MOSCOW (MIPT) — The atomic structure of the novel coronavirus envelope has explained why it is exceptionally contagious. Its structural features make it much easier for the Chinese coronavirus to bind to target receptors, compared with the previously known SARS pathogen.
Molecular biologists in the U.S. have obtained the first 3D photos of the proteins on the surface of the coronavirus SARS-CoV-2, which is the cause of the pneumonia outbreak in China. According to the authors of the paper published in the bioRxiv online preprint repository, new findings are helpful for creating the vaccine and drugs against the disease.
Pavel Volchkov, who heads the Genome Engineering Lab at the Moscow Institute of Physics and Technology is available for comment on the coronavirus.
Q: What are the benefits of knowing the structure of the 3D viral envelope?
A: The 3D structure is helpful for understanding the protein interactions inside the virus. In particular, the new study reports that the structure clarifies how the virus binds to its receptor, how it infiltrates the cell, how the viral RNA is delivered and concealed from the host.
In the case of an infection, the numerous viral RNAs are transcribed (expressed), leading to the synthesis of other RNAs — messenger RNAs — and therefore proteins. So we gain insights into the molecular mechanisms at play, that is, exactly how the infection occurs.
Q: How can this help to develop a vaccine?
A: By figuring out the structure of the viral particle, we understand which protein components — the so-called epitopes exposed on the surface — we can use to develop a vaccine. In doing that, we rely on those parts that experience the most effective immune response. Usually, a combination of epitopes is used, prioritizing those exposed on the surface and triggering the production of antibodies, which ultimately bind the viral particles. This means that a vaccine does not actually target the virus as a whole, or all of its genes, but certain protein subunits.
Q: Why is this pathogen so contagious?
A: The researchers have shown that while the SARS-CoV-2 structure is very similar to that of the previous coronavirus, the new one has a much higher affinity for a certain surface receptor. There is a stronger interaction between the virus and its target, making it more contagious. The pathogen effectively causes an infection with fewer viral particles.
The researchers have also concluded that the characteristic epitopes of the previous severe acute respiratory syndrome virus, for which antibodies are available, are not present in the new virus. As a result, a therapy based on antibodies against SARS is not applicable, which has already been confirmed on practice.
The only effective antibodies are those generated by the immune system of patients who recovered from a SARS-CoV-2 infection. Only they can be used in a serum based on plasma extracted from donor blood. These antibodies are mostly polyclonal and will target multiple epitope sites on the coronavirus surface.
Q: Is a pandemic possible?
A: The likelihood of a pandemic coronavirus scenario is low. For this to happen, the situation in China has to repeat in other countries. China has launched a large-scale campaign to prevent the epidemic. The outbreak epicenters have been closed down, and other nations’ health agencies are also stepping up epidemiologic protection measures. As of Feb. 20, Russia has temporarily banned Chinese citizens from entering the country.
The MIPT website has more news about the research done at the Institute.