Herpes virus can cause development of brain disorders, say scientists

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Alzheimer's patient
An Alzheimer's patient is seen sitting after a therapy session inside the Alzheimer foundation in Mexico City April 19, 2012. Alzheimer's is a progressive, degenerative disease that robs people of memory, reasoning and the ability to communicate. About 24 million people worldwide have the disease according to the World Health Organization. Reuters/Edgard Garrido

People with Alzheimer's disease could soon use antiviral drugs to treat their condition, a new study suggests. Scientists have found that certain species of herpes virus can potentially infect neurons and cause symptoms of brain disorders.

Earlier studies already showed the link between neurologic conditions and the species of herpes virus. However, it has been assumed that these viruses, called gamma herpesviruses, can not infect neurons.

But the new study, published in the journal mBio, shows that Epstein-Barr virus (EBV) and Kaposi's sarcoma-associated herpesvirus (KSHV) can infect and replicate in cultured and primary neurons. These herpes viruses could potentially infect patients with Alzheimer's disease, multiple sclerosis (MS) and cerebellar ataxia.

Researchers from the University of Pennsylvania found the viruses enriched in the cerebrospinal fluid and brain tissue of individuals with MS and Alzheimer's disease. In addition, people with a history of infectious mononucleosis caused by EBV are at higher risk of developing MS.

The researchers have analysed the effect of the drug acyclovir, which can block EBV and related viruses, as a new therapeutic strategy for MS. The study shows the drug delivered positive results.

The findings come from the analysis of effects of genetically modified viruses, expressing green fluorescent protein, to infected human neuroblastoma cells and primary human foetal neurons.

"I couldn't believe it. After 50 years of studying EBV, nobody had ever seen the virus in nerve cells,” said Professor Erle Robertson, director of the Tumour Virology Training Programme at the Abramson Cancer Centre.

Robertson said the findings indicate that viral infection of neurons could be linked with neuropathology, and the ability of gamma herpesviruses to infect neurons could provide a new model system to study viral life cycles. However, he noted that the infection might not be the major cause of the brain disorders.

"There's likely to be association of this virus with neurons," he said. "But more studies will be necessary to know whether it is actually associated with disease pathology.”

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