Direct purification of recombinant hepatitis B core antigen from two different pre-conditioned unclarified Escherichia coli feedstocks via expanded bed adsorption chromatography

Direct recovery of hepatitis B core antigen (HBcAg) from unclarified Escherichia coli homogenates via expanded bed adsorption chromatography (EBA) has been explored in this study. Streamline DEAE was selected as the anion exchanger to recover HBcAg from heat-treated and non-heat-treated unclarified feedstocks. The use of anion-exchanger for direct extraction of proteins from unclarified feedstock is not preferred due to lack of specificity of its ligand. In this study, thermal treatment of the unclarified feedstock at 60 °C has resulted in 1.2- and 1.8-fold increases in yield and purity of HBcAg, respectively, compared with that purified from non-heat-treated feedstock. Heating the crude feedstock has resulted in denaturation and precipitation of contaminants in the feedstock, hence reducing non-specific interactions between the cell debris and adsorbent. The selectivity of the anion-exchanger has also been increased as shown in the breakthrough curve obtained. Enzyme-linked immunosorbent assay showed that the antigenicity of the HBcAg from heat-treated unclarified feedstock is still preserved.