Intracellular degradation of SIV specific peptides from gas vesicle treated monolayers. Immunostaining of r-GVTat. Rev or Nef1 treated monolayers with anti-SHIV antisera demonstrates the time dependent disappearance of these epitopes from the macrophages. Note that for all three, the epitope specific immunostaining diminishes over time: 24-120 h post application. Additionally, the level of fluorescence detected is consistent with the SIV insert size. For the samples harvested at 48 h post addition, the larger Nef1 insert, expressed by r-GVNef1 appears more intensely stained than the inserts for r-GVTat or r-GVRev. Original magnification 1000 ×.