Several experimental vaccines COVID-19 are currently undergoing clinical trials. Moderna, the manufacturer of the vaccine mRNA-1273, says that their vaccine against the new coronavirus COVID-19 could be available this fall for a select group of people. This writes a Medium.
Phase I trials are mRNA-1273 began in early March. This experimental vaccine targeting proteins on the outside of the structure of the coronavirus. The vaccine works by introducing synthetic sequences in the mRNA of patients. These molecules allow the system host to translate them into proteins that mimic those contained in COVID-19. These proteins then circulate within humans and cause an immune response, which, as the researchers hope, will cause the immune system to COVID-19.
Introduction of mRNA vaccines for generation of protein expression is a complex process simply because it is contrary to the natural biology of the organism. In the cell, mRNA serves as an intermediary between the code recorded in the DNA of a cell, and ending protein, which she will create. mRNA formed in the nucleus of the cell, and as they Mature it moves to the cytoplasm (the space between the core and the outer plasma membrane), where it is translated into proteins by the ribosomes of cells. mRNA usually only stable within the cell long enough for the broadcast of proteins and shortly after that decays.
These vaccines require that the mRNA was introduced into the cytoplasm from outside the cells, which directly violates the basic biological dogma. In fact, the genetic material of any kind, which is introduced from the outside of the cell, is usually regarded as an alien invader and is rapidly degraded. This poses a challenge to vaccine efficacy of mRNA-1273.
Derrick Rossi of Harvard stem cell Institute and co-founder of Moderna has found a way to increase the stability of mRNA molecules introduced into the cell. RNA is a polymer consisting of only 4 main molecules known as nucleotides — adenine, guanine, cytosine and uracil (A, G, C, U), — associated with each other. Team Rossi found that modifying two of these molecules, it can improve stability of the molecule. One of the changes that he made — to replace the uracil with pseudorutile. This simple change allowed the mRNA injected cells, avoid degradation long enough to Express their encoded proteins.
Another problem facing mRNA-vaccines, is the shifting of mRNA through the outer cell membrane. Plasma membrane acts much like the skin cells, selectively deciding which molecules can penetrate into the cell or out of it, and which are not. The mRNA molecules cannot easily cross the plasma membrane, so mRNA vaccines need a little help.
There are technologies that bind mRNA vaccines with molecules, which allows them to penetrate the cell. They can include such molecules as the protamines, lipids and nanoparticles, all of which are intended to make them more permeable, or allow them to get into the cage.
Test results phase 1 for mRNA-1273 have to wait another few weeks, but the team hopes that they will be able to produce a vaccine in limited quantities in autumn 2020.
Who will get the vaccine?
If tests are successful, the release of mRNA-1273 will be carried out in a limited way, perhaps only for medical professionals. An experimental vaccine mRNA-1273 is still awaiting the results of the first phase of clinical trials, which currently takes place in Washington state.