Study Links Common Virus to Parkinson’s Disease

A virus, once thought to be benign, may actually contribute to Parkinson’s disease, a condition that impacts over one million Americans.

Researchers from Northwestern Medicine have identified human pegivirus (HPGV) in the brains and spinal fluid of individuals with Parkinson’s, while it was absent in healthy individuals. This discovery calls into question long-held beliefs about the virus.

“HPGV is a fairly common virus that was not known to frequently infect the brain,” stated Dr. Igor Kolarnik, who oversees neuroinfectious diseases in the Northwestern area. “We were taken aback to find such a high presence in Parkinson’s patients compared to controls.”

The research, published in JCI Insight, involved examining 10 patients diagnosed with Parkinson’s and 14 postmortem brain samples from those who passed away from unrelated causes. The virus was found in five of the ten Parkinson’s brains, but not in any of the control samples.

The virus was also detected in spinal fluid samples, indicating it could be active within the nervous system. Patients with HPGV exhibited more pronounced brain changes typically associated with Parkinson’s, such as protein build-up and altered brain chemistry.

Beyond analyzing brain tissue, researchers also examined blood samples from over 1,000 participants involved in a project led by the Michael J. Fox Foundation. They noticed immune system alterations linked to the virus.

Interestingly, individuals with Parkinson’s who had mutations in the LRRK2 gene reacted differently to HPGV than those without this mutation. “This hints that the virus may interact with the body in ways we haven’t fully recognized before,” Coralnik remarked.

This potential link may shed light on why some individuals develop Parkinson’s while others don’t and could pave the way for new treatments targeting both the virus and immune response.

However, caution remains necessary. Dr. Joel Salinas, a behavioral neurologist, notes that while these findings are intriguing, it’s too soon to conclude that the virus definitively causes Parkinson’s disease. “We require further, larger studies to determine the actual clinical relevance of this association,” he added. “It’s early-stage research, so there’s no need for alarm just yet—no compelling evidence indicates that this virus triggers Parkinson’s.”

Approximately 90,000 new cases of Parkinson’s are reported each year in the U.S., a figure anticipated to rise to 1.2 million by 2030.

The research team at Northwestern aims to delve deeper into how frequently HPGV is present in people with Parkinson’s compared to healthy individuals and to explore whether other viruses may be involved in the condition.

“For viruses previously labeled as harmless, this research suggests they could significantly influence the context of Parkinson’s,” Coralnik noted. “We’re also looking to explore how viruses and genetic factors interact, which may provide insights into how Parkinson’s begins and guide future therapeutic approaches.”