Complement component C3b binds directly to purified glycoprotein C of herpes simplex virus types 1 and 2.
Cells infected with herpes simplex virus type 1 (HSV-1), but not HSV-2, express on their surfaces a receptor for the complement component C3b. Receptor activity is markedly enhanced by treatment of the infected cells with neuraminidase. Employing a direct binding assay, consisting of purified HSV glycoproteins immobilized on nitrocellulose and iodinated C3b as a probe, we found that C3b binds directly to gC-1, as well as to gC-2, but not to gB or gD from either serotype. C3b binding was enhanced by treatment of gC-1 or gC-2 with neuraminidase. Endo F or endo H treatment of gC-1 had no effect on C3b binding. However, treatment of gC-2 with these endoglycosidases had a marked negative effect on C3b binding. These results suggest that N-linked oligosaccharides are involved in binding of C3b to gC-2, but not gC-1. Alternatively, removal of N-linked oligosaccharides from gC-2 might adversely affect polypeptide conformation. Glycoprotein C-2 also differs from gC-1 in its effects on the complement cascade. Whereas gC-1 accelerated the decay of the alternative pathway C3 convertase and impaired the efficiency of lysis by the components C5 through C9, gC-2 stabilized the active C3 convertase and had little effect on the late-acting components. The dissimilarity of gC-1 and gC-2 with regard to their effects on the complement cascade may have implications regarding the role of these glycoproteins in confronting the host immune response.
Eisenberg
R J
RJ
Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia 19104.
Ponce de Leon
M
M
Friedman
H M
HM
Fries
L F
LF
Frank
M M
MM
Hastings
J C
JC
Cohen
G H
GH
D000818:Animals; D015153:Blotting, Western; D002460:Cell Line; D003179:Complement C3b / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D006026:Glycoside Hydrolases / Q000494:pharmacology; D015151:Immunoblotting; D009439:Neuraminidase / Q000494:pharmacology; D018139:Simplexvirus / Q000276:immunology*; D014759:Viral Envelope Proteins / Q000378:metabolism*
D014759:Viral Envelope Proteins; C048232:glycoprotein C, herpes simplex virus type 2; C038535:glycoprotein gC, herpes simplex virus type 1; D003179:Complement C3b; D006026:Glycoside Hydrolases; D009439:Neuraminidase