Although in the past scientists have noted the link between certain species of the herpes virus and some neurological conditions, the exact nature of the link has remained a mystery until now. Researchers from the University of Pennsylvania discovered the Epstein-Barr virus (EBV) and Kaposi's sarcoma-associated herpesvirus (KSHV) can infect and multiply in human neurons, as outlined in their study. The current data does not prove causality between these viruses and neurological diseases such as Alzheimer's and multiple sclerosis, but does suggest the possibility these viral infections underlie these disorders.
The team of researchers used genetically-modified viruses that express green fluorescent protein (GFP) and purposefully infected human neurons. Through careful microscope monitoring, they were able to view the protein expression of the viruses. They found that in both types of infections, the fluorescent signal appeared in the infected neuronal cells and many key viral proteins also made an appearance.
"I couldn't believe it," said Erle Robertson, who oversaw the study, in a press release. "After 50 years of studying EBV, nobody had ever seen the virus in nerve cells. But maybe they just never looked."
Despite the intriguing findings, further studies will need to be conducted in order to establish a causal relationship between herpes viruses and neurological disorders.
"There's likely to be association of this virus with neurons," said Robertson. "But more studies will be necessary to know whether it is actually associated with disease pathology.
Interestingly, when the EBV and KSHV viruses infect other cells types, they become latent and remain relatively harmless. This contrasts with their infection of neurons, where they direct the cells to their death.
The findings could help scientists create a new model for studying viral life cycles as well as be useful in the study of disease etiology.
