Dataset Information

Surface-expressed mig protein protects Streptococcus dysgalactiae against phagocytosis by bovine neutrophils.

ABSTRACT: The mig gene of Streptococcus dysgalactiae, a major bovine mastitis pathogen, encodes two plasma protein-binding receptors, alpha2-macroglobulin (alpha2-M) and immunoglobulin G (IgG). In this study, the mig gene from one S. dysgalactiae isolate was cloned and expressed in Escherichia coli. The IgG receptor region encoded by mig was conserved in 16 S. dysgalactiae strains. An isogenic mig mutant was constructed by allele replacement mutagenesis of the wild-type gene in S. dysgalactiae. The IgG-binding activity was lost in the mig mutant strain, whereas the alpha2-M receptor activity was still expressed but was detected only in the culture supernatant. In flow cytometry phagocytosis and bacterial-colony-counting bactericidal assays, the wild-type strain was found to be significantly more resistant to phagocytosis and killing by bovine neutrophils (PMNs) than the mig mutant strain when bacteria were preincubated with bovine serum. We therefore speculate that the Mig protein of S. dysgalactiae plays a role in virulence of the bacteria by binding to the plasma protein alpha2-M or IgG and thus preventing phagocytosis by bovine PMNs.

SUBMITTER: Song XM

PROVIDER: S-EPMC98731 | biostudies-literature | 2001 Oct

REPOSITORIES: biostudies-literature

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Surface-expressed mig protein protects Streptococcus dysgalactiae against phagocytosis by bovine neutrophils.

Song X M XM Perez-Casal J J Bolton A A Potter A A AA

Infection and immunity 20011001 10

The mig gene of Streptococcus dysgalactiae, a major bovine mastitis pathogen, encodes two plasma protein-binding receptors, alpha2-macroglobulin (alpha2-M) and immunoglobulin G (IgG). In this study, the mig gene from one S. dysgalactiae isolate was cloned and expressed in Escherichia coli. The IgG receptor region encoded by mig was conserved in 16 S. dysgalactiae strains. An isogenic mig mutant was constructed by allele replacement mutagenesis of the wild-type gene in S. dysgalactiae. The IgG-bi ...[more]

PMID: 11553540

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Project description:Streptococcus dysgalactiae subsp. dysgalactiae (SDSD) has been considered a strict animal pathogen. Nevertheless, the recent reports of human infections suggest a niche expansion for this subspecies, which may be a consequence of the virulence gene acquisition that increases its pathogenicity. Previous studies reported the presence of virulence genes of Streptococcus pyogenes phages among bovine SDSD (collected in 2002-2003); however, the identity of these mobile genetic elements remains to be clarified. Thus, this study aimed to characterize the SDSD isolates collected in 2011-2013 and compare them with SDSD isolates collected in 2002-2003 and pyogenic streptococcus genomes available at the National Center for Biotechnology Information (NCBI) database, including human SDSD and S. dysgalactiae subsp. equisimilis (SDSE) strains to track temporal shifts on bovine SDSD genotypes. The very close genetic relationships between humans SDSD and SDSE were evident from the analysis of housekeeping genes, while bovine SDSD isolates seem more divergent. The results showed that all bovine SDSD harbor Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)/Cas IIA system. The widespread presence of this system among bovine SDSD isolates, high conservation of repeat sequences, and the polymorphism observed in spacer can be considered indicators of the system activity. Overall, comparative analysis shows that bovine SDSD isolates carry speK, speC, speL, speM, spd1, and sdn virulence genes of S. pyogenes prophages. Our data suggest that these genes are maintained over time and seem to be exclusively a property of bovine SDSD strains. Although the bovine SDSD genomes characterized in the present study were not sequenced, the data set, including the high homology of superantigens (SAgs) genes between bovine SDSD and S. pyogenes strains, may indicate that events of horizontal genetic transfer occurred before habitat separation. All bovine SDSD isolates were negative for genes of operon encoding streptolysin S, except for sagA gene, while the presence of this operon was detected in all SDSE and human SDSD strains. The data set of this study suggests that the separation between the subspecies "dysgalactiae" and "equisimilis" should be reconsidered. However, a study including the most comprehensive collection of strains from different environments would be required for definitive conclusions regarding the two taxa.

Dataset Information

Surface-expressed mig protein protects Streptococcus dysgalactiae against phagocytosis by bovine neutrophils.

Publications

Surface-expressed mig protein protects Streptococcus dysgalactiae against phagocytosis by bovine neutrophils.

Similar Datasets

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