, parasites and cancer cells has been demonstrated in preclinical and clinical assays. Furthermore, currently there are a few veterinary pDNA vaccines in the market. The application of a simple formulation of naked pDNA as a vaccine is attractive, but a low transfection efficiency is often obtained. The use of nanoparticles to increase transfection efficiency is an approach that has been tested clinically. This review provides a summary of vaccine production, advances and major challenges associated with pDNA lipid and polymeric nanovaccines applications.

The demand for plasmid DNA has increased vastly in response to rapid advances in its use in gene therapy and vaccines. These therapies are based on the same principle, i.e. the introduction of nucleic acids in human/non-human cells receptor to restore, cancel, enhance or introduce a biochemical function. Naked plasmid DNA as a vector has attracted a lot of interest since it offers several advantages over a viral vector, especially weak immunogenicity, better safety and easy to manufacture, but low transfection efficacy. Non-viral gene therapy may require considerable amounts (milligram scale) of pharmaceutical-grade pDNA per patient since the efficacy and duration of gene expression is presently relatively low. Reliance on fermentation, which generates large lysate volumes, for producing the needed quantities of pDNA is becoming more widespread. Through optimization of the biological system, growth environment and the growth mode, improvements can be achieved in biomass productivity, plasmid yield, plasmid quality and production costs. The information on large-scale plasmid production is scarce and usually not available to the scientific community. This review summarizes recent patents and patent applications relating to plasmid upstream processing manufacturing, ranging from plasmid design to growth strategies to produce plasmid-bearing E. coli.