Researchers image virus structure at atomic resolution

UCLA researchers led by Hong Zhou have used cryo-electron microscopy to image a virus structure at 3.3 angstroms. Structurally accurate 3-D reconstructions of biological complexes are possible with cryo-electron microscopy because the samples are flash frozen, which allows them to be imaged in their native environment. Also, the microscope operates in a vacuum an environment better for electron travel.

The researchers studied the structure of the aquareovirus, a non-envelope virus that causes disease in fish and shellfish, in an effort to better understand how non-envelope viruses infect host cells. Envelope viruses such as influenza and HIV have an envelope-like membrane that the virus uses to fuse with and infect a host cell. Non-envelope viruses lack this membrane and infect cells with a poorly understood process that involves using a protein to fuse with the cells.

The high-resolution 3-D cryo-electron microscopy images showed that the aquareovirus uses a priming stage to accomplish cell infection. In its dormant state, the virus has a protective protein covering, which it sheds during priming. Once primed, it is ready to use a protein called an "insertion finger" to infect a cell.

Zhou said that better knowledge of virus structures could help with engineering of medications that work against viruses or that use engineered viruses to deliver drugs and gene therapy.

Research paper:
3.3-A Cryo-EM Structure of a Nonenveloped Virus Reveals a Priming Mechanism for Cell Entry
Xing Zhang, Lei Jin, Qin Fang, Wong H. Hui, and Z. Hong Zhou

Cell, Volume 141, Issue 3, 472-482, 15 April 2010 DOI: 10.1016/j.cell.2010.03.041