Cell fusion by the envelope glycoproteins of persistent measles viruses which caused lethal human brain disease.
Measles virus (MV) rarely induces lethal diseases of the human central nervous system characterized by reduced expression of the viral envelope proteins and by lack of viral budding. The MV envelope contains two integral membrane proteins, termed fusion (F) protein and hemagglutinin (H) protein, and a membrane-associated matrix (M) protein. Previously, analysis of MV genes from autopsy material indicated that the M protein and the F protein intracellular domain are often drastically altered by mutations. Here, we present evidence that truncation of the F protein intracellular domain does not impair fusion function, and we suggest that this alteration interferes with viral budding. Unexpectedly, certain combinations of functional F and H proteins were unable to induce syncytium formation, an observation suggesting that specific F-H protein interactions are required for cell fusion. We also found that three of four H proteins of persistent MVs are defective in intracellular transport, oligosaccharide modification, dimerization, and fusion helper function. Thus, MVs replicating in the brain at the terminal stage of infection are typically defective in M protein and in the two integral membrane proteins. Whereas the M protein appears dispensable altogether, partial preservation of F-protein function and H-protein function seems to be required, presumably to allow local cell fusion. Certain subtle alterations of the F and H proteins may be instrumental for disease development.
Cattaneo
R
R
Department of Pathology, Yale University Medical School, New Haven, Connecticut 06510.
Rose
J K
JK
D001344:Autopsy; D017123:Bacteriophage T7 / Q000235:genetics; D001692:Biological Transport; D001927:Brain Diseases / Q000209:etiology; D002459:Cell Fusion / Q000502:physiology*; D002460:Cell Line; D003001:Cloning, Molecular; D004279:DNA, Viral / Q000235:genetics; D006031:Glycosylation; D006367:HeLa Cells; D006389:Hemagglutinins, Viral; D006801:Humans; D008457:Measles / Q000382:microbiology*; D008459:Measles virus / Q000472:pathogenicity / Q000502:physiology*; D009844:Oligosaccharides / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics; D011487:Protein Conformation; D011499:Protein Processing, Post-Translational; D012367:RNA, Viral / Q000235:genetics; D011994:Recombinant Proteins / Q000096:biosynthesis; D014759:Viral Envelope Proteins / Q000502:physiology*; D014760:Viral Fusion Proteins / Q000502:physiology*; D014762:Viral Interference; D014763:Viral Matrix Proteins; D014774:Virulence
D004279:DNA, Viral; D006389:Hemagglutinins, Viral; D009844:Oligosaccharides; D012367:RNA, Viral; D011994:Recombinant Proteins; D014759:Viral Envelope Proteins; D014760:Viral Fusion Proteins; D014763:Viral Matrix Proteins