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Mad Cow Disease
A study in prions
Prions are abnormal forms of proteins in the brain that can be caused by infection or genetic mutation. Once a prion enters the brain, they begin to multiply and influence otherwise harmless (benign) proteins to misfold into their abnormal structure.
Normally, these proteins would be made up of flexible coils known as alpha helices. However, these coils become flattened into new structures called beta strands in prion proteins. This shape prevents cellular enzymes or “proteases” from modifying them. As a result, the proteases cannot break down the prions when the multiply. Instead, the prions will continue to increase inside of the brain, destroying the neurons they inhabit. In other words, prion diseases are progressive in nature, worsening over time.
This kind of neuron destruction eats apart brain tissue, filling it with holes like a sponge. Fittingly, this effect is called spongiform.
In fact, the characteristic spongiform patterns allow scientists to verify the presence of prion proteins once an infected organism has died. This is done by analyzing the organism’s brain tissue under a microscope. Scientists do not have accurate test for suspected prion diseases in living organisms.
Mad Cow Disease is one type of prion induced disease. It’s also known as BSE, or “bovine spongiform encephalopathy.” As a bovine or cow disease, it cannot be transmitted to humans although we are susceptible to similar variants such as Creutzfeldt-Jakob disease (CJD). People with CJD can be infected by eating nerve tissue of cattle who had mad cow disease. You can’t catch CJD disease by being near someone, cow or human, who is infected though and, surprisingly, other dairy products (such as milk) from a sick cow are also safe to eat.
In cows, the disease spreads in a similar way. When cows are slaughtered, some of their parts are consumed by humans but other parts are sometimes reserved for making a special powder. This powder can be used to create animal feed. However, if part of the powder originated from a sick cow, other cows that eat the infected feed will become new BSE victims.
Signs of an infected cow can take years to become apparent. But when they do, symptoms of BSE look like poor coordination. For example, infected cows…
