High level expression, purification, and in vivo activity of bovine granulocyte-colony stimulating factor produced using a baculovirus system

A bovine granulocyte-colony stimulating factor (bG-CSF) cDNA clone bearing a C-terminal poly-His-tag (bG-CSFHis) was constructed and expressed by the baculovirus expression system. The bG-CSFHis was expressed as an approximately 19kDa protein in the culture supernatants and was purified using a nickel chelate column. The purified bG-CSFHis had bioactivity in vitro in the NFS-60 bioassay. In order to evaluate activity in vivo, purified bG-CSFHis was administered to cattle as single or multiple dosages. The bG-CSFHis increased neutrophil counts in peripheral blood and modulated the phagocytic activity of the neutrophils. The data indicates that the recombinant protein had activity in vivo.