IT LOOKS like a virus might trigger motor neuron disease. And if so, the devastating illness could one day be prevented by a vaccine.
Motor neuron disease is also known as amyotrophic lateral sclerosis (ALS) and Lou Gehrig鈥檚 disease, after the US baseball player who was diagnosed with the disorder in 1939. Physicist Stephen Hawking also suffers from the disease. ALS starts with a weakness in the arms or legs but gradually destroys all motor neurons, leaving its victims unable to move or breathe, although their minds remain unaffected.
No one knows what causes ALS. However, in the past scientists suggested a link with polio viruses. While that link hasn鈥檛 held up, researchers have now found a related virus in the spinal cords of people with ALS.
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Bruno Lina and his colleagues at the National Enterovirus Reference Centre in Lyon, France, were hunting for viruses in people with post-polio syndrome, a muscle wasting disorder that can start years after recovery from polio. The researchers used several samples from ALS patients as control samples that were meant to be clear of viruses related to polio.
But the team was surprised to find that some of the ALS samples tested positive for enteroviruses. This group of viruses includes polio viruses and echoviruses, some of which are known to attack neurons.
So Lina and his colleagues turned their attention to ALS. They looked for the type of RNA typical of enteroviruses in spinal cord samples from 17 French ALS patients and 29 people with no history of motor neuron disease. They found telltale sequences of enterovirus RNA in 15 of the ALS patients and only one of the controls. The sequences looked most similar to that of echoviruses 6 and 7, which can attack neurons.
鈥淚t was a surprise,鈥� says Lina, who is now looking for the same signs in British and Japanese ALS cases. Lina warns that they really need to confirm the link to the virus, which might just be an innocent bystander. But if a virus turns out to be the cause of motor neuron disease then a vaccine may one day prevent the illness.
鈥淚t certainly would be provocative,鈥� says Raymond Roos, a neurologist at the University of Chicago Medical Center in Illinois. But he adds that he鈥檇 like to see the results replicated and more of the enterovirus genomes sequenced, as other laboratories have found hints of viruses in the past that never held up. 鈥淚t鈥檚 probably worth keeping an open mind,鈥� he says.