Fig 1. Geographic location of porcine farms examined and results of encapsulated and unencapsulated S. suis isolates.

(A) The map shows the northern east area of the main island of Japan from which S. suis was isolated in the present study. The farms are indicated by the following symbols: blank circles and blank triangles: encapsulated and unencapsulated S. suis, respectively, were exclusively isolated, and filled circles: encapsulated and unencapsulated S. suis were both isolated. The farm identifiers (alphabetical characters) and sample Nos. of endocarditis samples are indicated along the above symbols. The map was publicly available from the Geospatial Information Authority in Japan. (B) The heat map shows the encapsulation traits of 24 S. suis isolates in each of 59 endocarditis samples, with the following colors: blue for encapsulated, and red for unencapsulated isolates. Untypeable isolates in serotype-specific PCR are indicated by blanks. Encapsulated and unencapsulated isolates were exclusively from 31 (Nos. 27–57) and 2 (Nos. 58 and 59) endocarditis samples, respectively. Sample Nos. 1 to 26 were hereafter used as the No. of the pair of encapsulated and unencapsulated isolates.