Antiviral screening assays for human herpesviruses 6 and 7

Human herpesviruses 6 and 7 are ubiquitous herpesviruses that normally infect their hosts early in life. There are two variant groups of human herpesvirus 6 (HHV-6): variants A (HHV-6A) and B (HHV-6B). Variant A has not been unambiguously associated with a specific disease but may contribute to disease in immunocompromised patients; variant B is the major etiologic agent of roseola (roseola infantum or exanthem subitum) and other febrile illnesses of young children, and has been associated with disease in immunocompromised patients. HHV-6B is frequently present in plaque regions in the brains of multiple sclerosis patients, although an etiologic association has not been proven. Human herpesvirus 7 (HHV-7) has been associated with some cases of roseola. The clinical spectrum of these viruses remains to be completely defined. Braun et al. (1) recently described three clinical scenarios that might warrant the use of antivirals to treat HHV-6 infections: (1) transplant recipients with idiopathic pneumonitis (2), multiple sclerosis patients, and (3) patients with HHV-6-associated encephalitis. For HHV-7, cases of neurologic involvement during primary infection might warrant investigation (2).