Polyclonal antibodies developed in transgenic chickens

08-10-2007 | |
Polyclonal antibodies developed in transgenic chickens

Origen Therapeutics in the US has been awarded a $2m (€1.4m) three-year grant from the National Institute of Standards and Technology (NIST) to develop human polyclonal antibodies by creating genetically modified chickens.

Thus far, the polyclonal antibody (PAbs) market has been stifled due to technology. But now, chickens are being looked at a little more closely – the transgenic animal system.
“In transgenic chickens, we will introduce human versions of these antibody genes . . . When the transgenic chicken is immunised with an antigen such as Staphylococcus aureus, it’s B cells will be activated and will produce human antibodies that bind specifically to the Staph bacteria. These antibodies will then form the basis for the polyclonal antibody therapeutic,” Fitzpatrick said.
The California-based company has so far developed the technology for inserting genetic modifications into the chicken genome. The technology involves removing or inactivating the genes that encode for chicken antibodies and in their place inserting gene sequences for human polyclonal antibodies. The modifications are carried out in cell cultures of chicken primordial germ cells.
These genetically modified cells are then injected into the developing vascular system of an early stage chicken embryo.
Apply the technology
The next step, which the grant enables, will be to apply the technology to insert human antibody sequences into the chicken and then to test and verify that the human sequence antibodies are produced as expected.
Found in the egg yolk, the antibodies will be extracted from the eggs produced by the transgenic chickens. A variety of fractionation and purification steps is then required to collect the pure antibody.
The PAbs can be collected at levels of about 200mg per egg. Origen estimates that if 100mg is collected per egg, a flock of 3,500 hens will produce approximately 75kg of antibody per year.
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