✦ The story
For two decades, RSAD2 ("Viperin") was a revered mystery among human immunologists: an interferon-induced gene that slows down HIV, HCV, flaviviruses, and even a few coronaviruses, but whose mechanism nobody could pin down. Then Aude Bernheim looked at bacteria. In 2021, her team showed that hundreds of bacteria carry a homolog doing exactly the same thing against phages: producing chain-terminator nucleotides (ddhCTP / ddhGTP). Once identified in the bacterium, the mechanism became obvious in humans — and the bacterial version provided a simpler structural model to crystallize and use as a scaffold for molecule optimization.
Discovered 2021
By Bernheim, Millman, Sorek, Pinilla-Redondo et al. (Weizmann + INSERM + Copenhagen)
★ Why we care
ddhCTP is a natural broad-spectrum antiviral. Chemically stabilized (resistant to the phosphatases that normally degrade it within minutes in plasma), it is a credible drug candidate. And the bacterial version remains the best structural template for design.
◇ The detail that lands
The name "viperin" was coined in 1995 as an acronym for virus inhibitory protein, endoplasmic reticulum-associated, interferon-inducible — five adjectives crammed together. The bacterial version dropped the "endoplasmic reticulum" (bacteria don't have one) but kept everything else. Science is rarely this economical with its vocabulary.