Zika takes brain cells to self-destruction, says study

                   
Aedes aegypti: According to the authors of the article, the death of brain stem cells after infection is associated with microcephaly cases caused by viruses


São Paulo - The infection zika virus triggers the cells of the human brain in forming an immune response that leads to self-destruction.

The discovery was made by scientists at the University of California (UC) in San Diego (United States) and published on Friday, 6, in the journal Cell.

According to the authors of the article, the death of brain stem cells after infection is associated with microcephaly cases caused by viruses. Block the innate immune response of the brain stem cells may be an alternative for them to survive the infection, reducing the possibility of occurrence of the malformation.

For the study, researchers used brain Organoids, popularly known as "minicérebros". The Organoids are brain tissue structures cultured in the laboratory to mimic the body in training and study how it reacts to infection.

According to scientists, the virus zika contributes to the self-destruction of cells to activate TLR3 receptor, which triggers the innate immune response in infected brain cells. It was known that this receptor leads the cells to produce viral proteins, as a first line of defense against microorganisms invasion.

The doctoral student Jason Dang, who researched as TLR3 responded to infection by several viruses, realized the connection when he decided to test the TLR3 levels in minicérebros infected zika.

"At first we did not know how the evidence was strong. We were excited when we found that by inhibiting the production of TLR3 in brain Organoids infected with zika, reducing its dimensions became much less dramatic. I still was not convinced, then we use a chemical to increase the activation of TLR3 and observed that the brain tissue began to shrink quickly, "said the study's lead author, Tariq Rana, the UC.

innovative method

Previous studies with minicérebros infected zika helped establish the connection between viral infection and death of neural stem cells. The group led by Brazilian Stevens Rehen, the Federal University of Rio de Janeiro and the D'Or Institute for Research and Education (er), used the Organoids in a study published in April in the journal Science, to conclude that the zika virus actually has the ability to infect and kill human brain cells.

Also in April, an American University Johns Hopkins group used the technique to prove that zika virus prefers neural stem cells. Now, Rana joined the team one more piece to the puzzle: the role of the immune system.

Inhibition of TLR3 can help neurons infected with zika to survive and maintain their functions, and preserves the uninfected cells. According to the authors may lead to the discovery of targets for the development of therapies.


"There are several other viruses that cause damage to the central nervous system. Now we want to study all of them to see how it behaves the immune response," Rana said.