Complement activation by gp160 glycoprotein of HIV-1.
The ability of the gp160 envelope glycoprotein of HIV-1 to activate human complement and to bind C3 fragments was investigated by incubating mammalian-derived recombinant gp160 with seronegative serum and by quantitating the binding of C3b/iC3b to the protein using a biotinylated monoclonal antibody directed against a neoepitope expressed by cleaved human C3. Recombinant gp160 activated complement in a dose- and time-dependent fashion. Complement activation occurred through the classical pathway, independently of antibodies, and required C1q. Binding of anti-HIV IgG to rgp160 prior to exposure of the envelope glycoprotein to serum resulted in enhanced complement activation. Complexes of rgp120 with anti-HIV IgG also cleaved C3 in serum, resulting in deposition of C3b on gp120. These results provide a basis for C3-mediated facilitation of viral entry into target cells expressing receptors for fragments of human C3.
Thieblemont
N
N
Institute National de la Santé et de la Recherche Médicale U28, Hôpital Broussais, Paris, France.
Haeffner-Cavaillon
N
N
Weiss
L
L
Maillet
F
F
Kazatchkine
M D
MD
D000918:Antibody Specificity; D003167:Complement Activation; D003176:Complement C3 / Q000276:immunology; D003171:Complement Pathway, Classical; D015686:Gene Products, env / Q000276:immunology*; D015483:HIV Antibodies / Q000276:immunology; D015699:HIV Envelope Protein gp120 / Q000276:immunology; D019302:HIV Envelope Protein gp160; D015497:HIV-1 / Q000276:immunology*; D006801:Humans; D007700:Kinetics; D011498:Protein Precursors / Q000276:immunology*
D003176:Complement C3; D015686:Gene Products, env; D015483:HIV Antibodies; D015699:HIV Envelope Protein gp120; D019302:HIV Envelope Protein gp160; D011498:Protein Precursors