FIG. 5.

Competition of viral entry by soluble receptors (A) and the effect of proteolytic cleavage of the specificity domain on entry (B). (A) Competition of viral infections by soluble EGF (sEGF; top panel) or soluble IGF1 (sIGF1; bottom panel). CHO-hEGFr and Vero cells pretreated or not with sEGF were infected with MV^green or MV^green-H/XhEGF at a MOI of 0.3. 3T3-hIGF1r and Vero cells pretreated or not with sIGF1 were infected with MV^green and MV^green-H/XhIGF1 at a MOI of 0.1. The number of infected cells was determined at 24 h p.i. by counting GFP-expressing cells in a standard area. Percentages are relative to the number of GFP-expressing cells in infections without added soluble receptor. Results obtained with MV Edmonston on Vero cells are indicated by gray columns. Results obtained with recombinant MV on Vero cells are indicated by white columns and on rodent cells by black columns. (B) Effects of the treatment of recombinant viruses with FXa protease prior to infection. Vero and CHO-hEGFr or Vero and 3T3-hIGF1r cells were infected with MV^green-H/XhEGF or MV^green-H/XhIGF1 (10⁴ PFU/well), respectively, and were pretreated with 0, 5, or 50 μg of FXa protease/ml. The number of GFP-expressing cells was determined 42 h p.i. Percentages refer to the number of cells infected with untreated virus. For details, see text.