Deadly in 3-D

Professor Stephen Fuller and some colleagues at Oxford University's Wellcome Trust Centre for Human Genetics have created a map of the 3-D structure of the virus (HIV) that causes AIDS.

They used a technique called cryo-electron tomography to see the virus. The technique has been used to look at the virus before, but its unusual variability in size and shape makes it hard to map. The Oxford scientists used a computer program to combine 100 images of 70 individual viruses. They looked for similarities to create a never-before-seen image of the virus' structure. (Read the original paper, published in the journal Structure.)

[IMAGE: To come]
[Caption: HIV, 60 times smaller than a red blood cell, is way too small to be seen with an ordinary microscope. Electron microscopes and x-rays can "see" it, but the images usually aren't great because the virus varies in size and shape. The variation is one of the unique features of HIV; most viruses are much more uniform.]

The shape of a killer

HIV particles, like other viruses, aren't cells but strands of genetic material wrapped in proteins. Viruses hijack living cells by replacing the cell's genetic code with their own, and then reproducing quickly. (Read about the life cycle of HIV and see an animation of how it all works.)

Scientists think that the size and shape variability that makes HIV hard to image is key to the virus' success, and they wondered how HIV, unlike other viruses, is so varied without losing its crucial structure. The new image provides some insight: the cone-shaped core of the virus spans the width of the viral membrane. Usually, the internal structure of a virus defines its size. But HIV's membrane determines its size instead, and limits the way it can assemble.

Understanding how the virus grows and assembles will help researchers develop new therapies for people infected with HIV.

Make it at the museum

A virus uses one protein over and over again to build a shape that encloses its RNA. HIV makes a geometric shape called an icosahedron—it has 20 identical triangular sides. HIV is an unusual virus—its internal structure is asymmetrical.

On Saturday, February 4, the Make It team will be on hand to help you make a virus model of your own to take home!

Your Comments, Thoughts, Questions, Ideas

Anonymous's picture
Anonymous says:

So this is pretty interesting news to follow that story about the shape of the virus...

posted on Tue, 02/07/2006 - 10:38pm
Rai's picture
Rai says:

wow, this is very interesting news never knew any of this stuff. thanks.

posted on Tue, 02/21/2006 - 9:45am

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