Ganciclovir
Ganciclovir has also been used with some success in treating "Human herpesvirus 6" infections.
Betaherpesvirinae
Betaherpesvirinae is a subfamily of viruses in the order Herpesvirales, in the family Herpesviridae. Mammals serve as natural hosts. There are currently 18 species in this subfamily, divided among 4 genera. Diseases associated with this subfamily include: human cytomegalovirus (HHV-5): congenital CMV infection; HHV-6: 'sixth disease' (also known as "roseola infantum" or "exanthem subitum"); HHV-7: symptoms analogous to the 'sixth disease'.