Worm expression (IMAGE) University of California - San Diego Caption Worms with alterations in purine metabolism are shown triggering an immune response without pathogen infection. The immune response is revealed through green fluorescence in mutant worm intestines (middle and right) and not in control worms (left). Credit Troemel Lab, UC San Diego Usage Restrictions Must be used in conjunction with PLOS Pathogens paper on immune response. License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.