Search

Summary: Background: Streptococcus equi subspecies equi (S equi) is the cause of Strangles, one of the most prevalent diseases of horses worldwide. Variation within the immunodominant SeM protein has been documented, but a new eight‐component fusion protein vaccine, Strangvac, does not contain live S equi or SeM and conservation of the antigens it contains have not been reported. Objective: To define the diversity of the eight Strangvac antigens across a diverse S equi population. Study design: Genomic description. Methods: Antigen sequences from the genomes of 759 S equi isolates from 19 countries, recovered between 1955 and 2018, were analysed. Predicted amino acid sequences in the antigen fragments of SEQ0256(Eq5), SEQ0402(Eq8), SEQ0721(EAG), SEQ0855(SclF), SEQ0935(CNE), SEQ0999(IdeE), SEQ1817(SclI) and SEQ2101(SclC) in Strangvac and SeM were extracted from the 759 assembled genomes and compared. Results: The predicted amino acid sequences of SclC, SclI and IdeE were identical across all 759 genomes. CNE was truncated in the genome of five (0.7%) isolates. SclF was absent from one genome and another encoded a single amino acid substitution. EAG was truncated in two genomes. Eq5 was truncated in four genomes and 123 genomes encoded a single amino acid substitution. Eq8 was truncated in three genomes, one genome encoded four amino acid substitutions and 398 genomes encoded a single amino acid substitution at the final amino acid of the Eq8 antigen fragment. Therefore, at least 1579 (99.9%) of 1580 amino acids in Strangvac were identical in 743 (97.9%) genomes, and all genomes encoded identical amino acid sequences for at least six of the eight Strangvac antigens. Main limitations: Three hundred and seven (40.4%) isolates in this study were recovered from horses in the UK. Conclusions: The predicted amino acid sequences of antigens in Strangvac were highly conserved across this collection of S equi. [ABSTRACT FROM AUTHOR]

Adherence of Staphylococcus aureus to the host tissue is an important step in the initiation of pathogenesis. At least 10 adhesins produced by S. aureus have been described and it is becoming clear that the expression of these adhesins and their interactions with eukaryotic cells involve complex processes. Some of these, such as the fibronectin-binding proteins (FnBPs) and Clumping Factor A, are well characterized. However, in the last 10 years a number of novel S. aureus adhesins have been described. Functional analyses of these proteins, one of which is Eap (extracellular_adherence protein, also known as Map and p70), are revealing important information on the pathogenesis of staphylococcal disease. More than 10 years after the first report of Eap, we are beginning to understand that this protein, which has a broad spectrum of functions, may be a critical factor in the pathogenesis of S. aureus. This review will focus on the interactions of Eap with eukaryotic cells, plasma proteins and the extracellular matrix as well as on the recently recognized role of Eap as an important mediator in the immune response to staphylococcal infection.

Research has been conducted on Staphylococcus aureus strain Newman. The use of the chromosomal DNA of this strain in investigating the shotgun phage-display library is described and the results indicate the discovery of the von Willebrand factor binding protein.

Research reveals that a 32-kilodalton neutral phosphatase is involved in the binding of the extracellular adherence protein Eap in Staphylococcus aureus. Data show that soluble form of the enzyme complexes with Eap without any loss of enzyme activity.

An examination of the extracellular adherence protein (Eap) purified from Staphylococcus aureus shows that it is capable of binding to at least seven plasma proteins and to the surface of S. aureus. The Eap is also found to adhere less to cells of Staphylococcus epidermidis, Streptococcus mutans or Escherichia coli. It is also able cause agglutination of S. aureus and enhances its adherence to fibroblasts and epithelial cells.

Insertional activation of the CnBP gene which encodes collagen-binding proteins in Staphylococcus aureus causes changes in phenotype. The insertional activation of cna genes in PH100 strains led to pleiotropic effects at the level of FnBP which affected the aggregation of intact cells in the presence of Fn. This reaction indicates aggregation ability of Ph100 strains is dependent on the amount of FnBps and their extracellular accessibility.