Bacterial Infection Assay in C. elegans

Following washing in phosphate-buffered saline, bacteria grown in LB for 18–24 h at 37°C and standardized to an OD₆₀₀ of 3.0 were prepared for tests. To obtain a synchronously growing population, eggs were prepared by treating a population of C. elegans with hypochlorite/NaOH solution and transferring the resulting eggs to NGM plates covered with E. coli OP50, as previously described (Chen et al., 2014b (link)). The synchronized adult L4 worms on NGM plates were washed in M9 buffer. After centrifugation, the pellets of worms were re-expanded with S medium, and 5 μl of solution containing approximately 30–40 worms were placed in each lawn of 48-well plates with 5 μl fluorodeoxyuridine (Sigma–Aldrich, Saint Louis, MO, USA) to prevent reproduction. Finally, 190 μl of bacteria in LB solution were added to achieve a total 200 μl in each lawn. Assay plates were incubated at 25°C for 3–6 days. The percentages of animal death were calculated as the numbers of dead animals/total animals found each day under a dissecting microscope.