Structural 3D visualization of the spike protein 5utf from HIV-1. This lateral ribbon view of the structure was visualized with UCSF ChimeraX software. Secondary structures are colour-coded: red for alpha helices, yellow for B-sheets and green for loops. HIV-1 is one of the strains of Human Immunodeficiency Virus, the virus that causes acquired immunodeficiency syndrome (AIDS) in humans. It uses these spike proteins to bind and enter cells. These spikes have two components: gp120 and gp41. Many possible candidate vaccines against HIV-1 focus on neutralizing these spikes by attaching antibodies that can prevent it binding to host cells.