Could pneumonia a year ago have been a coronavirus? What is the "missing link" of the pandemic

05/08/2020 - 15:32

• Clarín.com
• Society

Perhaps the spokesperson for the World Health Organization did not measure the effect that his statements would generate, but, after listening to it, hundreds or thousands of people must have been astonished wondering " What if that pneumonia, that time ... ?". What Christian Lindmeier did this week was launch an international order, following the news of an alleged “case zero” of coronavirus in France (prior to the reports in Wuhan, China): he asked the countries to “review” the samples of the last year compatible with pneumonia, so they can be reevaluated in light of the Covid-19. Everything is framed in a small scientific odyssey: determining the origin of the pandemic , that “missing link”or the instant when the coronavirus successfully leapt from animals to humans. Could it have been long before this summer? And could it have happened in more than one place at once?

Clarín discussed these issues with Jorge Quarleri , a researcher at the Institute for Biomedical Research in Retrovirus and AIDS (INBIRS), dependent on the UBA-CONICET, passionate about the subject that detailed the details of what was known so far, in addition to graphing the photo of what can be speculated, knowing the vagaries of these infectious agents.

It must be said that in the conversation with scholars of the stature of Quarleri, it is easy to be pedaling falsely with questions like " And the flu I had a year ago could have been ...? " Eloquently, the researcher said: “ We humans take 8 million years to modify 1% of our genome. For a virus like this, that task only takes a few days . ”

A woman sells fish in Villa 31, where several cases of Covid-19 positive have already been confirmed. / AP

The question, he said, is that "it cannot be stated nor, a priori, can it be ruled out that a pneumonia that occurred last year or even earlier was a coronavirus." It is more complex.

Once upon a time

Quarleri explained that the coronavirus that today has us in a tedious quarantine could have started trying to "pass" on to humans not this summer, not in December, but several decades ago . The scientist explained it by bringing up two unpublished papers , the precious content of which is in the evaluation stage. The authors are prestigious experts from institutes in England, the United States, Belgium, Denmark and China, among others.

"These studies approximate, with calculations based on statistics, that the SARS 2 virus that today generates this pandemic and that of bats - among whose genomes there is 96% homology - converge in history in a common ancestor, between 40 and 70 years ago ”, he explained.

The data is surprising, yes, but not to virologists. For example, “HIV was identified in 1983, after an avalanche of cases of pneumonia with non-commitment. However, ancestral dating  (beyond what there are records of HIV-compatible infections in the 1950s) indicates that the 'zero' patient infected with HIV occurred in 1921 . It is not that we have found an infected person at that time, but it is a calculation based on the genetic material and the variations of the virus over time. ”

Movement of people at the Liniers station. Photo: German Garcia Adrasti

Quarleri recalled that “although many coronaviruses live in the cells of non-human hosts, there are seven identified that cause infections in people . To study this particular coronavirus, one uses an immediate background in 2001, 2002, 2003, when the SARS-producing coronavirus and the subsequent MERS producer were seen in 2012. These viruses showed that they had an origin or relationship with others. coronavirus, the presence of which had been defined in bats . "

But how far does a bat make contact with a human? From the remoteness of this link, the hypothesis of " intermediate hosts " emerged that served as a "link" or "bridge" to humans. And hence the reference to pangolins and exotic animal markets in southern China.

But what about the patient from France? Quarleri explained that this requires clarifying the "abc" of how viruses evolve .

Smooth sailing

In plain words to "lower" a very complex matter, the virologist explained how bats don't even get sick with these pathogens. In other words, their immune system managed to keep them "under pressure". And it is in these conditions that the virus (in response, not to a value system such as "good and evil" but to its most essential nature), seeks to lodge elsewhere.

But "jumping" species represents a great effort, in addition to a risk that in most cases ends in nothing. Quarleri defined that luck as the great chance for the virus to become a " sterile monster ".

A virus makes an infinite number of unsuccessful attempts before making the "jump" to another host or "house" where it will try to continue replicating itself. Very particular conditions must be given for the operation to be "successful". Far from planning the “how”, the coronavirus, in particular, generates its adaptation to the new medium in a random way, through chance , recombining its complex and enormous genome .

"Huge" because the Covid-19 virus has a genome twice as large as that of influenza and ten times larger than that of hepatitis B.

What is the point of detailing this mechanism of survival and replication on the part of an agent that cannot even be conceived as a living being? That allows the existence of a story behind the pandemic to become visible . Today, hundreds of scientists in the world try to rebuild it.

Cosmopolitan

"At this time we cannot say that the jump can be attributed to a single event that occurred in China . It cannot be asserted in any way. It is true that there are conditions that make us think it was like this: the consumption of live animals that are hosts of these viruses, the fact that it is an overpopulated area ... in short, one hears music and everything indicates that the orchestra is there " , he described.

But "appealing to the well-known Greek myth, Pandora's box could have been opened elsewhere ," Quarleri clarified, referring to the meddling that humans are doing "by meddling in the ecology of other living beings, which exposes us to different pathogens. And not just viruses. "

Street market in Wuhan, China. / Hector RETAMAL / AFP)

For example, he said, “the jump could have occurred in multiple instances prior to this 'great instance', but with unsuccessful results in which the virus did not achieve what it wanted: to adapt to humans, its new host. He entered various dead ends until he finally achieved interhuman transmission . "

Going back to the patient from France, there are at least a couple of options that should be studied, he explained. Because either it was an infection resulting from one of those unsuccessful attempts, as if it had been a "dashed" line in the long history of attempts to "jump" humans; Or, instead, it could have come from China.

What is Coronavirus? How is it spread and what are its symptoms?

“We are talking about a respiratory infection that in most cases does not produce symptoms. It is not that it generates eye color change and is very visible. There are many ways that this person has been infected by third parties who did have contact with China, "he explained.

And, furthermore, “there could have been a very successful huge leap in China and another in Paris. To understand everything, you have to study the ancestrality of each place and make the corresponding calculations, "he said, adding:" It cannot be ruled out that the jump from the SARS-CoV-2 coronavirus to humans has occurred in different events temporarily and geographically. distant. "

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