Figure 4.

Both infectious and UV-inactivated HHV-6A, but neither HHV-6B nor Measles virus, could induce MSRV-Env expression. U87 cells were either infected or put in contact with UV-inactivated virus and observed 24 h later for the expression of MSRV-Env. Following viruses at MOI 1 were used: (A,C) HHV-6A, (B) UV-inactivated HHV-6A, (D) mock-infected control, (E) HHV-6B, and (F) recombinant measles virus (MeV) vaccine strain expressing EGFP (green staining, *syncytia formation). The expression of MSRV-Env was detected using anti-MSRV-Env mAb immunofluorescence analysis, followed by anti-mouse-Alexa 555 (red staining), including DAPI (blue staining) to visualize cell nuclei (bar = 50 μm). Alternatively, primary mAb was replaced with the isotype control (C).