Protection of pigs against challenge with virulent <i>Streptococcus suis</i> serotype 2 strains by a muramidase‐released protein and extracellular factor vaccine

Wisselink, Henk J.; Vecht, U.; Smith, Hilde E.; Stockhofe-Zurwieden, Norbert

doi:10.1136/vr.148.15.473

Cited by 73 publications

(66 citation statements)

References 27 publications

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“…Two previous studies demonstrated induction of protective immunity in 8-week-old weaning piglets through application of an S. suis serotype 2 bacterin at ages of 3 to 4 and 6 weeks postpartum (3,25). In the 3rd experiment of this study, pro-tection was not observed, though a similar bacterin was applied at the same age.…”

Section: Discussionmentioning

confidence: 68%

“…In the field, autogenous vaccines are commonly used in herds with S. suis problems. Serotype 2 bacterins elicited protection against serotype 2 but not serotype 9 strains in specific-pathogen-free (SPF) weaning piglets (3,25). Importantly, induction of opsonizing antibodies by bacterin immunization correlated with protection (3).…”

mentioning

confidence: 95%

“…Sera from convalescent and bacterin-vaccinated piglets have generally high MRP-specific antibody titers (3). Immunization of piglets with a subunit vaccine, including MRP and EF, elicited partial protection against the homologous, highly virulent MRP ϩ EF ϩ serotype 2 strain (25). However, vaccination with purified MRP alone failed to induce protection, and high MRP-specific-antibody titers were not associated with protection (3,25).…”

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confidence: 99%

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Immunogenicity of an AutogenousStreptococcus suisBacterin in Preparturient Sows and Their Piglets in Relation to Protection after Weaning

Baums

Brüggemann

Kock

et al. 2010

Clin Vaccine Immunol

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Streptococcus suis is an important porcine pathogen causing meningitis and other invasive diseases in piglets of different ages. Application of S. suis serotype 2 bacterins to specific-pathogen-free (SPF) weaning piglets has been demonstrated to protect against the homologous serotype. However, autogenous S. suis bacterins are also applied to sows and suckling piglets in the field. Therefore, comparative evaluation of different bacterin immunization regimes, including sow vaccination, was performed in this study. The main objectives were to determine the immunogenicity of an S. suis bacterin in sows prepartum and its influence on active immunization of piglets. Experimental infection of 6-and 8-week-old weaning piglets was performed to elucidate protective efficacies. Humoral immune responses were investigated by an enzyme-linked immunosorbent assay (ELISA) measuring muramidase-released protein (MRP)-specific IgG titers and by opsonophagocytosis assays. Bacterin application elicited high MRP-specific IgG titers in the serum and colostrum of sows, as well as opsonizing antibodies. Piglets from vaccinated sows had significantly higher MRP-specific titers than respective piglets from nonvaccinated sows until 6 weeks postpartum. Vaccination of suckling piglets did not result in high MRP-specific titers nor in induction of opsonizing antibodies. Furthermore, neither vaccination of suckling nor of weaning piglets from immunized sows was associated with a prominent active immune response and protection at 8 weeks postpartum. However, protection was observed in respective 6-week-old weaning piglets, most likely because of protective maternal immunity. In conclusion, this study provides the first results suggesting protective passive maternal immunity for S. suis serotype 2 after bacterin vaccination of sows and a strong inhibitory effect on active immunization of suckling and weaning piglets, leading to highly susceptible growers.Streptococcus suis causes various pathologies, such as meningitis, arthritis, serositis, bronchopneumonia, and endocarditis (11). Furthermore, S. suis serotype 2 is also an important zoonotic agent (9). S. suis is characterized by a high diversity, and different serotypes might be involved in invasive diseases in pigs (6,24). However, most of the experimental studies have been performed with serotype 2. Based on comparative evaluation of virulence of wild-type strains in intranasal infection experiments, serotype 2 isolates expressing the 136-kDa muramidase-released protein (MRP) and the 110-kDa extracellular factor (EF) are regarded as more virulent than serotype 2 strains which lack these factors or express MRP and a large variant of EF called EF* (22,23). On the other hand, MRP ϩ

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Section: Discussionmentioning

confidence: 68%

mentioning

confidence: 95%

mentioning

confidence: 99%

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Immunogenicity of an AutogenousStreptococcus suisBacterin in Preparturient Sows and Their Piglets in Relation to Protection after Weaning

Baums

Brüggemann

Kock

et al. 2010

Clin Vaccine Immunol

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“…Wisselink et al demonstrated that in comparison to immunization with a bacterin, immunization with MRP alone conferred little protection against challenge with serotype 2 strains (24). Combining MRP with EF substantially improved protective efficacy.…”

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confidence: 99%

Streptococcus suisBacterin and Subunit Vaccine Immunogenicities and Protective Efficacies against Serotypes 2 and 9

Baums

Kock

Beineke

et al. 2009

Clin Vaccine Immunol

103

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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.Streptococcus suis ranks among the five most important health challenges of pigs worldwide (11,12). It is associated with numerous diseases, such as meningitis, arthritis, serositis, and bronchopneumonia. S. suis isolates from diseased animals express a polysaccharide capsule which confers resistance to phagocytosis, as demonstrated for serotype 2 strains (21). Strains of various serotypes have been isolated from affected tissues. In Europe, serotype 2 and 9 strains are the most prevalent types isolated from infections. The 136-kDa muramidasereleased protein (MRP) and the 110-kDa extracellular factor (EF) are virulence-associated factors expressed only by virulent serotype 1 and 2 strains (22, 23). The majority of invasive serotype 9 isolates express a larger variant of MRP, termed MRP*, which shares high homology with the 136-kDa MRP protein of serotype 2 strains (20, 23).

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“…More recently, interest has shifted toward protein antigens of S. suis as vaccine candidates. Subunit vaccines using suilysin (27) or muramidase-released protein and extracellular protein factor (57) have been shown to protect pigs from homologous and heterologous serotype 2 strains, but their use is hindered by the fact that a substantial number of virulent strains in some geographical regions do not express these proteins (13,18,41). Thus, the identification of other antigenic factors, especially surface proteins, would contribute to the development of a subunit vaccine.…”

mentioning

confidence: 99%

Identification of a Surface Protein of Streptococcus suis and Evaluation of Its Immunogenic and Protective Capacity in Pigs

Martínez

Gottschalk

et al. 2006

Infect Immun

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A Streptococcus suis surface protein reacting with convalescent-phase sera from pigs clinically infected by S. suis type 2 was identified. The apparent 110-kDa protein, designated Sao, exhibits typical features of membraneanchored surface proteins of gram-positive bacteria, such as a signal sequence and an LPVTG membrane anchor motif. In spite of high identity with the partially sequenced genomes of S. suis Canadian strain 89/1591 and European strain P1/7, Sao does not share significant homology with other known sequences. However, a conserved avirulence domain that is often found in plant pathogens has been detected. Electron microscopy using an Sao-specific antiserum has confirmed the surface location of the Sao protein on S. suis. The Sao-specific antibody reacts with cell lysates of 28 of 33 S. suis serotypes and 25 of 26 serotype 2 isolates in immunoblots, suggesting its high conservation in S. suis species. The immunization of piglets with recombinant Sao elicits a significant humoral antibody response. However, the antibody response is not reflected in protection of pigs that are intratracheally challenged with a virulent strain in our conventional vaccination model.Streptococcus suis is an important swine pathogen that causes many pathological conditions, such as arthritis, endocarditis, meningitis, pneumonia, and septicemia (19,21). It is also an important zoonotic agent for humans in contact with colonized, otherwise healthy pigs or their by-products, causing meningitis and endocarditis (1, 53). Thirty-three serotypes (types 1 to 31, 33, and 1/2) based on capsular antigens are currently known (15-17, 22, 24, 43). Type 2 is considered the most virulent and prevalent type in diseased pigs. The mechanisms involved in the pathogenesis and virulence of S. suis are not completely understood (19), and attempts to control the infection are hampered by the lack of an effective vaccine.Several approaches have been used to develop vaccines for S. suis. However, little success was achieved because the protection was either serotype or strain dependent, and results in most instances were equivocal (23, 42). For example, some protection with killed whole cells or live avirulent vaccines was reported, but this required repeated immunization, and the protection against heterologous challenges was not evaluated (25, 56). Exposure of young pigs to live virulent strains showed a positive effect in reducing clinical signs characteristics of S. suis infection (52). Since the S. suis capsule plays an important role in virulence, attempts have been made to develop a vaccine based on capsular material. However, this vaccination approach was unsatisfactory because the capsular polysaccharide is poorly immunogenic (9). More recently, interest has shifted toward protein antigens of S. suis as vaccine candidates. Subunit vaccines using suilysin (27) or muramidase-released protein and extracellular protein factor (57) have been shown to protect pigs from homologous and heterologous serotype 2 strains, but their use is hindered by ...

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Protection of pigs against challenge with virulent Streptococcus suis serotype 2 strains by a muramidase‐released protein and extracellular factor vaccine

Abstract: The efficacy of a muramidase-released protein (MRP) and extracellular factor (EF)

Cited by 73 publications

References 27 publications

Immunogenicity of an AutogenousStreptococcus suisBacterin in Preparturient Sows and Their Piglets in Relation to Protection after Weaning

Immunogenicity of an AutogenousStreptococcus suisBacterin in Preparturient Sows and Their Piglets in Relation to Protection after Weaning

Streptococcus suisBacterin and Subunit Vaccine Immunogenicities and Protective Efficacies against Serotypes 2 and 9

Identification of a Surface Protein of Streptococcus suis and Evaluation of Its Immunogenic and Protective Capacity in Pigs

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