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By taking advantage of the latest technological advancement done in microscopy, scientists are getting a much clearer picture of viruses. In a recent study, researchers were able to study the how viruses infect and modify the cells they infect through the use of the cryo-CLEM technique.

In a study published in the January issue of Natural Protocols, researchers from Emory University School of Medicine have developed workflows using the cryo-CLEM technique to study viruses in infected cells. This refined technique in viruses helped the researchers to study the viruses in their natural state and see the various genetic modifications viruses make to alter and assemble themselves in the infected cell.

By using the latest in microscopy, the cryo-light and electron microscopy (cryo-CLEM), the researchers developed workflows to take advantage of the microscope to get a better and clearer image of the viruses. Virus-infected or transfected cells were grown on carbon-coated gold grids. These samples were then vitrified or cooled down rapidly so that ice crystals would not form. Once cooled, the not frozen cells are examined by cryo-fluorescent light microscopy and cryo-electron tomography.

By freezing the cells, the viruses in the infected cells are prevented from growing and moving. It is also important to freeze samples as the microscopes can only be used in extremely low temperatures. With the aid of a computer software, the images taken from both cryo-fluorescent light microscope and cryo-electron tomography are combined.

Using this technique, the researchers were able to study the respiratory syncytial virus (RSV). Their work, published in Nature Communications, demonstrated that an RSV and a live attenuated vaccine candidate resemble each other structurally.

"Potentially, the cryo-CLEM technique could be extended to study many systems including neuronal cells or bacterial biofilms", says Dr. Elizabeth R. Wright, director of Emory's Robert P. Apkarian Integrated Electron Microscopy Core and a Georgia Research Alliance Distinguished Investigator.