Zika virus tunnels to reach the placenta: proof in pictures

The Zika virus is proving to be decidedly insidious. An American team has just published in the journal Nature an original work that deciphers the fine mechanisms of transmission from mother to child.

It was already known that infection by the virus in a pregnant woman through a mosquito bite could cause significant risks to the unborn child (even if the mother does not show any symptoms) and that for the child, the consequences were mainly neurological, such as microcephaly, incomplete brain development, tone abnormalities or even limb malformations.

A virus that tunnels to the placenta

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But until now, the precise mechanisms of action of the virus responsible to date for four major epidemics (2007 in Micronesia, 2013 in French Polynesia, 2014 in New Caledonia, 2015 in South America, Antilles and Caribbean) remained poorly understood.

However, with this study, supported by photographic evidence (see images below), researchers from Baylor College (University of Texas, USA) went further. This time they have updated the viral strategy which consists of digging tunnels to the placenta in order to infect the so-called placental cells. trophoblasts.

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Images from the study show that the Zika virus tunnels into trophoblasts. Credit: Rafael T. Michita, Nature Communications

Placental cells gradually nibbled away

It was the use of sophisticated techniques such as mass spectrometry that allowed the Texan teams to demonstrate that the virus advances in a sort of disguise, by digging tunnels deep into the placenta, the organ that nourishes the developing fetus. “ We demonstrate that Zika virus induces tunneling nanotubes in trophoblasts, which facilitate the transfer of viral particles, proteins, mitochondria, and RNA to neighboring uninfected cells.", write the authors in their abstract.

He also clarified that the formation of these tunnels is exclusively induced by a non-structural protein of the virus called NS1, and that this ultimately stealthy mode of propagation therefore allows the virus to pass under the radar by avoiding the activation of placental antiviral defenses. So everything happens as if, eWhen exposed to NS1, the placental cells were gradually nibbled away as the tunnels progressed through the tissue, allowing the virus to gain ground. It now remains to find a therapeutic strategy targeting these mechanisms to limit the spread of the virus.