Fig. 1

Construction and expression of IL-15/SuIL-15Rα-dFc and IL-15/SuIL-15Rα-mFc. a Schematic diagram of the two IL-15/SuIL-15Rα-IgG4 Fc complexes. IL-15/SuIL-15Rα-dFc was composed of two molecules of mutated IL-15 noncovalently bound to a modified dimeric SuIL-15Rα-IgG4 Fc fusion protein, while IL-15/SuIL-15Rα-mFc consisted of a single molecule of mutated IL-15 noncovalently bound to a modified monomeric SuIL-15Rα-IgG4 Fc fusion protein. b The construction strategy of the two IL-15/SuIL-15Rα-IgG4 Fc complexes. pPIC9-SuIL-15Rα-dFc or pPIC9-SuIL-15Rα-mFc and pPICZα-IL-15 were inserted into the genome of GS115 through homologous recombination using the his4 and AOX1 sequences, respectively. c Screening for the expression of IL-15/SuIL-15Rα-dFc and IL-15/SuIL-15Rα-mFc. Expression clones were first screened by dot blotting using rabbit anti-human IL-15 antibody followed by donkey anti-rabbit IgG-HRP conjugate, and then high expression clones were further selected and confirmed by Western blotting under nonreducing conditions using anti-human IgG4-HRP conjugate. Clones No. 15–2 and 62–4 were selected as the expression clones used in pilot-scale fermentation of IL-15/SuIL-15Rα-dFc and IL-15/SuIL-15Rα-mFc, respectively. The numbers in the figure represent the clone numbers