A possible viral cause for multiple sclerosis (MS) has long been suspected. A progressive increase in MS has been reported in Mexico during the past 20 years; a conspicuous antecedent of varicella infection during childhood has been the most relevant finding in the medical history of patients with MS.
To investigate the possible participation of varicella-zoster virus (VZV) in the etiopathogenesis of MS.
Design, Setting, and Patients
We searched, by polymerase chain reaction (PCR), for VZV DNA in peripheral mononuclear cells of 82 patients with relapsing-remitting MS. Additionally, genes gD from herpes simplex viruses 1 and 2 were sought by PCR, as well as IgG and IgM serum antibodies to VZV.
Viral DNA from the genes open reading frame (ORF)31, ORF62, ORF63, and ORF67 of VZV was found in mononuclear cells from 13 (87%) of 15 patients with MS who were tested during acute relapse. All patients who were tested during remission (n = 67) were negative for the DNA, including patients who were initially positive and were tested again after 2 months of remission. All control patients with a comprehensive variety of neurologic diseases (n = 100) and healthy controls (n = 20) also tested negative. All subjects were negative for herpes simplex viruses 1 and 2 DNA, and no differences were found in serum antibodies to VZV.
The finding of genes of VZV in peripheral mononuclear cells, restricted to a brief period during clinical relapse of MS, suggests either its participation in the etiopathogenesis of MS or an epiphenomenon of viral activation simultaneous with the relapse of MS.