A study by researchers at the Institute of Biology at the State University of Campinas (Unicamp) revealed, through experiments with cell cultures, that the new coronavirus has the ability to infect and multiply in human neurons.
The study, coordinated by Unicamp professor Daniel Martins-de-Souza, started from the clinical finding that some people with covid-19 have symptoms such as difficulty organizing thoughts and speaking, in addition to seizures. Therefore, the researchers cultivated neurological cells and contaminated them with the new coronavirus, to verify how the interaction occurs.
According to the coordinator, the research is still in the beginning, but it was already possible to discover that Sars-CoV-2 not only entered neurons in culture, but multiplied easily. Now, the researchers want to find out what are the changes caused by it inside the neurons, which consequently affect the nervous system.
In addition, it is being investigated how the virus acts on glial cells, which play an essential role in the functioning of neurons.
Way to the brain
As the study points out, the angiotensin-converting enzyme 2 (or ACE-2) is the gateway to coronavirus in human cells. It is found in various parts of the body, such as in the cells of the lungs, kidneys, heart and brain.
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Sars-CoV-2 is believed to be able to invade any cell with the ACE-2 protein on the surface, but researchers still do not know how it occurs in neurons and why only a few infected people manifest neurological symptoms - around 30% show these signs, according to estimates.
One hypothesis is that such a reaction would be related to the way the virus enters the body. In the case of patients who have a loss of smell, for example, one of the main symptoms of covid-19, entry would occur through the nose, with multiplication in the olfactory nerve, which would be used to reach the brain.
Another possibility cited by the researchers for the arrival of neurons is that the path would happen through blood. But for that, he would need to overcome the blood-brain barrier, a kind of natural protection for the brain. Some pathogens do, but there is still no confirmation regarding the coronavirus.
Next steps
Following the study, which is supported by the São Paulo State Research Support Foundation (FAPESP), the Unicamp group of researchers plans to find out whether the coronavirus infects any neuron or whether it has a preference for a particular type - there are several of them , linked to cognition, senses and functions such as breathing and heartbeat.
Among the objectives, it is also to verify the impacts caused by the virus on the functions performed by the ACE-2 protein and what this represents for the development of covid-19.
There is at least one more question to be verified by scientists, in addition to those already mentioned: is there another gateway for cells, in addition to ACE-2? The evidence suggests that it is.
