BioEngineering Research GroupEngenharia Química: Indústria, Ciência e Tecnologia, 7, 34-39 (2007)
Prazeres, D. M. F., Monteiro, G. A.
Vaccines based on plasmid DNA (DNA vaccines) offer a credible alternative for the prevention of infectious
diseases and others. The first successful demonstration of the immunogenicity of an influenza DNA vaccine in
humans also supports claims that DNA vaccines may be the best way to respond to an influenza pandemic. Although a
number of publications describe how to produce plasmid DNA (pDNA) by growing an Escherichia coli host to high
cell densities (upstream processing), and how to purify it by coupling unit operations (downstream processing),
process optimization and intensification approaches are required to overcome the bottlenecks that make the
production of kg of pDNA currently unpractical. These bottlenecks are found mostly in the downstream processing,
and are related to: i) the peculiar shape and conformation of pDNA, ii) the large size of pDNA which translates
into low diffusion coefficients and small binding capacities with conventional sorbents, iii) the unusually high
viscosity of lysates generated from high cell density solutions, and iv) the presence of impurities (e.g. RNA,
genomic DNA) with properties similar to pDNA. Furthermore, the downstream processing also accounts for the
majority of manufacturing costs (50-80%). A new generation of pDNA manufacturing processes is thus required that
should be characterized by: i) decreased manufacturing time, ii) higher yields, iii) lower inventory,
specifically of mass separating agents, iv) environmental benefits, v) lower plant size, vi) capital and
manufacturing cost reduction, vii) scalability and viii) easier validation.
Keywords: DNA vaccines; plasmid DNA; production; purification
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