Polymerase chain reaction analysis of human herpesvirus-6 sequences in the sera and cerebrospinal fluid of patients with multiple sclerosis Steven H Goldberg 1 , Andrew V Albright 2,3 , Robert P Lisak 4 and Francisco Gonza´lez-Scarano 3 1 Clinical Neuroscience Track, 2 Cellular and Molecular Biology Graduate Group, the 3 Departments of Neurology and Microbiology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, and 4 Departments of Neurology and Immunology and Microbiology, Wayne State University School of Medicine, Detroit, Michigan, USA Several studies have suggested a possible association of human herpesvirus-6 (HHV-6) with multiple sclerosis (MS), a demyelinating disease with a variable course and progression. To determine whether HHV-6 could be detected in the sera of CSF of patients with different subtypes of MS, we performed nested polymerase chain reaction (PCR) on samples obtained from MS patients as well as samples from normal adults or individuals with other neurological diseases. Ninety-six serum samples from 24 patients with MS, including 13 individuals with relapsing remitting MS, one individual with primary progressive MS, seven individuals with secondary progressive MS and three individuals with an unspecified type were analyzed. Multiple serum samples were examined from individuals over varying periods of time and included samples obtained during exacerbations, remissions, and at different stages of progressive disease. HHV-6 DNA was detected only in one out of 15 serum samples that were collected over a number of years from one individual with secondary progressive MS. No HHV-6 DNA was detected in CSF from six patients with MS or 14 patients with other neurologic disease. These results indicate that the presence of HHV-6 DNA in the serum or CSF of patients with MS is not a common phenomenon, at least within the limits of the sensitivity of our assay. Keywords: HHV-6; multiple sclerosis; PCR amplification Introduction Multiple sclerosis (MS) is a demyelinating disease of the central nervous system with a variable course and progression. The search for the under- lying cause or causes of MS has encompassed extensive investigations of infectious (Cook et al, 1996), genetic (Hillert, 1996; Ebers et al, 1996; Sawcer et al, 1996; Haines et al, 1996, 1998) and environmental etiologies (Pryse-Phillips, 1996; Weinshenker, 1996), without resolution. Recent studies have proposed a relationship between MS and human herpesvirus-6 (HHV-6), and enveloped double stranded DNA virus with close homology to cytomegalovirus (CMV). HHV-6 is the etiologic agent of childhood febrile and exanthematous illnesses, hepatitis, and infectious mononucleosis- like illnesses, and is known to infect CD4+ T-cells (Lusso et al, 1988) and, at least in vitro, several CNS cell types including astrocytes, oligodendro- cytes, and microglia (He et al, 1996; Albright et al, 1998). In addition to MS, HHV-6 has been implicated in other disorders such as chronic myelopathy, chronic fatigue and lymphoprolifera- tive malignancies (Leach et al, 1992; Mackenzie et al, 1995). Primary HHV-6 infection may be either asympto- matic or result in non-specific symptoms, but PCR studies have indicated that the virus establishes a latent CNS infection in a large proportion of individuals with no known neurological disease (Luppi et al, 1994). The relationship between HHV- 6 and MS was first suggested by experiments where a DNA sequence nearly identical to the major DNA binding protein of HHV-6 was identified from one MS brain using representational display analysis (Challoner et al, 1995). Immunohistochemical studies showed that oligodendrocytes of MS pa- tients, but not those of control patients, expressed Correspondence: F Gonza´lez-Scarano, Department of Neurology, University of Pennsylvania School of Medicine, Clinical Research Building, Room 264, 415 Curie Boulevard, Philadelphia, Pennsyl- vania 19104-6146, USA Received 20 May 1998; revised 31 July 1998; accepted 3 August 1998 Journal of NeuroVirology (1999) 5, 134 – 139 ª http://www.jneurovirology.com 1999 Journal of NeuroVirology, Inc.