Biotrin's description of the role of HHV-6 in AIDS

"HHV-6 infects and persists in CD4 T-lymphocytes, a
unique characterstic that it shares with human
immunodeficiency virus and a feature that separates it
from other herpesviruses. There is evidence that it
may interact with HIV and in this way serve as an
important cofactor in the pathogenesis of AIDS."
http://www.biotrin.ie/clinician/hhv/hhv6aids.htm