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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