Dengue virus nonstructural protein 1 is expressed in a glycosyl-phosphatidylinositol-linked form that is capable of signal transduction.
Dengue virus nonstructural protein 1 (NS1) is expressed on the surface of infected cells and is a target of human antibody responses to dengue virus infection. We show here that dengue virus uses the cellular glycosyl-phosphatidylinositol (GPI) linkage pathway to express a GPI-anchored form of NS1 and that GPI anchoring imparts a capacity for signal transduction in response to binding of NS1-specific antibody. This study is the first to identify GPI linkage of a virus-encoded protein. The GPI anchor addition signal for NS1 was identified, by transfection of HeLa cells with dengue cDNA constructs, as a downstream hydrophobic domain in NS2A. GPI linkage of NS1 in both transfected and infected cells was demonstrated by cleavage of NS1 from the surface by PI-specific phospholipase C and by metabolic incorporation of the GPI-specific components ethanolamine and inositol. In common with other GPI-anchored proteins, addition of specific antibody resulted in signal transduction, as evidenced by tyrosine phosphorylation of cellular proteins. Antibody-induced signal transduction by GPI-linked NS1 suggests a mechanism of cellular activation that may contribute to the pathogenesis of human dengue disease. Signal transduction by a GPI-anchored viral antigen interacting with a specific antibody that it induces is a new concept in the pathogenesis of viral disease.
Department of Paediatrics, Imperial College School of Medicine, Norfolk Place, London W2 1PG, U.K.
M G
MG
Jacobs
P J
PJ
Robinson
C
C
Bletchly
J M
JM
Mackenzie
P R
PR
Young
D000595:Amino Acid Sequence; D000914:Antibodies, Viral / Q000276:immunology / Q000494:pharmacology; D003716:Dengue Virus / Q000235:genetics / Q000472:pathogenicity / Q000502:physiology*; D019856:Ethanolamine / Q000378:metabolism; D005434:Flow Cytometry; D017261:Glycosylphosphatidylinositols / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D007294:Inositol / Q000378:metabolism; D008969:Molecular Sequence Data; D043265:Phosphatidylinositol Diacylglycerol-Lyase; D010766:Phosphorylation / Q000187:drug effects; D019000:Phosphotyrosine / Q000378:metabolism; D021382:Protein Sorting Signals / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D014162:Transfection; D010738:Type C Phospholipases / Q000378:metabolism; D017361:Viral Nonstructural Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology / Q000378:metabolism*
D000914:Antibodies, Viral; D017261:Glycosylphosphatidylinositols; C082515:NS1 protein, dengue-1 virus; D021382:Protein Sorting Signals; D017361:Viral Nonstructural Proteins; D019000:Phosphotyrosine; D007294:Inositol; D019856:Ethanolamine; D010738:Type C Phospholipases; D043265:Phosphatidylinositol Diacylglycerol-Lyase