NFKB1 and infection: The result indicated that the UL24-KO virus manifested no significant difference from the WT virus at the early stage; however, the UL24-KO virus replicated more slowly than did the WT virus at the late stage (Figure 2E).To test the role of UL24 in the negative regulation of NF-κB in PRV infection, we used PRV HeN1 and PRV-UL24-KO to infect HEK293T cells at a multiplicity of infection (MOI) of 10.