Fig. 2

Schematics of cps loci and identification of a single-nucleotide polymorphism permitting differentiation of the S. suis serotypes 1 and 14, and 2 and 1/2. The cps loci of serotypes 1 and 14 are identical in gene content (top), as are the cps loci of serotypes 2 and 1/2 (bottom). However, analysis of all available serotype 1, 14, 2 and 1/2 strains in our collection revealed that serotype 14 strains consistently differed from serotype 1 strains, and that serotype 2 strains consistently differed from serotype 1/2 strains by a single-nucleotide change (G to T or C) in the cpsK gene, which is predicted to result in an amino acid change from tryptophan to cysteine. Our pipeline uses this amino acid change to differentiate between those otherwise unresolvable serotype pairs and assign the serotype to the strain under investigation. Red bars indicate regions used in the first step of the pipeline to differentiate serotypes 1 and 14 as well as serotypes 2 and 1/2 from other serotypes