Luis Enjuanes has lived against the clock since the pandemic began. At 76, he leads a team of 16 people whose goal is to finish what could be one of the best vaccines against SARS-CoV-2. For several reasons: It is self-amplifying, which means that the dose of RNA that is injected can be multiplied 5,000 times within the body. It generates a sterilizing immunity, that is, vaccinated people not only do not get sick, but they also do not become infected or transmit the virus. Its administration could be intranasal, which gives greater protection in the respiratory tract, the main entry point for the coronavirus.
Enjuanes, which operates at the National Center for Biotechnology (CNB-CSIC), foresees that its vaccine will be ready in a year. “We will come out later, but with everything updated,” he says. It refers to the fact that the mutations of the SARS-CoV-2 variants from the United Kingdom, South Africa and Brazil have been incorporated into the assays.
Beyond his investigation, the virologist explains why this coronavirus is more lethal than others, predicts new epidemics and changes in our way of life, and takes for granted the irruption of Spanish vaccines in the fight against covid-19. As soon as he started, he warned: “Now we cannot lower our guard.”
After a year of pandemic, how do you assess the current moment?
We are in a relatively optimistic moment. There are three vaccines that are already administered and the EU has just approved Janssen’s. This is the most important thing: vaccination is the only way to stop the pandemic on a massive scale. The Pfizer, Moderna and AstraZeneca vaccines are effective, but not perfect: you have to give two doses and vaccinated people, although they are protected from suffering an intense pathology and dying from COVID-19, they also become infected and can spread the virus. It is necessary to reach 70% of the immunized population. The figures have dropped, but now we cannot lower our guard and squander the work that the majority of the population and the institutions are doing. If we wait 2 or 3 more months, we will fix the problem. With 70% vaccinated, the virus is extinguished naturally: when it goes to infect a person, it fails in 70% of cases.
In addition to some optimism, vaccination is generating interest regarding the 3 vaccines that are developed at the CSIC. What phase is yours in? When will it be finished?
Ours is an original vaccine, none of this type has been made. It is based on the genetic manipulation of SARS-CoV-2 itself, from which we have derived an RNA replicon [that multiplies the gene dose that triggers protection]. That part is already defined, but we need complementary technologies for the administration of the vaccine. We have to combine both and check that everything works, that the vaccine is stable and safe. Between now and summer we will carry out the tests with mice and hamsters. If all goes well, we will do the same with macaques. I think it will be ready in the first quarter of 2022. Then we will have obtained data from clinical trials to test the safety of the vaccine and be able to administer it to the population. We would like to go faster, but it is a new model and it takes time.
It is difficult for us to understand the rhythms of science, although precisely what concerns us most is the safety of vaccines. And to guarantee it, it is necessary to carry out successive experiments with animals and clinical trials in humans.
That’s how it is. Generally, a vaccine takes 10-15 years to develop. Now the multinationals are working with teams of about 600 people, large facilities and many economic resources to go faster. We have not lacked funding in these early phases, and both the CSIC and the Ministry of Science support us a lot, but we have to complete the research for a new vaccine. Others, such as the one from AstraZeneca or the one developed by Mariano Esteban, are based on known vectors and therefore approved by drug regulatory agencies. That allows them to run more. Before making the vaccine against SARS-CoV-2, we had already developed another [similar] one for the MERS virus that was very effective in experimental animal models. It induced a sterilizing immunity: when we immunized humanized [genetically modified] mice and tried to infect them 3 weeks later, the virus could not enter because they were so well protected. That does not happen with the other vaccines.
Let’s say that on the one hand there is the heart of the vaccine, which you have already designed from genetic engineering, and on the other the technology that facilitates its administration, a kind of capsules that cover the RNA so that it does not degrade and can penetrate in cells.
Exactly. These coatings can be of different nature and are already manufactured, but they must be combined with the heart of the vaccine, which carries the RNA amplification machinery that causes the expression of proteins that induce protection. By combining them, we want to see which is the most effective method. For example, Moderna and Pfizer vaccines, based on messenger RNA molecules, need to be stored at minus 20 degrees; However, the German company CureVac has teamed up with Bayer to produce another messenger RNA vaccine to which they have added an excipient that makes it can be stored at 4 degrees in the refrigerator at home. Moderna and Pfizer will eventually talk to CureVac to transfer that technology to them. What I mean is that we are not only making one vaccine, but almost 30 variants to select the safest and most effective prototype.
Its vaccine is based on a synthetic RNA replicon, something intermediate between the Pfizer and Moderna vaccines, which are synthetic, and those that are based on viruses, that is, living organisms.
Yes. We have two versions and both are based on the same replicon, derived from the virus genome, from which we have removed a collection of genes. As a result, it is no longer a virus because it cannot spread and infect people or animals. That gives us the assurance that it will not revert to a virulent entity. We have been working on vaccines for many years and we know that there are many based on live attenuated viruses that work very well. But since viruses reproduce at great speed, there is a possibility that some will manage to become virulent. In addition, our vaccine includes a very large RNA that carries the ‘motor’ for autoamplificarse: if we 1 microgram once it enters the cells of the human body, can ‘make’ from 1 000 and 5 000. That neither do from Moderna or Pfizer.
How will your vaccine be administered?
We have used an intranasal route of administration, but drug safety agencies prefer the intramuscular route, which has been used more and is safe. However, it is not the most suitable because it induces a general immunity in the whole organism, systemic, and less strong in the mucous membranes. The mucous membranes (nasal, ocular, respiratory, etc.) are open spaces to the outside and immunity in these areas is better induced locally, presenting there the antigen [the substance that elicits the immune response; in this case, the vaccine]. This virus enters our body primarily through the respiratory tract, so if you administer the vaccine intranasally, you immunize that area and protection is greater. We saw this with the vaccine prototype that we developed for the MERS that came from the Middle East; its effectiveness was very high because it generated strong immunity. In return, more tests have to be done to prove safety. We have two routes of administration under study: intranasal and intramuscular, which is injected into an arm. Several companies that have manufactured intramuscular vaccines are investigating ways to administer them intranasally – with sprays – safely. We are going for a very powerful intranasal single-dose vaccine.
Are there other covid-19 vaccines that are self-amplifying? This feature, in addition to increasing its effectiveness, what other advantages does it provide?
I have already said that this implies that the system itself can multiply between 1000 and 5000 times the dose of RNA that you give at the beginning. Therefore, a much smaller initial quantity would be needed and the cost would be reduced. Scientists at Moderna and Pfizer know this, but they have chosen to go fast and the first version of the vaccine they have released is not self-amplifying. Now they are working on others that have simple self-amplifying machinery to carry out the controls quickly. In contrast, ours carries the virus’s own engine and amplifies not just one but several of its genes. It focuses not only on the protein S gene of the most important- the spicules to induce protection-, also in others such as the nucleoprotein, which promotes cell by T lymphocytes response These cells destroy the organism that have been infected, then the virus goes outside and is neutralized by the antibodies. Thus we achieve a broader and more powerful immunity.
In some media it has been stated that its vaccine could be among the best in the world. Let’s recap, what are your strengths compared to others?
First of all, as I just said, it does not use a single antigen to immunize, but several from the virus itself. Second, being self-amplifying it can multiply up to 5,000 times the initial dose. Third, the use of the intranasal route increases its potency because it induces immunity in the respiratory mucosa, which differs from systemic immunity in that it generates a large amount of immunoglobulins of the IgA isotype. There are several classes of antibodies. IgMs are the first to be made but they quickly decline. Then the IgGs are generated, which are long-lasting. But in the mucosa, IgA antibodies are also produced, which show a particularity: they have four binding sites to catch the virus. When they bind to the virus, it can no longer be released, it is neutralized. For this reason, these IgA immunoglobulins are more potent, and also because, as they have been selected to work in external environments such as respiratory or enteric mucosa, their nature is more stable against degradation. Every day we eat foods of diverse origin that bring many pollutants; we need to have a very strong immunity throughout the intestine. That tract degrades everything we eat, but also antibodies, so it is essential that we have tetravalent IgA that bind to the virus with a very high avidity.
Is there a vaccine that combines these characteristics?
In operation, no. But many companies are already making self-amplifying vaccines that are administered intranasally. Although none have been approved yet, they will not take long to achieve it, because that lowers costs and makes them more effective. These technologies are known and there are already several prototypes. More than technological, I would say that the problem is getting approval, making products safe.
He explained that his vaccine is self-amplifying and generates sterilizing immunity. Two questions remain crucial: how long will that immunity last and how effective will a vaccine be against new strains or variants of the virus?
Being based on a self-replicating RNA, it induces not only high-level immunity, but also long-lasting. In principle, our vaccine should be more immunogenic than the ones being supplied now, because it also includes several virus proteins. However, this duration, for any vaccine that induces immunity in the respiratory mucosa, can be 1, 2 or at most 3 years. Before, I compared mucosal immunity with systemic immunity, the one given by vaccines against the polio virus, measles or smallpox. That can last 20, 30 or 40 years with a single dose. We have the matter of the new variants under control. The version we are focusing on includes mutations from viruses from the UK, South Africa and Brazil , and surely also from some variant from the US that has appeared in California and New York. We will come out later, but with everything updated. In any case, if this continues, the vaccines will have to be updated every year, as with the influenza virus, depending on the variants that arise.
Have you ever stated that SARS-CoV-2 is very different from other coronaviruses – only 7 are known to infect humans – and that you yourself predicted that by now it would be attenuated. The disparity of reactions it causes continues to be disconcerting: some organisms become ill to the point of death and in others the symptoms are very mild or non-existent.
The reasons for the severity of this virus are multiple, but I highlight one: normally viruses are specific to a tissue, that is, a liver virus produces a type of infection in the liver. SARS 1, the 2002 coronavirus, basically infected the respiratory tract and the enteric tract. In general, when a coronavirus infects a cell, it binds to it, but does not enter its interior; spicule protein S has to be cut in two places in order for it to change its structure, become activated, and penetrate the cell. With SARS 1, that cut could only be made in the lung or the intestine, which is why it infected those tissues. But due to the insertion of 4 amino acids in the protein S of the spicules, it can now be cut by an enzyme (furin) that is in all the organs of the body: lungs, intestinal tract, heart, brain, veins, liver, kidney , pancreas … SARS-Cov-2 has what is called polytropism, it can infect any organ. That is why it causes at least 50 different pathologies.
Was this insert produced by a mutation in the virus?
The correct thing to say is ‘insertion’, which means that you have acquired a new component from another virus or from a cell. It has incorporated it and therefore can cause a variety of pathologies. Hospitalized patients are usually infected in several organs. This virus causes diarrhea, disorders of the nervous system and behavior, problems in the mouth that make you lose taste and smell, disrupts the circulatory system because it affects the endothelial cells of the veins … And on top of that, it has the ability to infect silent. Sometimes you don’t realize it because you don’t have a fever, or respiratory problems, or any symptoms; you continue with your normal life and you are spreading the virus. That combination makes it so deadly.
In addition, there are aspects that generate a lot of confusion. For example, among people who have been infected, the evolution of antibodies is very uneven. And among those who develop the disease, it is not clear how long they can continue to spread after recovery.
I have personally spoken with José Ramón Arribas, head of the infectious diseases service at the La Paz hospital, and Rafel Delgado, director of the microbiology service at the 12 de Octubre Hospital. Both are at the bottom of the canyon and know very well the variety of pathologies that the virus produces. I will summarize his vast knowledge by saying that the analytics of infected people are supervariable. Some become infected and immediately become seriously ill, others become infected and are asymptomatic; There are some that induce many antibodies, compared to others that do not; There are people who, in addition to inducing many antibodies, last for a long time, while in others they disappear in a few weeks. Every conceivable combination is given. Some people become infected, sick, and recover, while others remain infected for 3, 4, or 5 months. Anything can happen.
That also makes it difficult to control the pandemic.
Of course. That is why doctors, when faced with someone with two or three negative CRPs, usually say: ‘Go home, but keep using the mask, be very careful and in a few weeks come to have another test.’ You have to instill that culture of caution. When a person still shows viral load, but at the same time has developed many antibodies, they are asked to be careful, even if they are already going to work because they do not usually transmit. In this, emphatic affirmations do not serve, not everything is black or white. Sometimes you have to give generic rules of conduct, but each of us has genetics and an immune system.
Within the scientific community, he is not the only one who predicts another pandemic in 4 or 5 years.
But with a nuance: a pandemic is a worldwide infection, like this one, that has spread to 192 countries. What I affirm is that there will be epidemics restricted to 2, 3, 5 countries … Statistics say that every one or two years a new coronavirus appears or one already known in animals reappears. In humans a new one appears every 6-8 years, which can be even fatal, such as SARS-CoV-2. But fortunately not all are universal pandemics, like this one or the 1918 flu. I can only assure you that there will be epidemics of this or other viruses. Now the WHO is predicting an outbreak of Nipah, a virus carried by bats. What has happened in the past will continue to happen even more intensely; Now transportation systems allow us to be in the antipodes in 24 hours, the population density has increased a lot, and we access spaces that were previously inaccessible.
For a year, we have lived in a kind of race for vaccines that has geopolitical overtones. Will Spain be in what would be the second wave of vaccines?
It is very likely that the one developed by my colleague Mariano Esteban, who uses a viral vector with which they have already manufactured 7 vaccines, will be ready for that second wave by the end of the year. Vicente Larraga’s is quite advanced and easy to produce, so it could be the second. Ours, if all goes well, will be the third, but it won’t be ready before the beginning of 2022.
As a result of this pandemic, will science have a greater role in the political sphere?
Much thought is being given to this because the pandemic has put global health in danger, has caused great socioeconomic impact, the media are focused on its evolution … Logically, those who make political decisions do so in accordance with the urgencies and needs created because of the crisis. I know that in Spain real efforts are being made to promote science and better prepare ourselves for other epidemics or pandemics, through early diagnostic methods, research in antivirals, immunotherapies and new vaccines. Yes, I think this is going to be a before and after, although, as always happens, the current momentum will decline.
Do you think that to some extent this crisis is going to change the way we live?
I think so. It has greatly affected our way of life, family and social life, leisure … People are going to become more cautious. We have learned that wearing a mask, disinfecting hands, and maintaining a safe distance drastically decrease flu and other infections. Wearing a mask is going to be more frequent among those who travel by means of transport or go to places of great influx, especially at certain times of the year when seasonal viruses appear. I plan to use it more often in some public spaces. I believe that the segment of the population that is more prudent is going to change their lifestyle significantly.
How has your life changed in the last year?
It has changed me a lot. I was starting to reduce my scientific activity, but for those of us who are specialists in coronavirus, it was hard to abandon ship under these circumstances. That is why we continue working. I have extended my period as an ad honorem until I see that the situation is on track and that the management of the laboratory is in good hands. The 16 people who set it up are working hard. This situation has brought us all together around a central project: obtaining the vaccine.
Luis Enjuanes, Director of the coronavirus laboratory of the CNB-CSIC, National Center for Biotechnology (CNB – CSIC)
This article was originally published on The Conversation. Read the original.
