[
International Worm Meeting,
2003]
ASABF (Ascaris suum antibacterial factor) is a peptide antibiotic isolated from nematodes. To date, 7 members of ASABF-type antimicrobial peptides (ASABF-alpha, beta, gamma, delta, epsilon, zeta, and 6Cys-alpha) have been identified in Ascaris suum. Two homologs, ABF-1 and ABF-2, were also found in C. elegans. Although no significant toxicity was detected for human erythrocytes, ASABF-alpha and ABF-2 killed Gram+ and Gram- bacteria, and yeasts. It is noteworthy that ASABF is highly effective against the common pathogen, Staphylococcus aureus. We are curious to use ASABF as a novel anti-S. aureus agent. Susceptibility for various standard strains of S. aureus (mainly whose genome sequencing has been finished or in progress) were estimated. The vancomycin and methicillin resistant strain (VRSA-MRSA), Mu50, was identified as one of the most resistant strain to ASABF-alpha. Extreme cell wall thickening has been reported in Mu50. To test whether the thickening of cell wall affect susceptibility to ASABF, we also estimated the ASABF-susceptibility in the pre-MRSA, N315, whose cell wall artificially thickened by overexpression of sigma factor B (SigB). The cell wall thickened N315 was more resistant than parent N315, suggesting that the thickness of cell wall may affect the susceptibility to ASABF. The molecular mechanism of SigB-induced resistance is under investigation.