Coronavirus (COVID 19) has significant social, economic and educational implications worldwide. At present, public health officials rely on tools such as social isolation to minimize the spread of the virus, but in the long run, they are trying to develop a vaccine if we want to hope for a return to normalcy.
It usually takes a few years for a vaccine to be developed, but in the run-up to the coronavirus, companies and regulators are taking aggressive steps to develop a vaccine for COVID 19 much faster.
Public and private laboratories around the world are seeking to create a vaccine with strategies that have never been tested on such a large scale. If these efforts succeed, the vaccine will be an essential tool in combating or preventing future COVID epidemics 19.
How vaccines work
When the body is exposed to a new virus, it usually takes weeks for antibodies and other defense mechanisms to develop that can fight it. This gives the virus enough time to reproduce and make someone sick.
However, the immune system has memory. If it has been exposed to another virus, the body can quickly develop its defenses against the invader and neutralize the virus before the infection develops and spreads.
This is the idea behind vaccines: they give the body the opportunity to build defenses against a virus so that it can stop it in the future. Not all vaccines produce the same level of immune readiness. The stronger the initial immune response, the better the vaccine. But even a simple preparation is better than nothing.
Vaccines have been around for almost 150 years and until recently science has not changed anything substantially.
The traditional way to grow a vaccine is to grow inactivated viruses. These viruses are injected into the body. No they will not make you feel sick, but the body recognizing the "threat" begins to strengthen its immune system to fight this virus sometime in the future when needed.
Unfortunately, finding ways to grow a new virus on an industrial scale is complicated, and once it is, the process itself is often very slow, difficult, and potentially dangerous. For example, the flu vaccine is produced by growing the virus in millions of eggs chickenU.
This process usually takes four months. In addition, when a virus is created for which there is no drug or vaccine, it is safer to avoid growing it in large quantities, because there is always the fear of accidentally leaking from the plant and making the situation even worse than it is. already.
But the coronavirus does not wait. Thus, almost 50 public and private laboratories are turning to new, safer and faster methods for developing a vaccine.
Protein vaccines
Instead of using the whole virus, it is possible to vaccinate a person with a single component of the virus. What is most often used is the proteins from the surface of a virus. If a live virus enters the body, these surface proteins are easily recognized by the immune system. This approach is easier, faster and safer because the virus protein can be produced in cell cultures.
Using proteins from the surface of the virus, it is possible to vaccinate a person without going through the complicated process of developing a dangerous virus.
Two companies, Sanofi and Novawax, are developing both protein-based vaccines based on the SARS-CoV-2 spike protein present on the surface of the new coronavirus caused by COVID-19.
Protein-based vaccines, also known as recombinant vaccines, are already being used to vaccinate against viral infections such as the HPV virus. They are much simpler to produce than traditional vaccines that use the whole virus, but it may take another year for a new process to develop and several weeks for the vaccine to produce after the manufacturing process has developed. But people need something faster.
Gene vaccines
Theoretically, the simplest and fastest way to create a vaccine would be for an individual's own cells to be able to produce minimal amounts of a viral protein, which would trigger an immune response. To do this, researchers are turning to genetics.
The first genetic approach uses DNA. A unique one gene encodes a protein from the coronavirus is injected into the patient's cells in the hope that a small fraction of the DNA molecules will find their way into the cell's nucleus. There they will be copied into an RNA molecule which is then read by the cell to produce the necessary viral protein.
But it is difficult to get the human body to produce enough protein using this approach. Often, DNA converts the cell nucleus and the cell does not produce the necessary protein in sufficient quantity to elicit a strong enough immune response.
To date, there are no DNA vaccines approved by the FDA for human use and the success of this method appears to be limited. But he makes promises. In 2016, several research teams developed candidate vaccines using this technology and at least one company, INOVIO Pharmaceuticals, Inc. develops INO-4800, a candidate DNA vaccine for the coronavirus.
The difficulty of DNA vaccines to pass the “information” in the nucleus appears to be handled using the RNA directly. Vaccines using RNA directly could overcome this problem. Because RNA is translated into proteins once it enters the cell, this approach results in stronger immune responses than DNA vaccines. However, the RNA breaks down faster than DNA.
This did not discourage some companies from trying this technique. Remarkable effort in the USA. Moderna has done and on March 16, together with the National Institutes of Health began clinical trials of a candidate coronavirus lead vaccine, mRNA-1273.
On March 16, 2020, Jennifer Haller of Seattle became the first person to test Moderna's experimental RNA vaccine.
The production of DNA and RNA vaccines is based on standard and fairly simple procedures. DNA vaccines are produced by bacteria that grow overnight, while RNA vaccines are produced in test tubes using a biochemical reaction that takes a few hours. Gene vaccines could be produced extremely quickly compared to traditional protein-based vaccines.
Friendly viral vaccines
The main problem with gene-based vaccines is how they can reach DNA or RNA. An elegant way to solve this challenge is to use a harmless virus as a delivery system. Viruses are extremely good at penetrating cells. A virus with genes from SARS-CoV-2 could use the cell mechanism to produce proteins to elicit an immune response to the coronavirus (COVID 19).
This technique is being pursued by a few companies around the world. For example, Hong Kong-based CanSino Biologics inserts the coronavirus gene that encodes the spike protein into an adenovirus. They used this technique to produce the first approved by government Ebola vaccine and the clinical trials of an “engineered” adenovirus that could protect us from corona have already started in China.
The production of vaccines provided by harmless viruses is slower than the production of DNA or RNA vaccines because it involves the culture of slow-growing mammalian cells. However, like the production of gene vaccines, they are based on existing processes that exploit viruses that have been optimized for manufacturing.
Endless vaccines
While the growth rate of the COVID 19 vaccine is unprecedented, a timeline for mass vaccination does not exist and remains uncertain. The large number of approaches followed may give the impression of despair and confusion, but the multilevel approach is one way to offset the development bet of a vaccine.
It is unlikely that the first vaccines to be developed for COVID 19 will be 100% effective and will not be easy to produce on a large scale.
Realistically, researchers will develop good enough vaccines that can be produced using different production infrastructures. These vaccines may initially have limited effectiveness, but the variety of production processes will allow companies to manufacture and distribute them very quickly, "buying" time to contain the current epidemic and prevent future epidemics.
The article was published in The Conversation by Jean Peccoud, Professor, Abell Chair in Synthetic Biology, Colorado State University licensed by Creative Commons
