Scientists Use Cryo-electron Microscopy to Study the Immature Form of the Zika Virus

A team of researchers has analyzed the structure of the immature form of the Zika virus. Although the mature version of the virus is pathogenic, host cells also release the immature form. By learning the molecular structure of these immature viruses, scientists may be able to determine if they play a role in infection. The findings are in a paper that was just published in the journal Nature Structural & Molecular Biology.

The Zika virus, which is spread by mosquitos and sexual contact, causes only mild symptoms in most patients. The problem is that while the virus may seem like a mild version of the flu, it’s much more dangerous to pregnant women. If a woman contracts the virus while pregnant, it can cause severe birth defects, including microcephaly, developmental problems, and an immune system disease called Guillain-Barré syndrome. There is currently no vaccine or cure but treatments can manage certain symptoms. There is unfortunately no way to avoid birth defects if a pregnant woman becomes infected.

Scientists from Purdue University studied the structure of the immature form of the Zika virus. The team used a technique called cryo-electron microscopy to analyze the molecular structure. Cryo-electron microscopy allowed the researchers to observe the virus at a resolution of 9 Ångstroms, a high enough resolution to note tiny structural details.

The research team found that the immature Zika virus had a similar structure to other related viruses, such as the West Nile virus and dengue fever. One major difference was the presence of a partially ordered capsid protein shell, which the authors point out as being uncommon in other flaviviruses. The immature form of Zika also arranges its membrane proteins as external spikes while the mature virus contains them inside a membrane.

The team’s findings provide new insights into the structural details of the immature Zika virus. Only the mature virus is pathogenic but infected host cells release both mature and immature viruses. By studying the immature form, scientists may be able to better understand how the virus functions.


Prasad et al. Structure of the immature Zika virus at 9 Å resolution. Nature Structural & Molecular Biology (2017).

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