Survival Probability Patterns of Flies Deficient in PGRP-SA or PGRP-LC (or Both) following Infection with WTA-less Bacteria
(A) Following infection with S. aureus, there was a statistically significant difference in the contribution of survival to infection when comparing either PGRP-SAseml or PGRP-LCΔE12 single mutants with the wild-type control w1118 (which survived more often) or with the homozygous PGRP-SAseml; PGRP-LCΔE12 double mutant (which survived less often). However, PGRP-SA contributed more since PGRP-SAseml was statistically closer to the double mutant.
(B) Infection with S. aureusΔTagO increased the statistical difference between PGRP-SA and PGRP-SAseml; PGRP-LCΔE12. This indicated the augmented participation of PGRP-LC in survival.
(C) After infection with B. subtilis, the survival probabilities of flies followed a pattern in which both PGRPs participated and the double homozygote mutant displayed the highest susceptibility, while w1118 displayed the lowest susceptibility.
(D) Nevertheless, removal of WTAs rendered both single mutants resistant to B. subtilisΔTagO as w1118 and the double heterozygote, whereas only the double homozygous mutant displayed a moderate susceptibility to infection.
The results shown here are from pooled survival data (n = 87–100 for each genotype) from three independent sets of injections (there were no significant departures between repeats; p > 0.1, log rank test) and plotted estimates of survival probabilities. To extract p values, populations were compared using log rank and Wilcoxon tests.
See also the statistics in Table S3.