Sea Anemone CARDIB Protein Inverts MAVS Function to Enable Antiviral Defense

Researchers at Hebrew University and UNC Charlotte identified CARDIB, a MAVS-like protein in Nematostella vectensis that normally dampens rather than activates antiviral signaling. CRISPR knockouts produced animals hypersensitive to viral challenge, with elevated viral loads and blunted downstream responses, overturning expectations based on vertebrate MAVS mechanics. Mesocosm transplants confirmed the phenotype under realistic microbial pressure, isolating the effect from laboratory artifacts.

The finding exposes deep evolutionary divergence in animal immunity. While vertebrates rely on MAVS to amplify interferon responses, cnidarians appear to have co-opted a structurally similar scaffold for negative regulation that paradoxically licenses full pathway engagement only when the brake is present. This suggests multiple independent solutions to antiviral control emerged after the cnidarian-bilaterian split more than 600 million years ago.

Therapeutic implications extend beyond vaccines. Pharmacologic tuning of analogous negative regulators in humans could yield host-directed antivirals that avoid resistance-prone viral targets and address broad pathogen classes. Existing MAVS pathway modulators already in oncology trials provide an immediate chemical starting point for such exploration.

Future work must map CARDIB interactors and test whether synthetic suppression of human MAVS regulators recapitulates protective effects in mammalian cells without triggering autoimmunity.