Urocanic acid is a major chemoattractant for the skin-penetrating parasitic nematode Strongyloides stercoralis
- *Department of Physiology, School of Medicine, and
- †Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA 19104
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Communicated by William C. Campbell, Drew University, Madison, NJ, November 16, 2006 (received for review September 19, 2006)
Abstract
Host-seeking behavior by parasitic nematodes relies heavily on chemical cues emanating from potential hosts. Nonspecific cues for Strongyloides stercoralis, a nematode that infects humans and a few other mammals, include carbon dioxide and sodium chloride; however, the characteristic species specificity of this parasite suggested the existence of other, more specific cues. Here we show that the infective larva of S. stercoralis is strongly attracted to an extract of mammalian skin and that the active component in this skin extract is urocanic acid. Urocanic acid, a histidine metabolite, is particularly abundant in mammalian skin and skin secretions, suggesting that it serves as an attractant specific to mammalian hosts. The attractant activity of urocanic acid is suppressed by divalent metal ions, suggesting a possible strategy for preventing infection.
Footnotes
- ‡To whom correspondence should be addressed. E-mail: schad{at}vet.upenn.edu
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Author contributions: D.S. and G.S. designed research; D.S., M.B., and S.D. performed research; D.S., M.B., S.D., and G.S. analyzed data; and D.S. and G.S. wrote the paper.
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The authors declare no conflict of interest.
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See Commentary on page 1447.
- © 2007 by The National Academy of Sciences of the USA
