Construction and Characterization of Pilus Backbone Gene Knock-out Mutant of Streptococcus suis Serotype 2

Abstract:

Based on the principle of homologous recombination, we construct gene knock-out mutant of the pilus backbone gene in Streptococcus suis serotype 2 virulent strain 05ZYH33. PCR analysis, Southern hybridization and RT-PCR analysis showed that the target gene was replaced by SpcR cassette. Analysis of biological characteristics showed that there were no differences in mycelial morphology, hemolytic activity and dyeing properties between the mutant and the wild type strain 05ZYH33. Virulence assays with murine model confirmed that the mutant is significantly less virulent than the wild type strain. The results suggest pili plays an important role in the pathogenesis, which laid the foundation for the study of the mechanisms of pilus assembly and biological function in the S. suis serotype 2.

Key words:Streptococcus suis serotype 2, Pilus backbone, Gene knock-out, Pathogenesis