Population structure, genetic diversity and pathotypes of Streptococcus suis isolated during the last 13  years from diseased pigs in Switzerland

In this study, a detailed characterization of 88 porcineS. suis isolates was performed by analyzing capsular (cps) types, multilocus sequence typing (MLST) and investigation of the minimum core genome (MCG). In order to focus on the virulence potential of presumable invasive disease-associatedS. suis isolates, virulence-associated gene profiles were assessed followed by screening a chosen subset ofS. suis strains with a molecular pathotyping tool. Results showed a high genetic variability within this strain collection. In total, seventeencps types were identified with a predominance ofcps type 9 (15.9%) and 6 (14.8%). MLST revealed 48 sequence types (STs) including 41 novel ones. The population structure ofS. suis was heterogenous and isolates belonged to eight different clonal complexes (CCs) including CC28 (9.1%), CC1109 (8%), CC13/149 (6.8%), CC1237 (5.7%), CC1 (3.4%), CC17 (3.4%), CC87 (2.3%), and CC1112 (1.1%), whereas a significant portion of isolates (60.2%) could not be assigned to any described CCs. Virulence-associated markers, namely extracellular protein factor (epf), muramidase-released protein (mrp), and suilysin (sly), showed a link with STs rather than withcps types. With this study an expanded knowledge about the population structure and the genetic diversity ofS. suis could be achieved, which helps to contribute to an optimal public health surveillance system by promoting a focus on strains with an increased virulence and zoonotic potential.
Source: Veterinary Research - Category: Veterinary Research Source Type: research