Isolation of human herpesvirus-6 (HHV-6) from patients with collagen vascular diseases.

The prevalence and activity of human herpesvirus-6 in patients with collagen vascular diseases (CVD) was determined. One hundred and fifty patients with CVD (56 with systemic lupus erythematosus-SLE, 92 with rheumatoid arthritis-RA, 1 with Sharp's syndrome and 1 with atypical polyclonal lymphoproliferation-APL and rheumatoid features) were screened serologically (IFA and ELISA) for antibodies against human herpesvirus-6 (HHV-6), Epstein-Barr virus (EBV) and cytomegalovirus (CMV). Virus isolation was attempted from peripheral blood lymphocytes (PBL) of 25 persons with various disorders. PBL were grown in tissue culture and tested with standard HHV-6-positive antisera for viral antigen expression. Supernatants of the patient's lymphocyte cultures were used to infect HSB2 cells, and virus infection in these cells was proven by IFA, in situ hybridization and by electron microscopy. Fifty-five percent of the SLE patients, 6.5% of the RA patients and both patients with Sharp's syndrome or with APL had antibody titers indicative of active HHV-6 infection. Virus cultures were positive in 9 of the 25 attempts with establishment of stable virus lines. These patients were 5 with SLE or UCVD, and one each with RA, CFS, APL as well as one healthy control. Reactivated and chronic active HHV-6 infections are frequent in SLE like EBV in RA. The role of these viruses in the pathogenesis of the diseases or in their reactivation still needs further investigation.