Identification and Characterization of an Antigen I/II Family Protein Produced by Group A Streptococcus
S Zhang, NM Green, I Sitkiewicz… - Infection and …, 2006 - journals.asm.org
S Zhang, NM Green, I Sitkiewicz, RB LeFebvre, JM Musser
Infection and immunity, 2006•journals.asm.orgABSTRACT Group A Streptococcus (GAS) is a gram-positive human bacterial pathogen that
causes infections ranging in severity from pharyngitis to life-threatening invasive disease,
such as necrotizing fasciitis. Serotype M28 strains are consistently isolated from invasive
infections, particularly puerperal sepsis, a severe infection that occurs during or after
childbirth. We recently sequenced the genome of a serotype M28 GAS strain and discovered
a novel 37.4-kb foreign genetic element designated region of difference 2 (RD2). RD2 is …
causes infections ranging in severity from pharyngitis to life-threatening invasive disease,
such as necrotizing fasciitis. Serotype M28 strains are consistently isolated from invasive
infections, particularly puerperal sepsis, a severe infection that occurs during or after
childbirth. We recently sequenced the genome of a serotype M28 GAS strain and discovered
a novel 37.4-kb foreign genetic element designated region of difference 2 (RD2). RD2 is …
Abstract
Group A Streptococcus (GAS) is a gram-positive human bacterial pathogen that causes infections ranging in severity from pharyngitis to life-threatening invasive disease, such as necrotizing fasciitis. Serotype M28 strains are consistently isolated from invasive infections, particularly puerperal sepsis, a severe infection that occurs during or after childbirth. We recently sequenced the genome of a serotype M28 GAS strain and discovered a novel 37.4-kb foreign genetic element designated region of difference 2 (RD2). RD2 is similar in gene content and organization to genomic islands found in group B streptococci (GBS), the major cause of neonatal infections. RD2 encodes seven proteins with conventional gram-positive secretion signal sequences, six of which have not been characterized. Herein, we report that one of these six proteins (M28_Spy1325; Spy1325) is a member of the antigen I/II family of cell surface-anchored molecules produced by oral streptococci. PCR and DNA sequence analysis found that Spy1325 is very well conserved in GAS strains of distinct M protein serotypes. As assessed by real-time TaqMan quantitative PCR, the Spy1325 gene was expressed in vitro, and Spy1325 protein was present in culture supernatants and on the GAS cell surface. Western immunoblotting and enzyme-linked immunosorbent assays indicated that Spy1325 was produced by GAS in infected mice and humans. Importantly, the immunization of mice with recombinant Spy1325 fragments conferred protection against GAS-mediated mortality. Similar to other antigen I/II proteins, recombinant Spy1325 bound purified human salivary agglutinin glycoprotein. Spy1325 may represent a shared virulence factor among GAS, GBS, and oral streptococci.
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