World's First Zika Virus Clone May be the Key to Vaccine Development

Researchers at the University of Texas Medical Branch (UTMB) at Galveston have successfully cloned the Zika virus strain.

Infection with the Zika virus only causes symptoms in 20% of individuals; however, infection during pregnancy has proven harmful to the fetus, causing serious complications, such as microcephaly and even stillbirth. To aid in the fight against this devastating virus, the Centers for Disease Control and Prevention (CDC) recently announced that they are providing a total of $85 million to US states and territories to fight local transmission of the Zika virus. Shortly after this announcement, the US Senate voted to approve a bill to grant $1.2 billion in Zika funding.

In addition, research teams across the globe are working to learn more about the virus itself. A multidisciplinary group of scientists from UTMB is the first in the world to genetically engineer a clone of the Zika virus. In its development, the scientists individually cloned and later assembled 5 fragments of Zika’s complete viral genome, allowing for viral reproduction in the lab. The cloned virus was then tested on a mouse model produced in the same lab, which resulted in the infected mice developing Zika-related neurological diseases. Following these results, the scientists decided to test the infectiousness of the lab-developed strain in comparison to the original Zika virus. Human blood infected with either the original Zika strain or a clone was fed to Aedes aegypti mosquitoes, the mosquito vector which transmits Zika, Chikungunya and Dengue, among others. The cloned virus was found to be “highly infectious.”

The researchers also engineered a luciferase reporter Zika virus, which would allow for antiviral drug screening. The glowing reporter could also be used to track infection in mosquitoes, as well as in small animal models.

With the development of the cloned Zika strain, scientists hope to uncover the key points behind the current Zika epidemic, as well as trace the evolution of the virus. They hope that, by infecting mosquitoes with the original Zika strain and then manipulating the cloned virus, they can explore the possibility of recent Zika mutations attributing to enhanced viral transmission: scientists believe that the original Zika virus strain may have evolved in order to “maintain higher virus concentrations” in human blood, which would in turn ease viral transmission to the fetus through the placenta.

Lead author, Pei-Yong Shi, UTMB endowed professor stated, “The new Zika clone, together with mosquito infection models and the UTMB-developed Zika mouse model, represent a major advance towards deciphering why the virus is tied to serious diseases.” It is believed that this breakthrough may speed vaccine and antiviral therapy development.