Examination of alternative technologies for optimising soluble recombinant antigen expression

Abstract

ABSTRACT

Recombinant proteins are manufactured using different methods depending on the intended use and scale of production. The Protein Development and Production Unit (PDPU) manufactures several recombinant proteins, including soluble recombinant blood group antigens, which are used to neutralise nuisance antibodies in serological testing. These proteins must be immunogenic, with a structure and profile of post-translational modifications that are as close to the native antigen as possible. There is a growing need to modify the current approach for manufacturing proteins in the PDPU to increase yield, as newly approved therapeutic monoclonal antibodies require far larger amounts of protein to be neutralised. This thesis has therefore been written in order to propose a new strategy. To do so, the main factors involved in recombinant protein expression are analysed using the existing literature, to examine the merits of the current PDPU approach and find alternatives. Accordingly, several alterations are proposed which may enhance protein yield, including the use of enzymatic integration (transposase) and suspension cell culture, which will increase specific productivity and cell mass, respectively. To analyse the efficiency of these changes an estimation of the increase of yield is required. The changes should increase specific productivity in theory, but accurate estimation proves challenging, as it is highly variable from one protein to another. In contrast, the improvement in cell mass using stirred bioreactors can be readily estimated and compared with the current approach using Hyperflasks. This leads to the conclusion that using bioreactors can produce up to ten times higher cell mass than Hyperflasks for the same volume of media. This indicates that the new modifications can improve yield considerably. However, before adopting the proposal, the full cost must be compared between both strategies, taking into account materials and the potential cost of licensing commercial technologies.