共查询到20条相似文献，搜索用时 15 毫秒
1.
Anding Zhang Xiaofeng Mu Bo Chen Cheng Liu Li Han Huanchun Chen Meilin Jin 《Veterinary microbiology》2010,140(1-2):171-175
Streptococcus suis (S. suis) is a major swine pathogen and an emerging zoonotic agent. However, the current understanding of the S. suis pathogenesis of infection remains limited. In the present study, an IgA1 protease of S. suis was identified for the first time. The protein was recombinantly expressed in Escherichia coli, and the purified recombinant protein showed good cleaving reactivity to IgA1 and was highly immunoreactive to convalescent sera. The gene was found to exist in most pathogenic strains but scarcely in non-invasive isolates. These findings suggested that the IgA1 protease might play an important role in the pathogenesis of S. suis. 相似文献
2.
Bonifait L Vaillancourt K Gottschalk M Frenette M Grenier D 《Veterinary microbiology》2011,148(2-4):333-340
Streptococcus suis is a major swine pathogen that is responsible for severe infections such as meningitis, endocarditis, and septicemia. S. suis is also recognized as a zoonotic agent and expresses several virulence factors. The recently identified subtilisin-like protease (SspA) of S. suis plays an important role in the pathogenicity of this bacterium in animal models. The objective of the present study was to clone, purify, and characterize the SspA of serotype 2 S. suis P1/7. The SSU0757 gene encoding SspA was amplified and a 4798-bp DNA fragment was obtained. It was cloned into the expression plasmid pBAD/HisB and then inserted into Escherichia coli to overproduce the protein. The recombinant protease was purified by chromatography procedures and showed a molecular weight of 170 kDa by SDS-PAGE. Its activity was optimal at pH 7 and at temperatures ranging from 25°C to 37°C. It had a high specificity for the chromogenic substrate succinyl-Ala-Ala-Pro-Phe-pNa while specific inhibitors of serine proteases inhibited its activity. In addition to degrading gelatin, the protease hydrolyzed the Aα chain of fibrinogen, which prevented fibrin formation by thrombin. The recombinant subtilisin-like protease also showed toxicity towards brain microvascular endothelial cells. Lastly, sera from pigs infected with S. suis reacted with the recombinant SspA, indicating that it is produced during infections. In conclusion, the SspA of S. suis shared similarities with subtilisin-like proteases produced by other pathogenic streptococci and may contribute to the pathogenic process of S. suis infections. 相似文献
3.
4.
5.
Haemophilus parasuis, the bacterium responsible for Gl?sser's disease, is a pathogen of significant concern in modern high-health swine production systems but there is little information regarding the identity or function of its virulence factors. Several important human mucosal pathogens, including the closely related bacterium Haemophilus influenzae, utilize IgA proteases to aid in defeating the host immune response and facilitate disease but it is unknown whether H. parasuis synthesizes any product with IgA protease activity. To investigate potential virulence mechanisms of H. parasuis, we evaluated five strains for their ability to digest purified IgA. Western blotting demonstrated cleavage of swine IgA, but not human IgA1, following incubation with culture supernatants from three strains, two of which are known to cause invasive disease. No genes with homology to the H. influenzae IgA protease genes iga and igaB could be identified in any H. parasuis strain using either PCR or Southern blotting. These results demonstrate that a novel IgA protease produced by some strains of H. parasuis cleaves the swine IgA heavy chain at a site not found in human IgA1. 相似文献
6.
通过细胞培养板法研究了猪链球菌2型生物被膜的生物学特性。结果显示:大部分猪链球菌均具有不同程度形成生物被膜的能力,其中3株(3/15)形成能力较强;猪链球菌生物被膜的成熟约需60 h,培养基中葡萄糖浓度是影响生物被膜形成的重要因素;生物被膜中的多糖含量显著高于浮游菌;氨苄青霉素钠和阿莫西林对这3株猪链球菌生物被膜的最低抑菌浓度(MIC)和最低杀菌浓度(MBC)均高于游离菌约2 500倍;扫描电镜观察发现,生物被膜内猪链球菌彼此黏连,形成致密的三维立体结构。对猪链球菌生物被膜生物学特性的研究为进一步揭示生物被膜的形成机制、耐药机理,以及清除生物被膜等提供理论依据。 相似文献
7.
Streptococcus Suis: Past and Present 总被引：109，自引：0，他引：109
Staats J.J. Feder I. Okwumabua O. Chengappa M.M. 《Veterinary research communications》1997,21(6):381-407
Staats, J.J., Feder, I., Okwumabua, O. and Chengappa, M.M., 1997. Streptococcus suis: past and present. Veterinary Research Communications, 21 (6), 381-407Steptococcus suis is a Gram-positive, facultatively anaerobic coccus that has been implicated as the cause of a wide range of clinical disease syndromes in swine and other domestic animals. In swine, the disease has spread worldwide but is more prevalent in countries with intensive swine management practices. The disease syndromes caused by S. suis in swine include arthritis, meningitis, pneumonia, septicaemia, endocarditis, polyserositis, abortions and abscesses. S. suis has also been implicated in disease in humans, especially among abattoir workers and swine and pork handlers. In humans, S. suis type 2 can cause meningitis, which may result in permanent hearing loss, septicaemia, endocarditis and death. The pathogenic mechanism of S. suis is not well defined. Several virulence factors have been identified, but their roles in pathogenesis and disease have not been well elucidated. Much work is in progress on characterization of virulence factors and mechanisms, with emphasis on the control of the disease. Because of the non-availability of suitable immunoprophylaxis, control of S. suis infection has depended mainly on the use of antimicrobials. 相似文献
8.
为优化猪种布氏杆菌WboA基因缺失株(B.suisΔWboA)对绵羊的免疫条件,本研究采用1岁左右的成年雌性绵羊对B.suisΔWboA的免疫剂量及免程序进行了比较研究。实验分5个组进行,其中A、B、C 3个试验组分别以2倍剂量重复接种、4倍剂量重复接种和单剂量1次接种B.suisΔWboA,D组单剂量1次接种猪种布氏杆菌S2疫苗株(B.suis S2),E组为空白对照组。各组羊首免后7 d、21 d和35 d分别采血,测定血清抗体水平;在首免后35 d,分别采用布氏杆菌强毒菌M28株(B.melitensis M28),经腹股沟皮下注射攻毒。攻毒后28 d,分别取试验羊的脾脏分离攻毒菌株。所有试验羊,在实施攻毒前,其精神、食欲均正常。血清抗体测定结果表明,在二免7 d、21 d后,A组和B组试验羊的抗体水平明显高于C组,而且均超过D组试验羊的抗体水平。攻毒后的细菌分离结果表明,攻毒后28 d,A组和B组试验羊的脾脏细菌分离数量明显低于C组试验羊,并且均低于D组试验羊的细菌分离水平。实验结果表明,B.suisΔWboA的免疫剂量由单倍改为2倍或4倍,免疫程序由单剂量1次改为2倍或4倍剂量2次,可以明显提高免疫效果,并达到与亲本疫苗菌株B.suis S2的免疫水平。 相似文献
9.
Experimental exposure of young pigs using a pathogenic strain of Streptococcus suis serotype 2 and evaluation of this method for disease prevention. 总被引：1，自引：1，他引：0 
下载免费PDF全文
下载免费PDF全文 Control of Streptococcus suis infections and associated disease have proven to be a difficult challenge under most farm conditions. The objective of this study was to experimentally expose young pigs with a pathogenic strain of S. suis serotype 2 as a means of controlling the disease in a commercial swine farm. Prior to the start of the study, the pathogenic S. suis strain responsible for mortality in the farm was identified and used to experimentally inoculate baby piglets. Over a 3-week period, groups of pigs were selected (100 pigs/wk) and divided into 2 groups: control (50 pigs/week) and experimentally exposed (50 pigs/week). Pigs in the experimentally exposed group were inoculated at 5 d old by tonsillar swabbing with the pathogenic S. suis farm isolate. The effect of exposure with this pathogenic strain was evaluated during the nursery and finishing stages and was based on: morbidity (pigs with central nervous signs (CNS) and/or lameness), mortality and number of treatments required by pigs that had either CNS or lameness. The relative risk (RR) of acquiring disease due to S. suis infection was also calculated. Results showed that morbidity in the experimentally exposed groups was lower than in the control group and these results were statistically different (P = 0.006). Experimentally exposed pigs also showed a statistically significant reduction in lameness problems (P = 0.012), but not in CNS (P = 0.20) or mortality (P = 0.59). Pigs in the control group had an increased RR of 4.76, 8.77 and 2.7 for morbidity, to have lameness or to have CNS signs, respectively. In conclusion, experimental exposure of young pigs with the farm's pathogenic S. suis strain at a young age, had a positive effect in reducing clinical signs characteristics of S. suis infection. This method constitutes a novel approach to the control of S. suis infections in swine farms. 相似文献
10.
Valentin-Weigand P 《Berliner und Münchener tier?rztliche Wochenschrift》2004,117(11-12):459-463
Streptococcus (S.) suis and Mycobacterium avium ssp. paratuberculosis (MAP) differ substantially in their host specificity and tissue tropism. S. suis is a facultative pathogen in swine, which mainly colonises the upper respiratory tract and can cause meningitis, septicemia, arthritis and pneumonia. In contrast, MAP is an obligatory pathogen causing paratuberculosis in ruminants, and shows high tropism for the intestinal tract. Both pathogens are able to invade and persist in host cells. In S. suis, the significance of invasion for pathogenesis is a matter of controversial discussions. In vitro it has been shown that S. suis is internalized by epithelial cells and survives intracellularly for at least 24 h. However, at present there is no evidence that S. suis invades epithelial cells also in vivo. In MAP, on the other hand, persistence in macrophages is generally considered a crucial step in pathogenesis, but it remains to be elucidated, how it contributes to pathophysiology of the disease. The two pathogens exemplify how intracellular invasion and persistence might play different roles in pathogenesis. In S. suis, intracellular life may represent only a transient retreat phase, whereas in MAP it is the predominant in vivo niche of the pathogen. 相似文献
11.
Streptococcus suis isolated from pigs in Finland 总被引：6，自引：0，他引：6
A total of 58 Streptococcus suis strains were isolated from deceased pigs submitted to the National Veterinary Institute, Regional Laboratory in Kuopio, Finland, over a 3 1/2 year period, most frequently from cases of pneumonia. The bacteria were isolated from cases of meningitis, sepsis, rhinitis, endocarditis and abortion. S. suis was also isolated from nasal cavity, lung and brain of some sick piglets without signs of inflammation. Further S. suis was detected in 12 out of 107 tonsils of healthy fatteners tested. S. suis strains were identified by biochemical methods followed by typing. The most common capsular types were 7, 3 and 2, respectively. Only one type 1 strain and no types 6 and 9 strains were found. All S. suis strains tested were sensitive to penicillin and ampicillin.S. suis is not uncommon in Finnish pig herds. S. suis may be regarded as a potentially pathogenic organism which under certain predisposing conditions may cause serious disease. 相似文献
12.
Madsen LW Bak H Nielsen B Jensen HE Aalbaek B Riising HJ 《Journal of veterinary medicine. B, Infectious diseases and veterinary public health》2002,49(5):211-215
A recently developed porcine model for aerogenous infection with Streptococcus suis serotype 2 was applied in a study of the phases of bacterial colonization and initial invasion. Eighteen pigs were exposed to aerosolized S. suis serotype 2 after pre-exposure to mild acetic acid in aerosol. The animals were killed consecutively within the first six days after challenge. After death, all animals were necropsied and examined by bacteriology, histopathology, and immunohistochemistry. Systemic infection was established in four out of 18 animals exposed to S. suis serotype 2. All systemically infected animals developed clinical signs and lesions typical of the infection. In four additional animals, subclinical infection was demonstrated by re-isolation of S. suis from the palatine tonsil. However, in all 18 challenged animals, immunohistochemistry demonstrated S. suis serotype 2 antigen in the palatine and/or nasopharyngeal tonsils. In all four systemically infected animals, S. suis serotype 2 antigen was also found in the mandibular lymph node. These observations point towards the tonsils as possible portals of entry for S. suis serotype 2 with subsequent lymphogenous spread. Thus, the present findings parallel the proposed pathogenesis for S. suis serotype 1 infection in pigs. 相似文献
13.
Streptococcus suis type 2 is a pathogen responsible for diverse diseases in both pigs and humans. In order to understand the pathogenesis of the S. suis type 2 infection, the gene encoding a cell surface protein, 6-phosphogluconate-dehydrogenase (6PGD) of S. suis type 2 was cloned and sequenced, and recombinant 6PGD protein (r6PGD) was produced in a prokaryotic expression system. Sequence analysis of the cloned 6 pdg gene showed 82% similarity with Streptococcus pneumoniae 6 pdg at the nucleic acid level. Western blotting using r6PGD-specific antiserum confirmed the cell surface location of the 6PGD protein of S. suis type 2. The role of 6PGD in S. suis type 2 pathogenesis as an adhesin and its immunogenicity in mice was further investigated. The results showed that the recombinant protein interfered with the adhesion of S. suis type 2 to Hep2 and HeLa cells by 72% and 66%, respectively. Immunization of CD-1 mice with r6PGD increased the protective efficacy by 80% following intraperitoneal administration of a lethal dose of S. suis type 2. Immunization of CD-1 mice with r6PGD elicited a significant protective immune response, which demonstrated the importance of 6PGD to bacterial pathogenesis. Identification and characterization of the role of S. suis type 2 6PGD in adhesion and immunogenicity will allow us to use this protein to develop new antimicrobial therapies and/or vaccines. 相似文献
14.
猪链球菌2型毒力相关因子的研究进展 总被引：3，自引：2，他引：1
目前,猪链球菌(Streptococcus suis)病已成为严重影响各国养猪业发展和人类健康的一种重要的人兽共患传染病。猪链球菌的血清型众多,有35个血清型,其中猪链球菌2型(Streptococcus suistype 2,SS2)的致病性强、流行范围广,而且它的毒力因子在该菌的致病过程中发挥着重要的作用。但是猪链球菌2型毒力因子认识的缺乏是制约该病有效防制的关键,因此作者对SS2已发现的毒力因子和新发现的一些毒力相关因子进行了广泛深入的论述,为该病的预防、治疗提供科学依据和参考。 相似文献
15.
The present trial was conducted in Hungary in neighboring large indoor and outdoor pig production units, belonging to the same breeding company. Rejected kidneys from 201 (out of 241; 83.4%) outdoor, and 191 (out of 512, 37.3%) indoor high parity sows, with previous history of recidiving postparturient fever and excessive postparturient vulvovaginal discharge were gross pathologically bacteriologically, and histologically evaluated. All rejected kidneys revealed chronic pyelonephritis. In outdoor sows Escherichia (E.) coli and Actinobaculum (A.) suis were cultured from all kidneys. Besides E. coli and A. suis, Clostridium spp., Arcanobacterium pyogenes, gram-positive streptococci (enterococci, Streptococcus faecalis), staphylococci (Staphylococcus (S.) albus, S. epidermis, S. aureus), Erysipelothrix rhusiopathiae, and Klebsiella spp. were concurrently found in 131 (64.7%) kidneys; Pseudomonas aeruginosa, Citrobacter, Pasteurella multocida, Proteus spp. were concurrently found beside E. coli and A. suis in 71 (35.3%) kidneys. In indoor sows E. coli and A. suis were cultured from all kidneys as well. Pseudomonas aeruginosa, Citrobacter, Pasteurella multocida, Proteus spp. were found beside E. coli and A. suis in 21 (11%) kidneys. However only 6 sows (3.1%) revealed the concurrent presence of Clostridium spp., Arcanobacterium pyogenes, gram-positive streptococci (enterococci, Streptococcus faecalis), staphylococci (S. albus, S. epidermis, S. aureus), Erysipelothrix rhusiopathiae, and Klebsiella spp. Implications: in Eastern European climate, more high parity outdoor sows with recidiving postparturient fever and vulvovaginal discharge have pyelonephritis and higher diversity of pathogenic bacteria in the renal pelvis compared with indoor sows. 相似文献
16.
Hoelzle LE Felder KM Hoelzle K 《Tier?rztliche Praxis. Ausgabe G, Grosstiere/Nutztiere》2011,39(4):215-220
Mycoplasma suis (formerly known as Eperythrozoon suis ) is the most prevalent agent causing haemolytic anaemia in swine. The disease is also known as porcine eperythrozoonosis. M.suis is a small, pleomorphic bacteria parasitizing porcine erythrocytes. To date, no in vitro cultivation system for M.suis has been established and, therefore, our knowledge about the characteristics of M.suis and the pathogenesis of porcine eperythrozoonosis is rather limited. M.suis can cause acute disease, but the major significance of M.suis infections lies in the fact that M.suis can establish chronic and persistent infections leading to a higher susceptibility to other infections, especially of the respiratory and digestive tracts. The present article summarizes the current knowledge of the pathogen, the clinical signs and pathogenesis, diagnostic as well as therapy and prophylaxis. 相似文献
17.
Streptococcus suis is a major cause of meningitis, sepsis and arthritis in piglets and a zoonotic agent. Survival in the blood circulation system represents a major step in pathogenesis of S. suis infections. To get further insights into the mechanisms of S. suis survival in the host, we compared a highly virulent S. suis serotype 2 strain with its non-encapsulated and suilysin-deficient mutants in their abilities to resist phagocytosis and killing by polymorphonuclear neutrophils (PMNs) and mononuclear cells. PMNs displayed a higher capacity to take up encapsulated bacteria than mononuclear cells, whereas both cell types internalized efficiently non-encapsulated S. suis. Differentiation of extracellular and intracellular survival of the WT strain revealed that in PMNs the majority of the cell-associated streptococci were intracellular, whereas in mononuclear cells the majority remained attached to the cell surface. S. suis survived mainly extracellularly, since both cells killed intracellular bacteria to a similar extent. As a consequence of different resistance to phagocytosis, only the encapsulated S. suis strains survived co-cultivation with PMNs. Comparison of the WT strain with its encapsulated suilysin-deficient mutant revealed reduced survival of the mutant after co-cultivation with PMNs. Involvement of suilysin in inhibition of phagocytosis was further confirmed by the use of anti-suilysin antibodies and recombinant suilysin. Kinetic experiments with PMNs suggested that reduced survival of the mutant strain was mainly associated with an increased uptake, whilst both strains adhered similarly. Concluding, our results indicate that the capsule and the suilysin play important roles in S. suis survival in the host by interfering with phagocytic uptake. 相似文献
18.
Swildens B Stockhofe-Zurwieden N van der Meulen J Wisselink HJ Nielen M Niewold TA 《Veterinary microbiology》2004,103(1-2):29-33
Sepsis with subsequent multisystem organ failure after translocation of bacteria from the gut is a serious risk associated with stress situations. We showed that intestinal bacterial translocation could be one of the pathways for pathogenic Streptococcus suis infections in the pig. In 24 piglets weighing 10-14 kg, free of the extracellular factor (EF+) producing phenotype of S. suis serotype 2, a silicon canula was placed in the proximal jejunum to enable intestinal inoculation and bypassing the upper alimentary tract. The pigs were individually housed. After stress induction in 18 pigs by means of a truck drive in individual cages for 1h, pigs were inoculated through the intestinal canula either with S. suis type 2 EF+ or with growth medium only, and put back in their original housing. The six not transported pigs were also inoculated with the same strain. To prevent oral self-infection, faeces were collected in a bag that was glued around the anus. Clinical and behavioral symptoms were recorded for 72 h post inoculation, and then the animals were sacrificed for pathological and bacteriological examination. In three animals, the inoculation strain was re-isolated from mesenterial lymph nodes and typically affected organs. No S. suis type 2 EF+ was detected by specific polymerase chain reaction (PCR) in any of the tonsil-swabs and -homogenates. We concluded that infection of the organs had taken place after bacterial translocation out of the gut and that the intestinal tract can be a porte d'entree for S. suis type 2 EF+. 相似文献
19.
Streptococcus suis is an important agent of swine and human meningitis. Sequence type (ST) 7 emerged in China and was responsible for the human epidemic caused by S. suis in 2005. The virulence of S. suis ST7 is greater than the wild type pathogenic S. suis, ST1; however, the mechanisms for this increased pathogenicity are unknown. The aim of this study was to determine the role of different toll-like receptors (TLRs) involved in regulating the host response to the S. suis infection and to speculate on differing mechanisms used by ST7 strains to induce disease. Here we compared two ST7 strains isolated in the 2005 Sichuan outbreak to two ST1 strains. Our data show TLR2, 6 and 9 are involved in the recognition of heat-killed S. suis independent of the ST type. We found the TLR-dependent cytokine production differed between the two types of strains using whole cell lysate proteins. TLR6 played a greater role in cytokine production induced by the whole cell lysate proteins from the ST7 strain than in that induced by the ST1 strain lysates. The data suggest that mechanisms of inflammation induced by S. suis strains differ where this will be useful in designing efficient strategies in combating streptococcal toxic shock-like syndrome caused by the S. suis ST7 strains. 相似文献
20.
山西猪链球菌的分离鉴定及药敏实验 总被引：2，自引：0，他引：2
猪链球菌是一种常见的病原菌,能引起动物和人类发生猪链球菌病,本实验通过在山西灵石某猪场发病猪群中取样,分离病原菌,并且对病原菌进行培养、镜检、生化鉴定以及PCR的技术扩增其gdh和16srRNA的序列,然后进行药敏实验。鉴定出分离菌能够在鲜血平板上形成溶血环、革兰氏染色阳性、43种生化试验结果以及扩增出特异性条带,表明分离到的病原菌为猪链球菌。药敏实验结果可见其对强力霉素等药物敏感,而对头孢曲松和磷霉素完全耐药。为山西地区猪链球菌的防治提供参考。 相似文献