MUTANTS OF THE PARAMYXOVIRUS SV5 FUSION PROTEIN - REGULATED AND EXTENSIVE SYNCYTIUM FORMATION

To study paramyxovirus-medialed cell fusion it would be advantageous t o express in a cell a single protein that could cause regulated syncyt ium formation at neutral pH following a specific activation signal. We have constructed two SV5 fusion (F) protein mutants that contain thre e arginine residues in the cleavage site and two separate glycine to a lanine changes in the fusion peptide. The mutants were expressed in CV -1 cells using an SV40 recombinant virus vector. The mutant F proteins required addition of exogenous trypsin to cleave F-0 to F-1 and F-2. Massive syncytium formation occurred within 2-4 hr following addition of trypsin to the SV40 recombinant F virus-infected CV-1 cells. (C) 19 95 Academic Press, Inc.