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Infection and Immunity, November 1998, p. 5399-5405, Vol. 66, No. 11
Department of Microbiology, University of
Minnesota, Minneapolis, Minnesota,1 and
Institute of Medical Microbiology and National Reference
Laboratory for Streptococci, University Hospital, Aachen,
Germany2
Received 29 June 1998/Accepted 27 August 1998
Resistance to phagocytosis is a hallmark of virulent
Streptococcus pyogenes (group A streptococcus).
Surface-bound C5a peptidase reduces recruitment of phagocytes to the
site of infection, and hyaluronic acid capsules and/or the M protein
limit the uptake of streptococci. In this study the relative impact of
M and M-like proteins and the C5a peptidase on the virulence of a
serotype M49 strain was assessed. The capacities of isogenic strains
with an insertion mutation in emm49; with a deletion
mutation in scpA49 (C5a peptidase gene); and with a
deletion that removes all three M-like genes, mrp49,
emm49, and enn49, to colonize mice and resist phagocytosis were compared. Experiments confirmed results obtained in
an earlier study, which showed that the M49 protein was not required
for in vitro resistance to phagocytosis, and also showed that the M
protein was not required for colonization of mice. Failure to produce
all three M-like proteins, M49, Mrp, and Enn49, significantly reduced
the ability of these streptococci to resist phagocytosis in vitro but
did not significantly alter the persistence of streptococci on the oral
mucosa. In vitro experiments indicate that M+ streptococci
are phagocytized by polymorphonuclear leukocytes that have been
activated with phorbol-12-myristate 13-acetate or recombinant human
C5a. This observation may explain the finding that expression of M49
protein is not essential for short-term colonization of the mouse oral
mucosa.
0019-9567/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
Impact of M49, Mrp, Enn, and C5a Peptidase Proteins
on Colonization of the Mouse Oral Mucosa by Streptococcus
pyogenes
*
Corresponding author. Mailing address: Box 196 FUMC,
Department of Microbiology, University of Minnesota, Minneapolis, MN 55455. Phone: (612) 624-6190. Fax: (612) 626-0623. E-mail:
cleary{at}lenti.med.umn.edu.
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