Treatable Human Endogenous Retroviruses (HERVs) in Multiple Sclerosis (MS), ALS and other Neurological Diseases – an Enemy from Within?

A microglial cell, labelled in green, contacts and attacks a myelinated axon (in red). In the presence of the pHERV-W envelope protein, this interaction leads to axonal injury. The blue structures are cell nuclei. Credit: HHU / Joel Gruchot / Patrick Küry It is surprising that only about 2% of human DNA encodes the 20,000 or so genes we all have. The other 98% used to be called junk DNA. About 8% of your DNA is made up of Endogenous retroviruses (ERVs) that have been picked up during evolution and most of which have been inactivated and can indeed be regarded as junk. Some of these old viruses that became part of human DNA remain fully functional, can be activated; they are implicated in disease ranging from Multiple Sclerosis (MS), to cancer, to schizophrenia and ALS (motor neuron disease). The best documented ERV is the one that affects some people with MS, it is called HERV-W (the H is for Human). Only in the presence of a protein ...