HIV: The Ultimate Evolver (1 of 3)

Evolutionary biologists can help uncover clues to new ways to treat or vaccinate against HIV. These clues emerge from the evolutionary origins of the virus, how human populations have evolved under pressure from other deadly pathogens, and how the virus evolves resistance to the drugs we’ve designed. Controlling the disease may be a matter of controlling the evolution of this constantly adapting virus.

HIV micrographThe human immunodeficiency virus (HIV, shown here budding from a white blood cell) is one of the fastest evolving entities known. It reproduces sloppily, accumulating lots of mutations when it copies its genetic material. It also reproduces at a lightning-fast rate—a single virus can spawn billions of copies in just one day. To fight HIV, we must understand its evolution within the human body and then ultimately find a way to control its evolution.

Taking an evolutionary perspective on HIV has led scientists to look in three new directions in their search for treatments and vaccines:

• What are the evolutionary origins of HIV?
• Why are some people resistant to HIV?, and
• How can we control HIV’s evolution of resistance to our drugs?

Origins of HIV-1

1. What are the evolutionary origins of HIV?
HIV, like any evolving entity, has been deeply marked by its history. Scientists studying the evolutionary history of HIV found that it is closely related to other viruses. Those viruses include SIVs (simian immunodeficiency viruses), which infect primates, and the more distantly related FIVs (the feline strains), which infect cats.

However, studies of these related viral lineages showed something surprising: primates with SIV and wild cats with FIV don’t seem to be harmed by the viruses they carry. If scientists can figure out how non-human primates and wild cats are able to live with these viruses, they may learn how to better treat HIV infections or prevent them altogether.

The diagram shows some of the evolutionary history of HIV as we know it today. An ancestral virus (bottom) evolved into strains that infected chimpanzees (SIV). Over time, new strains began to infect humans (HIV).




• Scanning electron micrograph of HIV-1 budding from a white blood cell courtesy of the CDC.
• Evolutionary origin of HIV diagram, adapted from Evolution: The Triumph of an Idea, by Carl Zimmer, © 2001, Harper Collins Publishers. Used with permission.

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