Genotype of mrp and its relationship with the virulence of Streptococcus suis serotype 2

Abstract:

[Objective] Streptococcus suis serotype 2 (SS2) is an important zoonotic pathogen, showing high diversity in virulence in different strains. Lacking suitable target(s) has, to date, hindered evaluation of virulence in SS2. Therefore, we investigated the relationship between the genotype of mrp and the virulence of SS2. [Methods] Different genotypes of mrp were identified by PCR; Virulence of SS2 strains was evaluated by internally standardized zebrafish model; and the transcription level of mrp in different strains was evaluated by real time PCR (quantitative PCR, qPCR). [Results] Two genotypes, named mrp-A (27 strains) and mrp-B (26 strains), were identified in 53 SS2 strains. Strains belonged to genotype mrp-A showed stronger virulence and higher transcription level of mrp than mrp-B strains. [Conclusion] mrp was widespread but various in different SS2 strains; and mrp-A strains tended to be highly pathogenic. Furthermore, the non-conservative region of mrp could be a virulence-marker for SS2.