Virus Explorer

Click and drag or use the buttons below to move the model.

The viral envelope (gray) and viral proteins (red) involved in binding to and entering host cells are shown. The conical core is not visible.

HIV Cross Section

A. Glycoprotein; B. Reverse transcriptase; C. Integrase; D. Protease; E. Nucleocapsid protein; F. RNA genome; G. Capsid protein; H. Matrix protein; I. Lipid envelope

Human Immunodeficiency Virus (HIV)

  • Retroviridae family
  • ~120-nm enveloped particles with a conical core
  • Linear, ss + RNA genome of ~9,700 bp
  • Thought to have evolved from the simian immunodeficiency virus (SIV), HIV is a distinct virus that infects humans
  • No vaccine is currently available

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HIV was first recognized in humans in the 1980s. The virus infects and destroys immune cells, which means that as the infection progresses, people lose their ability to fight off disease. Acquired immunodeficiency syndrome (AIDS) refers to the advanced stages of HIV infection, when a person's immune system is severely impaired. Because HIV has evolved to permanently incorporate its genome into that of a host cell, the infection lasts a lifetime. There is no vaccine against HIV, although numerous drugs can keep infection at bay and hinder disease progression. Nearly 37 million people worldwide were infected with HIV by the end of 2014 and an estimated 2 million new infections occur every year.

Worldwide Prevalence of HIV

world map

Adult HIV prevalence (%), 2014, by WHO (World Health Organization) region

  1. Western Pacific: 0.1
  2. Eastern Mediterranean: 0.1
  3. South East Asia: 0.3
  4. Europe: 0.4
  5. Americas: 0.5
  6. Africa: 4.5
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Relative Sizes

Chart showing size comparison of different viruses.

The white line represents 100 nanometers (nm). For comparison, the width of a human hair is about 75,000 nm, so it would be 750 times as long!