Virologists led by Serge Barcy, PhD at the Seattle Children’s Research Institute and the University of Washington have identified a homolog for HHV-7 in pigtail macaques. They were surprised to learn that it could be detected in the peripheral nerve ganglia, and hope to use their new animal model to explore how HHV-7 might play a role in demyelinating diseases.
“More and more evidence is building that herpes viruses may use the nervous system as a highway to spread and could be interfering with normal nerve function under certain circumstances” commented Barcy in an interview with Contagion Live. “Our next step in the research is to investigate this possible link.” The newly discovered virus has been named Macaca nemestrina herpesvirus 7 (MneHV7).
The KR4 antibody used to stain for human herpesvirus 7 showed positive staining for cells in peripheral ganglia tissues, including glial cells, as well as cells in the macaque salivary gland. Some of the positively stained cells appeared to be Schwann cells, a type of glial cell that helps keep peripheral nerve fibers alive. Since both HHV-6 and HHV-7 have been associated with demyelinating diseases of the nervous system (Tomsone 2001), the group speculates that Schwann cells may be susceptible to HHV-7/MneHV7 infection.
The salivary glands were also found to be a major reservoir for the HHV-7 homolog, and gene expression was much higher in the macaques with elevated DNA loads in the saliva. Similarly, the salivary gland tissue stained positive only in those macaques with high viral loads.
Positive staining using the HHV-7 KR4 antibody (brown) in salivary gland tissue (left) and peripheral nerve ganglia (right). Source: Journal of Virology
In humans, HHV-7 is both lymphotropic and neurotropic (Chan 1999, Chan 2000).
HHV-7 homologs have also been discovered in great apes, including gorillas and chimpanzees (Lavergne 2014). The group has also identified a homolog for HHV-6 that they have provisionally named MneHV6.
For more information, read the full paper: Staheli 2016