Zika Virus: A Stealthy Attack on the Placenta

US researchers have uncovered how the Zika virus stealthily spreads within placental cells, disrupting the immune system and leading to fetal death. The study, conducted by Baylor College of Medicine and Pennsylvania State University, sheds light on how the virus overcomes the placenta's natural defense barriers (1^✔ ✔Trusted Source
Zika virus NS1 drives tunneling nanotube formation for mitochondrial transfer and stealth transmission in trophoblasts

Go to source). Zika virus, a mosquito-borne pathogen, is known to cause neurological disorders, birth defects, and pregnancy loss. However, until now, the precise mechanism by which it crosses the placenta was unclear.

NS1 Protein Facilitates Viral Spread in Placenta

The research team discovered that the Zika virus creates tunneling nanotubes—tiny cellular tunnels that allow viral particles to move between neighboring cells undetected. They identified that a viral protein, NS1, plays a key role in triggering the formation of these tunnels, enabling the virus to spread more efficiently.

"Exposure of placental cells to the NS1 protein of Zika virus triggers tunnel formation. As the tunnels develop and connect neighboring cells, a path opens for the virus to invade new cells," said Dr. Rafael T. Michita, postdoctoral research associate at Baylor College of Medicine.

The study, published in Nature Communications, also revealed that these tunnels transport not just viral particles, but also RNA, proteins, and mitochondria—the cell's energy source. This may help infected cells survive longer and evade the immune system, giving Zika a strategic advantage in sustaining infection.

Interestingly, while other viruses like HIV, herpes, influenza A, and SARS-CoV-2 also use similar tunneling mechanisms, Zika is the first in its family—including dengue and West Nile viruses—to exhibit this behavior in placental cells.

Reference:

1. Zika virus NS1 drives tunneling nanotube formation for mitochondrial transfer and stealth transmission in trophoblasts - (https://www.nature.com/articles/s41467-025-56927-2)

Source-Medindia