Effects of the D286R mutation in UL31 on HSV-1 nuclear egress in Vero cells. Vero cells were infected with wild-type HSV-1(F), YK726 (UL31-D286R), or YK727 (UL31-D286R-repair) at an MOI of 3, fixed at 18 h postinfection, and examined by transmission electron microscopy. N, nucleus; C, cytoplasm; NM, nuclear membrane. Bars, 500 nm.