Is Deltacron a new particularly diabolical variant or a "scariant", that is to say an alleged virus simply there to scare, according to the term of the American scientist Eric Topol?
Presumably the answer 2, according to the experts.
But this combination of Delta and Omicron (hence the name “Deltacron”) has caused a lot of reaction in recent days.
What you may have read or heard
It all started with articles in the Cypriot press at the end of last week.
"There are currently Omicron and Delta co-infections and we have found this strain which is a combination of the two," Leondios Kostrikis, professor of biological sciences at the University of Cyprus and head of the Biotechnology Laboratory, told Sigma TV. and molecular virology, then taken up by the Bloomberg agency.
The virus in question is said to contain both Delta mutations and Omicron mutations.
A total of 25 cases of "Deltacron" have been identified, including 11 hospital patients, according to the
Cyprus Mail
.
The positive tests in question were sequenced, i.e. their genome was completely dissected, then they were added to the international Gisaid database.
What the experts say
Researchers who have access to it observe that these samples "do not cluster on a phylogenetic tree", according to Tom Peacock, a virologist at Imperial College London.
In other words, they do not have the same family ties.
It would therefore not be a new variant, but rather a series of accidental contaminations from different samples of Omicron.
Small update: the Cypriot 'Deltacron' sequences reported by several large media outlets look to be quite clearly contamination - they do not cluster on a phylogenetic tree and have a whole Artic primer sequencing amplicon of Omicron in an otherwise Delta backbone.
- Tom Peacock (@PeacockFlu) January 8, 2022
The explanation could come from a kind of "mixing" between several samples in the laboratory. “Potentially mixing small amounts (…) in sequencing labs - which then gives the impression that the virus has mixed in real life - happens quite often because tiny volumes can cause this problem,” said Tom Peacock. . The 25 cases in question could thus have been sequenced on the same day at the same location.
“Tom Peacock's analysis is very good.
The distribution in the tree of these sequences is revealing, and these sequencing problems are very frequent, including with Omicron ”, confirms Etienne Simon-Lorière, head of the RNA virus evolutionary genomics unit at the Institute. Pastor.
Asked this Monday morning on RMC, Professor Arnaud Fontanet also "ruled out" the hypothesis of a new variant.
However, Leonidos Kostrikis maintained his version in a statement sent to Bloomberg on Sunday evening.
Read also Covid-19: why the Delta variant will still put hospitals under pressure
While waiting to see more clearly, the emergence of real recombinants is something quite possible, for almost a year.
This can occur when two viruses infect the same cell, and we end up with "the product of the crossing of two parental viruses", Vincent Maréchal, professor of virology at Sorbonne-University, told us last March.
A recombinant lineage between the Alpha and Delta variants had, for example, been identified in Japan a few months ago.
In summary :
A Cypriot researcher claims to have identified a new variant, born from a recombination between Delta and Omicron.
Experts unanimously believe that this is most likely accidental contamination in the laboratory, a phenomenon that can be quite common during sequencing.
