The use of particle concentration fluorescence immunoassay technology for the analysis of rDNA products

The electrophoretic and immunological techniques typically used to detect potentially useful biopharmaceutical proteins are sensitive with detection limits in the nanogram range. However, quantitation of a recombinant protein can be cumbersome, and involve large numbers of samples throughout process optimization schemes. Although electrophoretic methods (i.e., SDS-PAGE and Western blots) now avail themselves to quantitation by densitometry, these techniques are time consuming because of the lack of appropriate automated systems. Biological activity assays, when available, often require relatively pure material and are not suitable for analyzing and quantitating impure or semi-purified samples, typical of the fermentation milieu. The optimization of several rDNA-derived protein systems from both prokaryotic and eukaryotic hosts has been completed using PCFIA, a rapid, sensitive system with high throughput. The development of Particle Concentration Fluorescence Immunoassay (CFIA) procedures for several of these rDNA-derived proteins of interest as potential biopharmaceuticals (e.g., alpha-1-antitrypsin, tPA, soluble CD4, and a malaria vaccine candidate) are discussed.