Very high expression of an anti-carcinoembryonic antigen single chain Fv antibody fragment in the yeast Pichia pastoris

In this paper we report the development of a recombinant strain of the yeas t Pichia pastoris, which secretes an anti-carcinoembryonic antigen single c hain Fv (scFv) antibody fragment to the culture supernatant as a biological ly active protein, at levels of 1.2 g l(-1). The yeast scFv was purified by IMAC, with a final yield of approximately 0.440 g of 93% pure scFv per lit er of culture supernatant. The specific activity in ELISA of the yeast scFv was almost three times higher than that of a bacterial periplasmic counter part. These results reaffirm that the yeast P. pastoris is a suitable host for high level production of scFv antibody fragments with potential in vivo diagnostic and therapeutic applications. (C) 2000 Elsevier Science B.V. Al l rights reserved.