[Human herpesvirus 6 and 7 infections]

Abstract

HHV-6 was first isolated in 1986 from patients with lymphoproliferative disorders and was classified into 2 variants such as HHV-6A and HHV-6B. It was reported that HHV-6B is the causative agent of exanthem subitum (ES). Children start to be infected with HHV-6 at 6 month of age and almost all get antibody by 2 years old. HHV-6 infects latently after the primary infection and reactivates especially under the immunosuppressive condition. HHV-7 was first isolated in 1990 and the HHV-7 infection occurs later than HHV-6. Children get HHV-7 infection mostly inapparently, but HHV-7 also cause ES. Since HHV-6 has several genes which transactivate long terminal repeat (LTR) of HIV, it is proposed that HHV-6 may have a role as the cofactor for AIDS.