Many people have a new awareness of the disease known as amyotrophic lateral sclerosis, or ALS, thanks to the Ice Bucket Challenge initiated by the ALS Association. Fewer might know that retroviruses have been proposed to play a role in the development of the disease.
I previously summarized a 2008 paper on ALS in a piece called Retroviruses and amyotrophic lateral sclerosis. Sera from some ALS patients had previously been shown to contain elevated levels of reverse transcriptase, an enzyme found in retrovirus particles. In the 2008 paper, RNAs encoding this enzyme were reported in the brains of ALS patients, and their origin appears to be the human endogenous retrovirus HERV-K.
The progress made in understanding the relationship of endogenous retroviruses with ALS is summarized in a review published in August of 2014 entitled Retroviruses and amyotrophic lateral sclerosis (the paper is open access). The authors conclude:
A comprehensive study of the expression or reactivation of endogenous retroviral elements in ALS has not yet been undertaken. The literature on HERV-W involvement in ALS is difficult to interpret. Two independent reports, however, have shown increased HERV-K expression in both serum and brain tissue in ALS patients. It remains unknown if HERV-K expression is an epiphenomenon or plays a pathophysiological role in the disease.
I am pleased to participate in the Ice Bucket Challenge to help raise awareness of ALS and raise money to work on the disease.