Are Viruses Trigger For ALS?

Doctors associated with the MDA ALS Center at Massachusetts General Hospital in Boston are following up on a recent finding of elevated activity of an enzyme called reverse transcriptase in the blood of people with ALS.

When the MGH researchers found that reverse transcriptase, an enzyme used by retroviruses to replicate themselves, had higher activity in people with ALS and their relatives than in others tested, they surmised that supposedly dormant retroviruses might be responsible for the difference. However, they were unsure of the meaning of the finding and whether the retroviruses might sometimes become active or contribute to ALS development.

Now, the Boston-based group is asking 60 people with ALS and 120 without the disease to provide blood samples and answer detailed questions about their medical and family histories. The study is now closed.

Watch this site and http://www.als-mda.org for results.

Elsewhere, another research team has been inquiring about an ALS-virus connection.

Roger Pamphlett and colleagues at the University of Sydney in Australia, who published their report in the July issue of Muscle & Nerve, found no evidence that the mosquito-borne West Nile virus plays a role in the disease.

West Nile virus, which belongs to the flavivirus family, can attack motor neurons, the cells that die in ALS, so this virus group became a candidate for investigation.

However, the researchers say they aren’t ruling out a connection, even though they didn’t detect any flaviviruses in spinal cord samples from 10 people who had died of ALS.

“One reason for our negative findings may be that the virus is cleared quickly after an acute infection,” they write. They say that a “remote [long ago] infection with later cell death is a possibility” and that the role of viruses in motor neuron disease “remains uncertain.”