Affiliation:
1. Department of Microbiology and Immunology, The University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73190,1 and
2. Institute for Molecular Biology, Jena University, D-07745 Jena, Germany2
Abstract
ABSTRACT
The CAMP reaction is a synergistic lysis of erythrocytes by the interaction of an extracellular protein (CAMP factor) produced by some streptococcal species with the
Staphylococcus aureus
sphingomyelinase C (beta-toxin). Group A streptococci (GAS [
Streptococcus pyogenes
]) have been long considered CAMP negative, and this reaction commonly has been used to distinguish GAS from
Streptococcus agalactiae
. We here provide evidence that GAS possess this gene and produce an extracellular CAMP factor capable of participating in a positive CAMP reaction. The
S. pyogenes
CAMP factor is specified by a 774-bp open reading frame homologous to the CAMP factor genes from
S. agalactiae
and
Streptococcus uberis
. This gene, designated
cfa
, was isolated on a 1,256-bp fragment and cloned in
Escherichia coli
. Recombinant clones of
E. coli
expressing
cfa
secreted an active CAMP factor. The deduced 28.5-kDa protein encoded by
cfa
consists of 257 amino acids, with a predicted 28-amino-acid signal peptide. The
cfa
gene is widely spread among GAS: 82 of 100 clinical GAS isolates produced a positive CAMP reaction. Of the CAMP-negative strains, 17 of the 18 GAS strains contained the
cfa
gene. Additionally, CAMP activity was detected in streptococci from serogroups C, M, P, R, and U. The
cfa
gene was cloned and actively expressed in
Escherichia coli
and gene fusions were made, placing the β-galactosidase gene (
lacZ
) under control of the
cfa
promoter. These
cfa
promoter-
lacZ
fusions were introduced into
S. pyogenes
via a bacteriophage-derived site-specific integration vector where they showed that the
cfa
gene has a strong promoter that may be subject to as-yet-unidentified regulatory factors. The results presented here, along with previous reports, indicate that the CAMP factor gene is fairly widespread among streptococci, being present at least in groups A, B, C, G, M, P, R, and U.
Publisher
American Society for Microbiology
Subject
Infectious Diseases,Immunology,Microbiology,Parasitology
Cited by
63 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献