Zika virus can mutate to become more infectious and deadly

The Zika virus can change to become more infective, according to researchers at the La Jolla Institute for Immunology (LJI). This could allow it to overcome pre-existing immunity.

“The world should monitor the emergence of this Zika virus variant,” says LJI Professor Sujan Shresta, Ph.D., who co-led the Cell Reports study with Professor Pei-Yong Shi, Ph.D., of the University of Texas Medical Branch (UTMB).

The Zika virus is spread by mosquitos, and the signs of infection in humans are usually mild. The virus, on the other hand, can infect a growing foetus, causing birth abnormalities including microcephaly.

In many countries throughout the world, the Zika virus and dengue virus coexist. Dengue virus, like Zika, is a mosquito-borne flavivirus with numerous biological similarities. In fact, the viruses are so similar that the immune response elicited by earlier dengue infection can protect against Zika.

Professor Shresta explained, “Dengue and Zika are RNA viruses, which means they can change their genome.”

The researchers discovered that it is quite simple for the Zika virus to acquire a single amino acid mutation that permits it to create more copies of itself and spread more quickly.

The NS2B I39V/I39T mutation improves the virus’s capacity to reproduce in both mice and mosquitoes. In human cells, this Zika variant demonstrated enhanced replication.

“This single mutation is sufficient to enhance Zika virus virulence,” says study first author Jose Angel Regla-Nava, Ph.D.

Shresta added, “The Zika variant that we identified had evolved to the point where the cross-protective immunity afforded by prior dengue infection was no longer effective in mice. Unfortunately for us, if this variant becomes prevalent, we may have the same issues in real life.”

So, how can we prepare for such a scenario? Shresta’s team is already working on customising Zika vaccines and treatments to combat this hazardous mutation.

“We want to understand at what point in the viral life cycle this mutation makes a difference,” says Shresta.