New research by Ayres and Schneider published in this issue of PLoS Biology [10] reveals all this and more—and all for a single mutation.
Earlier this year, the same authors [11] reported a screen of 1,000 mutant fruit fly lines from which they identified 18 more likely to die from infection with the intracellular bacterial pathogen Listeria monocytogenes.
Of the 18, infection intensities were higher in 12, suggesting that these were resistance-defective mutants.
The remaining six, though, died faster without elevated pathogen titres, and so were most likely tolerance-defective mutants. The phenotypic description of these mutants came just two years after the existence of genetic variation in tolerance in flies was first proposed [12] and 114 years after tolerance was recognised by plant scientists.