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

Equine chorionic gonadotropin (eCG) is a heterodimeric glycoprotein hormone produced by pregnant mares that has been used to improve reproduction activity in different types of livestock. Several strategies to produce the hormone in a recombinant way have been reported; nevertheless, none 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 not only demonstrated biological activity in bovine cattle but also this bioactivity appeared to be higher than PMSG, since 140 IU of reCG were needed to exert the same biologic effect in an ovulation synchronization protocol compared to 400 IU of PMSG. The results obtained show that the developed strategy represents an attractive option to produce reCG and constitutes an auspicious alternative for the replacement of animals as a source of PMSG.