Human betaherpesvirus 7 (HHV-7) is one of nine known members of the Herpesviridae family that infects humans. HHV-7 is a member of Betaherpesvirinae, a subfamily of the Herpesviridae that also includes HHV-6 and Cytomegalovirus (HHV-5 or HCMV).[2][3] HHV-7 often acts together with HHV-6, and the viruses together are sometimes referred to by their genus, Roseolovirus.[4] HHV-7 was first isolated in 1990 from CD4+ T cells taken from peripheral blood lymphocytes.[5]