New Delhi, July 12: Zika virus could pose a far greater threat to pregnancy than recent studies of miscarriage and stillbirth in human infections have reported. This virus do not show any symptoms and thusraises concerns about the complications which are likely to arise from this condition.
The results of an animal-based study showed that 26% non-human primates infected with Zika suffered miscarriage or stillbirth despite very few symptoms of the infection.
By administering Zika virus directly into the reproductive tract of pregnant mice that have an intact immune system, the researchers found that the Zika virus appears to create disorganization in the cellular layers of the placenta that keep toxins, bacteria and viruses from crossing.
This disorganisation could be how the virus penetrates the placenta to infect the foetus.
The researchers at Johns Hopkins University in the US also discovered a mechanism by which Zika may be keeping antiviral proteins in the body from doing their job of protecting cells from the virus.
The findings put scientists one step closer to developing targets for vaccines or other treatments for Zika.
Currently there is no cure or treatment for the virus, which has been linked to serious neurological problems in infants whose mothers were exposed in early pregnancy.
For much of 2016, Zika was considered a public health emergency by the World Health Organisation (WHO).
"We need to find a way to stop transmission of Zika through the placenta into the fetus, because that is where the damage is being done," said Sabra L Klein, from the Johns Hopkins Bloomberg School of Public Health.
"In the placentas of our mice, we're seeing a defense against Zika being mounted, but falling short, especially in early pregnancy, a time that corresponds to the first trimester in humans," said Klein.
Irina Burd, from the Johns Hopkins Medicine, is hopeful that this is an important step toward halting the transmission of Zika from mother to child.
"If we can determine what is happening, we may be able to find ways to minimise or even eliminate what can be devastating consequences for children of infected mothers," Burd said.
Scientists developed a new mouse model that helps understand the mechanisms behind Zika transmission to the foetus.
Unlike other mice used to study the virus, the Hopkins mice have completely intact immune systems more similar to humans, which enable researchers to see all that is involved in mounting an immune response. They intend to continue to follow up on their initial findings using the same model.
Researchers injected Zika virus directly into the reproductive tract of the pregnant mice during what would be the equivalent of the first trimester in a human.
Since different species of animals may clear infections in different ways, they wanted to make sure the virus was getting to the most relevant tissues of the pregnant mice.
The researchers used several different strains of the virus, using older strains - one from an outbreak in Nigeria in 1968 and another from Cambodia in 2010 - and contemporary ones from Brazil and Puerto Rico from the most recent epidemics.
OneIndia News (with PTI inputs)