Novel membrane extraction procedure for the purification of hepatitis B surface antigen from Pichia pastoris

The recombinant hepatitis B surface antigen (HBsAg) vaccine provides excellent protection against hepatitis B virus (HBV). However, high costs of its production prevents many underdeveloped and developing nations from implementing HBsAg vaccination. This in turn increases the risk of contracting HBV related diseases. Majority of the commercial HBV vaccines are derived from purified HBsAg expressed in recombinant yeasts. Most of the cost in production of the vaccine is incurred during the downstream processing. The costs associated with HBsAg purification can be decreased by optimizing the pre-chromatography steps and by reducing the impurity burden on chromatography operations. Here in this work we present a novel strategy for the enriched extraction of recombinant HBsAg from Pichia pastoris membranes. We have also developed a simple, easy to operate process for the purification of HBsAg VLPs from the membranes of P. pastoris. This novel strategy, while utilizing a single column chromatographic step in the purification scheme results in the highest recovery of HBsAg VLPs reported in the literature. The yield of HBsAg at the end of purification was nearly 5% (85 μg/g of induced wet cell biomass). The HBsAg purified from this process has shown the presence of VLPs. The immunization of these VLPs in BALB/c mice with alhydrogel adjuvant has shown good titers of neutralizing antibodies.

► HBsAg protein, when over expressed in P. patoris gets associated with membranes.
► The membrane association of HBsAg can be disrupted by 2% Tween-20.
► A centrifugation step followed by lysis ensures removal of supernatant impurities.
► Phenyl-600M Toyopearl resin can purify HBsAg to homogeneity.
► Membrane purified HBsAg elicits protective antibody responses in mice.