Prophenoloxidase Activation Is Required for Survival to Microbial Infections in Drosophila
Figure 8
Contribution of PPO1 and PPO2 to wound healing and to host defense.
(A, B) Survival rate of flies following injury with clean needle show that concomitant deletion of PPO1 and PPO2 impairs the capacity of flies to survive severe wounding (p<0.0001) compared to wild-type flies. (C, D) PPO1 and PPO2 are not required to survive septic injury with Gram-negative bacteria (S. typhimurium and E. cloacae). (E, F) PPO1Δ, PPO2Δ mutant flies are less resistant to infections with Gram-positive DAP-type bacteria L. monocytogenes (p = 0.0002) and B. subtilis (p<0.0001) compared to wild-type animals. (G, H) PPO1Δ, PPO2Δ mutant flies are severely affected in their capacity to resist infection with Gram-positive Lys-type bacteria E. faecalis and S. aureus (p<0.0001). PPO1Δ and PPO1Δ, PPO2Δ flies are even more susceptible to S. aureus than spzrm7 flies p<0.0001. PPO1Δ mutant flies also exhibit a reduced survival to S. aureus infection (p<0.0001). (I, J) PPO1Δ, PPO2Δ mutant flies exhibit a moderate susceptibility upon septic injury with the yeast C. albicans (p = 0.0101) and a strong susceptibility to injection of A. fumigatus spores (p<0.0001). PPO2Δ mutant flies also die significantly faster from A. fumigatus infection (p = 0.0018 (K, L) Natural infection with entomopathogenic fungi B. bassiana and M. anisopliae reveals that PPO1Δ, PPO2Δ flies have a reduced survival rate compared to wild-type flies (p<0.0001); so did PPO1Δ single mutant flies (p = 0.0084). Black cells (A, B), Relish E20 (C, D) and spätzlerm7 (E, L), respectively, were used as controls. x-axis: Time post-infection in days; y-axis: Percentage of living flies. Data were analyzed by Log-rank test and values are pooled from three independent experiments. Survival to E. faecalis, S. aureus and B. bassiana have been repeated using fly lines carrying the PPO mutations in an OregonR background (Fig. S4C–E).