Although discovered in the late 1940s, the Zika virus was not well studied until recently. Zika is not a life-threatening disease for adults, and didn’t attract the attention of most researchers who study mosquito-borne diseases until this past year, when the number of cases increased dramatically in South and Central America. In fact, it’s likely there have been many cases in which people didn’t even know they were exposed to Zika.
We now know that in 2015, there was a sharp increase in women in Brazil who contracted Zika during pregnancy and later delivered babies showing signs of microcephaly, a congenital condition associated with incomplete brain development and an abnormally small head. This led to the realization that Zika infection – while not seriously impacting the health of pregnant women – may be contributing to a very drastic outcome for their developing babies.
The big question that scientists want to answer now is: what is it about infection with Zika virus that causes microcephaly in a developing fetus? For instance, how does the virus cross the placenta, infect the fetus, and stop or alter the development of the brain? Or are chemicals produced by the mother’s immune response to Zika crossing the placenta and affecting the fetus?
To address this question and, more generally, the growing problem of Zika, researchers from across SRI have formed a Zika-virus task force to determine how we can apply our range of capabilities to help address this emerging global crisis. We have the combined expertise of our infectious disease team, along with reproductive toxicologists who understand how drugs and vaccines affect pregnancy, neuroscientists who understand brain development in the fetus and experts on the ecology of mosquitoes to explore genetic or biochemical approaches to mitigating mosquitoes’ role in transmitting the disease. This expert team is approaching Zika from a variety of angles.
The overall goal at SRI – and in the broader scientific community – is to find ways to prevent or treat Zika infection and to prevent microcephaly. This will be a particularly difficult research challenge due to changes that naturally occur in the immune systems of pregnant women. An additional challenge is the uncertainty of how drugs or vaccines given to pregnant women will affect or effectively reach the developing fetus.
Prevention of microcephaly depends on understanding the cause of the disorder, so the first step is to see whether we can recreate the human infection in a model. Our laboratory in SRI Biosciences’ Center for Infectious Diseases has extensively studied how pregnancy affects the immune system. Through this research, we have developed a unique way to model Zika that will allow us to understand what occurs when a pregnant woman becomes infected with the virus.
Using our laboratory model systems, we also want to examine the role of direct infection of the fetus and confirm whether the virus can travel into, or otherwise affect the developing brain. Perhaps the immune response of the mother is causing the developmental delay in her developing baby.
While we are using a number of approaches to understand how Zika virus operates, we can simultaneously work to identify therapies that will stop its devastating effects. One strategy that SRI has successfully employed before is to screen existing drugs for potential activity in treating a virus. There may be an existing drug that has antiviral activity against Zika, but we don’t know it yet. By screening known drugs, we may find one that is active against Zika virus and already FDA approved, so its safety profile is known and its dosage already understood.
In addition, SRI has developed technology that can test a drop of blood to quickly identify Zika viral genes in the bloodstream of affected patients or antibodies to Zika that the patients have naturally developed. This technology may help us identify infected women more quickly to treat them once there is a therapy to offer.
The international emergency caused by the Zika virus is an example of the type of important, global challenges around which SRI has built its mission to develop world-changing solutions that make people safer, healthier, and more productive.