PAEP and infection: No gD positivity was detected in U937-pcDNA and U937-DN-IκB cells infected with UV-irradiated virus at any time assayed (Figures 3b and d), while in cells infected with non-irradiated HSV-1 gD positivity was detected as early as at 6 h after infection in the case of U937-DN-IκB cells and at a lesser extent at 12 h after infection in U937-pcDNA cells (Figures 3a and c), confirming that increased gD positivity was due to de-novo transcription and not due to residual gD from virus inoculum.