Detection of human herpesvirus-6 DNA by polymerase chain reaction in serum or plasma.

Human herpesvirus-6 (HHV-6) is a newly identified human pathogen. Currently clinicians rely mainly on blood lymphocyte culture and serological tests to diagnose HHV-6 infection. The polymerase chain reaction (PCR) was carried out on the plasma or sera of patients to determine the value of PCR in the diagnosis of HHV-6 infection. A total of 30 patients entered the study; 10 were experiencing acute HHV-6 infections and 20 were healthy and served as controls. HHV-6 DNA was detected by PCR in the serum or plasma of the 10 cases with acute HHV-6 infections. All 20 controls had no HHV-6 DNA in their sera. The time for serum to become PCR-positive coincided with the appearance of IgG HHV-6 antibody. The relatively late presence of HHV-6 DNA in serum might result from late lysis of infected cells by immune responses. It is concluded that detection of HHV-6 DNA by PCR in the serum is a valuable tool for the diagnosis of acute and/or active viral infection.