First mad cow disease immune cattle made

Mad cow disease, or bovine spongiform encephalopathy (BSE), is caused by prions (a vital protein) getting
damaged and spreading to the animal’s brain tissue. It causes the collapse of
the cow’s central nervous system.

In their study, the team took the breed
of Holstein cows to genetically engineer calves without a prion. Though the team
from research centres in South Dakota, Idaho and Tokyo produced the genetically
engineered cattle two years ago, it was only after carrying out checks on 20
months old cattle that they were able to confidentially declare the animals to
be free of the BSE causing prion.

Researchers say the breakthrough could
signal the end to massive health fears by breeding cows that are incapable of
catching the disease. The disease is passed on to humans through infected beef
and cause death.

Yoshimi Kuroiwa, of Tokyo, and US-based colleagues James
Robl and Juergen Richt, now want to find out what function the prion has in
normal cattle to see if it can be missed. The team plans to carry out further
checks over several years to see if cattle can remain prion-free and therefore
safe from any possible infection.

The scientists also want to see if
there is any downside to the animals not growing up with the protein that is
found in all other cattle, reports The Scotsman. According to the journal,
Nature Biotechnology, where the findings were first reported, the genetically
modified cows are identical to normal cows in every other way, but for the
missing prion.