SLTM and infection: To test this, we fixed infected cells 6 h after infection and stained them for either ICP4 (an immediate early protein that is required for HSV-1 gene expression) or ICP8 (an early protein required for HSV-1 genomic replication) and found that the nuclear foci of SLTM and YTHDC1 do not colocalize with replication compartments (Fig. 7G).