Zika proteins that stunt brain growth

Two Zika proteins responsible for microcephaly - a birth defect where a baby's head is abnormally small - have been identified by researchers at the University of Southern California (USC).

The Zika virus contains 10 proteins, but only two - NS4A and NS4B - are responsible for microcephaly, according to a USC-led study published recently in the journal Cell Stem Cell.

In April, the Centres for Disease Control and Prevention in the United States confirmed that Zika causes microcephaly and other severe foetal brain defects. But it was unclear how this happens.

The study, however, explained the molecular mechanisms that lead to the devastating condition and found that these proteins stunt human brain development. "We now know the molecular pathway, so we made the first big step towards target therapy for Zika-induced microcephaly," said senior corresponding author of the paper Jae Jung from the USC Department of Molecular Microbiology and Immunology.

Female mozzies can transmit virus to egg

In the fight against Zika, killing adult mosquitoes may no longer be enough.

According to research by the University of Texas Medical Branch in Galveston in the US, female Aedes aegypti mosquitoes - also vectors for dengue and chikungunya - can pass the virus to their eggs and offspring.

Researchers injected laboratory-reared Aedes aegypti mosquitoes with the virus. Eggs were then collected, incubated and the hatched larvae reared until adult mosquitoes emerged.

A culture of these adults found Zika in one of every 290 mosquitoes tested.

While the ratio seems low, Professor Robert Tash, study author, said the number of mosquitoes in a tropical urban community is likely high enough to allow the virus to persist even when infected adult mosquitoes are killed.

Virus may persist in vagina for days

Researchers have found that the virus can replicate in the vagina and persist days after a person has been infected.

In a recently published study, scientists from Yale University in the US observed replication of the Zika virus in the vaginal tissue of mice. It was observed that Zika reproduces in the vaginal tissue of pregnant mice several days after infection.

From the genitals, the virus spreads and infects the brain of the foetus.

The study was published in the journal Cell.