Human herpesvirus 6 is latent in peripheral blood of patients with relapsing-remitting multiple sclerosis.

Studies of the association between HHV-6 and multiple sclerosis are hindered by the difficulty in discriminating between latent and active infection. A follow up study was undertaken of patients with multiple sclerosis, searching peripheral blood mononuclear cells for molecular markers associated with HHV-6 latency and lytic replication. The results show that HHV-6 is latent and did not support systemic infection in patients with multiple sclerosis. Likewise, patients with multiple sclerosis did not show any evidence of active infection with other human herpesviruses HHV-7 and HHV-8.