Dormant genes from an ancient infection may awaken ALS

BETHESDA, Md., Sept. 30 (UPI) -- The reactivation of human endogenous retroviral genes, or HERVs, may be linked to the development of amyotrophic lateral sclerosis, or ALS, suggesting a path of treatment for people with the debilitating condition.

Researchers who found the link between genetic remnants of HERV infections millions of years ago think treating patients antiretroviral drugs, similar to those used with HIV patients, may be able to help patients with ALS.

"People call the genes for these viruses junk DNA," said Dr. Avindra Nath, clinical director at the NIH's National Institute of Neurological Disorders and Stroke, in a press release. "Our results suggest they may become activated during ALS. Ultimately we hope the results will lead to effective treatments for a heartbreaking disorder."

Based on previous research that found reverse transcriptase, a protein encoded by retroviral genes, in the blood of ALS patients, researchers looked for links between retroviruses and ALS.

According to the new study, brain samples from patients with ALS had high levels of messenger RNA encoded by human endogenous retrovirus K, or HERV-K. A protein encoded by HERV-K was in brain samples from ALS patients, but not in healthy people or those with Alzheimer's disease. The genes also killed human neurons in the lab when they were activated in petri dishes.

To test this in living animals, researchers altered mice to activate the HERV-K gene. The mice died earlier than normal while displaying movements similar to ALS. When they examined the dead mice, the researchers found motor neurons in their brains, spinal cords and muscles were damaged while cells in other parts of the nervous system were fine -- seemingly confirming the role HERV-K played in their death.

"We showed that motor neurons may be susceptible to activation of these genes during ALS," Nath said. "We may have discovered a precision medicine solution for treating a neurodegenerative disorder."

He said the research team is now working with Johns Hopkins University to test whether antiretroviral treatments used with HIV patients will be able to help control HERV-K, offering a potential treatment for ALS.