Protein composition of PrV-ΔUS3 virions. PrV-Ka (lanes 1) and PrV-ΔUS3 (lanes 2) virions were purified by sucrose gradient centrifugation and analyzed in sodium dodecyl sulfate-polyacrylamide gel electrophoresis with 10% (A and C) or 15% (B) polyacrylamide. After electrotransfer onto nitrocellulose membranes, blots were analyzed with antibodies against the US3, UL37, UL46, UL47, UL48, UL49, UL11, gB, gC, gD, gE, gI, gH, gK, and gM proteins. The locations of molecular mass markers are indicated on the left.