Genomic differences between sequence types 1 and 104 of Streptococcus suis Serotype 2

Area of Science:

• Microbiology
• Genomics
• Infectious Diseases

Background:

• Streptococcus suis is a zoonotic pathogen causing invasive infections in humans.
• Serotype 2 strains exhibit distinct sequence types (STs) associated with specific clinical manifestations: ST1 with meningitis and ST104 with sepsis.
• Limited genomic data exist for comparing ST1 and ST104, particularly regarding virulence factors.

Purpose of the Study:

• To perform a whole-genome comparison of Streptococcus suis serotype 2, sequence type 1 (ST1) and sequence type 104 (ST104) strains.
• To identify genomic differences, specifically regions of difference (RDs), between these two sequence types.
• To investigate the potential role of these genomic variations in the distinct pathogenesis of meningitis and sepsis caused by S. suis.

Main Methods:

• Whole-genome sequencing of one ST1 isolate (meningitis) and one ST104 isolate (sepsis) using 454 GS Junior System.
• Comparative genomic analysis using Artemis Comparison Tool (ACT) to identify regions of difference (RDs).

Main Results:

• Fifty-eight RDs were identified as unique to the ST104 genome.
• These unique regions in ST104 are primarily associated with metabolism, cell function, cell wall anchored proteins, bacteriophages, mobile genetic elements, ABC-type transporters, signal transduction, and lantibiotic production.
• Some virulence genes typically found in ST1 strains were also detected in the ST104 genome.

Conclusions:

• Whole-genome comparison is effective for distinguishing between S. suis STs and identifying genomic variations.
• The identified genomic differences, particularly in ST104, likely contribute to the distinct clinical presentations of S. suis infections.
• This study provides a foundation for understanding the molecular basis of virulence in different S. suis sequence types.