Affiliation:
1. Veterans Affairs Medical Center
2. Department of Medicine
3. Department of Anatomy and Neurobiology, University of Tennessee, Memphis, Tennessee
Abstract
ABSTRACT
Serum opacity factor (SOF) is a protein expressed by
Streptococcus pyogenes
that opacifies mammalian serum. SOF is also a virulence factor of
S. pyogenes
, but it has not been previously shown to elicit a protective immune response. Herein, we report that SOF evokes bactericidal antibodies against
S. pyogenes
in humans, rabbits, and mice. Rabbit antiserum against purified recombinant SOF2 opsonized SOF-positive M type 2, 4, and 28
S. pyogenes
in human blood but had no effect on SOF-negative M type 5
S. pyogenes
. Furthermore, affinity-purified human antibodies against SOF2 also opsonized SOF-positive streptococci. A combination of antisera against M2 and SOF2 proteins was dramatically more effective in killing streptococci than either antiserum alone, indicating that antibodies against SOF2 enhance the opsonic efficiency of M protein antibodies. Mice tolerated an intravenous injection of 100 μg of SOF without overt signs of toxicity, and immunization with SOF protected mice against challenge infections with M type 2
S. pyogenes
. These data indicate that SOF evokes opsonic antibodies that may protect against infections by SOF-positive serotypes of group A streptococci and suggest that different serotypes of SOF have common epitopes that may be useful vaccine candidates to protect against group A streptococcal infections.
Publisher
American Society for Microbiology
Subject
Infectious Diseases,Immunology,Microbiology,Parasitology
Cited by
56 articles.
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