Transport of human immunoglobulin G and Fc-fusion proteins to chicken egg yolk

We examined the transport of human immunoglobulin G (IgG) subclasses and fusion proteins with the Fc region of human IgG to the egg yolk, after the proteins were injected into a vein of hens. Human IgGs were efficiently transported and accumulated into the yolk, whereas the proteins were not detected in the egg white. Among human IgG subclasses, IgG2 was transported most efficiently. Fc-fusion proteins injected were also transported into the yolk. A fusion protein with the Fc region derived from human IgG2 was more efficiently transported into the yolk than the counterpart fusion with the Fc region from human IgG1. This study shows that the recovery of recombinant antibodies and Fc-fusion proteins from the yolk is an effective method in transgenic chicken bioreactors.