The Zika virus shocked the world in 2015, spreading to 50 countries and territories before the World Health Organization declared the epidemic over last November. However, the Government Accountability Office reported in May that the United States remains unprepared to handle another outbreak. Recently, researchers may have made a breakthrough as part of the ongoing efforts to understand the virus.
Dr. Alysson Muotri, a professor in the Departments of Pediatrics and Cellular & Molecular Medicine at UC San Diego, along with his research group, have contributed greatly to our understanding of the Zika virus’ mechanism. The Zika virus is spread through a bite by an Aedes species mosquito and then passed on through sexual contact, which could lead to the development of microcephaly, a condition in which the head and brain are abnormally small in the fetuses of infected pregnant women.
Muotri’s group made a connection between the virus and its ability to cause microcephaly. Their study, published in Nature, found that the mother’s virus can travel to the fetus’ brain by employing what Muotri described as a “Trojan horse” strategy. The virus first crosses the placenta and infects immune progenitor cells. These cells circulate throughout the fetus, with some eventually becoming trapped in the brain when the fetus develops a blood-brain barrier. The trapped cells mature into microglia, which are the immune cells of the brain. These infected microglia protect the virus against the body’s usual defenses.
Chinese researchers also discovered recently that the Zika virus has genetic mutations that make it more efficient at replicating inside cells. Muotri acknowledged that because the virus can mutate, it will be challenging to develop a conventional vaccine. However, he suggested that there may be another way to protect people from the virus. In a study that was recently accepted for publication, Muotri’s group and their collaborators found that Chloroquine, an FDA-approved drug used to treat and prevent malaria, can be used to protect against the Zika virus.
“We tested the efficacy [of Chloroquine] in human mini-brains, and we do see a great neuroprotection against cell death,” Muotri said. “It also works on pregnant mice—treated moms that are infected don’t have pups with birth defects. This is really cool. Because this drug is quite safe, people can just take it if they know they will be exposed in endemic areas.”
Muotri cautioned that even though the virus seems to be dormant, it can still strike again, especially since we don’t fully understand how it spreads. He also warned that a generation of children who were born with birth defects from the virus are showing signs of neurodevelopmental disorders, as well as vision and hearing problems. Muotri is concerned that even babies born without a trace of the virus or microcephaly showed signs of vision and hearing problems, suggesting that even indirect exposure to the virus can impact a newborn’s health.
Despite the passing of the immediate threat, Muotri warned, “We tend to ignore the risks when the threat is not visible or obvious, but that is a huge mistake and we can learn from the past.”
Natalie Lam is a staff writer at The Triton.