Figure 1. Pulsed-field gel electrophoresis (PFGE) profiles of selected isolates from various parts of China. All isolates of Streptococcus suis were digested with SmaI. The molecular size of each restriction fragment was calculated with the Comparative Quantification/Polymorphism analysis feature of the Molecular Analyst Fingerprinting Plus software (Quantity One version 4.0, Bio-Rad, Beijing, People's Republic of China) based on mobility of S. suis isolates on the same gel with Salmonella enterica serovar Braenderup H9812 digested with XbaI, as universal standard of PulseNet International. Clustering of PFGE patterns was performed by an unweighted paired group with arithmetic averaging (UPGMA). The dendrogram of PFGE patterns of isolates tested were drawn with PulseNet software BioNumerics, with a 1.5% position tolerance and 1% optimization.