Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Electron microscopy captures snapshot of structure coronaviruses use to enter cells

29.02.2016

Atomic model suggests vaccine strategies against deadly pandemic viruses such as SARS-CoV and MERS-CoV

High-resolution cryo-electron microscopy and supercomputing have now made it possible to analyze in detail the infection mechanisms of coronaviruses. These viruses are notorious for attacking the respiratory tract of humans and animals.


Coronaviruses -- the agents behind outbreaks of new kinds of pneumonia -- employ molecular tactics to infect cells.

Credit: Veesler Lab/University of Washington

A research team that included scientists from the University of Washington (UW), the Pasteur Institute and the University of Utrecht has obtained an atomic model of a coronavirus spike protein that promotes entry into cells. Analysis of the model is providing ideas for specific vaccine strategies. The study results are outlined in a recent UW Medicine-led study published in Nature. David Veesler, UW assistant professor of biochemistry, headed the project.

These viruses, with their crowns of spikes, are responsible for almost a third of mild, cold-like symptoms and atypical pneumonia worldwide, Veesler explained. But deadly forms of coronaviruses emerged in the form of SARS-CoV (severe acute respiratory syndrome coronavirus) in 2002 and of MERS-CoV (Middle East respiratory syndrome coronavirus) in 2012 with fatality rates between 10 percent to 37 percent.

These outbreaks of deadly pneumonia showed that coronaviruses can transmit from various animals to people. Currently, only six coronaviruses are known to infect people, but many coronaviruses naturally infect animals. The recent deadly outbreaks resulted from coronaviruses overcoming the species barrier. This suggests that other new, emerging coronavirus with pandemic potential are likely to emerge. There are no approved vaccines or antiviral treatments against SARS-CoV or MERS-CoV.

The ability of coronaviruses to attach to and enter specific cells is mediated by a transmembrane spike glycoprotein. It forms trimers decorating the virus surface. Trimers are structures assembled from three identical protein units. The structure the researchers studied is in charge of binding to and fusing with the membrane of a living cell. The spike determines what kinds of animals and what types of cells in their bodies each coronavirus can infect.

Using state of the art, single particle cryo-electron microscopy and supercomputing analysis, Veesler and his colleagues revealed the architecture of a mouse coronavirus spike glycoprotein trimer. They uncovered an unprecedented level of detail. The resolution is 4 angstroms, a unit of measurement that expresses the size of atoms and the distances between them and that is equivalent to one-tenth of a nanometer.

"The structure is maintained in its pre-fusion state, and then undergoes major rearrangements to trigger fusion of the viral and host membranes and initiate infection," Veesler explained.

The coronavirus fusion machinery is reminiscent of the fusion proteins found in another family of viruses, the paramyxoviruses, which include respiratory syncytial virus (the leading cause of infant hospitalizations and wheezing in children) as well as the viruses that cause measles and mumps. This resemblance implies that the coronavirus and paramyxovirus fusion proteins could employ similar mechanisms to promote viral entry and share a common evolutionary origin.

The researchers also compared crystal structures of parts of the spike protein in mouse and human coronaviruses. Their findings provide clues as to how the molecular structure of these protein domains might influence which specific animal species the virus is able to infect.

The researchers also analyzed the structure for possible targets for vaccine design and anti-viral therapies. They observed that the outer edge of the coronavirus spike trimer has a fusion peptide - a chain of amino acids - that is involved in viral entry into host cells. The easy accessibility of this peptide, and its expected similarity among a number of coronaviruses, suggests possible vaccine strategies to neutralize a variety of these viruses.

"Our studies revealed a weakness in this family of viruses that may be an ideal target for neutralizing coronaviruses," Veesler said.

There may be a way, the researchers noted, to elicit broadly neutralizing antibodies recognizing this peripheral peptide. Neutralizing antibodies protect against infections by stopping a mechanism in a pathogen. Broadly neutralizing antibodies would be effective against several strains of pathogen, in this case coronaviruses. The physical structure of the fusion peptide inspires ideas for the design of proteins that would disable it.

"Small molecules or protein scaffolds might eventually be designed to bind to this site," Veesler said, "to hinder insertion of the fusion peptide into the host cell membrane and to prevent it from undergoing changes conducive to fusion with the host cell. We hope that this might be the case, but much more work needs to be done to see if it is possible."

The coronavirus spike protein structure described in this Letter to Nature is expected to resemble other coronavirus spike proteins.

"Therefore, the structure we analyzed in the mouse coronavirus is likely to be representative of the architecture of other coronavirus spike proteins such as those of MERS-CoV and SARS-CoV," the researchers observed.

The researchers summed up their paper, "Our results now provide a framework to understand coronavirus entry and suggest ways for preventing or treating future coronavirus outbreaks."

"Such strategies," Veesler said, "would be applicable to several existing coronaviruses and to emerging future strains of coronavirus that conserve this same structure for entering cells."

###

Co-authors of the paper included University of Washington lab heads David Veesler and Frank DiMaio, Pasteur Institute lab head Felix A. Rey and University of Utrecht lab heads Berend-Jan Bosch and Peter J.M. Rottier. The other authors of the study "Cryo-electron microscopy structure of a coronavirus spike glycoprotein trimer" were Alexandra C. Walls, M. Alejandra Tortorici and Brandon Frenz.

The research was supported by a grant from the National Institute of General Medical Sciences at the National Institutes of Health (T32GM008268). The research also benefited from the National Resource for Automated Molecular Microscopy (grant GM103310) and from the Hyak supercomputer system at the University of Washington.

Media Contact

Leila Gray
leilag@uw.edu
206-685-0381

http://hsnewsbeat.uw.edu/ 

Leila Gray | EurekAlert!

More articles from Health and Medicine:

nachricht NIST scientists discover how to switch liver cancer cell growth from 2-D to 3-D structures
17.11.2017 | National Institute of Standards and Technology (NIST)

nachricht High speed video recording precisely measures blood cell velocity
15.11.2017 | ITMO University

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: A “cosmic snake” reveals the structure of remote galaxies

The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.

Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...

Im Focus: Visual intelligence is not the same as IQ

Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.

That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...

Im Focus: Novel Nano-CT device creates high-resolution 3D-X-rays of tiny velvet worm legs

Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.

During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....

Im Focus: Researchers Develop Data Bus for Quantum Computer

The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.

Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...

Im Focus: Wrinkles give heat a jolt in pillared graphene

Rice University researchers test 3-D carbon nanostructures' thermal transport abilities

Pillared graphene would transfer heat better if the theoretical material had a few asymmetric junctions that caused wrinkles, according to Rice University...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Ecology Across Borders: International conference brings together 1,500 ecologists

15.11.2017 | Event News

Road into laboratory: Users discuss biaxial fatigue-testing for car and truck wheel

15.11.2017 | Event News

#Berlin5GWeek: The right network for Industry 4.0

30.10.2017 | Event News

 
Latest News

NASA detects solar flare pulses at Sun and Earth

17.11.2017 | Physics and Astronomy

NIST scientists discover how to switch liver cancer cell growth from 2-D to 3-D structures

17.11.2017 | Health and Medicine

The importance of biodiversity in forests could increase due to climate change

17.11.2017 | Studies and Analyses

VideoLinks
B2B-VideoLinks
More VideoLinks >>>