Bryan Ericksen - Antibacterial activity and specificity of the six human alpha defensins

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Ericksen B, Wu Z, Lu W, Lehrer RI. Antibacterial activity and specificity of the six human {alpha}-defensins. Antimicrob Agents Chemother. 2005 Jan;49(1):269-75. PubMed PMID: 15616305; PubMed Central PMCID: PMC538877.


    We developed a kinetic, 96-well turbidimetric procedure that is   capable of testing the antimicrobial properties of six human   alpha-defensins concurrently on a single microplate. The   defensins were prepared by solid-phase peptide synthesis and   tested against gram-positive bacteria (Staphylococcus aureus and   Bacillus cereus) and gram-negative bacteria (Enterobacter   aerogenes and Escherichia coli). Analysis of the growth curves   provided virtual lethal doses (vLDs) equivalent to conventional   50% lethal doses (LD(50)s), LD(90)s, LD(99)s, and LD(99.9)s   obtained from colony counts. On the basis of their respective   vLD(90)s and vLD(99)s, the relative potencies of human myeloid   alpha-defensins against S. aureus were HNP2 > HNP1 > HNP3   > HNP4. In contrast, their relative potencies against E. coli   and E. aerogenes were HNP4 > HNP2 > HNP1 = HNP3. HD5 was as   effective as HNP2 against S. aureus and as effective as HNP4   against the gram-negative bacteria in our panel. HD6 showed   little or no activity against any of the bacteria in our panel,   including B. cereus, which was highly susceptible to the other   five alpha-defensins. The assay described provides a   quantitative, precise, and economical way to study the   antimicrobial activities of host-defense peptides. Its use has   clarified the relative potencies of human alpha-defensins and   raised intriguing questions about the in vivo function(s) of   HD6.

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