Repeats in an extracellular protein of weakly pathogenic strains of Streptococcus suis type 2 are absent in pathogenic strains

Abstract

Streptococcus suis type 2 strains that are pathogenic for pigs produce a 110-kDa extracellular protein factor (EF). Nonpathogenic and weakly pathogenic strains do not produce EF or produce a protein (EF*) that is immunologically related to EF. To study the pathogenesis of S. suis type 2 in pigs and to develop tools and methods for the control of S. suis type 2 infections, we cloned and characterized the genes encoding EF and various EF* proteins. Analysis of the deduced amino acid sequences showed that the first 833 amino acids at the N terminus of the EF and EF* proteins were nearly identical. The proteins differed, however, at their C termini. Unlike the 110-kDa EF protein, the EF* proteins contained several repeated units of 76 amino acids. The number and arrangement of the repeats in the EF* proteins varied. The data suggest that the gene encoding EF could have evolved from an epfp gene by a specific deletion event. The lack of repeated amino acid units in the EF protein may be related to virulence.

Existence and characterization of allelic variants of Sao, a newly identified surface protein fromStreptococcus suis

“…The most frequently observed form of the sao gene was sao-M, which is the medium-sized version at $1.7 kb. The results resemble those reported by Smith et al (1993). In that study, the authors also found EF, a derivative of EF Ã lacking the repeat units at its C-terminus, and was correlated with increased virulence (Smith et al, 1993).…”

“…The results resemble those reported by Smith et al (1993). In that study, the authors also found EF, a derivative of EF Ã lacking the repeat units at its C-terminus, and was correlated with increased virulence (Smith et al, 1993). Therefore, it would be of interest to determine whether or not the present deletion variants in Sao proteins have any correlation with their pathogenicity of the organisms.…”

“…Several bacterial components have been previously implicated in S. suis virulence, but the exact role remains unclear (Staats et al, 1997;Gottschalk et al, 1999;Gottschalk & Segura, 2000). So far, the virulence-associated factors identified include components of capsule polysaccharide (CPS) (Smith et al, 2000), extracellular factor (EF) (Smith et al, 1993;Staats et al, 1999), muraminidase-released protein (MRP) (Staats et al, 1999), suilysin (Allen et al, 2001;Lun et al, 2003), adhesions (Tikkanen et al, 1996;Brassard et al, 2004), 38 kDa protein (Okwumabua & Chinnapapakkagari, 2005), glutamate dehydrogenase (GDH) (Okwumabua et al, 2001), fibronectin-binding protein (FBP) (de Greeff et al, 2002;Wang, 2006), hayluronate lyase (King et al, 2004), sortase A (srtA) (Osaki et al, 2002), arginine deiminase (Gruening et al, 2006), etc. In some instances, the virulence determination of some S. suis strains was still ambiguous, indicating that the virulence of S. suis is a complex interplay between the pathogen, its host, and the environment (Gottschalk et al, 1999).…”

Probing genomic diversity and evolution of Streptococcus suis serotype 2 by NimbleGen tiling arrays

“…significantly variant genes, respectively, including 88 genes shared by all three avirulent strains (additional file 3). The virulence-related epf gene cluster [10,11], which encodes extracellular protein factor (EF; a putative virulence marker that widely exists in virulent strains) was absent in the avirulent strains [12]. Consistent with previous research, this gene cluster is present in all of the analyzed virulent strains.…”

Streptococci and enterococci as animal pathogens

“…must have 5% carbon dioxide for growth. canis as a commensal organism which can cause opportunist pyogenic infections (Laughton 1948).…”