Paramyxovirus fusion: real-time measurement of parainfluenza virus 5 virus-cell fusion.
Although cell-cell fusion assays are useful surrogate methods for studying virus fusion, differences between cell-cell and virus-cell fusion exist. To examine paramyxovirus fusion in real time, we labeled viruses with fluorescent lipid probes and monitored virus-cell fusion by fluorimetry. Two parainfluenza virus 5 (PIV5) isolates (W3A and SER) and PIV5 containing mutations within the fusion protein (F) were studied. Fusion was specific and temperature-dependent. Compared to many low pH-dependent viruses, the kinetics of PIV5 fusion was slow, approaching completion within several minutes. As predicted from cell-cell fusion assays, virus containing an F protein with an extended cytoplasmic tail (rSV5 F551) had reduced fusion compared to wild-type virus (W3A). In contrast, virus-cell fusion for SER occurred at near wild-type levels, despite the fact that this isolate exhibits a severely reduced cell-cell fusion phenotype. These results support the notion that virus-cell and cell-cell fusion have significant differences.
Connolly
Sarah A
SA
Howard Hughes Medical Institute, Northwestern University, Evanston, IL 60208-3500, USA.
Lamb
Robert A
RA
D000818:Animals; D002459:Cell Fusion; D002460:Cell Line; D006224:Cricetinae; D004285:Dogs; D005456:Fluorescent Dyes; D005470:Fluorometry; D007700:Kinetics; D009154:Mutation; D045402:Parainfluenza Virus 5 / Q000502:physiology*; D013194:Staining and Labeling; D013696:Temperature; D014760:Viral Fusion Proteins / Q000235:genetics / Q000502:physiology; D053586:Virus Internalization
D005456:Fluorescent Dyes; D014760:Viral Fusion Proteins