Abstract

Plasmid DNA (pDNA) vaccines are promising means to prevent and treat infectious diseases, such as leishmaniasis, but immunisation protocols require large amounts of supercoiled plasmid DNA (sc-pDNA). Although pDNA can be produced at a reasonable cost in bioreactors; this scale of production may not be the best method at the initial step of a vaccine development when many antigens need to be tested. Then, with the goal of improving the production of VR1012-NH36 and pVAX-NH36 pDNA vaccines against leishmaniasis, the effect of the culture medium and temperature on the pDNA yield was studied in flask cultures. The results indicate that the plasmid volumetric yield increased up to 65 mg/l in flask cultures by using a semi-defined medium, and shifting the culture temperature from 37 to 42°C at the late exponential growth phase. This pDNA production, with at least 80% of sc-pDNA at a laboratory scale seems sufficient to evaluate this and other pDNA vaccine candidates in the initial steps of vaccine development.

Key words: Plasmid DNA vaccine, plasmid DNA production, growth medium, flask culture, trace metal optimisation, leishmaniasis.