Currently, a great deal of interest is in the newly recognized family of viruses known as HSV-6. This virus family is distantly related to HSV-1 (the cold sore virus) but is very closely related to the EBV and yet another family of viruses called HSV-7. Both HSV-6 and another closely related virus HSV-7 share two thirds of their DNA structure with the EBV virus.
Cross-reactivity of antibody to these viruses might be one explanation of the finding of “antibody to EBV” in MS. Both HSV-6 and HSV-7, as well as EBV, can infect the cells of the immune system (lymphocytes) and stimulate them to uncontrolled reproduction (immortalize them). Although all three viruses can infect the immune system and immortalize them, only HSV-6 and HSV-7 can infect cells in the nervous system. The HSV-6 virus has been found in the cells that make myelin, the oligodendrocytes, of MS patients.
Research into a possible role for EBV, HSV-6, and other related viruses continues. No convincing relationship of HSV-6 or HSV-7 to MS has, as yet, been firmly established. However, this remains an active and important area of research.