RESUMO
Streptococcus suis is an encapsulated bacterium and one of the most important swine pathogens and a zoonotic agent for which no effective vaccine exists. Bacterial capsular polysaccharides (CPSs) are poorly immunogenic, but anti-CPS antibodies are essential to the host defense against encapsulated bacteria. In addition to the previously known serotypes 2 and 14, which are nonimmunogenic, we have recently purified and described the CPS structures for serotypes 1, 1/2, 3, 7, 8, and 9. Here, we aimed to elucidate how these new structurally diverse CPSs interact with the immune system to generate anti-CPS antibody responses. CPS-stimulated dendritic cells produced significant levels of C-C motif chemokine ligand 3 (CCL3), partially via Toll-like receptor 2 (TLR2)- and myeloid differentiation factor 88-dependent pathways, and CCL2, via TLR-independent mechanisms. Mice immunized with purified serotype 3 CPS adjuvanted with TiterMax Gold produced an opsonizing IgG response, whereas other CPSs or adjuvants were negative. Mice hyperimmunized with heat-killed S. suis serotypes 3 and 9 both produced anti-CPS type 1 IgGs, whereas serotypes 7 and 8 remained negative. Also, mice infected with sublethal doses of S. suis serotype 3 produced primary anti-CPS IgM and IgG responses, of which only IgM were boosted after a secondary infection. In contrast, mice sublethally infected with S. suis serotype 9 produced weak anti-CPS IgM and IgG responses following a secondary infection. This study provides important information on the divergent evolution of CPS serotypes with highly different structural and/or biochemical properties within S. suis and their interaction with the immune system.
Assuntos
Antígenos de Bactérias/imunologia , Cápsulas Bacterianas/imunologia , Imunoglobulina G/imunologia , Polissacarídeos Bacterianos/imunologia , Infecções Estreptocócicas/imunologia , Streptococcus suis/imunologia , Adjuvantes Imunológicos/administração & dosagem , Animais , Antígenos de Bactérias/administração & dosagem , Antígenos de Bactérias/química , Cápsulas Bacterianas/genética , Quimiocinas/imunologia , Células Dendríticas/imunologia , Imunização , Imunoglobulina M/imunologia , Camundongos , Fator 88 de Diferenciação Mieloide/imunologia , Polissacarídeos Bacterianos/administração & dosagem , Polissacarídeos Bacterianos/química , Sorogrupo , Infecções Estreptocócicas/microbiologia , Streptococcus suis/genética , Receptor 2 Toll-Like/imunologiaRESUMO
Royal jelly (RJ), a brood food of honey bees, has strong antimicrobial activity. Melissococcus plutonius, the causative agent of European foulbrood of honey bees, exhibits resistance to this antimicrobial activity and infects larvae orally. Among three genetically distinct groups (CC3, CC12 and CC13) of M. plutonius, CC3 strains exhibit the strongest RJ resistance. In this study, to identify genes involved in RJ resistance, we generated an RJ-susceptible derivative from a highly RJ-resistant CC3 strain by UV mutagenesis. Genome sequence analysis of the derivative revealed the presence of a frameshift mutation in the putative regulator gene spxA1a. The deletion of spxA1a from a CC3 strain resulted in increased susceptibility to RJ and its antimicrobial component 10-hydroxy-2-decenoic acid. Moreover, the mutant became susceptible to low-pH and oxidative stress, which may be encountered in brood foods. Differentially expressed gene analysis using wild-type and spxA1a mutants revealed that 45 protein-coding genes were commonly upregulated in spxA1a-positive strains. Many upregulated genes were located in a prophage region, and some highly upregulated genes were annotated as universal/general stress proteins, oxidoreductase/reductase, chaperons and superoxide dismutase. These results suggest that SpxA1a is a key regulator to control the tolerance status of M. plutonius against stress in honey bee colonies.
Assuntos
Abelhas/microbiologia , Farmacorresistência Bacteriana/genética , Enterococcaceae/efeitos dos fármacos , Enterococcaceae/genética , Ácidos Graxos Monoinsaturados/farmacologia , Ácidos Graxos/farmacologia , Animais , Antibacterianos/farmacologia , Ácidos Graxos/química , Mutação da Fase de Leitura , Deleção de Genes , Larva/microbiologia , Mutagênese , Raios UltravioletaRESUMO
Virulence factors responsible for bacterial pathogenicity are often encoded by plasmids. In Melissococcus plutonius, the causative agent of European foulbrood of honey bees, a putative virulence plasmid (pMP19) possessing mtxA, which encodes a putative insecticidal toxin, was found by comparative genome analyses. However, as the role of pMP19 in the pathogenesis of European foulbrood remains to be elucidated, we generated pMP19 cured-M. plutonius from representative strains of the three genetically distinct groups (CC3, CC12 and CC13) and compared their virulence against Apis mellifera larvae using our in vitro infection model. Under the conditions tested, the loss of pMP19 abrogated the pathogenicity in CC3 strains, and > 94% of pMP19-cured CC3 strain-infected larvae became adult bees, suggesting that pMP19 is a virulence determinant of CC3 strains. However, introduction of mtxA on its own did not increase the virulence of pMP19-cured strains. In contrast to CC3 strains, the representative CC12 strain remained virulent even in the absence of pMP19, whereas the representative CC13 strain was avirulent even in the presence of the plasmid. Thus, pMP19 plays a role in the virulence of M. plutonius; however, its impact on the virulence varies among strains with different genetic backgrounds.
Assuntos
Abelhas/microbiologia , Enterococcaceae/genética , Enterococcaceae/patogenicidade , Virulência/genética , Animais , Toxinas Bacterianas/genética , Genoma Bacteriano/genética , Larva/microbiologia , PlasmídeosRESUMO
Although Streptococcus suis has attracted public attention as a major swine and human pathogen, this bacterium has also been isolated from other animals, including ruminants. However, recent taxonomic studies revealed the existence of other species that were previously identified as S. suis, and some of these isolates were reclassified as the novel species Streptococcus ruminantium. In Japan, biochemically identified S. suis is frequently isolated from diseased ruminants; however, such isolates have not yet been identified accurately, and their aetiological importance in ruminants is unclear. Therefore, to understand the importance of S. suis and S. suis-like bacteria in ruminants, we reclassified S. suis isolates from ruminants according to the updated classification and investigated their genetic diversity. Although both S. suis and S. ruminantium were isolated from healthy and diseased ruminants, most of the isolates from diseased animals were S. ruminantium, implying that S. ruminantium is more likely to be associated with ruminant disease than S. suis. However, the ruminant S. suis and S. ruminantium isolates from diseased animals were classified into diverse genotypes rather than belonging to certain clonal groups. Genome sequence analysis of 20 S. ruminantium isolates provided information about the antibiotic resistance, potential virulence, and serological diversity of this species. We further developed an S. ruminantium-specific PCR assay to aid in the identification of this bacterium. The information obtained and the method established in this study will contribute to the accurate diagnosis of ruminant streptococcal infections.
Assuntos
Variação Genética , Genótipo , Infecções Estreptocócicas/veterinária , Streptococcus suis/genética , Streptococcus/genética , Animais , Bovinos , Doenças dos Bovinos/epidemiologia , Doenças dos Bovinos/microbiologia , Doenças das Cabras/epidemiologia , Doenças das Cabras/microbiologia , Cabras , Japão/epidemiologia , Prevalência , Ovinos , Doenças dos Ovinos/epidemiologia , Doenças dos Ovinos/microbiologia , Infecções Estreptocócicas/epidemiologia , Infecções Estreptocócicas/microbiologia , Streptococcus/classificação , Streptococcus suis/classificaçãoRESUMO
American foulbrood (AFB) and European foulbrood (EFB) caused by Paenibacillus larvae and Melissococcus plutonius, respectively, are major bacterial infections of honey bees. Although macrolides (mirosamicin [MRM] and tylosin) have been used to prevent AFB in Japan, macrolide-resistant P. larvae have yet to be found. In this study, we revealed that both MRM-resistant and -susceptible strains exist in Japanese M. plutonius and that a methyltransferase gene (rlmA II ) was disrupted exclusively in MRM-susceptible strains due to a single-nucleotide insertion. The M. plutonius RlmAII modified G748 of 23S rRNA, and the deletion of rlmA II resulted in increased susceptibility to MRM and the loss of modification at G748, suggesting that methylation at G748 by RlmAII confers MRM resistance in M. plutonius. The single-nucleotide mutation in MRM-susceptible strains was easily repaired by spontaneous deletion of the inserted nucleotide; however, intact rlmA II was only found in Japanese M. plutonius and not in a Paraguayan strain tested or any of the whole-genome-sequenced European strains. MRM has been used in apiculture only in Japan. Although M. plutonius is not the target of this drug, the use of MRM as a prophylactic drug for AFB may have influenced the antibiotic susceptibility of the causative agent of EFB.
Assuntos
Antibacterianos/farmacologia , Abelhas/microbiologia , Enterococcaceae/efeitos dos fármacos , Mutação da Fase de Leitura , Macrolídeos/farmacologia , Metiltransferases/genética , Animais , Farmacorresistência Bacteriana/genética , Enterococcaceae/enzimologia , Larva/microbiologia , Metilação , RNA Ribossômico 23SRESUMO
The capsular polysaccharide (CPS) is a major virulence factor in many encapsulated pathogens, as it is the case for Streptococcus suis, an important swine pathogen and emerging zoonotic agent. Moreover, the CPS is the antigen at the origin of S. suis classification into serotypes. Hence, analyses of the CPS structure are an essential step to dissect its role in virulence and the serological relations between important serotypes. Here, the CPSs of serotypes 1 and 1/2 were purified and characterized for the first time. Chemical and spectroscopic data gave the following repeating unit sequences: [6)[Neu5Ac(α2-6)GalNAc(ß1-4)GlcNAc(ß1-3)]Gal(ß1-3)Gal(ß1-4)Glc(ß1-]n (serotype 1) and [4)[Neu5Ac(α2-6)GalNAc(ß1-4)GlcNAc(ß1-3)]Gal(ß1-4)[Gal(α1-3)]Rha(ß1-4)Glc(ß1-]n (serotype 1/2). The Sambucus nigra lectin, which recognizes the Neu5Ac(α2-6)Gal/GalNAc sequence, showed binding to both CPSs. Compared with previously characterized serotype 14 and 2 CPSs, N-acetylgalactosamine replaces galactose as the sugar bearing the sialic acid residue in the side chain. Serological analyses of the cross-reaction of serotype 1/2 with serotypes 1 and 2 and that between serotypes 1 and 14 suggested that the side chain, and more particularly the terminal sialic acid, constitutes one important epitope for serotypes 1/2 and 2. The side chain is also an important serological determinant for serotype 1, yet sialic acid seems to play a limited role. In contrast, the side chain does not seem to be part of a major epitope for serotype 14. These results contribute to the understanding of the relationship between S. suis serotypes and provide the basis for improving diagnostic tools.
Assuntos
Cápsulas Bacterianas/imunologia , Polissacarídeos Bacterianos/imunologia , Sorogrupo , Streptococcus suis/imunologia , Cápsulas Bacterianas/metabolismo , Polissacarídeos Bacterianos/metabolismo , Streptococcus suis/metabolismoRESUMO
Many Streptococcus suis isolates from porcine endocarditis in slaughterhouses have lost their capsule and are considered avirulent. However, we retrieved capsule- and virulence-recovered S. suis after in vivo passages of a nonencapsulated strain in mice, suggesting that nonencapsulated S. suis are still potentially hazardous for persons in the swine industry.
Assuntos
Cápsulas Bacterianas/genética , Streptococcus suis/patogenicidade , Fatores de Virulência/genética , Animais , Cápsulas Bacterianas/fisiologia , Endocardite Bacteriana/microbiologia , Endocardite Bacteriana/veterinária , Genes Bacterianos , Camundongos , Camundongos Endogâmicos C57BL , Família Multigênica , Mutação , Polissacarídeos Bacterianos/genética , Inoculações Seriadas , Sorotipagem , Infecções Estreptocócicas/microbiologia , Infecções Estreptocócicas/veterinária , Streptococcus suis/classificação , Streptococcus suis/genética , Streptococcus suis/isolamento & purificação , Suínos , Doenças dos Suínos/microbiologia , Virulência/genéticaRESUMO
BACKGROUND: Streptococcus suis is divided into 29 serotypes based on a serological reaction against the capsular polysaccharide (CPS). Multiplex PCR tests targeting the cps locus are also used to determine S. suis serotypes, but they cannot differentiate between serotypes 1 and 14, and between serotypes 2 and 1/2. Here, we developed a pipeline permitting in silico serotype determination from whole-genome sequencing (WGS) short-read data that can readily identify all 29 S. suis serotypes. RESULTS: We sequenced the genomes of 121 strains representing all 29 known S. suis serotypes. We next combined available software into an automated pipeline permitting in silico serotyping of strains by differential alignment of short-read sequencing data to a custom S. suis cps loci database. Strains of serotype pairs 1 and 14, and 2 and 1/2 could be differentiated by a missense mutation in the cpsK gene. We report a 99 % match between coagglutination- and pipeline-determined serotypes for strains in our collection. We used 375 additional S. suis genomes downloaded from the NCBI's Sequence Read Archive (SRA) to validate the pipeline. Validation with SRA WGS data resulted in a 92 % match. Included pipeline subroutines permitted us to assess strain virulence marker content and obtain multilocus sequence typing directly from WGS data. CONCLUSIONS: Our pipeline permits rapid and accurate determination of S. suis serotype, and other lineage information, directly from WGS data. By discriminating between serotypes 1 and 14, and between serotypes 2 and 1/2, our approach solves a three-decade longstanding S. suis typing issue.
Assuntos
Sorogrupo , Sorotipagem , Streptococcus suis/genética , Streptococcus suis/isolamento & purificação , Cápsulas Bacterianas , Proteínas de Bactérias , Sequência de Bases , DNA Bacteriano/genética , Marcação de Genes , Genes Bacterianos , Loci Gênicos , Genoma Bacteriano , Reação em Cadeia da Polimerase Multiplex , Polissacarídeos Bacterianos/classificação , Polissacarídeos Bacterianos/genética , Polissacarídeos Bacterianos/imunologia , Polissacarídeos Bacterianos/isolamento & purificação , Alinhamento de Sequência , Análise de Sequência de DNA , Streptococcus suis/classificação , Streptococcus suis/imunologia , Virulência/genética , Fatores de VirulênciaRESUMO
We developed a practical and easy two-step multiplex PCR assay to aid in serotyping of Streptococcus suis. The assay accurately typed almost all of the serotype reference strains and field isolates of various serotypes and also identified the genotypes of capsular polysaccharide synthesis gene clusters of some serologically nontypeable strains.
Assuntos
Cápsulas Bacterianas/genética , Genes Bacterianos/genética , Reação em Cadeia da Polimerase Multiplex/métodos , Polissacarídeos/genética , Infecções Estreptocócicas/diagnóstico , Streptococcus suis/genética , Animais , Humanos , Sorotipagem/métodos , Infecções Estreptocócicas/microbiologia , Suínos/microbiologia , Doenças dos Suínos/diagnóstico , Doenças dos Suínos/microbiologiaRESUMO
European foulbrood is a contagious bacterial disease of honey bee larvae. Studies have shown that the intestinal bacteria of insects, including honey bees, act as probiotic organisms. Microbial flora from the gut of the Japanese honey bee, Apis cerana japonica F. (Hymenoptera: Apidae), were characterized and evaluated for their potential to inhibit the growth of Melissococcus plutonius corrig. (ex White) Bailey and Collins (Lactobacillales: Enterococcaceae), the causative agent of European foulbrood. Analysis of 16S rRNA gene sequences from 17 bacterial strains isolated by using a culture-dependent method revealed that most isolates belonged to Bacillus, Staphylococcus, and Pantoea. The isolates were screened against the pathogenic bacterium M. plutonius by using an in vitro growth inhibition assay, and one isolate (Acja3) belonging to the genus Bacillus exhibited inhibitory activity against M. plutonius. In addition, in vivo feeding assays revealed that isolate Acja3 decreased the mortality of honey bee larvae infected with M plutonius, suggesting that this bacterial strain could potentially be used as a probiotic agent against European foulbrood.
Assuntos
Bactérias/isolamento & purificação , Abelhas/microbiologia , Enterococcaceae/fisiologia , Animais , Bacillus/genética , Bacillus/crescimento & desenvolvimento , Bacillus/isolamento & purificação , Bactérias/genética , DNA Bacteriano/genética , Japão , Larva/microbiologia , Controle Biológico de Vetores , Filogenia , Probióticos , RNA Bacteriano/genética , RNA Ribossômico 16S/genéticaRESUMO
Clostridium sp. was detected in the organs of a cow with black watery diarrhea in Japan. Results identifying this species were inconsistent; Clostridium novyi type A infection was suggested by PCR assay targeting Clostridium fliC region (fliC-multiplex PCR), while 16S rRNA gene sequencing identified the isolated bacteria as Clostridium massiliodielmoense. Sequencing of fliC-multiplex PCR products from the isolates revealed the presence of fliC region in C. massiliodielmoense, which had 92.7% nucleotide similarity to that of C. novyi type A JCM 1406T, leading to the false positive detection of C. novyi by the PCR. This is the first C. massiliodielmoense isolation from clinical specimens, suggesting the need for further research on its pathogenicity and improvement in fliC-multiplex PCR.
Assuntos
Doenças dos Bovinos , Infecções por Clostridium , Clostridium , RNA Ribossômico 16S , Animais , Bovinos , Clostridium/isolamento & purificação , Clostridium/genética , Japão , Doenças dos Bovinos/microbiologia , Doenças dos Bovinos/diagnóstico , Infecções por Clostridium/veterinária , Infecções por Clostridium/microbiologia , Infecções por Clostridium/diagnóstico , RNA Ribossômico 16S/genética , Feminino , Diarreia/microbiologia , Diarreia/veterinária , Reação em Cadeia da Polimerase Multiplex/veterináriaRESUMO
Tyramine, a trace monoamine produced from tyrosine by decarboxylation and found naturally in foods, plants, and animals, is a suspected virulence factor of Melissococcus plutonius that causes European foulbrood in honey bee brood. In the present study, we developed a method for quantitative analysis of tyramine in culture medium and honey bee larvae with a limit of quantitation of 3 ng/mL and a recovery rate of >97% using Liquid Chromatography-Mass Spectrometry/Mass Spectrometry and deuterium-labeled tyramine, demonstrating for the first time that a highly virulent M. plutonius strain actually produces tyramine in infected larvae. This method will be an indispensable tool to elucidate the role of tyramine in European foulbrood pathogenesis in combination with exposure bioassays using artificially reared bee larvae.
Assuntos
Enterococcaceae , Larva , Tiramina , Animais , Larva/microbiologia , Abelhas/microbiologia , Tiramina/análise , Enterococcaceae/isolamento & purificação , Cromatografia Líquida/veterinária , Espectrometria de Massas em Tandem/veterináriaRESUMO
The capsular polysaccharide (CPS) of Streptococcus suis serotype 14 was purified, chemically modified, and characterized. Sugar and absolute configuration analyses gave the following CPS composition: D-Gal, 3; D-Glc, 1; D-GlcNAc, 1; D-Neu5Ac, 1. The Sambucus nigra lectin, which recognizes the Neu5Ac(α2-6)Gal/GalNAc sequence, showed binding to the native CPS. Sialic acid was found to be terminal, and the CPS was quantitatively desialylated by mild acid hydrolysis. It was also submitted to periodate oxidation followed by borohydride reduction and Smith degradation. Sugar and methylation analyses, (1)H and (13)C nuclear magnetic resonance, and mass spectrometry of the native CPS or of its specifically modified products allowed to determine the repeating unit sequence: [6)[Neu5Ac(α2-6)Gal(ß1-4)GlcNAc(ß1-3)]Gal(ß1-3)Gal(ß1-4)Glc(ß1-](n). S. suis serotype 14 CPS has an identical sialic acid-containing side chain as serotype 2 CPS, but differs by the absence of rhamnose in its composition. The same side chain is also present in group B Streptococcus type Ia CPS, except that in the latter sialic acid is 2,3- rather than 2,6-linked to the following galactose. A correlation between the S. suis CPS sequence and genes of the serotype 14 cps locus encoding putative glycosyltransferases and polymerase responsible for the biosynthesis of the repeating unit is proposed.
Assuntos
Polissacarídeos Bacterianos/química , Streptococcus suis/química , Configuração de Carboidratos , Sequência de Carboidratos , Loci Gênicos , Espectroscopia de Ressonância Magnética , Dados de Sequência Molecular , Oxirredução , Lectinas de Plantas/química , Polissacarídeos Bacterianos/isolamento & purificação , Ligação Proteica , Proteínas Inativadoras de Ribossomos/química , Ácidos Siálicos/análise , Streptococcus suis/genéticaRESUMO
Melissococcus plutonius is a fastidious honeybee pathogen, and the addition of KH(2)PO(4) to culture medium is required for its growth. Using genome sequences and a newly developed vector, we showed that mutations in genes encoding Na(+)/H(+) antiporter and cation-transporting ATPase are involved in the potassium requirement for growth.
Assuntos
Abelhas/microbiologia , ATPases Transportadoras de Cálcio/genética , Enterococcaceae/crescimento & desenvolvimento , Enterococcaceae/genética , Genoma Bacteriano/genética , Potássio/metabolismo , Trocadores de Sódio-Hidrogênio/genética , Sequência de Aminoácidos , Animais , Sequência de Bases , Mapeamento Cromossômico , Biologia Computacional , Enterococcaceae/metabolismo , Teste de Complementação Genética , Vetores Genéticos/genética , Dados de Sequência Molecular , Mutação/genética , Análise de Sequência de DNARESUMO
Streptococcus suis strains are classified into 35 serotypes on the basis of the antigenicity of their capsular polysaccharides (CPs). CP synthesis genes are known to be clustered on the chromosome (cps gene cluster). The entire cps gene clusters of S. suis have so far been sequenced in 15 serotypes and found to be located between orfZ and aroA. In this study, to provide comprehensive information about S. suis CPs, we sequenced the entire cps gene clusters of the remaining serotypes and analyzed the complete set of S. suis cps gene clusters. Among the 35 cps gene clusters, 22 were located between orfZ and aroA, whereas the other 13 were flanked by other gene(s) on the chromosomes, and the chromosomal locus was classified into five patterns. By clustering analysis, the predicted products of cps genes found in the 35 serotypes were assigned into 291 homology groups, and all serotypes possessed a serotype-specific gene, except for serotypes 1, 2, 1/2, and 14. Because of the presence of genes encoding flippase (wzx) and polymerase (wzy), CPs of all serotypes were thought to be synthesized by the Wzx/Wzy pathway. Our data also implied the possibility of the transfer of the entire or partial cps gene clusters among S. suis strains, as well as the influence of spontaneous mutations in a single gene or a few genes on the antigenicity of some serotypes. Accumulation of these gene transfers and small-scale mutations may have generated the antigenic diversity of S. suis CPs.
Assuntos
Cápsulas Bacterianas/genética , Cápsulas Bacterianas/metabolismo , Polissacarídeos Bacterianos/biossíntese , Streptococcus suis/genética , Cápsulas Bacterianas/imunologia , Sequência de Bases , Genes Bacterianos , Dados de Sequência Molecular , Família Multigênica , Polissacarídeos Bacterianos/imunologia , Alinhamento de Sequência , Análise de Sequência de DNA , Sorotipagem , Streptococcus suis/classificaçãoRESUMO
Bifidobacteria were isolated from the intestinal tract of the Japanese honeybee, Apis cerana japonica, and investigated for potential application as a probiotic agent against Melissococcus plutonius, the causal agent of European foulbrood (EFB), based on the findings of in vitro inhibition assays. A total of 11 bifidobacteria strains (designated as AcjBF1-AcjBF11) were isolated using a culture-dependent method and their 16S rRNA gene sequences were analyzed. The AcjBF isolates belonged to three distinct bifidobacterial phylotypes that were similar to those found in the European honeybee, Apis mellifera. Although the Japanese and European honeybees are distinct species with different traits and habits, the observation that they share highly similar bifidobacterial phylotypes suggests that bifidobacteria are conserved among honeybee species. Despite having extremely high 16S rRNA gene sequence similarities, the AcjBF isolates had markedly different carbohydrate fermentation profiles. In addition, in vitro growth inhibition assays revealed that the cell-free supernatants of all AcjBF isolates exhibited antagonistic effects on M. plutonius growth. These results indicate that the bifidobacteria isolated from the gut of Japanese honeybee could potentially be employed as a new biological agent to control EFB.
Assuntos
Abelhas/microbiologia , Bifidobacterium/genética , Bifidobacterium/isolamento & purificação , Controle Biológico de Vetores/métodos , Animais , Japão , Microscopia Eletrônica de Varredura , Filogenia , Reação em Cadeia da Polimerase , ProbióticosRESUMO
Melissococcus plutonius is a Gram-positive lanceolate coccus that is the causative agent of European foulbrood, an important bacterial disease of honey bee brood. Although this bacterium was originally described in the early 20th century, a culture method for this bacterium was not established until more than 40 years after its discovery due to its fastidious characteristics, including the requirement for high potassium and anaerobic/microaerophilic conditions. These characteristics were considered to be common to the majority of M. plutonius strains isolated worldwide, and M. plutonius was also thought to be genetically homologous or clonal for years. However, non-fastidious variants of this species (designated as atypical M. plutonius) were very recently identified in Japan. Although the morphology of these unusual strains was similar to that of traditionally well-known M. plutonius strains, atypical strains were genetically very different from most of the M. plutonius strains previously isolated and were highly virulent to individual bee larva. These atypical variants were initially considered to be unique to Japan, but were subsequently found worldwide; however, the frequency of isolation varied from country to country. The background of the discovery of atypical M. plutonius in Japan and current knowledge on atypical strains, including their biochemical and culture characteristics, virulence, detection methods, and global distribution, are described in this review. Remaining mysteries related to atypical M. plutonius and directions for future research are also discussed.
Assuntos
Infecções Bacterianas , Enterococcaceae , Abelhas , Animais , Virulência , Larva/microbiologia , Enterococcaceae/genética , Infecções Bacterianas/veterináriaRESUMO
Streptococcus suis is an encapsulated bacterium causing severe diseases in swine. Here, we compared the protective properties of the capsular polysaccharide (CPS) of different S. suis serotypes by using serotype-switched mutants in a mouse model of infection. CPS structure influenced bacterial survival in mice, antibody binding, and antibody-mediated bacterial killing. The CPS of serotypes 3, 4 and 14 allowed more antibody binding and bacterial elimination than the CPS of serotypes 2, 7 and 9. Results suggest that the different CPS structures of S. suis provide varying levels of protection by influencing antigen availability and elimination by the host immune system.
Assuntos
Infecções Estreptocócicas , Streptococcus suis , Animais , Camundongos , Suínos , Polissacarídeos Bacterianos , Streptococcus suis/metabolismo , Cápsulas Bacterianas , Sorogrupo , Anticorpos , Infecções Estreptocócicas/microbiologia , Anticorpos AntibacterianosRESUMO
A mismatch amplification mutation assay (MAMA)-PCR, which detects a single-nucleotide polymorphism contributed to serological difference between Streptococcus suis serotypes 2 and 1/2, is used to discriminate between these serotypes. The present study reports unusual serotype 1/2 isolates untypable by the MAMA-PCR and improvement of the MAMA-PCR for typing such isolates.
Assuntos
Infecções Estreptocócicas , Streptococcus suis , Doenças dos Suínos , Humanos , Animais , Suínos , Sorogrupo , Sorotipagem , Streptococcus suis/genética , Infecções Estreptocócicas/diagnóstico , Reação em Cadeia da Polimerase , Mutação , Doenças dos Suínos/diagnósticoRESUMO
Clostridium perfringens toxinotype E infections are rare in calves, and the development of intestinal lesions were commonly observed. In 2012, a 6-day-old calf in Japan exhibited swelling with emphysema on the right gluteal region, sudden paralysis of the hind limb and dysstasia. A pathological examination revealed myositis of the gluteal muscle and neuritis of the ischiatic nerve. C. perfringens type E strain CP118 was isolated from the affected muscle. However, the intestinal symptoms and lesions that commonly develop in type E infections in calves were not detected in the present case. Genome analyses revealed that CP118 possessed 16 virulence-related genes, including enterotoxin, and was closely related to other type E and F strains. Particularly, CP118 was more closely related to type E strains from humans, including a food poisoning case, than calf isolates, suggesting its potential to cause food poisoning in humans and, thus, its importance as a potential risk to public health. Since CP118 did not possess the reported toxin genes associated with neuropathy, pyogenic inflammation caused by CP118 and/or other bacteria may have damaged the ischiatic nerve, resulting in neuropathy. Alternatively, unidentified CP118 toxins may have caused the neuropathy. This is the first study to report C. perfringens type E infection with peripheral neuropathy. The distribution of all the reported virulence-related genes in the C. perfringens population as well as the details of this rare case will provide further insights into C. perfringens type E infections.