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Complement activation by gp160 glycoprotein of HIV-1
N Thieblemont1, N Haeffner-Cavaillon, L Weiss
1Institute National de la Santé et de la Recherche Médicale U28, Hôpital Broussais, Paris, France.
AIDS Research and Human Retroviruses
|March 1, 1993
Summary
The HIV-1 envelope glycoprotein gp160 activates the human complement system and binds C3 fragments. This interaction, particularly with antibodies, may facilitate viral entry into target cells.
Area of Science:
- Immunology
- Virology
- Biochemistry
Background:
- The human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein gp160 plays a crucial role in viral entry.
- The complement system is a key component of innate immunity that can be activated by various pathogens.
Purpose of the Study:
- To investigate the capacity of HIV-1 gp160 to activate the human complement system.
- To determine if gp160 binds to C3 fragments and if this binding is antibody-dependent.
Main Methods:
- Incubation of mammalian-derived recombinant gp160 with seronegative human serum.
- Quantification of C3b/iC3b binding to gp160 using a specific biotinylated monoclonal antibody.
- Assessment of complement activation pathways (classical pathway) and requirement for C1q.
Main Results:
- Recombinant gp160 activated complement in a dose- and time-dependent manner.
- Complement activation proceeded via the classical pathway, independent of antibodies, and required C1q.
- Binding of anti-HIV IgG to gp160 enhanced complement activation and C3 cleavage, leading to C3b deposition.
Conclusions:
- HIV-1 gp160 directly activates the human complement system.
- Antibody binding significantly enhances complement activation by gp160.
- These findings suggest a mechanism for complement-mediated facilitation of HIV-1 entry into host cells.