Production and product quality assessment of human hepatitis B virus pre-S2 antigen in submerged and solid-state cultures of Aspergillus oryzae

Pre-S2 is a diagnostically important antigen of human hepatitis B virus (HBV). In order to produce pre-S2 antigen in Aspergillus oryzae, the gene [pre-S2]₃, which encodes a tandemly triplicated repeat of pre-S2 polypeptides was fused with the partial glaA gene encoding glucoamylase lacking the starch-binding domain. In submerged culture, A. oryzae transformants carrying glaA-[pre-S2]₃ secreted a heterogeneously glycosylated form of the fusion protein that was partially degraded. Contrarily, utilization of a wheat bran solid-state culture system resulted in the secretion of a homogeneous glycosylated form of the whole fusion protein. This is the first report of a dissimilarity in glycosylated modification between submerged and solid-state culture conditions in heterologous protein production in A. oryzae.