Packaging of actin into VLPs. A) Human 293T cells were mock-transfected (lane 1), or transfected with VP40 alone (lane 2), VP40 + GP (lane 3), VP40 + GPΔM (lane 4), or VP40 + sGP (lane 5). Radiolabeled VP40 was detected in cell extracts (cells) and in VLPs. Actin was detected in VLPs by immunoprecipitation using an anti-actin polyclonal Ab. B) VP40 VLP samples were untreated (lane 1), treated with trypsin alone (lane 2), or treated with trypsin + TX-100 (lane 3). VP40 and actin were detected by immunoprecipitation. C) Indirect immunofluorescence of VP40 (green) and actin (red) with the merged image shown in yellow.