American molecular biologists have created another vaccine against a new type of coronavirus, replacing part of the genome of a weakened form of the flu virus with SARS-CoV-2 RNA. The drug was successfully tested on mice, scientists write in an article published by the electronic scientific library bioRxiv.
вЂњA single dose of this vaccine caused the body of mice to produce about the same amount of antibodies that neutralize SARS-CV-2 as they are contained in the blood serum of people who have been ill with COVID-19. However, the vaccine did not cause any symptoms of the disease in rodents. It can be produced on an industrial scale, using existing platforms for flu shots,вЂќ the researchers write.
In recent months, scientists have begun testing various types of new-type coronavirus (SARS-CoV-2) vaccines. Some of them are tested on animals, others-on people. Scientists expect to learn the first results of the tests next year if the method of testing vaccines does not change.
Many of these drugs are based on an untested technology that inserts RNA fragments into human cells and causes them to produce a lot of virus proteins. Scientists are developing both classic inactivated and recombinant vaccines based on weakened viral particles and ready-made fragments of the virus envelope. In both cases, the creation of mass production of these drugs will be very difficult to implement, and there are no guarantees of success yet.
A group of American virologists and molecular biologists led by associate Professor of the University of Washington (USA) Jesse bloom tried to circumvent many of these problems. They used a widely used flu shot as the basis for the coronavirus vaccine.
In its role is a regular seasonal flu vaccine, which is based on a weakened form of the H1N1 virus. Scientists have suggested that the structure of the RNA of the influenza pathogen can be changed so that its particles are not molecules of the enzyme neuraminidase, but the protein RBD вЂ” a key component of the SARS-CoV-2 envelope, which is involved in the penetration of the coronavirus into the cell. In this way, the flu vaccine can be turned into a COVID-19 treatment.
Based on these considerations, virologists created a short copy of the part of the RNA of the coronavirus that is responsible for the formation of RBD molecules and changed it so that when irradiated with ultraviolet light, this protein began to glow green. Biologists inserted this segment of RNA into the genome of the flu virus and multiplied it in cell cultures.
After making sure that the modified H1N1 strain successfully entered the cells and infected them, the scientists tested the vaccine's performance on ordinary laboratory mice. Experiments showed that two to three weeks after the introduction of the vaccine, all seven rodents began to produce antibodies to the RBD protein. Moreover, their concentration was the same or even higher than in the body of people who had undergone COVID-19.
At the same time, the researchers note, the mice did not show visible symptoms of anxiety or illness. This suggests that due to genetic manipulation, the virus was sufficiently weakened. As aвЂќ bonus вЂњ rodents received protection from the form of seasonal flu that was used in the creation of the vaccine.
The biggest obstacle to using this vaccine, according to biologists, maybe that the human immune system can recognize the flu virus and destroy it with the help of existing antibodies. The researchers hope that subsequent clinical trials and experiments on mice who have had the flu will help them understand whether this is really the case and find a solution to this problem. If, of course, it really exists.