FIG. 2.
Fv1 and Ref1 restrictions of MLV particles harboring chimeric CA. Allelic fragment exchanges between Friend NB-tropic MLV (F, open boxes), N-tropic Akr-623 MLV (N, grey boxes), and B-tropic WNB5 MLV (B, black boxes) were generated using BamHI, EheI, XhoI, and BstXI restriction sites. Fragment combinations are designated by a three-letter code corresponding to the parental MLV fragments delineated by residues 33 to 86, 87 to 100, and 101 to 133, respectively. Infections were performed as described in Fig. 1. Relative decreases in titers with Fv1b are shown as mean ratios ± standard errors of the means of viral titers obtained on dunnin cells over dunnib cells whereas relative decreases in titers with Ref1 are shown as mean ratios ± standard errors of the means of titers obtained on dunnin cells over Ref1-positive HT1080 human cells. Data were calculated from at least three independent experiments. Underlined values indicate chimeras that are susceptible to Fv1b or Ref1 restrictions.