A new study shows how Zika virus infects the placenta and gets passed through to the fetuses. Scientists have discovered that the deadly virus can infect and imitate immune cells found in the placenta. The clinical research can shed light on how Zika gets transferred from an infected pregnant woman to the developing brain cells of her unborn.
The study showing how Zika virus infects the placenta was conducted by Mehul Suthar, Ph.D., at Emory University School of Medicine. The research was conducted on full-term placentae obtained from non-infected volunteers who delivered the babies by C-section. The virus strain used in the study came from Puerto Rico, and it is similar to the one currently circulating in Brazil.
Suthar and his team of researchers discovered that the virus can infect placental macrophages (Hofbauer cells) in cell culture. Hofbauer cells were believed to be less sensitive to invasions than other types of immune cells. However, researchers found signs of inflammatory and antiviral responses in placental macrophages. The discovery raised questions whether receptor allowed the virus to enter the cells or did they change their immune status over time.
Zika can also infect cytotrophoblasts, which are another type of placental cells, but with a few days delay. The syncytiotrophoblasts, however, are resistant to the infection.
The study can lead to a better understanding as to why the first and second trimesters of pregnancy show the highest risk for infection.
Other viruses related to Zika, such as West Nile virus, dengue virus, and yellow fever virus, rarely transmit the disease from the mother to the fetus. It is believed to be because of the placenta’s protective role, separating the circulatory systems of the mothers and the fetuses.
Zika, however, might be unique in its ability to cross the placental barrier.
The findings also proved that not all pregnant women infected by Zika give birth to babies with defects caused by the deadly virus. A number of genetic and non-viral factors can influence infectivity. It is crucial to understand these factors because they might help in the development of more-effective treatments and preventive measures against the mosquito-borne virus.
The findings of the study demonstrating how Zika virus infects the placenta were published on May 27 in Cell Host & Microbe journal.
IMAGE SOURCE: sbs.com.au