title: Comparative evaluation of virulence and pathology of Streptococcus suis serotypes 2 and 9 in experimentally infected growers.
abstract: Streptococcus (S.) suis is an invasive porcine pathogen causing meningitis, septicemia, arthritis and other diseases. Studies on pathogenesis as well as vaccine trials have focused on serotype 2 strains, which are worldwide the most prevalent among invasive isolates. However, in Europe serotype 9 strains also contribute substantially to S. suis-associated invasive diseases of piglets. The objective of this study was to determine the virulence of an MRP* SLY+ serotype 9 S. suis strain in comparison to an MRP+ EF+ SLY+ serotype 2 strain. Experimental intranasal and intravenous infections of 7-8 weeks old SPF piglets were investigated with regard to clinic and pathology. In contrast to the virulent serotype 2 strain, the serotype 9 strain did not cause disease with clinical manifestations after intranasal administration. However, histological screenings of these animals revealed pathological lesions, such as mild focal suppurative meningitis. Clinical manifestations related to meningitis, arthritis and serositis could be induced by intravenous application of this serotype 9 strain. Bacteriological culture and immunohistochemistry of the brain confirmed association with the S. suis challenge strains in all cases with clinical manifestations. Interestingly, expression of MRP within meningitis lesions was demonstrated for both pathotypes via immunohistochemistry. In conclusion, this study demonstrates that MRP* SLY+ serotype 9 strains are less virulent for growers than MRP+ EF+ SLY+ serotype 2 strains. Thus, intravenous application of this serotype 9 strain is required to evaluate heterologous protection in the course of vaccine development based on serotype 2 strains in the future.
authors: Institut für Pathologie, Stiftung Tierärztliche Hochschule Hannover, D-30173 Hannover, Germany.
authors: Andreas
authors: A
authors: Beineke
authors: Katharina
authors: K
authors: Bennecke
authors: Christina
authors: C
authors: Neis
authors: Charlotte
authors: C
authors: Schröder
authors: Karl-Heinz
authors: KH
authors: Waldmann
authors: Wolfgang
authors: W
authors: Baumgärtner
authors: Peter
authors: P
authors: Valentin-Weigand
authors: Christoph Georg
authors: CG
authors: Baums
mesh_terms: D000281:Administration, Intranasal; D000818:Animals; D000831:Animals, Newborn; D001428:Bacterial Vaccines; D007150:Immunohistochemistry / Q000662:veterinary; D007275:Injections, Intravenous / Q000662:veterinary; D016920:Meningitis, Bacterial / Q000382:microbiology / Q000473:pathology / Q000662:veterinary*; D010802:Phylogeny; D011897:Random Allocation; D012703:Serotyping / Q000662:veterinary; D013290:Streptococcal Infections / Q000382:microbiology / Q000473:pathology / Q000662:veterinary*; D017011:Streptococcus suis / Q000145:classification / Q000235:genetics / Q000472:pathogenicity*; D013552:Swine; D013553:Swine Diseases / Q000382:microbiology* / Q000473:pathology; D013997:Time Factors; D037521:Virulence Factors / Q000235:genetics*
chemical_list: D001428:Bacterial Vaccines; D037521:Virulence Factors