“…34 This fact can be attributed to some key advantages: i) robust growth in chemically-defined and serum-free suspension culture, (ii) a reasonable safety profile regarding human pathogenic virus replication, (iii) ease generation of cell clones which are able to stably express the recombinant protein in sufficient yields and acceptable quality for human use, and (iv) ability to express recombinant proteins with human-like post-translational modifications. 35,36 However, recombinant therapeutic proteins produced in non-human cells may contain glycan epitopes, mainly Gala1,3-gal (a-Gal) residues and N-glycolylneuraminic acid (Neu5Gc), that are antigenic to humans, 34,37 and can potentially affect the efficacy of the recombinant product, since all humans tested have circulating antibodies against these epitopes. 38,39 Although few adverse immunogenic reactions have been ascribed to CHOderived recombinant proteins, this cell line possesses the enzymes (a1,3 galactosyltransferase and CMPNeu5Ac hydroxylase) responsible for the formation of this non-human epitope.…”