Fifteen HHV-6 isolates from normal donors, patients with immunodeficiency syndromes, systemic lupus erythematosus (SLE). atypical polyclonal lymphoproliferation (APL), leukopenia and Exanthum subitum revealed biological, immunological and molecular differences which may be important for seroepidemiological and other immunovirological studies. Active HHV-6 infection was observed in patients with APL, AIDS, Sjogren's syndrome. Hodgkin's disease, chronic fatigue syndrome, SLE and some transplant patients, based on reactivities of HHV-6 monoclonal antibodies with lymphocytes from the patients, presence of IgM antibody to HHV-6 and significant elevation in IgG antibody. Reactivation of HHV-6 may contribute to immune disturbances, either by interfering with function of immunocytes or by polyclonal stimulation of T-cells, which, in turn, lead to disease manifestations.
