Western-blot analysis of cell free virions and Gag expression in cell lysates. 293T cells were transfected with WT or derived CA mutant HIV-1 molecular clones. Cell-associated proteins (A) or normalized amounts of viral particles present in culture supernatant (B) were processed for Western blotting experiments as described under "Materials and Methods" and revealed with anti-CA mAbs. Position of unprocessed Gag, p41 and p25 processing intermediates and mature CA is indicated. (C) Expression and maturation of the RTase subunits were determined from pelleted cell-free virions using anti-RTase mAbs. (D) Incorporation levels of CypA into WT and mutant virions were determined using anti-CypA. The mean CypA to CA ratio determined by densitometry scanning from three different experiments is indicated for each lane.