The deadly new coronavirus has infected more than 1,000,000 people worldwide brought global society to a screeching halt. Scientists across the world are racing to understand: What makes this submicroscopic pathogen super contagious between humans? Understanding the transmission of the virus can identify its containment and future prevention.
Despite the fact that the SARS-CoV-2 originated in animals,
it is very effective in causing the disease in humans.
Researchers have identified key features that make it very successful in causing the pandemic.
Coronaviruses are surrounded by a halo of spike proteins.
These spike proteins look like a crown and help the virus latch onto the host cell membrane.
The spike protein binds to the cell membrane and changes its shape.
It morphs from looking like a club, to looking like a spear – According to a study at McGill University’s department of medicine.
It fuses with the human cell membrane, allowing the genome of the virus to enter human cells and begin infection.
It then replicates, making million copies of itself, which then exit to infect other cells or spread to the next human.
The coronavirus attaches itself to the host cell membrane through its activation sites.
Its spike protein has a site that becomes activated by a host-cell enzyme called furin.
Furin is found in human tissues ranging from liver, lungs, to small intestines.
This means that the virus can potentially attack multiple organs at once.
– Report by Li Hua, structural biologist at Huazhong University of Science and Technology in Wuhan, China
The furin activation sites set-up for the virus entry into cells very differently to SARS, thus possibly affects virus stability and hence transmission.
– Report by Professor Gary Whittaker, a virologist at Cornell University in Ithaca, New York.
Researchers at the University of Texas have also identified another feature that makes the human cell so vulnerable to the new coronavirus.
The spike protein recognizes and sticks to a receptor protein called ACE2, known as angiotensin-converting enzyme found on the surface of human cell.
The spikes of SARS-CoV-2 allow it to stick to our cells far more effectively than other types of SARS virus.
Most respiratory viruses infect and replicate in either the upper or lower airways.
In the case of the new coronavirus, both upper and lower airways are infected.
It resides in the upper respiratory tract, where it is easily coughed or sneezed onto its next victim.
In some patients, it can penetrate far more deeply within the lungs, where the disease can kill.
That combination gives it the contagiousness and lethality.
Some viruses are highly contagious, while other viruses are less so.
The new coronavirus spreads between people before any symptoms show up, which makes it easy for the virus to transmit to multiple hosts, and makes it difficult for us to identify and contain it.
Researchers worldwide are racing to develop potential vaccines and drugs to fight this new coronavirus.
Understanding the structure of the coronavirus and how it invades human cells, opening the door to the development of a vaccine.
For instance, finding specific molecules that could block furin as possible therapies, or developing a drug that blocks the ACE2 receptor and prevents the virus to enter cells.
- Walls, A. C. et al. Preprint at bioRxiv https://doi.org/10.1101/2020.02.19.956581 (2020).
- Li, H. et al. Preprint at ChinaXiv http://chinaxiv.org/abs/202002.00062 (2020).
- Jaimes, J. A., André, N. M., Millet, J. K. & Whittaker, G. R. Preprint at bioRxiv https://doi.org/10.1101/2020.02.10.942185 (2020).
- Coutard, B. et al. Antiviral Res. https://doi.org/10.1016/j.antiviral.2020.104742 (2020).
- Wrapp, D. et al. Science https://doi.org/10.1126/science.abb2507 (2020).
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