Figure 3.

(A) Representative selectivity and specificity assay for select phage clones from the f8/8 library. Individual phage clones were incubated at a constant concentration with: 1) target Calu-3 cells (black), 2) non-related MCF-7 cancer cells (striped), 3) phenotypically normal lung small airway epithelial cells (white), and 4) culture medium with 10% serum (grey). After washing, mammalian cells were lysed and the remaining phage were titered as described in the methods section. Percent recovery was plotted as the number of recovered phage per number of input phage particles for each phage clone. All phage clones binding Calu-3 cells were statistically different from an unrelated phage (P < 0.0001) and also different from paired phage samples with different targets (P < 0.0001). Phage interactions with MCF-7 cells were compared between paired phage samples with different targets and significant interactions were marked (* P < 0.0001). (B–D) Phage mode of interaction with Calu-3 cells after recovery of cell-associated phage by different elution steps with acid and detergent. Cells were split into three general subcellular fractions and the amount of phage associated with each fraction was determined by titering in K91BluKan E. coli. The portion of each fraction was calculated as the part of each fraction per total recovered phage. Three different classes of phage were identified: B) surface bound, C) cytoplasmic, and D) membrane bound.