Background
Although the aetiology of multiple sclerosis (MS) remains elusive, it is clear that Epstein Barr virus (EBV) and possibly other viruses play a role in the pathogenesis of MS. Laboratory evidence suggests that human endogenous retroviruses (HERVs) could also have a role, but no interventional therapy has determined what will happen if HERVs are suppressed. Recent epidemiological evidence indicates patients with HIV infection have a significantly lower risk of developing MS and that HIV antiretroviral therapies may be coincidentally inhibiting HERVs, or other retroelements, that could be implicated in MS.