Zika virus has triggered global concerns in the past due to its ability to cause microcephaly and other fetal abnormalities in women infected with the mosquito-borne disease. Previously it was thought that Zika only infects neuronal progenitor cells or neurons that are still immature in the developing brain but the latest research has found that a Zika infection can prove to be equally harmful to the adult brain.
Researchers led by neuroscientists Sergio T. Ferreira e Claudia Figueiredo and virologist Andrea Da Poian at the Federal University of Rio de Janeiro, Brazil, found that the virus replicated in adult human tissue by producing new viral particles capable of infecting more cells.
The researchers reached the conclusion by injecting the Zika virus directly into the brains of mice, which then “ exhibited marked memory impairment that persisted even after infection had been fought off by the organism.”
“Moreover, this was consistent with the fact that brain regions responsible for learning and memory processing were the main sites of viral replication in their brains," they said, according to Zika News.
The research showed that Zika infection caused a strong inflammatory response in the brains of mice including activation of brain resident immune cells called microglia.
Fernanda Barros-Aragão, a Ph.D. student and author of the study, said that this exaggerated inflammatory response eventually led to memory loss.
"Neurons communicate through highly specialized regions called synapses,” Fernanda said.
“Surprisingly, we found that microglia that become aberrantly activated upon infection by ZIKV (Zika virus) attack and engulf synapses.”
“This impairs communication between neurons and, therefore, the formation of new memories." Interestingly, when animals were treated for about one week with anti-inflammatory drugs capable of blocking microglial activation, they recovered memory.”
The study, therefore, points to the need of carefully evaluating learning and memory performance in follow-up assessments of Zika virus-infected adults.
The study titled "Zika virus replicates in adult human brain tissue and impairs synapse function and memory in adult mice" was published in Nature Communications.
It was was funded by the Carlos Chagas Filho Foundation for Research Support in the State of Rio de Janeiro (FAPERJ), the National Council for Scientific and Technological Development (CNPq), the Coordination for the Improvement of Higher Education Personnel, Ministry of Education (CAPES / MEC), the Funding Agency for Studies and Projects (FINEP), the National Institute of Science and Technology for Structural Biology and Bioimaging (INBEB), the National Institute for Innovation in Pharmaceutical Products and Identification of New Therapeutic Targets (INOVAMED), and the National Institute of Science and Technology for Translational Neuroscience (INNT).