The Zika virus may have undergone a genetic mutation that enabled it to become the serious public health concern, according to the latest research from a team of researchers from the U.S. and China.

In a paper published in the journal Nature the researchers explain that Zika virus isolates from the recent outbreak in the Americas were much more infectious in mosquitoes than Zika virus isolates collected in Cambodia in 2010. The increase in the virus’s infectivity in mosquito was likely due to a genetic mutation found in a particular non–structural protein.

“This research helped us understand how and why the Zika virus, which we’ve known about since the 1940s, suddenly spread so quickly,” said Pei–Yong Shi, a professor at The University of Texas Medical Branch at Galveston. “The current study used a well–adapted laboratory mosquito strains. The next step is to examine whether field mosquitoes could recapitulate the same conclusion.”

The researchers who participated in this work included scientists from The University of Texas Medical Branch at Galveston, along with collaborators from Dr. Gong Cheng’s team at the Tsinghua University, and other participants from the Shenzhen Center for Disease Control and Prevention, the Institute of Microbiology and Epidemiology, the Southern University of Science and Technology, and the New York Medical College.

“Our data offer a potential explanation for the recent re–emergence of the Zika virus,” Shi said.