UL16 is bound to cytoplasmic capsids that are blocked in maturation budding. Cytoplasmic capsids from detergent lysed (A) WT, ΔUL37, or gE-/gD- infected cells were sedimented in 20 to 50% (wt/vol) sucrose gradients for 1 h. Fractions containing capsid bands were pulled with a needle syringe and pelleted through another 30% sucrose cushion. Purified capsids and associated proteins were separated by SDS-PAGE in 10% gels and analyzed by immunoblot with anti-VP5, anti-UL37, anti-UL16, anti-gE, and anti-gD rabbit serum. (B) ΔUL36 and ΔUL37 capsids were isolated from infected cells in parallel with WT as described above. cyto, cytoplasmic. WT, wild-type.