Scientists have succeeded in producing multiple generations of transgenic hens, that produce pharmaceutical proteins in white part of their eggs. For transferring drug making gene into chickens lentivirus carrier are used. The genetic material was replaced with the gene regulating ovalbumin production combined with genes for making antibody targeting malignant melanoma. When genetically altered hens lay eggs, the foreign protein is expressed in the oviduct where the eggs white is made.

Source: reuters.com