Mechanism of antibody action against virus infection

Consequences of Antigen-Antibody Binding

Antigen-Antibody Complex:  Formed when an antibody binds to an antigen

 it recognizes affinity: A measure of binding strength.

1.  Agglutination(Clumping of Virus) : Antibodies cause antigens (microbes) to clump together.

•          IgM (decavalent) is more effective that IgG (bivalent).

•          Hemagglutination:  Agglutination of red blood cells.  Used to determine ABO blood types and to detect influenza and measles viruses.

2.  Opsonization: Antigen (microbe) is covered with antibodies that enhances its ingestion and lysis by phagocytic cells.

3.  Neutralization: IgG inactivates viruses by binding to their surface preventing it from  penetrating and entering cells and neutralize toxins by blocking their active sites.

4.  Antibody-dependent cell-mediated cytotoxicity: Used to destroy large organisms (e.g.: worms).  Target organism is coated with antibodies and bombarded with chemicals from nonspecific immune cells.

5.  Complement Activation: Both IgG and IgM trigger the complement system which results in cell lysis and inflammation.