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Infection and Immunity, April 1999, p. 1723-1728, Vol. 67, No. 4
Department of Veterinary Science and
Microbiology, The University of Arizona, Tucson, Arizona 85721
Received 18 November 1998/Returned for modification 4 January
1999/Accepted 14 January 1999
Pyolysin (PLO), the hemolytic exotoxin expressed by
Arcanobacterium (Actinomyces)
pyogenes, is a member of the thiol-activated cytolysin
family of bacterial toxins. Insertional inactivation of the
plo gene results in loss of expression of PLO with a
concomitant loss in hemolytic activity. The plo mutant,
PLO-1, has an approximately 1.8-log10 reduction in the 50%
infectious dose compared to that for wild-type A. pyogenes
in a mouse intraperitoneal infection model. Studies involving
cochallenge of wild-type and PLO-1 bacteria resulted in recovery of
similar numbers of both strains, suggesting that PLO production is
required for survival in vivo. Recombinant, His-tagged PLO (His-PLO) is
cytotoxic for mouse peritoneal macrophages and J774 cells in a
dose-dependent manner. Protection against challenge with A. pyogenes could be afforded by vaccination with formalin-inactivated His-PLO, suggesting that PLO is a host-protective antigen, as well as a virulence determinant.
0019-9567/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
An Arcanobacterium
(Actinomyces) pyogenes Mutant Deficient in
Production of the Pore-Forming Cytolysin Pyolysin Has Reduced
Virulence
*
Corresponding author. Mailing address: Department of
Veterinary Science and Microbiology, The University of Arizona, 1117 East Lowell St., Tucson, AZ 85721. Phone: (520) 621-2745. Fax: (520)
621-6366. E-mail: jost{at}u.arizona.edu.
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