Laminin-binding protein of Streptococcus suis serotype 2 influences zinc acquisition and cytokine responses

Abstract

Streptococcus suis serotype 2 is an important bacterial pathogen of swine, responsible for substantial economic losses to the swine industry worldwide. The knowledge on the pathogenesis of the infection caused by S. suis is still poorly known. It has been previously described that S. suis possesses at least one lipoprotein with double laminin and zinc (Zn)-binding properties, which was described in the literature as either laminin-binding protein (Lmb, as in the current study), lipoprotein 103, CDS 0330 or AdcAII. In the present study, the role of the Lmb in the pathogenesis of the infection caused by S. suis serotype 2 was dissected. Using isogenic mutants, results showed that Lmb does not play an important role in the laminin-binding activity of S. suis, even when clearly exposed at the bacterial surface. In addition, the presence of this lipoprotein does not influence bacterial adhesion to and invasion of porcine respiratory epithelial and brain endothelial cells and it does not increase the susceptibility of S. suis to phagocytosis. On the other hand, the Lmb was shown to play an important role as cytokine activator when tested in vitro with dendritic cells. Finally, this lipoprotein plays a critical role in Zn acquisition from the host environment allowing bacteria to grow in vivo. The significant lower virulence of the Lmb defective mutant may be related to a combination of a lower bacterial survival due to the incapacity to acquire Zn from their surrounding milieu and a reduced cytokine activation.

Lipoteichoic acids influence cell shape and bacterial division of Streptococcus suis serotype 2, but play a limited role in the pathogenesis of the infection

“…The neonatal porcine tracheal epithelial cell line (NPTr), frequently used in S. suis studies [ 35 – 37 ], was used. Cells were cultured until confluence as previously described [ 34 ], then infected with 1 × 10 6 CFU/well (multiplicity of infection (MOI) = 10) of the different S. suis strains and incubated for 2 or 4 h at 37 °C in 5% CO 2 .…”

Study of the Role of Lipoprotein Maturation Enzymes in the Pathogenesis of the Infection Caused by the Streptococcus suis Serotype 2 Sequence Type 25 North American Prototype Strain

“…The porcine brain microvascular endothelial cell line (PBMEC; kindly provided by Dr. A. Friedl) [29] and the neonatal porcine tracheal epithelial cell line (NPTr; kindly provided by Dr. M. Jacques) [30,31] were used and cultured until confluence as previously described [16,[32][33][34][35]. Cells were infected with 1 × 10 6 CFU/well (multiplicity of infection or MOI = 10) of the different S. suis strains and incubated for 2 h at 37 • C in 5% CO 2 .…”

“…Cells were infected with 1 × 10 6 CFU/well (multiplicity of infection or MOI = 10) of the different S. suis strains and incubated for 2 h at 37 • C in 5% CO 2 . The adhesion assay, which quantifies total cell-associated bacteria (surface-adherent and intracellular bacteria), and invasion assay (using the antibiotic protection assay) were performed as previously described [16,[32][33][34][35].…”