CD4 and Epstein-Barr virus infection: Whether astrocytes, oligodendrocytes and thyrocytes are part of the normal tropism of HHV-6 is not clear, or similar to EBV infection of T and NK cells in CAEBV, and of smooth muscle cells in CD4 immunosuppression or GATA2 PID, unknown circumstances promote/sustain infection in atypical cells.