Mind fog, holes in memoryconfusion, headaches, disorientation… Since the beginning of the pandemicmany people report this type of neurological manifestation following infection with SARS-CoV-2, including in some long Covid cases. If the causes behind these symptoms initially remained rather vague, autopsies carried out on deceased patients sometimes revealed the presence of the coronavirus in the brain.
However, according to previous studies, “the ACE2 receptor, which the virus normally used to penetrate cellsis barely detectable in the brain, unlike the cells that line the nose, mouth and lungs”, reports New Scientist. How SARS-CoV-2 travels to the brain therefore remained a mystery. A recent study published on July 20 in the journal Science Advancesled by Chiara Zurzolo and her team at the Institut Pasteur, could nevertheless provide new answers.
To carry out it, the scientists decided to observe, in Petri dishes, the way in which the virus acted against two types of cells: “One, called SH-SY5Y, was used to model human brain cells; the other, Vero E6, to model the cells that line the surfaces of the body, including the nez.»
The modeled brain cells could not, on their own, be infected with Covid-19, “because they did not have the ACE2 receptor”. However, after incubation in the same Petri dish as the cells present in the nose and which do have these receptors, “they were infected”.
A “simple and effective” mechanism
Thanks to a microscope electronics, the research team discovered that after successfully penetrating the modeled cells of the nose, “the virus has stimulated [ces dernières] so that they develop tiny tubes, called nanotubes […]which have formed connections with brain cells”. These tiny tunnels could explain how SARS-CoV-2 travels to the brain.
“I think it’s a study very interesting, because it offers a simple and effective mechanism for transferring the virus from one cell to another, without using ACE2 receptors”comments Frederic Meunier, from the University of Queensland, Australia, in the columns of New Scientist. “However, as the experiments were limited to cells in Petri dishes, further studies are needed to confirm that the same mechanism occurs inside the brain.”
If the virus actually circulates through these nanotubes to the brain, Chiara Zurzolo hopes that this discovery could be useful for the development of a medication blocking this process. “At the moment, we do not have a molecule specific blocking nanotubes, but we are screening to find some”she announces.