A Big Look at Small Invaders

A model of an alphavirus, which is closely related to West Nile virus; diameter about 70nm. A hepatitis E virus-like particle made of protein compounds along the edges of a 20-faced cage—an ideal nano-scale (about 27nm) template for designing vaccine or gene-therapy transport vehicles.

These three-dimensional images of viruses have been created by R. Holland Cheng, professor of molecular and cellular biology, and his fellow researchers, using cryoelectron microscopy—a new method that captures information not available with traditional techniques.

In conventional electron microscopy, samples are “fixed” with heavy metals that deflect electrons, providing image contrast. But that means only the surface can be imaged, said Cheng. In cryoelectron microscopy, liquid nitrogen or helium is used to fix samples by rapidly freezing them to extremely low temperatures. Researchers then take pictures from different angles and reconstruct them with a computer to create a three-dimensional image.

Cheng’s laboratory is using the technique to better understand the structure of viruses in the hope of developing new methods of treatment and prevention.

For more information, go to pioms.ucdavis.edu.

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