Development of a suitable manufacturing process for production of a bioactive recombinant equine chorionic gonadotropin (reCG) in CHO-K1 cells

Abstract

Equine chorionic gonadotropin (eCG) is a heterodimeric glycoprotein hormone produced by pregnant mares that has been used to improve reproductive performance in different domestic species. Several strategies to produce the hormone in a recombinant way have been reported; nevertheless, no approach has been able to produce a recombinant eCG (reCG) with significant in vivo bioactivity or in sufficient quantities for commercial purposes. For this reason, the only current product available on the market consists of partially purified preparations from serum of pregnant mares (PMSG). Herein, we describe a highly efficient process based on third-generation lentiviral vectors as delivery method for the production of reCG in suspension CHO-K1 cells, with productivities above 20 IU 10⁶ cell^-1.d^-1 and 70% purification yields after one purification step. Importantly, reCG demonstrated biological activity in cattle, since around 30 μg of reCG were needed to exert the same biologic effect of 400 IU of PMSG in an ovulation synchronization protocol. The results obtained demonstrate that the developed strategy represents an attractive option for the production of reCG and constitutes an auspicious alternative for the replacement of animals as a source of PMSG.

Keywords: Glycoprotein hormones; Lentiviral particles (LP); PMSG; Pregnancy rate; Suspension CHO-K1; reCG.