HIV stands for Human Immunodeficiency Virus. Like all viruses, HIV cannot grow or reproduce on its own. In order to make new copies of itself it must

What does HIV look like?

Outside of a human cell, HIV exists as roughly spherical particles (sometimes called virions). The surface of each particle is studded with lots of little spikes.

An HIV particle is around 100-150 billionths of a metre in diameter. That's about the same as:

• 0.1 microns
• 4 millionths of an inch
• one twentieth of the length of an E. coli bacterium
• one seventieth of the diameter of a human CD4+ white blood cell.