Per H. Mygind, Rikke L. Fischer, Kirk M. Schnorr, Mogens T. Hansen, Carsten P. S"nksen, Svend Ludvigsen, Dorotea Raventøs, Steen Buskov, Bjarke Christensen, Leonardo De Maria, Olivier Taboureau, Debbie Yaver, Signe G. Elvig-Jørgensen, Marianne V. Sørensen, Bjørn E. Christensen, Søren Kjærulff, Niels Frimodt-Moller, Robert I. Lehrer, Michael Zasloff and Hans-Henrik Kristensen.
"Plectasin is a peptide antibiotic with therapeutic potential from a saprophytic fungus."
Nature 437, 975-980 (13 October 2005)
Abstract
Animals and higher plants express endogenous peptide antibiotics called defensins. These small cysteine-rich peptides are active against bacteria, fungi and viruses. Here we describe plectasin - the first defensin to be isolated from a fungus, the saprophytic ascomycete Pseudoplectania nigrella. Plectasin has primary, secondary and tertiary structures that closely resemble those of defensins found in spiders, scorpions, dragonflies and mussels. Recombinant plectasin was produced at a very high, and commercially viable, yield and purity. In vitro, the recombinant peptide was especially active against Streptococcus pneumoniae, including strains resistant to conventional antibiotics. Plectasin showed extremely low toxicity in mice, and cured them of experimental peritonitis and pneumonia caused by S. pneumoniae as efficaciously as vancomycin and penicillin. These findings identify fungi as a novel source of antimicrobial defensins, and show the therapeutic potential of plectasin. They also suggest that the defensins of insects, molluscs and fungi arose from a common ancestral gene.
Song ZJ, Wu H, Mygind P, Raventos D, Sonksen C, Kristensen HH, Hoiby N.
"Effects of intratracheal administration of novispirin G10 on a rat model of mucoid Pseudomonas aeruginosa lung infection."
Antimicrobial Agents and Chemotherapy, Vol. 49 (9) pp. 3868-3874 (2005)
Abstract
Chronic Pseudomonas aeruginosa lung infection is a major problem for patients with cystic fibrosis (CF). The biofilm mode of growth of the pathogen makes it highly resistant to antibiotic treatment, and this is especially pronounced with mucoid strains. In this study, novispirin G10, a synthetic antimicrobial peptide patterned loosely on sheep myeloid antimicrobial peptide 29, was tested in a rat model of mucoid P. aeruginosa lung infection. P. aeruginosa NH57388A, a mucoid strain isolated from a CF patient, was mixed with the alginate produced by the bacterium itself and adjusted to a concentration of 10(10) CFU/ml. Each rat received 10(9) CFU of bacteria intratracheally in the left lung to establish lung infection. At 0 and 3 h post P. aeruginosa infection, the treated group of rats received novispirin G10 (0.1 mg/ml, 0.1 ml/rat) intratracheally, whereas the control group received vehicle treatment only. The animals were sacrificed on days 3, 5, 7, and 10 after challenge for evaluation of various parameters. On day 5, 50% of the rats in the treated group had cleared the bacteria from the lungs, whereas in the control group, none of the rats cleared the pathogen (P < 0.03). The average bacterial loads remaining in the lungs of treated rats on days 3 and 5 were more than 170- and 330-fold lower than in the control groups (P < 0.0005 and P < 0.0003) . In accordance, the macroscopic and microscopic lung pathology was also significantly milder in the treated group compared to the control group (P < 0.0002). Lung cytokine responses in the treated group were significantly lower than in the control group. The results suggest that novispirin G10 might be useful in treating antibiotic-resistant P. aeruginosa lung infections.
Raventos D, Taboureau O, Mygind PH, Nielsen JD, Sonksen CP, Kristensen HH.
"Improving on nature's defenses: Optimization & high throughput screening of antimicrobial peptides."
Combinatorial Chemistry and High Throughput Screening, Vol. 8 (3) pp. 219-233 (2005)
Abstract:
Antimicrobial peptides (AMPs) are ubiquitous in nature where they play important roles in host defense and microbial control. Despite their natural origin, antimicrobial spectrum and potency, the lead peptide candidates that so far have entered pharmaceutical development have all been further optimized by rational or semi-rational approaches. In recent years, several high throughput screening (HTS) systems have been developed to specifically address optimization of AMPs. These include a range of computational in silico systems and cell-based in vivo systems. The in silico-based screening systems comprise several computational methods such as Quantitative Structure/Activity Relationships (QSAR) as well as simulation methods mimicking peptide/membrane interactions. The in vivo-based systems can be divided in cis-acting and trans-acting screening systems. The cis- acting pre-screens, where the AMP exerts its antimicrobial effect on the producing cell, allow screen ing of millions or even billions of lead candidates for their basic antimicrobial or membrane-perturbating activity. The transacting screens, where the AMP is secreted or actively liberated from the producing cell and interacts with cells different from the producing cell, allow for screening under more complex and application-relevant conditions. This review describes the application of HTS systems employed for AMPs and lists advantages as well as limitations of these systems.