Construction and characterization of Dbp gene knock-out mutant in Streptococcus suis 2

Abstract:

[Objective] The contribution of DNA-binding membrane protein (Dbp) to the virulence of Streptococcus suis 2 was evaluated by constructing a gene knock-out mutant of Dbp. [Methods] The distribution of Dbp was analyzed by PCR. An isogenic Streptococcus suis 2 mutant of Dbp, ?Dbp, was constructed based on the principle of homologous recombination, and the biological characteristics, pathogenicity of ?Dbp and wild type ZY05719 was compared. [Results] The Dbp gene may be a relatively conserved in different source of Streptococcus suis 2. Compared with wild type ZY05719, the growth rate of ?Dbp is significantly slower in the logarithmic phase, and the capsule of ?Dbp is different from wild type ZY05719. Zebrafish pathogenicity test showed that the LD50 of ?Dbp had a significant decrease as compared with wild type ZY05719. [Conclusion] Dbp gene is critical for the full virulence of Streptococcus suis 2. All these help us to understand its pathogenic mechanism.

Key words:Streptococcus suis 2, Gene knock-out mutant, Biological characteristics, Pathogenicity