Genes, amino acid mutations: it is in the innumerable genetic sequences and in the folds of the molecular structure of its proteins that
the answer on the origin of the SarsCoV2 virus is being sought
While the G7 is urging a new investigation by the World Health Organization (WHO), pending further data, the only useful source of information is the virus itself.
This is indicated by the journal Nature, which on its website presents the points in favor of both hypotheses.
It is a challenge
: at the moment there are not enough elements to support the
hypothesis of natural origin
, as there are none to support the
hypothesis of escape from a laboratory
", observes Gianguglielmo Zehender, Professor of Hygiene of the State University of Milan. What is certain, he adds, is that "we are witnessing
something never seen before in such a direct way
, namely the
adaptation of a virus to its host
". Until now, he notes, "there were in fact no tools to do this, not even in the 2009 flu pandemic".
Among the first elements in favor of the natural hypothesis is the great
of the SarsCoV2 virus with the
coronavirus of bats
, the animals known to be the most important natural reservoir of coronavirus.
However, the animal in which the bat virus has changed so as to become infectious for humans
has not yet been identified
and this, according to some experts heard by Nature, could be a point in favor of the hypothesis of a originated in the laboratory.
"It is also true, however, that we do not know the
for many other infections," Zehender observes.
In favor of the natural origin there is also the same
evolution of the SarsCoV2 virus
. "At first it was not very transmissible, but over time we have seen that it has learned to pass easily," says Zehender. The virus accumulates mutations and we see its variants in action: "As it transforms it acquires new abilities, selecting the most effective mutations." This is how the alpha variant (English according to the old terminology) ended up prevailing over the others.
The fact that since January 2020 the sequences of the virus have been collected has made it possible to push the analysis to a level of great detail, for example by bringing to light characteristics of some
that could lead to one hypothesis or the other. In both cases, the focus is on the Spike protein that the virus uses to penetrate cells.
For example, there are those who see the clue of a possible origin in the laboratory in some observations that indicate, on the protein, a site activated by an enzyme in the human cell called
, which would not be present on other coronaviruses. It is also true, however, that "we are often seeing mutations in the receptor binding site: they are adaptations of the virus to their host," observes Zehender.
"Given that everyone says that there is no definitive proof either for one hypothesis or the other, it seems to me - he notes - that there is a certain justifiable persistence in the search for elements that indicate that the origin comes from a laboratory . I would not - he concludes - that this would overshadow the most serious problem, namely that we have been taken aback by this pandemic. We must not make this mistake: it is a bad story that we have faced with inadequate means and making mistakes ". .