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Structure of Zika virus revealed for first time in near-atomic resolution
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The structure of Zika virus has been revealed for the first time, captured in near-atomic detail by researchers who say their work could provide insight into how the growing disease might be treated or cured.
Scientists now have a map of the virus that shows potential regions that could be vulnerable to therapeutic treatment or vaccines, or be used to improve the ability to diagnose and distinguish Zika infection from that of other related viruses, according to Richard J. Kuhn, PhD, director of Purdue University’s Institute for Inflammation, Immunology and Infectious Diseases.
Figure 1. Researchers from Purdue University have captured the structure of Zika virus in near-atomic resolution.
Source: Purdue University
The researchers, led by Kuhn and Michael G. Rossmann, PhD, MSc, Hanley Distinguished Professor of Biological Sciences at Purdue, used cryogenic electron microscopy to capture a strain of the virus from the epidemic in French Polynesia in 3.8Å resolution.
Kuhn and Rossmann also were the first to map the structure of dengue virus in 2002 and West Nile virus in 2003.
“Determining the structure greatly advances our understanding of Zika — a virus about which little is known,” Kuhn said in a news release. “It illuminates the most promising areas for further testing and research to combat infection.”
Zika’s structure is very similar to other flaviviruses, with an RNA genome surrounded by a fatty membrane inside an icosahedral shell, according to the release. This was not surprising, according to Devika Sirohi, a graduate student at Purdue, who said the similarity to other flaviviruses may be helpful in terms of developing a Zika vaccine.
There are differences, however, she said. Mounting evidence has linked Zika virus to microcephaly and other grave fetal outcomes, as well as Guillain-Barré syndrome.
“Most viruses don’t invade the nervous system or the developing fetus due to blood-brain and placental barriers, but the association with improper brain development in fetuses suggest Zika does,” Sirohi said. “It is not clear how Zika gains access to these cells and infects them, but these areas of structural difference may be involved. These unique areas may be crucial and warrant further investigation.”
All known flavivirus structures differ in the amino acids that surround a glycosylation site in the virus wall, the researchers found, according to the release. In Zika, this site protrudes from the surface of the virus, and a carbohydrate molecule consisting of various sugars is attached to the viral protein surface. This may be what attracts human cells to the virus, the researchers said.
Further, the difference in amino acids between flaviviruses could signify differences in the kinds of molecules to which the virus can attach and the different human cells it can infect, according to Rossmann.
“If this site functions as it does in dengue and is involved in attachment to human cells, it could be a good spot to target an antiviral compound,” Rossmann said. “If this is the case, perhaps an inhibitor could be designed to block this function and keep the virus from attaching to and infecting human cells.”
Process recently captures image of HIV protein
Cryogenic electron microscopy also was used recently to capture a high-resolution image of an almost fully intact HIV protein responsible for infecting host cells.
Since the 1950s, X-ray crystallography has been the standard method for determining the structure of viruses, but the process is slow and requires a relatively large amount of virus, Rossmann said. Further, it can be difficult, especially for viruses like Zika that have a lipid membrane and do not organize accurately in a crystal, he said.
Comparatively, according to Rossmann, cryogenic electron microscopy allows researchers to view the virus in a more native state.
“This was unthinkable only a few years ago,” he said. – by Gerard Gallagher
Disclosure: The researchers report no relevant financial disclosures.
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