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Protection of experimentally infected pigs by suilysin, the thiol‐activated haemolysin of Streptococcus suis
Author(s) -
Jacobs A. A. C.,
Berg A. J. G.,
Loeffen P. L. W.
Publication year - 1996
Publication title -
veterinary record
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.261
H-Index - 99
eISSN - 2042-7670
pISSN - 0042-4900
DOI - 10.1136/vr.139.10.225
Subject(s) - streptococcus suis , medicine , placebo , hemolysin , serotype , vaccination , meningitis , microbiology and biotechnology , biology , immunology , pathology , virulence , surgery , biochemistry , alternative medicine , gene
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.