Both companies reported they had successfully cloned pigs in which a single copy of the alpha 1, 3 galactosyl transferase
gene had been knocked out - "single knock-out pigs.
A company spokesman in Edinburgh said the ability to 'knock out' both copies of the alpha 1,3 galactosyl transferase
(GT) gene was a vital step forward.
Scientists at PPL, which was behind the cloning of Dolly the sheep, have found a way to inactivate the alpha 1,3 galactosyl transferase
This barrier is related to the enzyme, alpha (1,3) galactosyl transferase
, or [eth]-GT, which is expressed in the cells of lower mammals but not present in human or other Old World primate cells.
In January 2002, PPL announced the birth of pigs lacking one copy of this gene for the enzyme alpha1, 3 galactosyl transferase
(alpha-gal), which adds a sugar to the surface of cells that the human immune system immediately recognizes as being foreign.
Each lacked both copies of the gene responsible for making the enzyme alpha1, 3 galactosyl transferase
, a feat that could bring in the next generation of organ donors, making animal-to-human transplantation feasible.
Earlier this year PPL announced the birth of pigs in which a single copy of the alpha 1,3 galactosyl transferase
(GT) gene had been knocked out -- the single 'knock-out' pigs.
The gene that has been 'knocked-out', the alpha 1,3 galactosyl transferase
(GT) gene is responsible for making an enzyme that adds a sugar to the surface of pig cells which is recognized by the human immune system as foreign, and which therefore triggers an immune response leading to hyperacute rejection by the human patient, of the transplanted organ or cell, within minutes.
It is generally recognised that a considerable move forward in this field would be the availability of a pig in which a particular pig gene, called alpha 1-3 galactosyl transferase
(alpha 1-3 GT) has been inactivated.