Michelle Dickinson: nanotechnologist on scientists creating an allergy-free dog

If you love dogs but can’t own one because of allergies, scientists may have a solution. In a new study, published in The CRISPR Journal, researchers used CRISPR gene editing to remove the gene responsible for producing the major protein called Can f 1 that triggers dog allergies in many people.  Using CRISPR-Cas9, the scientists edited skin cells taken from the beagles. CRISPR acts a bit like molecular scissors, cutting DNA at a precise location. In this case, they introduced a tiny one-letter insertion into the Can f 1 gene that disrupted its instructions, preventing the protein from being made.  Those edited cells were then used in somatic cell nuclear transfer, the same cloning technique used to create Dolly the sheep. The DNA from an edited cell was placed into a donor egg, creating an embryo carrying the genetic change.  The team produced 25 embryos and implanted them into a surrogate beagle.  Two embryos developed successfully and became puppies called Bailey and Alfie.  The researchers then sequenced the puppies' DNA to confirm that the intended genetic change was present and checked if any other parts of the genome were accidentally edited.  Next the scientists collected saliva, hair and dander from the edited beagles.  They also collected samples from a normal beagle, a standard poodle and a goldendoodle.  Using a laboratory technique called a Western blot, which detects specific proteins, they searched for Can f 1. The results showed the normal beagle, poodle and goldendoodle all produced the allergen but the gene-edited dogs didn’t.  This also reinforced something many allergy specialists have said for years: poodles and doodles still produce the major dog allergen despite often being described as hypoallergenic.  Finally the experiment involved testing these new Beagles on humans with known dog allergies using a classic skin prick test.  Tiny drops containing extracts from different dogs were placed on the volunteer's arm before gently pricking the skin. If the immune system recognised the allergen, a raised itchy bump called a wheal would appear within about 20 minutes.  The normal beagle, poodle and goldendoodle produced the expected allergic reaction, but extracts from Bailey and Alfie produced no detectable skin reaction at all.  So far, Bailey and Alfie appear to be developing normally with no obvious health problems linked to the missing gene.  For decades we've treated allergies by trying to change the person, using medications or immunotherapy to calm the immune system.  Instead of changing the immune system, the researchers changed the source of the allergen.  Whether gene-edited allergy-friendly dogs eventually become widely available remains to be seen. There are still ethical, regulatory and practical questions to answer.  But scientifically, it's an elegant demonstration of what modern gene editing can achieve. LISTEN ABOVESee omnystudio.com/listener for privacy information.