RNA therapies ⋅ Inserm, From science to health

07/03/2023 By gifsauce 741 Views

mRNA vaccines

Two first mRNA vaccines were marketed at the end of 2020, to fight against Covid-19. Several others are being developed against Zika virus infection or against the flu. With these vaccines, the goal is to produce a protein of the targeted infectious agent (an “antigen”) by cells of the vaccinated person. For this, he is administered the corresponding mRNA.

In the case of anti-Covid vaccination, it is the mRNA coding for the protein that allows the SARS-CoV2 virus to enter our cells, the Spike protein. Our cells then manufacture this protein and “present” it on their surface. The immune system recognizes it as if it were carried by the virus itself and activates the defense mechanisms and the memory response. Following this, the cells that have received the mRNA and express the protein of interest on their surface are rapidly destroyed. And the vaccine mRNA with. This mechanism is therefore very transitory.

Compared to traditional vaccines, the advantage of this approach is the ease of production of an mRNA: no need to cultivate potentially dangerous germs and to purify some of their components, two complex and expensive processes necessary for production conventional vaccines. Moreover, in addition to coding for an antigen, RNA molecules stimulate innate immunity: thus, it is not necessary to add an adjuvant to the vaccine preparation.

RNA therapies ⋅ Inserm, Science for health

However, these vaccines have drawbacks. First of all, mRNAs are particularly fragile molecules: to avoid their degradation, they must be stored at ultra-low temperatures. Researchers are currently working on new, less restrictive methods of preservation, for example with freeze-drying. Moreover, these molecules are unable to cross the cell membrane to be translated into protein. To facilitate their internalization in the cells, they are therefore vectorized by lipid particles (see below).

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