Since the 2016 Summer Olympics in Rio de Janeiro, Brazil, concerns about a possible Zika pandemic have taken the world by storm. The World Health Organization no longer lists Zika virus as a Public Health Emergency of International Concern, but stresses that it remains a serious "long-term problem" nevertheless.
Zika was first discovered in Uganda in 1947. Since then, it has been infecting a lot of new human victims and spreading around the world. The resulting disease, known as Zika fever, causes symptoms similar to those of the dengue or yellow fever. But the most vulnerable group is pregnant women owing to the fact that the virus can tragically affect fetal development. Only recently have scientists understood why Zika causes microcephaly in fetuses. The discovery could help develop stronger antiviral drugs in the future.
Scientists from the University of Texas studied the impact of the Asian lineage of the virus — the one known to cause microcephaly — in fetal brain cell samples. Hypothesizing that the virus affects stem cell activity during brain development, the multidisciplinary team observed how the virus affects stem cell synthesis, survival and maturation. Indeed, they discovered that the Zika interfered with the natural process of stem cell differentiation and proliferation into brain cells. They also observed differences in global patterns of gene expression, which were likely caused by the virus.
According to Nikos Vasilakis, one of the authors of the study and pathology specialist at UTMB (University of Texas Medical Branch), the virus was also detected on glia two weeks after the stem cells had differentiated and developed into specialized types. The glial cells provide essential protection and support to the brains neurons. They also produce the myelin protective layers around the axons.
Around 1.5 million people are thought to be infected in Brazil alone, and 3,500 cases of fetal microcephaly were reported in the country during the few months when the virus was most active prior to the Olympics.
Several research teams worldwide are currently trying to develop effective immunization against Zika. The FDA approved the first trial of a vaccine for humans in June 2016, but it is estimated that a vaccine will be available to the public only in the next decade. Meanwhile, research efforts such as this one provide valuable insights into the genetic and cellular mechanisms of the virus. The new data is supposed to help develop more effective defenses, specially for pregnant and child-bearing aged women.