Herpesviruses, including human herpesvirus-6 and varicella zoster virus, have been implicated in the disease aetiology of multiple sclerosis. These viruses are capable of reactivation, reminiscent of the relapsing-remitting nature of multiple sclerosis. However, viral DNA has also been reported present in healthy controls, often at similar prevalence rates. This study aimed to determine whether prevalence could be associated with different stages of activity of the disease as well as the inflammatory status of the patients. Polymerase chain reaction assays were used to screen for human herpesvirus-6 and varicella zoster virus DNA in blood from 31 Caucasian patients with multiple sclerosis and 30 healthy age, sex and race matched control subjects. The patients were screened for inflammation using C-reactive protein as a marker and were also categorized according to their remitting/relapsing status. Results were positive for human herpesvirus-6 in blood from only one patient (3.2%) and human herpesvirus-6 DNA was not present in any control subjects. Varicella zoster virus was not detected in either the patients or control subjects. Similar to some other studies we saw an absence or very low viral positivity in blood from both patients and controls. These findings were irrespective of relapse episodes, increased inflammatory status or duration of the disease. Results therefore do not support a causative role for either human herpesvirus-6 or varicella zoster virus in the disease aetiology of multiple sclerosis, but rather that prevalence in patients may be linked to that of the general population
This papers for a causal link between MS and two different viruses and comes up short in both cases as there are too many people with MS who don’t have evidence of infection. This has constantly been the case for HHV-6 so it it is either one of many causative agents or more likely a secondary effect that this virus has been spotted in MS.