The work on 200 various coronavirus vaccines is being conducted at present in different countries. We can categorize them into the following kinds: vector, activated, nucleic acid (DNA, mRNA) and recombinant protein vaccines.
The importance to obtain a vaccine that would solve the pandemic problem throughout the world can’t be underestimated. The vaccine is the only solution to the pandemic problem. The COVID virus is clustered and spreads among certain groups of people. It is enough to vaccinate people subjected to high infection risk and those who are dealing with other people on a daily basis – doctors, police officers, sellers, teachers, etc. The level of infection in society will fall significantly after their vaccination.
The registration of the first vaccine against a new Coronavirus SARS-COV-2 took place on the 11th of August in Russia. The innovative breakthrough became a special moment for the country and the whole world and it was name as Sputnik V after the Soviet-era artificial satellite.
The mechanism of action of adenoviral vector vaccines
Vectors perform the function of carriers capable of transporting genetic material from another virus into a cell removing the genetic adenovirus material that causes the infection and inserting material with the protein code from another virus, or in particular the spike of coronavirus. The vaccine invokes an immune system response. If the invoke is successful does, then the goal is achieved. The reaction means that the immune system got down to work and began producing antibodies for protection from the invading infection.
A viral vector is only capable of delivering information, it is not capable of anything else. It does not fit into the genome, it just enters the cell and delivers the desired piece of genetic information – a gene encoding the S-protein of the coronavirus. When the immune system recognizes a foreign protein, humoral and cytotoxic immunity is formed.
The vaccine should induce an immune response, so its developers were trying hard to achieve this effect. When a virus enters our body, it digs into the cell membrane and is fixed there with the help of spikes, turning it into a “factory” for the production of its clones – it multiplies. Only the immunity is capable of striking back and preventing it, therefore a vaccine is required to train it to do so.
Designed by the research team adenovirus-based vector technology platform paved the way to make the creation of new vaccines a less complicated process. The creation doesn’t take much time thanks to the modification of the original carrier vector using genetic material from newly emerging viruses. This scheme enables the production of new vaccines within a short time.
The platform mentioned above was developed a quarter of a century ago as a method of gene therapy. In 2015, a vaccine against Ebola was created on a vector matrix, in 2017, trials of a drug against the Middle East respiratory syndrome (MERS) began, in 2020 the carrier virus is forced to act against SARS-CoV-2.
The vaccines of this kind work perfectly in terms of eliciting a strong reaction from the person’s immune system. Scientists state that the human adenoviruses are easily subjected to modification and this explains the popularity of their use as vectors.
When the pandemic started, the researchers from Russia began conducting work on a vaccine. Russian scientists did not even have a living sample of SARS-CoV-2 at their disposal – only a decoded genome. But after reading the sequence, they immediately set about developing the medicine.
The idea of how to make the vaccine work was brilliant. The team extracted a piece of the genetic material of the new coronavirus SARS-COV-2 that encodes data concerning the structure of S spike protein of the virus, which is shaped like a crown, hence its name. This type of protein is in charge of binding with human cells. After the extraction, a different adenovirus was inserted so it could be delivered into the cell of a person. This is how the first-ever vaccine against the SARS-COV-2 coronavirus was developed.
To make sure the vaccine is efficient and safe for use, the research team has conducted all stages of preliminary trials, including the tests on animals before embarking on clinical trials.
The technology makes it possible to synthesize a DNA virus in 2-3 weeks, revive it, and obtain the desired vector. This is its main benefit.
By August 2020 the second stage of clinical trials had been over. Only volunteers participated in it and the level of its toleration was very good. Over 40 000 volunteers were involved in the trials after the vaccine registration including people from other countries of the world. The vaccine acquired the name Sputnik V vaccine.
The vaccine is being prepared at the time of writing to conduct overall vaccination of people in Russia. Since September it has been produced on a massive scale.
The method applied by scientists for the production of the vaccine has become innovative and was patented in Russia. The center developing it has been awarded for the best patent of the year. After the acquisition of the patent in Russia, the transfer into an international patenting system occurred. The request was submitted in 158 countries.
It’s very important to form durable immunity for the long-term efficiency of the vaccine. The tricky question is how long the vaccine will last.
Typically, a vaccine works like this: It produces antibodies that live in the blood for three weeks. Antibodies are produced by plasma cells. As long as the virus is present, the cells produce antibodies. If the virus disappears, these plasma cells die off, but some of them usually turn into memory cells. They go to the bone marrow staying there. The next time you encounter the same antigen, memory cells wake up quickly, plasma cells quickly emerge from them, and they begin to produce antibodies quickly again.
The problem is for some antigens, this short-term immune memory (antibodies) does not translate into long-term memory (memory cells). Two phases of the introduction of the vaccine solve this problem and enable that. According to the experience of using vector vaccines when a 2-phase scheme is used, the immunity is preserved in the course of 2 years.
Using this scheme that is considered the future of Russian immunology it’s possible to design universal vector models and create a vaccine in an extremely short time. In the opinion of the Director of the Gamaleya Research Center, modern genetic engineering methods make it possible to create prototypes of vaccines in advance against those epidemically significant strains that may appear. These prototypes can be developed in advance and stored simply in refrigerators as a specific preparation. Therefore, the process of the development of a new drug can be significantly reduced – to a month, or even to a shorter time.