Characterization of the zinc metalloprotease of Streptococcus suis serotype 2

Audrey Dumesnil,Josée Harel,Peter Valentin-Weigand,Daniel Grenier,Pyong Woo Park,Marcelo Gottschalk,David Roy,Maren Willenborg,Nahuel Fittipaldi,Jean-Philippe Auger,Désirée Vötsch

doi:10.1186/s13567-018-0606-y

Abstract

Streptococcus suis is a swine pathogen and zoonotic agent responsible for meningitis and septic shock. Although several putative virulence factors have been described, the initial steps of the S. suis pathogenesis remain poorly understood. While controversial results have been reported for a S. suis serotype 2 zinc metalloprotease (Zmp) regarding its IgA protease activity, recent phylogenetic analyses suggested that this protein is homologous to the ZmpC of Streptococcus pneumoniae, which is not an IgA protease. Based on the previously described functions of metalloproteases (including IgA protease and ZmpC), different experiments were carried out to study the activities of that of S. suis serotype 2. First, results showed that S. suis, as well as the recombinant Zmp, were unable to cleave human IgA1, confirming lack of IgA protease activity. Similarly, S. suis was unable to cleave P-selectin glycoprotein ligand-1 and to activate matrix metalloprotease 9, at least under the conditions tested. However, S. suis was able to partially cleave mucin 16 and syndecan-1 ectodomains. Experiments carried out with an isogenic Δzmp mutant showed that the Zmp protein was partially involved in such activities. The absence of a functional Zmp protein did not affect the ability of S. suis to adhere to porcine bronchial epithelial cells in vitro, or to colonize the upper respiratory tract of pigs in vivo. Taken together, our results show that S. suis serotype 2 Zmp is not a critical virulence factor and highlight the importance of independently confirming results on S. suis virulence by different teams.

Highlights

Streptococcus suis is a swine pathogen responsible for cases of meningitis, arthritis, endocarditis, and sudden death in post-weaned piglets
Increased research over the past decade has led to the identification of a myriad of novel factors putatively involved in the first steps of the S. suis pathogenesis of infection
One example is the zinc metalloprotease (Zmp) protease encoded by gene iga [8, 10, 38]

Summary

Introduction

Streptococcus suis is a swine pathogen responsible for cases of meningitis, arthritis, endocarditis, and sudden death in post-weaned piglets. It is responsible for substantial economic losses to the porcine industry and it represents a serious problem due to the routine use of antimicrobials in the field in attempts to control the infection [1]. It is an emerging zoonotic agent causing meningitis and septic shock in individuals associated with the swine/pork industry in Western countries or among the general population in some Asian countries [1]. Controversy continues to persist regarding the role of so-called critical S. suis virulence factors [7]

Methods

Results

Conclusion