Zika can't be cured and there is no vaccine for it yet, but a team of Chinese and American scientists have reported progress in developing a new, potentially effective and economically feasible, way to inhibit infection by the virus – a variant of which can cause severe brain developmental abnormalities in newborns. It has been shown effective on cells in the lab and in mice.
"Z2 has potential to be further developed as an antiviral treatment against ZIKV infection in high-risk populations, particularly pregnant women," the scientists say in their paper, "A peptide-based viral inactivator inhibits Zika virus infection in pregnant mice and fetuses."
Transmitted by mosquito, Zika apparently originated in Africa and, with the advent of international travel, has spread to 73 countries and regions.
Its effects on adults can range from nothing to flu-like effects to Guillain-Barre syndrome. But a variant, particularly afflicting South and Central America, can cause microcephaly and other grave nervous-system defects in newborns.
Vaccines in development have shown positive results in mice, but none are tested and approved for humans. Work is also being done on prevention, and some molecules have shown efficacy in inhibiting Zika infection.
One such class, small-molecule drugs, remains to be proven safe for pregnant women, says the paper by lead author Yufeng Yu of Fudan University, Shanghai and the team.
Another class, engineered antibodies, have at the least economic feasibility issues. Now the team reports developing a synthetic molecule that potently inhibits infection of cells (derived from green monkeys and baby hamsters) by Zika and other flaviviruses, in vitro, meaning in the lab.
They also showed that the prophylactic molecule, called Z2, has broad inhibitory activity against Zika strains isolated from patients and rhesus monkeys in different regions of the world.
Crucially, Z2 can penetrate the placental barrier and enter fetal tissues. It has been shown safe for use in pregnant mice, the team states.
Z2 is a peptide – a short protein chain – that works by interacting with a protein embedded in the outer membrane of the virus, and disrupting the integrity of that membrane.
So the peptide has efficacy in kidney cell lines originating in green monkeys and baby hamsters, a normal vehicle for such research, and in rodents. Arguments for continuing research include why developing peptide drugs has become the rage in anti-viral circles: because they have better safety and lower development cost compared to small-molecule and antibody-based antiviral drugs. Another is that other peptide drugs work in inhibiting certain viral infections, such as mother-to-child HIV infection during pregnancy.
The team included scientists from the Beijing Institute of Microbiology and Epidemiology, Fudan University, New York Blood Center, the Beijing Hospital of Traditional Chinese Medicine, University of Hong Kong.