title: Streptococcus suis bacterin and subunit vaccine immunogenicities and protective efficacies against serotypes 2 and 9.
abstract: Streptococcus suis causes numerous diseases in pigs, most importantly, meningitis, arthritis, septicemia, and bronchopneumonia. One of the major problems in modern swine production is the lack of a vaccine protecting against more than one S. suis serotype. The objective of this study was to determine the protective efficacy of a serotype 2 murein-associated protein (MAP) fraction subunit vaccine in comparison to that of a bacterin against experimental challenge with serotype 2 (containing muramidase-released protein [MRP], extracellular factor, and suilysin [SLY]) and serotype 9 (containing MRP variant MRP* and SLY) strains. MAP was shown to include different surface-associated proteins, such as the MRP and surface antigen one (SAO) expressed by both pathotypes used for challenge. The results of this study demonstrated that the serotype 2 bacterin induced protective immunity against homologous challenge. In contrast, the protective efficacy of the MAP subunit vaccine was low, though MAP immunization resulted in high serum immunoglobulin G2 titers against MRP and SAO. Importantly, immunization with bacterin but not with MAP induced opsonizing antibody titers against the serotype 2 strain, and these antibody titers were found to correlate with protection. However, after absorption with a nonencapsulated isogenic mutant, the sera from bacterin-immunized piglets failed to facilitate neutrophil killing, indicating that antibodies directed against capsule may not have been essential for opsonophagocytosis. Furthermore, induction of opsonizing antibodies against serotype 9 was not detectable in the group receiving bacterin or in the group receiving the MAP vaccine. In agreement, protection against the heterologous serotype 9 strain was low in both groups. Thus, identification of an antigen protecting against these two important S. suis pathotypes remains an important goal of future studies.
authors.affiliation: Institut für Mikrobiologie, Zentrum für Infektionsmedizin, Stiftung Tierärztliche Hochschule Hannover, D-30173 Hannover, Germany. christoph.baums@gmx.de
authors.forename: Christoph Georg
authors.initials: CG
authors.lastname: Baums
authors.forename: Christoph
authors.initials: C
authors.lastname: Kock
authors.forename: Andreas
authors.initials: A
authors.lastname: Beineke
authors.forename: Katharina
authors.initials: K
authors.lastname: Bennecke
authors.forename: Ralph
authors.initials: R
authors.lastname: Goethe
authors.forename: Charlotte
authors.initials: C
authors.lastname: Schröder
authors.forename: Karl-Heinz
authors.initials: KH
authors.lastname: Waldmann
authors.forename: Peter
authors.initials: P
authors.lastname: Valentin-Weigand
mesh_terms: D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood; D016667:Bacterial Capsules / Q000276:immunology; D001426:Bacterial Proteins / Q000276:immunology*; D001428:Bacterial Vaccines / Q000276:immunology*; D009895:Opsonin Proteins / Q000276:immunology; D010587:Phagocytosis / Q000276:immunology; D013290:Streptococcal Infections / Q000517:prevention & control / Q000662:veterinary*; D017011:Streptococcus suis / Q000276:immunology*; D013552:Swine; D013553:Swine Diseases / Q000276:immunology / Q000517:prevention & control*; D022223:Vaccines, Subunit / Q000276:immunology
chemical_list: D000907:Antibodies, Bacterial; D001426:Bacterial Proteins; D001428:Bacterial Vaccines; D009895:Opsonin Proteins; D022223:Vaccines, Subunit