HUMAN-HERPES-VIRUS-6 AND HUMAN-HERPES-VIRUS-8 DNA-SEQUENCES IN BRAINSOF MULTIPLE-SCLEROSIS PATIENTS, NORMAL ADULTS AND CHILDREN

In order to determine whether the newly discovered human herpesviruses (HHVs) are involved in multiple sclerosis (MS), we investigated by po lymerase chain reaction the presence of specific deoxyribonucleic acid (DNA) sequences belonging to human herpesvirus 6 (HHV-6) and to human herpesvirus 8 (HHV-s), in the peripheral blood mononuclear cells (PBM Cs), and in the brain and spinal cord plaques from MS patients. Normal adult and stillborn children's brains were investigated as controls. PBMCs from 56 MS patients contained HHV-6 DNA in only 3 cases and in n one were there HHV-8 sequences. The cerebral DNA from 5 MS patients wa s positive for HHV-8 and not for HHV-6 sequences, while the nervous ti ssue of one patient who died with neuromyelitis optica was positive fo r HHV-6 and negative for HHV-8. The brains of 4/8 adult controls were positive for HHV-6, as were 3/8 for HHV-8; none of the 7 stillborn chi ldren's cerebral tissue contained HHV-6 sequences, while 2 contained H HV-8 DNA. Although these data do not support a hypothesis that there i s a role for these two HHVs in the pathogenesis of MS, nevertheless it may be suggested that(1) the two viruses possess strong neurotropism and the central nervous system seems to be a reservoir for them (2) HH V-6 infection is probably not transmitted maternally, but is acquired later in infancy.