Xinhua news agency, Beijing, January, 23 (reporter Peng Qian) COVID-19 is killing the world. How does it infect hundreds of millions of people around the world?
For the first time, an international team including Chinese researchers “captured” 3D images of the new coronavirus.
In the nanoscale image, the new coronavirus with an average diameter of less than 100 nm looks like a strange planet, with free swinging spike protein “tentacles” distributed on its surface. In the “planet” interior, ultra long RNA strands are tightly wound on the orderly arranged ribonucleoprotein complex (RNP).
On January 21, the high-definition popular science image of the new coronavirus was released by the team of Lisai Laboratory of School of life sciences of Tsinghua University, nanographics of Austria and Ivan Viola of King Abdullah University of science and technology of Saudi Arabia.
For human beings, the new coronavirus is a “familiar and strange” existence. It belongs to the same coronavirus family as severe acute respiratory syndrome (SARS) coronavirus and Middle East respiratory syndrome (mers) coronavirus. It is the third coronavirus that has caused large-scale human infection in the past 18 years.
The new coronavirus mainly infects human body by binding spike protein on the surface of the virus with human ACE2 receptor. Spike protein is like a “key”, while ACE2 receptor is like a “lock”. Only when the key is unlocked can the virus enter the cell. The main goal of the new vaccine is to prevent the key from opening the lock to prevent the virus from infecting cells.
The latest 3D images show the process of the new coronavirus invading human cells: at the moment of invasion, the new coronavirus binds to the receptor and fuses with the cell membrane.
Lisai research team introduced to reporters on the 23rd that the research found that spike protein is flexible and can swing freely on the surface of the virus like a chain hammer. The swing of spike protein will make the new coronavirus more flexible when attacking cells, which is conducive to the binding of spike protein with ACE2 receptor on cells.
The video image shows the angle between the spike protein and the tangent and vertical line of the new coronavirus membrane, as well as the swing angle range of spike protein on the surface of the virus membrane.
As early as September 15 last year, cell, an international authoritative academic journal, published online the cooperation results of Li Sai Laboratory of School of life sciences of Tsinghua University and Academician Li Lanjuan research group of State Key Laboratory of infectious disease diagnosis and treatment of the First Affiliated Hospital of Medical College of Zhejiang University.
They successfully analyzed the whole virus three-dimensional structure of the new coronavirus by using frozen electron microscopy tomography and sub section average reconstruction technology. This research result provides the basis for the latest 3D virus popular science image.
Freeze electron microscopic picture of new coronavirus inactivated by paraformaldehyde
In the laboratory of Tsinghua University, the inactivated new coronavirus was placed under the frozen electron microscope, and a total of 41 photos were taken every 3 ° rotation, and then three-dimensional reconstruction was carried out, just like “whole body CT examination” of the virus.
The team also “flashed a flashlight” to the inside of the virus, passed through the envelope, clearly illuminated the arrangement structure of the ribonucleoprotein complex inside the virus, showing the most complete image of the new coronavirus so far.
Frozen transmission electron microscope (TEM) is widely used in structural biology. It uses electrons as light source to penetrate virus samples to obtain the internal structural information of virus.
Three dimensional fine structure of whole virus of inactivated new coronavirus
Based on the virus structure analyzed by the frozen electron microscope tomography and sub section average reconstruction technology, the international research team used 3D rendering technology to produce fine 3D images of the new coronavirus, so that we can have a glimpse of the inside and outside of the virus. However, it should be noted that the contrast color of the virus in the video does not represent its real color, but the effect of 3D rendering.
The analysis of the structure of the new coronavirus also makes the research and development of vaccines and neutralizing antibodies more targeted. For example, Lisai’s team observed that the spike proteins on the surface of the new coronavirus were randomly distributed and in a variety of states. Such a complex antigen distribution makes it necessary to consider the specific distribution and structure of spike proteins on the surface of the virus when developing vaccines and neutralizing antibodies.
Li Sai told reporters that some agencies had previously released some hypothetical 3D models of the new coronavirus, but there were a lot of errors, such as the wrong distribution of spike proteins and the overall proportion of the virus. The research team hopes to make every detail of the virus image respect the cutting-edge scientific research findings of the virus.
Photo of Lisai team (provided by Lisai Lab) wpap60303br
In August last year, after seeing the scientific research achievements of Lisai laboratory submitted in biorxiv, the computer vision team of King Abdullah University of science and technology of Saudi Arabia took the initiative to contact each other, hoping to jointly create more scientific and more realistic popular science images of new coronavirus.
After several months of long-distance communication, the two sides made use of their own structural biology, virology expertise and image processing and programming advantages to construct a real 3D image of the virus, which was finally made into a video by the Austrian nanographics company.
“This is not an achievement that can be published, but we spent so much time making these new coronavirus image materials to show the true image of the virus and provide them to the world for free as epidemic prevention and control publicity and science education materials.” Lisai said that in some countries, there are still doubts about the real existence of the new coronavirus, and these images will be the scientific evidence for the existence of the virus. (edited by Wang Shen, Tang Zhiqiang and Xu Xiaolei, edited by sun Shuo)