Molecular model of an HIV protein and an antibody that binds it

Neutralizing HIV

This colorful 3D molecular diagram represents an antibody (green) bound to a critical target on a specific protein present on the surface of the Human Immunodeficiency Virus (HIV), the virus that causes AIDS. This protein facilitates the entry of HIV into our cells. When an antibody neutralizes it, the HIV infection is significantly slowed or even stopped.

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Neutralizing HIV

What am I looking at?

This image is a visual representation of molecular data gathered via x-ray crystallography. The green lines and ribbons (1) represent antibody B12 which binds to a critical area, in yellow (2), on protein hiv-1 gp120, in red (3), of HIV virus particles.

Biology in the Background

HIV spreads through direct contact with the bodily fluids of infected individuals. Once individuals are infected, HIV particles target our T cells, a type of white blood cell. Healthy T cells identify and destroy pathogens in the bloodstream, earning a subset of them the descriptive name “killer T cells.” However, HIV invades and destroys these T cells, leaving the immune system less equipped to handle other infections.

However, our bodies can still defend against HIV in several ways. One defense strategy is producing antibodies against HIV particles. Antibodies are small molecules created by the immune system that identify and bind to specific targets on the surface of pathogens. This binding can generate different results, including preventing their target from carrying out its function and recruiting other immune cells to come and destroy whatever the antibody is bound to. The antibody in this image does the former: It binds to a surface protein on HIV particles, which prevents this protein from helping the virus enter our T cells.

The hiv-1 gp120 protein is about 125 nanometers long, roughly 600 times smaller than the width of a human hair.

Technique

This image was digitally constructed using x-ray crystallography data.