Effects of mutation(s) in UL51 and/or UL14 on HSV-1 secondary envelopment. Vero cells were infected with wild-type HSV-1(F), YK5015 (ΔUL14), YK5016 (ΔUL14-repair), YK5011 (ΔUL51), YK5012 (ΔUL51-repair), YK5013 (UL51LIY/AAA), YK5014 (UL51LIY/AAA-repair), YK5017 (ΔUL51/ΔUL14), YK5018 (ΔUL51/ΔUL14-repair), or R7356 (ΔUL13) at an MOI of 5, fixed at 18 h postinfection, embedded, sectioned, stained, and examined by transmission electron microscopy. Black arrows indicate unenveloped capsids. White arrows indicate partially enveloped capsids. Scale bar, 200 nm.