In a step toward a drug to treat Zika infections, researchers have discovered a compound that prevents the virus from spreading.

The compound could serve as basis for drugs to prevent neurological complications of Zika.

"We identified a small molecule that inhibits the Zika virus protease, and show that it blocks viral propagation in human cells and in mice," said lead researcher Alexey Terskikh, Associate Professor at Sanford Burnham Prebys Medical Discovery Institute (SBP) in San Diego, California, US.

"Anti-Zika drugs are desperately needed. The fact that the compound seems to work in vivo is really promising, so we plan to use it as a starting point to make an even more potent and effective drug," Terskikh said. 

The screening process process that the researchers used identified three promising compounds, which were then tested for their ability to prevent Zika infection of human brain cells. 

The best one of these also reduced the amount of virus circulating in the blood of Zika-infected mice, according to the study published in the journal Antiviral Research.

"The inhibitor's efficacy in animals is the key to the study's significance," Terskikh said. 

"This, and the fact that the compound is likely to be safe make it especially promising. The compound blocks a part of the protease that's unique to viruses, so it doesn't inhibit similar human proteases. It's also much more potent than previously identified inhibitors of the Zika protease," Terskikh said.

Zika has been linked to an increase in cases of microcephaly, a birth abnormality in which the head and brain are unusually small, and Guillain-Barre syndrome, a rapidly developing neurological condition that causes weakness of the arms and legs and can progress to life-threatening respiratory failure.

"Microcephaly is likely just the tip of the iceberg in terms of the potential adverse effects of maternal Zika infection," Terskikh said. 

"There may be other, less obvious impacts on brain develo pment that wouldn't be apparent until later. That's something we're also investigating," he noted.