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The Lantibiotic NAI-107 Efficiently Rescues Drosophila melanogaster from Infection with Methicillin-Resistant Staphylococcus aureus USA300

View Article: PubMed Central - PubMed

ABSTRACT

We used the fruit fly Drosophila melanogaster as a cost-effective in vivo model to evaluate the efficacy of novel antibacterial peptides and peptoids for treatment of methicillin-resistant Staphylococcus aureus (MRSA) infections. A panel of peptides with known antibacterial activity in vitro and/or in vivo was tested in Drosophila. Although most peptides and peptoids that were effective in vitro failed to rescue lethal effects of S. aureus infections in vivo, we found that two lantibiotics, nisin and NAI-107, rescued adult flies from fatal infections. Furthermore, NAI-107 rescued mortality of infection with the MRSA strain USA300 with an efficacy equivalent to that of vancomycin, a widely applied antibiotic for the treatment of serious MRSA infections. These results establish Drosophila as a useful model for in vivo drug evaluation of antibacterial peptides.

No MeSH data available.


Induction of immune response genes. Drosomycin (A), Cecropin A1 (B), and Attacin B (C) transcript levels were determined by qPCR. A noninfected control group was used as a reference for normal expression, and the average expression levels for this group were set at 1. Flies infected with S. aureus 8325-4 were sampled for qPCR analysis at 6 and 12 h postinfection. Drug treatment was performed at 3 h, and injection of vehicle (VEH) alone was used as a control. Due to the small sample size, statistical analysis was not performed. Error bars indicate standard errors (n = 3).
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Figure 3: Induction of immune response genes. Drosomycin (A), Cecropin A1 (B), and Attacin B (C) transcript levels were determined by qPCR. A noninfected control group was used as a reference for normal expression, and the average expression levels for this group were set at 1. Flies infected with S. aureus 8325-4 were sampled for qPCR analysis at 6 and 12 h postinfection. Drug treatment was performed at 3 h, and injection of vehicle (VEH) alone was used as a control. Due to the small sample size, statistical analysis was not performed. Error bars indicate standard errors (n = 3).

Mentions: To further test the drug efficacy of the lantibiotics nisin and NAI-107 in vivo, we examined the immune responses of both treated and nontreated infected animals. We rationalized that infected animals treated with these compounds would mount less of an immune response provided that bacterial proliferation in the host was inhibited by the compounds. To test this, we used flies infected with S. aureus strain 8325-4. We administered NAI-107 at 100× MIC, while nisin, due to its detrimental side effect at high concentrations, was injected only at 3× MIC. Treatment of infected animals with ampicillin (>1,000× MIC) was included for comparison with an efficacious compound. Samples were taken in triplicate at 6 and 12 h postinfection, and uninfected flies served as controls. As a measure of the immune response, we analyzed the expression of the Drosomycin (Drs), Cecropin A1 (CecA1), and Attacin-B (AttB) immunity genes, which have all been implicated in the immune response of Drosophila to infection by Gram-positive bacteria (49, 50). In general, we observed that animals that received any form of treatment had elevated transcription of immune response genes (Fig. 3), most likely because any injection into the animals damaged the tissue, thereby elevating the immune response. Moreover, it is highly plausible that injection of any protein-like structure will elicit some degree of immune response. Another general observation was the presence of higher expression levels of immune response genes in infected untreated animals than in animals treated with nisin and NAI-107.


The Lantibiotic NAI-107 Efficiently Rescues Drosophila melanogaster from Infection with Methicillin-Resistant Staphylococcus aureus USA300
Induction of immune response genes. Drosomycin (A), Cecropin A1 (B), and Attacin B (C) transcript levels were determined by qPCR. A noninfected control group was used as a reference for normal expression, and the average expression levels for this group were set at 1. Flies infected with S. aureus 8325-4 were sampled for qPCR analysis at 6 and 12 h postinfection. Drug treatment was performed at 3 h, and injection of vehicle (VEH) alone was used as a control. Due to the small sample size, statistical analysis was not performed. Error bars indicate standard errors (n = 3).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4997821&req=5

Figure 3: Induction of immune response genes. Drosomycin (A), Cecropin A1 (B), and Attacin B (C) transcript levels were determined by qPCR. A noninfected control group was used as a reference for normal expression, and the average expression levels for this group were set at 1. Flies infected with S. aureus 8325-4 were sampled for qPCR analysis at 6 and 12 h postinfection. Drug treatment was performed at 3 h, and injection of vehicle (VEH) alone was used as a control. Due to the small sample size, statistical analysis was not performed. Error bars indicate standard errors (n = 3).
Mentions: To further test the drug efficacy of the lantibiotics nisin and NAI-107 in vivo, we examined the immune responses of both treated and nontreated infected animals. We rationalized that infected animals treated with these compounds would mount less of an immune response provided that bacterial proliferation in the host was inhibited by the compounds. To test this, we used flies infected with S. aureus strain 8325-4. We administered NAI-107 at 100× MIC, while nisin, due to its detrimental side effect at high concentrations, was injected only at 3× MIC. Treatment of infected animals with ampicillin (>1,000× MIC) was included for comparison with an efficacious compound. Samples were taken in triplicate at 6 and 12 h postinfection, and uninfected flies served as controls. As a measure of the immune response, we analyzed the expression of the Drosomycin (Drs), Cecropin A1 (CecA1), and Attacin-B (AttB) immunity genes, which have all been implicated in the immune response of Drosophila to infection by Gram-positive bacteria (49, 50). In general, we observed that animals that received any form of treatment had elevated transcription of immune response genes (Fig. 3), most likely because any injection into the animals damaged the tissue, thereby elevating the immune response. Moreover, it is highly plausible that injection of any protein-like structure will elicit some degree of immune response. Another general observation was the presence of higher expression levels of immune response genes in infected untreated animals than in animals treated with nisin and NAI-107.

View Article: PubMed Central - PubMed

ABSTRACT

We used the fruit fly Drosophila melanogaster as a cost-effective in vivo model to evaluate the efficacy of novel antibacterial peptides and peptoids for treatment of methicillin-resistant Staphylococcus aureus (MRSA) infections. A panel of peptides with known antibacterial activity in vitro and/or in vivo was tested in Drosophila. Although most peptides and peptoids that were effective in vitro failed to rescue lethal effects of S. aureus infections in vivo, we found that two lantibiotics, nisin and NAI-107, rescued adult flies from fatal infections. Furthermore, NAI-107 rescued mortality of infection with the MRSA strain USA300 with an efficacy equivalent to that of vancomycin, a widely applied antibiotic for the treatment of serious MRSA infections. These results establish Drosophila as a useful model for in vivo drug evaluation of antibacterial peptides.

No MeSH data available.