title: Protection of experimentally infected pigs by suilysin, the thiol-activated haemolysin of Streptococcus suis.
abstract: Three groups of three pigs were vaccinated either with vaccine VAC-SLY, containing purified suilysin derived from Streptococcus suis strain P1/7 (serotype 2), or with vaccine VAC-SCF, containing most of the other extracellular antigens produced by strain P1/7 (but essentially free from suilysin), or with a placebo vaccine. The pigs were vaccinated twice at four weeks and six weeks of age and were challenged intravenously with S suis strain P1/7 at eight weeks of age. On the day of challenge, only the VAC-SLY vaccinated pigs showed an increase in haemolysin neutralisation titre. After challenge the placebo vaccinated pigs developed severe clinical signs characterised by lameness involving several joints, a depressed appearance, high temperatures and/or neurological signs. The VAC-SCF vaccinated pigs showed the same clinical signs but less severely. The VAC-SLY vaccinated pigs were the least affected and showed only mild signs which subsided more quickly than those of the other groups. A post mortem investigation and histology of brain tissue samples confirmed the clinical findings; fibrinous arthritis was less severe and less frequently observed in the VAC-SLY vaccinated pigs than in the VAC-SCF or placebo vaccinated pigs, and none of the VAC-SLY vaccinated pigs had meningitis whereas two of the VAC-SCF and two of the placebo vaccinated pigs did so. All the samples of brain, lung and tarsus taken from the VAC-SLY vaccinated pigs were sterile whereas S suis was reisolated from most of these tissues from the other groups.
authors.affiliation: Bacteriological Research Department, Intervet International BV, Boxmeer, The Netherlands.
authors.forename: A A
authors.initials: AA
authors.lastname: Jacobs
authors.forename: A J
authors.initials: AJ
authors.lastname: van den Berg
authors.forename: P L
authors.initials: PL
authors.lastname: Loeffen
mesh_terms: D000818:Animals; D000942:Antigens, Bacterial / Q000276:immunology / Q000627:therapeutic use*; D001921:Brain / Q000473:pathology; D004591:Electrophoresis, Polyacrylamide Gel / Q000662:veterinary; D006460:Hemolysin Proteins / Q000378:metabolism / Q000627:therapeutic use*; D015151:Immunoblotting / Q000662:veterinary; D007794:Lameness, Animal / Q000209:etiology / Q000276:immunology / Q000517:prevention & control; D008581:Meningitis / Q000209:etiology / Q000517:prevention & control / Q000662:veterinary; D009930:Organic Chemicals; D010493:Pericarditis / Q000209:etiology / Q000517:prevention & control / Q000662:veterinary; D011014:Pneumonia / Q000209:etiology / Q000517:prevention & control / Q000662:veterinary; D011897:Random Allocation; D013290:Streptococcal Infections / Q000150:complications / Q000517:prevention & control / Q000662:veterinary*; D017011:Streptococcus suis / Q000276:immunology / Q000378:metabolism*; D013552:Swine; D013553:Swine Diseases / Q000209:etiology / Q000276:immunology / Q000517:prevention & control*; D014612:Vaccines / Q000276:immunology / Q000592:standards*
chemical_list: D000942:Antigens, Bacterial; D006460:Hemolysin Proteins; D009930:Organic Chemicals; D014612:Vaccines; C104760:suilysin