The simultaneous expression of costly immune effectors such as multiple antimicrobial peptides is a hallmark of innate immunity of multicellular organisms, yet the adaptive advantage remains unresolved. Here, we test current hypotheses on the evolution of such defence cocktails. We use RNAi gene knock-down to explore, the effects of three highly expressed antimicrobial peptides, displaying different degrees of activity in vitro against Staphylococcus aureus, during an infection in the beetle Tenebrio molitor. We find that a defensin confers no survival benefit but reduces bacterial loads. A coleoptericin contributes to host survival without affecting bacterial loads. An attacin has no individual effect. Simultaneous knock-down of the defensin with the other AMPs results in increased mortality and elevated bacterial loads. Contrary to common expectations, the effects on host survival and bacterial load can be independent. The expression of multiple AMPs increases host survival and contributes to the control of persisting infections and tolerance. This is an emerging property that explains the adaptive benefit of defence cocktails.
survival_singleKD_ten1
Survival data of the control and tenecin 1 knock-down beetles over 35 days after infection with Staphylococcus aureus of inejction of a saline solution. Experiment 1.
survival_simpleKD_ten1.csv
CFU_singleKD_ten1
Number of CFU of Staphylococcus aureus recovered from Tenebrio molitor along time in control and tenecin 1 knock down beetles. Experiment 1.
CFU_simpleKD_ten1.csv
survival_doubleKD_ten1ten2_ten1ten4
Survival data of Tenebrio molitor after infection with Staphylococcus aureus or a saline solution over 35 days in control, tenecin 1 and tenecin 2 or tenecin 1 and tenecin 4 knock down beetles. Experiment 2.
CFU_doubleKD_ten1ten2_ten1ten4
Number of Staphylococcus aureus CFU recovered from Tenebrio molitor across time after infection in control, tenecin one and tenecin 2 or tenecin 1 and tenecin 4 beetles. Experiment 2.
survival_singleKD_ten2_ten4
Survival data of Tenebrio molitor after infection with Staphylococcus aureus or injection of a saline solution in control, tenecin 2 knock down and tenecin 4 knock down beetles over 35 days. Experiment 3.
survival_simpleKD_ten2_ten4.csv
CFU_singleKD_ten2_ten4
Number of CFU of Staphylococcus aureus recovered from Tenebrio molitor across time after infection in control, tenecin 2 or tenecin 4 knock down beetles. Experiment 3.
CFU_simpleKD_ten2_ten4.csv
singleKD_ten1KD_deltact_CFU
Data on the efficiency of the knock down by qPCR in the single knock down of tenecin 1 in relationship to the number of CFU of Staphylococcus aureus recovered from tenecin 1 knock down and control beetles.
simpleKD_ten1KD_deltact_CFU.csv
doubleKD_ten1ten2KD_deltaCt_CFU
Data on the efficiency of the knock down by qPCR in the double knock down of tenecin 1 and tenecin 2 in relationship to the number of CFU of Staphylococcus aureus recovered from beetls of each treatment.
doubleKD_ten1ten4KD_deltaCt_CFU
Data on the efficiency of the knock down by qPCR in the double knock down of tenecin 1 and tenecin 4 in relationship to the number of CFU of Staphylococcus aureus recovered from beetls of each treatment.
singleKD_ten2_deltact
Data on the efficiency of the knock down by qPCR in the single knock down of tenecin 2 in tenecin 2 knock down and control beetles.
singleKD_ten4_deltact
Data on the efficiency of the knock down by qPCR in the single knock down of tenecin 4 in tenecin 4 knock down and control beetles.