08/04/2021 at 2:30 AM #33476Anonymous UserParticipant
Corona: first look at vaccine proteins
Deceptively similar: for the first time, recordings show what the virus proteins formed by our cells after the corona vaccination look like – and how close they come to their role model, the spike protein of SARS-CoV-23. According to this, vaccination with vector vaccines such as AstraZeneca not only causes abundant viral proteins to sprout on the cells, they also resemble their model right down to the sugar deposits, as the researchers report.
The aim of all corona vaccines is to familiarize our immune system with the SARS-CoV-2 spike protein. Because then it forms suitable antibodies and T cells against this virus protein. If an infection with the coronavirus then occurs, it is neutralized before it can multiply in our cells. mRNA vaccines achieve this effect by smuggling the assembly instructions for the spike protein into the cells as messenger RNA. Vector vaccines such as Sputnik-V, AstraZeneca or Johnson & Johnson use a harmless carrier virus to bring the gene code into our cells.
However, what all vaccines have in common is that our cells then produce the viral spike protein and present it on their cell surface – this gives the immune system the incentive to remember this protein.
Vaccine proteins in sight
But how well does this principle work? And how perfectly do our cells mimic the viral protein? Yasunori Watanabe from the University of Southampton and his colleagues have now investigated this using the example of the AstraZeneca vaccine AZD1222. It is important here how well the vaccine proteins reproduce the viral protein structure, but also whether the sugar deposits typical for this protein match – because these glycans are also a distinguishing feature for the antibodies.
For their study, the researchers inoculated various human cell cultures with the vaccine viruses from this vaccine. After these cells had read out the instructions and formed the first viral proteins, they used antibody tests and high-resolution images from cryo-electron microscopy to check how well the viral model and the cellular vaccine product matched.
“Prickly” cells and a suitable structure
The result: around 60 to 70 percent of all cells in the inoculated culture showed the typical prickly spike proteins on their cell surface after a short time, as the images showed. “They revealed that the surface of these cells is densely littered with protruding structures whose shape and size match the conformation of the spike protein of SARS-CoV-2,” report Watanabe and his colleagues.
The structure of these cell-produced spike proteins corresponds to that which the virus shows before it attaches to the cell. Tests with various antibodies also showed that both the binding site and the three-part “head” of the protein and the stem region correspond to the original – at least so well that the antibodies successfully bound to it, as the team reports.
The sugar coating is also the same
Also important: the spike proteins generated by the cells also matched their viral model in terms of their sugar coating. These glycans first attach to the virus proteins in the body and thus mask their characteristic ends. Because they are very similar to the body’s own sugars, they help camouflage the virus from the immune system, but they also provide antibodies with additional identifiers.
The recordings and tests confirmed that the spike proteins newly formed by the vaccinated cells also quickly put on a sugar coating. “The expression of the SARS-CoV-2 spike proteins provoked by the vaccine results in the presentation of features similar to those of a natural infection,” said the researchers. “Overall, our study reveals a deceptively real mimicry of the spike protein, from the binding site to the protein structure to the glycan modification.”
Good sign of vaccine effectiveness
According to the research team, this confirms that the vector vaccine is doing its job, causing our cells to recreate the viral spike proteins. “This gives us confirmation that this vaccine is doing its job and producing the material that our immune system needs,” says Watanabe’s colleague Max Crispin. (ACS Central Science, 2021; doi: 10.1021 / acscentsci.1c00080)
Source: University of Southampton
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