The Protective Power of a Fake 'Infection' During Pregnancy

Researchers have discovered that during pregnancy, the placenta activates a low-level immune response by mimicking a viral infection using Alu repeats, chunks of DNA that make up 13% of the human genome. The placental cells produce double-stranded RNA, which triggers the production of interferon lambda, a milder immune response that protects the developing embryos without causing tissue damage. This strategy allows the placenta to balance the health of the fetus with a potentially risky immune response. Similar immune trickery has also been observed in neurons, suggesting that this phenomenon may be more common than previously thought.