A small mutation may make Zika more dangerous

Researchers at the La Jolla Institute for Immunology (LJI) have discovered that the Zika virus can mutate to become more contagious -- potentially overcoming existing immunity

"The world should monitor the emergence of Zika virus variants," said LJI Professor Sujan Shresta, PhD, who co-led the Cell Reports study with Professor Shi Peiyong from the University of Texas Medical School (UTMB)

Microcephaly is a birth defect in which a baby has a smaller head than other babies of the same sex and age

Zika virus is transmitted by mosquitoes, and symptoms of Zika virus infection in adults are usually mild

Zika and dengue viruses overlap in many countries around the world

"In areas where Zika is endemic, the vast majority of people have been exposed to dengue virus, with cross-reactive T cells and antibodies," Shresta said

Unfortunately, both viruses also mutate rapidly

Repeated switching between mosquito cells and mouse cells gives scientists a window into how Zika naturally evolves as it encounters more hosts

To study the fast-paced evolution of the Zika virus, the LJI team recreated infection cycles that repeatedly switch between mosquito cells and mice

The researchers found that Zika virus relatively easily acquires single amino acid changes that allow the virus to replicate more of itself, making infection more likely

"This single mutation is sufficient to enhance the virulence of Zika virus," said study first author Jose Angel Regla-Nava, Ph.

Shresta added: "The Zika virus variant we found has evolved to the point where the cross-protective immunity from previous dengue infections is no longer effective in mice

So how do we deal with this variant? Shresta's lab is already looking for a custom Zika vaccine and treatments to combat this dangerous variant

"We wanted to understand at which stage of the viral life cycle this mutation plays a role," Shresta said