KNOW YOUR ENEMY: Natural killer cells, like the one attacking this larger cancer cell, can be activated by cell-surface receptors called activating KIRs. GWENOLINE BORHIS

EDITOR'S CHOICE IN IMMUNOLOGY

The paper
M.M. Naiyer, “KIR2DS2 recognizes conserved peptides derived from viral helicases in the context of HLA-C,” Science Immunology, 2:eaal5296, 2017.

Killing machines
Natural killer (NK) cells help fight viral infections as part of the body’s innate immune response. Activation of these cells depends partly on a set of NK cell-surface proteins called activating killer cell immunoglobulin-like receptors (KIRs). But how activating KIRs recognize pathogens is poorly understood.

Searching for a match
While screening for viral peptides that stimulate one receptor, KIR2DS2, hepatologist Salim Khakoo’s group at the University of Southampton, U.K., stumbled across an amino acid sequence that appears highly conserved across multiple flaviviruses, from Zika to Japanese encephalitis. “There are about 63 different flaviviruses, and they almost...