FIG. 2.
Replication profiles and Gag-Pol expression of chimeric EIAV containing variant slippery sequences. (A) EIAVuk provirus containing the indicated mutations was transfected into ED cells. Supernatant medium of each transfected sample was collected at the indicated days posttransfection (dpt). RT activity of the collected supernatant was assayed as a measure of virus production from transfected cells. Slippery sequences and the origin of each mutant are indicated. Duplicates of each mutant were transfected, and the presented data are representative of three independent experiments. (B) Cellular lysates of Cos-1 cells transfected with CMVuk pro− proviruses carrying the indicated mutants were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis on a 3 to 8% gradient Tris-acetate gel (see Materials and Methods). EIAV-specific proteins were identified by immunoblotting with a reference immune serum from a naturally infected horse (8, 24). The data represent at least duplicate experiments. (C) Digitally quantified frameshifting efficiencies of the mutants from the Western blotting, with the mean value of duplicate wild-type controls set as 100%, using a Kodak imaging station (see Materials and Methods). The data presented here were calculated from at least duplicate samples.