Thousands of pregnant women from South America are now infected with the Zika virus, which causes horrible skull and brain deformities in the babies. The situation is tense, and the concern is amplified because scientists still don’t know that much about this highly contagious virus. In the past couple of months, though, efforts have been drastically ramped. All Zika-related papers have been made open to facilitate and accelerate research, and thousands of scientists all over the world are collaborating to get to the bottom of things and hopefully find a vaccine.
A massive breakthrough in the fight against the Zika virus was made by Emory University School of Medicine who recently report a possible mechanism for the viruses’ migration from mother to baby. If this route is indeed the right one, then there’s a good chance we can develop drugs that act like roadblocks, keeping the virus from infecting the fetus.
Zika at a glance
Zika virus is an emerging mosquito-borne virus that was first identified in Uganda in 1947 in rhesus monkeys through a monitoring network of sylvatic yellow fever. It was subsequently identified in humans in 1952 in Uganda and the United Republic of Tanzania. Outbreaks of Zika virus disease have been recorded in Africa, the Americas, Asia and the Pacific.
- Zika virus disease is caused by a virus transmitted primarily by Aedesmosquitoes.
- People with Zika virus disease can have symptoms that can include mild fever, skin rash, conjunctivitis, muscle and joint pain, malaise or headache. These symptoms normally last for 2-7 days.
- There is no specific treatment or vaccine currently available.
- The best form of prevention is protection against mosquito bites.
- Zika virus can be passed from a pregnant woman to her fetus during pregnancy or at delivery. The babies can be born with microcephaly, a birth defect where a baby’s head is smaller than expected when compared to babies of the same sex and age. Babies with microcephaly often have smaller brains that might not have developed properly.
The Zika is a member of the flaviviruses, a group which includes dengue, West Nile, and yellow fever. All of these viruses are very rarely transmitted from mother to offspring — except for Zika. What makes it so special?
To investigate, the Emory University researchers infected healthy placentas which were donated by women who had a Cesarean section with Zika strain from Puerto Rico. Strikingly, they learned that the virus wasn’t killing Hofbauer cells. These cells are produced heavily when the body signals an infection and their job, being macrophages, is to swallow foreign bodies.
The Hofbauer cells, however, also have direct access to the fetal blood vessels. It seems that the Zika is basically infecting these cells which it uses to hide and cross into the fetus through the placenta.
This might explain why observational studies reported first and early second trimesters as the most vulnerable pregnancy phases. During these phases, the placenta is not developed enough and vulnerable to infections. Some donor cells were more susceptible than others, which might also explain why not all infected women pass on the virus to their babies.
“Our results substantiate the limited evidence from pathology case reports,” says senior author of the study Mehul Suthar, PhD, assistant professor of pediatrics at Emory University School of Medicine.. “It was known that the virus was getting into the placenta. But little was known about where the virus was replicating and in what cell type.”
“Zika may be unique in its ability to infect placental cells and cross the placental barrier, in comparison with other flaviviruses,” Suthar says.
Suthar says that next scientists need to find which receptors allow the virus to enter Hofbauer cells. If we can block these receptors a potentially global crisis might be averted.
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