To distinguish between necrosis by viral replication and apoptosis by repression of HDAC1 and overexpression of p73, we monitored the changes in expression of the pro-apoptotic genes Apaf-1, Bax, Bim, and PUMA 48 hours after infection of SK-Mel-147 cells with the oncolytic viruses by real-time PCR. The gene discussed is HDAC1; the disease is infection.