rProtein, Protein and Polysaccharide Vaccines

Many vaccines are being developed based on the ability of proteins to invoke an immune response. Some traditional vaccines are protein toxoids, and modified toxoids are used in most conjugate vaccines to promote an immune response against the conjugated species, typically a polysaccharide. Protein production follows the same route as described in the Biotechnology pages.

Polysaccharide production has a similar set of unit operations, although there is either a size-exclusion chromatography (SEC) step to select for molecular weight class of the polysaccharide fragment, or this can be achieved using an ultrafilter cascade where the molecular weight species of interest is fractionated between two ultrafilters rated above and below the molecular weight desired. 10 KDa at the lower end and 100 KDa or 300 KDa at the upper end are often used. Tangential flow filtration (TFF) has advantages over SEC as the resulting product with selected molecular weight is not highly diluted as it may be with SEC, and may then require a further TFF concentration step.