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.

Relatedness of Streptococcus suis Isolates of Various Serotypes and Clinical Backgrounds as Evaluated by Macrorestriction Analysis and Expression of Potential Virulence Traits

“…As with many other pathogens, a single marker that is sufficient for the identification of all highly virulent strains has not yet been identified (and probably does not exist), but there is strong evidence that highly virulent strains share certain features and might be more related than others (4,21,23,26). Some of these virulence-associated features seem to be production of serotype-specific capsular polysaccharides (25), expression of proteins MRP and EF (35), and expression of hemolysin activity and suilysin (10,17,18). However, on the basis of the high prevalence of serotype 2 isolates, most studies have been restricted to serotype 2.…”

Prevalência de Streptococcus suis tipo 2 por meio da técnica de reação em cadeia da polimerase em suínos abatidos no Estado do Mato Grosso

“…Vários fatores de virulência têm sido descritos, tais como a cápsula (SMITH et al, 1999(SMITH et al, , 2000, "muraminidase-released-protein" (mrp), fator proteico extracelular (ef) (SMITH et al, 1992(SMITH et al, , 1997, suilisina (NORTON et al, 1999;JACOBS et al, 1996) e adesinas ( DE GREEFF et al, 2002), sendo as proteínas destes genes utilizados como potenciais candidatos a vacina pela metodologia da vacina reversa (LIU et al, 2008). Amostras de sorotipo 2, positivo para os genes mrp e ef, são associadas à maior virulência (BAUMS et al, 2007), e outras variantes do gene (ef*) são consideradas menos virulentas ou associadas a infecções em seres humanos (SMITH, et al, 1993).…”

Generation and Characterization of a Defined Mutant of Streptococcus suis Lacking Suilysin

“…Streptococcus suis has been described as the etiological agent for a number of infectious disease syndromes in pigs, including arthritis, septicemia, meningitis, and pneumonia. S. suis produces a secreted hemolysin (suilysin) which has been suggested as playing a role in virulence (2,(4)(5)(6)(7)10). In order to investigate the role played by suilysin in the pathogenesis of a European serotype 2 isolate of S. suis, we generated a defined allelic-replacement mutant of the sly gene and compared the wild-type organism with the sly mutant in a number of assays.…”