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1.
无乳链球菌亦称为B组链球菌,是一种在自然界广泛存在的革兰阳性菌,是人类的重要病原之一,也是鱼类的重要病原菌。近年来,无乳链球菌成为鱼类链球菌病的主要病原之一,鱼类感染无乳链球菌的常见临床症状包括眼球突出、腹部肿胀、脊骨弯曲、鳍条基部出血等,发病率和死亡率高,常造成严重的经济损失,危害着水产养殖业的健康发展。论文对鱼类无乳链球菌病的研究进行了总结,对鱼类无乳链球菌病病原、致病机理进行综述,介绍了鱼类无乳链球菌病常见的诊断方法,以及现阶段针对鱼类无乳链球菌病的疫苗开发情况,旨在进一步丰富、完善鱼类无乳链球菌病的研究资料,为更好的防治鱼类无乳链球菌病提供参考。 相似文献
2.
Ⅶ型分泌系统(T7SS)是近年来发现的分泌系统,分泌两种胞外蛋白,EsxA基因编码的ESAT6蛋白和EsxB基因编码的CFP-10蛋白。分泌蛋白具有良好的免疫原性,促进细菌从巨噬细胞吞噬体逃逸、影响巨噬细胞凋亡及裂解细胞等生物学功能,与致病性密切相关。以罗非鱼源无乳链球菌为模板,克隆到294bp的EsxA基因,将目的序列克隆到pMD18-T载体,经测序,目的序列与无乳链球菌EsxA基因同源率在99%以上。EsxA基因克隆到pET32a载体中,重组载体在28℃、0.5mmol/L IPTG诱导条件下表达量最大,可溶性表达。将纯化的ESAT6蛋白免疫Balb/c鼠,成功制备ESAT6蛋白鼠多克隆抗体,经Western blot,ESAT6蛋白具有良好的反应原性。研究结果为进一步进行无乳链球菌ESAT6蛋白的免疫学功能研究奠定了基础。 相似文献
3.
Jacobsson K 《Veterinary microbiology》2003,96(1):103-113
Streptococcus agalactiae is a contagious pathogen in bovine mastitis. It is also one of the leading causes to neonatal pneumonia, sepsis and meningitis in Europe and North America. Although extracellular bacterial proteins that interact with host structures are putative vaccine components, so far only a few receptins have been identified and characterised from this organism. The aim of the present study was to identify fibrinogen-binding receptins from a shotgun phage display library constructed from the bovine type strain CCUG 4208. A novel extracellular receptin was identified after selecting the library against bovine fibrinogen. This protein is a member of a family of at least three proteins that share the fibrinogen-binding region as well as the N-terminal signal sequence, whereas the intervening region varies in size and has almost no sequence similarity. Proteins of this family are present also in human isolates of S. agalactiae, although binding to human fibrinogen has not been detected. 相似文献
4.
The milk excretion of group B streptococci (Streptococcus agalactiae) from the udder quarters was examined in thirty cows of a heavily infected herd. Six samplings were performed in ten- to fourteen-day intervals. With respect to excretion rate, the set of cows could be divided into three groups: 1. group of cows excreting S. agalactiae from all udder quarters permanently and absolutely regularly; 2. cows excreting S. agalactiae regularly only from some quarters, certain quarter being negative at all samplings; 3. cows excreting streptococci from all quarters absolutely irregularly, without any conclusive order or dependence. The cytological picture of all samples exhibited no signs of inflammation. The discussion deals with some factors that may influence the excretion of streptococci with milk. 相似文献
5.
Seven group B streptococcal cultures isolated from three horses reacted with group B-specific antiserum, were CAMP positive, pigmented and showed the typical biochemical properties of Streptococcus agalactiae. The identification could be confirmed by PCR amplification of the 16S rRNA gene and a subsequent RsaI restriction pattern typical for S. agalactiae. In addition, the isolates were identified by amplification of species specific parts of the 16S rRNA gene, the 16S-23S rRNA intergenic spacer region and by amplification of the CAMP-factor (cfb) gene. Six isolates could be classified as serotype III/Rib, one isolate as serotype Ia/cbeta. The occurrence of the protein antigens Rib and cbeta could be confirmed by PCR amplification of the respective genes. The six isolates of serotype III/Rib were hyaluronidase negative, had a hylB gene with a size of 4.6 kb and an insertion element IS1548 of 0.98 kb. The isolate of serotype Ia/cbeta was hyaluronidase positive, had a hylB gene with a size of 3.3 kb and no insertion element IS1548. In addition, all seven isolates had the insertion element ISSag2 and the gene lmb encoding the laminin binding surface protein Lmb and the gene scpB encoding C5a peptidase. According to the present results the group B streptococci isolated from horses showed characteristics of human isolates of this species. 相似文献
6.
无乳链球菌是导致奶牛乳腺炎的重要病原菌,本研究评价了SIP(surface immunogenic protein)亚单位疫苗对小鼠无乳链球菌乳腺炎的免疫保护效果。制备无乳链球菌SIP亚单位疫苗和灭活疫苗,对小鼠进行免疫,并设PBS阴性对照。免疫前后采血测定IgG及IgG亚类的抗体滴度。免疫小鼠分娩后第4天,进行无乳链球菌乳腺攻毒试验。24h后扑杀攻毒鼠,进行乳腺内CFU的测定,制作并观察乳腺组织病理切片。结果显示,SIP亚单位疫苗免疫组IgG及IgG亚类抗体滴度显著高于灭活疫苗组(P0.01)。免疫哺乳小鼠乳腺攻毒后,SIP亚单位疫苗免疫组小鼠乳腺CFU显著低于灭活疫苗组及对照组(P0.001)。乳腺病理切片显示SIP亚单位疫苗组乳腺组织结构较对照组完整,且中性粒细胞浸润程度最小。本研究表明,无乳链球菌SIP亚单位疫苗有望作为奶牛无乳链球菌乳腺炎的候选亚单位疫苗。 相似文献
7.
多重PCR检测奶牛乳腺炎金黄色葡萄球菌、无乳链球菌、停乳链球菌和酵母菌方法的建立与应用 总被引：2，自引：0，他引：2
参照GenBank发表的序列，在金黄色葡萄球菌、无乳链球菌和停乳链球菌16SrRNA与23SrRNA之间的区域设计了3对引物，参照念珠菌和隐球菌的18SrRNA的序列设计1对引物，建立了检测金黄色葡萄球菌、无乳链球菌、停乳链球菌和酵母真菌4种乳腺炎主要致病菌的多重PCR方法。参照Skladny的方法制备模拟了细菌感染l临床标本。结果表明：本试验建立的多重PCR方法具有较好的特异性，多重PCR方法检测乳样中的金黄色葡萄球菌的细菌最小浓度为10^4CFU／mL，检测无乳链球菌、停乳链球菌和酵母真菌的细菌最小浓度分别为10^4CFU／mL、10^3CFU／mL和10^3CFU／mL。通过对采自临床型乳腺炎（46个）和隐性乳腺炎（167个）动物共计213个乳样分别用传统细菌学培养法和多重PCR方法进行检测，多重PCR对金黄色葡萄球菌和酵母真菌的检测具有更高的检出率（P〈0．01），但该方法对无乳链球菌和停乳链球菌的检出率与培养法差异不显著（P〉0．05）。 相似文献
8.
利用THB固体培养基和色素培养基初步筛选出奶牛乳房炎中无乳链球菌，以分离的12株疑似菌的基因组DNA为模板进行PCR扩增，对扩增产物进行分析，结合选择培养的生理生化特性对分离菌进行鉴定。结果表明，12株疑似菌中有8株为无乳链球菌. 相似文献
9.
Development of a system for genetic and molecular analysis of Streptococcus agalactiae 总被引：4，自引：0，他引：4
DNA-DNA hybridisation was used to compare the genetic relation of human and bovine strains of Streptococcus agalactiae. All strains showed significant homology under very stringent hybridisation conditions. The extent of relatedness did not correlate with the serological type. It was demonstrated that the S faecalis transposon Tn916 could be inserted randomly into the S agalactiae chromosome when introduced by conjugation. The ability of Tn916 insertion to cause genetic changes in S agalactiae was confirmed by identification of a mutation in lactose and trehalose fermentation associated with acquisition of the transposon. This system should be useful in genetic analysis of the pathogenicity of S agalactiae. 相似文献
10.
Ingestion and killing of Streptococcus agalactiae by bovine granulocytes in the presence of natural opsonins 总被引：3，自引：0，他引：3
An enzyme-linked immunosorbent assay (ELISA) demonstrated the presence of naturally acquired antibodies against Streptococcus agalactiae in normal bovine serum (NBS). In milk wheys, ELISA values were much lower than in sera. Pre-colostral calf serum (PCS) was shown to lack antibodies to type II and III S. agalactiae. The opsonic requirements of 10 human and 10 bovine strains were investigated by evaluating the phagocytosis-induced reduction of the incorporation of radiolabeled thymidine by streptococci. Antibodies present in NBS were required for the efficient ingestion of both human and bovine isolates type II by bovine granulocytes. Three out of five type III bovine isolates were opsonized in the absence of specific antibodies (opsonization by PCS) and type II and III bovine isolates did not require complement opsonization. By contrast, inactivation of complement reduced phagocytosis of human isolates and only one type III strain of human origin was opsonized by PCS. These findings suggest that human isolates had higher opsonic requirements. The phagocytic killing of 6 type III strains (5 mastitis isolates and the reference typing strain) was investigated. Opsonization by normal serum enabled bovine blood granulocytes to ingest and kill S. agalactiae. Nevertheless, greater than or equal to 35% of bacteria remained viable at the end of the phagocytosis incubation in 10% NBS. Heat treatment of serum decreased the efficacy of killing for only 3 of the 6 tested strains. An IgG2 fraction of normal adult bovine serum promoted active ingestion, which was still increased in the presence of PCS. Normal wheys displayed large variations in their ability to promote ingestion of S. agalactiae by blood granulocytes. The promoting effect was systematically less than that of serum from the same cow, and this can be related to the lower ELISA values found in wheys. 相似文献
11.
Intraspecific variation in the 16S rRNA genes of 17 Mycoplasma agalactiae and eight Mycoplasma bovis isolates was investigated to determine the degree of sequence variation in these two species and to determine whether the polymorphisms in the 16S rRNA genes could be used for the construction of an evolutionary tree and as epidemiological markers. A high degree of variation was found within isolates (between operons) and between isolates of both species. In contrast to M. capripneumoniae no distinct evolutionary pattern could be seen, probably because there are functional systems for gene conversion in M. agalactiae and M. bovis. However, the non-European isolates of M. agalactiae shared three characteristic nucleotides and European isolates from the same or neighbouring countries were very similar. Differences within isolates included both polymorphic positions and sequence length differences between operons. The amount of variation within isolates of the respective species ranged from zero to seven polymorphisms for M. agalactiae and from zero to four polymorphisms for M. bovis. The high degree of variation suggests the potential for misdiagnosis of species in diagnostic PCR assays based on the 16S rRNA gene sequences. All isolates of both species had a thymidine in position 912 (E. coli numbering) that causes streptomycin resistance in several bacterial species and which is characteristic for the members of the hominis group. As expected, when five M. agalactiae and three M. bovis isolates were tested for streptomycin susceptibility, they all demonstrated streptomycin resistance. M. agalactiae and M. bovis were found to have high intraspecific variation in their 16S rRNA gene and the polymorphisms patterns indicate that gene conversion takes place. 相似文献
12.
Four pregnant heifers were immunized by the intramammary route with killed or live Streptococcus agalactiae vaccine, and a 5th heifer was vaccinated by the intramuscular route with killed vaccine. Antibody in the colostrum from vaccinated and non-vaccinated glands was compared. Antibacterial glands was compared. Antibacterial antibody titers of the 4 immunoglobulin classes were determined by indirect fluorescent antibody assay. Although the content of immunoglobulin G1 (IgG1), IgG2, and IgM in the colostrum from the vaccinated glands was not substantially different from the nonvaccinated glands, IgA content was considerably greater in the former. Antibody specific to S agalactiae was isolated from all colostrum samples. The mouse passive protection test and Ouchterlony analysis were used to demonstrate the presence of type-specific antibody to Ia strain used for vaccination. The passive mouse protection test also was useful to compare the protective capacity of specific S agalactiae, type Ia, antibodies of immunoglobulin classes IgG, IgM, and IgA. Increased protective capacity of IgM and IgA over IgG1, on a weight basis, was demonstrated. The present study indicates that S agalactiae preparations, when introduced into the mammary gland, can give rise to local antibody synthesis in the vaccinated glands. 相似文献
13.
Specific detection by PCR of Streptococcus agalactiae in milk. 总被引：3，自引：0，他引：3
The aim of this study was to develop a simple and specific method for direct detection of Streptococcus agalactiae from cow's milk. The method was based on polymerase chain reaction (PCR) using species-specific and universal primers derived from the 16S rRNA gene. The amplification product was verified by restriction endonuclease digest and sequencing. Specific identification was proven on a collection of 147 S. agalactiae isolates of bovine and human origin. In addition, 17 strains belonging to different bacterial species that potentially can be found in milk samples also tested negative. The PCR developed was used for direct detection of S. agalactiae in milk, using for the first time with gram-positive bacteria the nucleic acid-binding properties of diatomaceous earth. The test, which has high specificity, high sensitivity (100 cfu/mL), and can be carried out in less than 24 h, represents an innovative diagnostic tool for the detection of S. agalactiae in milk. 相似文献
14.
Estuningsih S Soedarmanto I Fink K Lämmler C Wibawan IW 《Journal of veterinary medicine. B, Infectious diseases and veterinary public health》2002,49(4):185-187
All 83 bacterial strains isolated from seven farms in three areas of the island of Java in Indonesia investigated in the present study could be identified as Streptococcus agalactiae. Identification was performed by cultural, biochemical and serological properties and by polymerase chain reaction amplification of species-specific parts of the gene encoding the 16S rRNA, the 16S-23S rDNA intergenic spacer region and the CAMP factor (cfb) gene. All isolates were unpigmented. almost all of the isolates had the serotype pattern II/X. Despite these similarities a macrorestriction analysis of the chromosomal DNA of the bacteria revealed no significant homologies of the DNA-fingerprints of the S. agalactiae from the various areas. This last finding might possibly indicate that a single ancestral unpigmented serotype II/X S. agalactiae clone was responsible for the mastitis situation on Java and had evolved separately in the various farms and regions. 相似文献
15.
G P Keefe 《The Canadian veterinary journal. La revue veterinaire canadienne》1997,38(7):429-437
Streptococcus agalactiae continues to be a major cause of subclinical mastitis in dairy cattle and a source of economic loss for the industry. Veterinarians are often asked to provide information on herd level control and eradication of S. agalactiae mastitis. This review collects and collates relevant publications on the subject. The literature search was conducted in 1993 on the Agricola database. Articles related to S. agalactiae epidemiology, pathogen identification techniques, milk quality consequences, and control, prevention, and therapy were included. Streptococcus agalactiae is an oblique parasite of the bovine mammary gland and is susceptible to treatment with a variety of antibiotics. Despite this fact, where state or provincial census data are available, herd prevalence levels range from 11% (Alberta, 1991) to 47% (Vermont, 1985). Infection with S. agalactiae is associated with elevated somatic cell count and total bacteria count and a decrease in the quantity and quality of milk products produced. Bulk tank milk culture has, using traditional milk culture techniques, had a low sensitivity for identifying S. agalactiae at the herd level. New culture methods, using selective media and large inocula, have substantially improved the sensitivity of bulk tank culture. Efficacy of therapy on individual cows remains high. Protocols for therapy of all infected animals in a herd are generally successful in eradicating the pathogen from the herd, especially if they are followed up with good udder hygiene techniques. 相似文献
16.
无乳链球菌是引起奶牛乳房炎的常见病原微生物之一,其表面蛋白作为一种高免疫原性的生物大分子,具有较高的种内特异性,是理想的候选疫苗与免疫检测靶标。本研究通过对无乳链球菌高免疫原性表面蛋白Rib的重组表达与抗体制备,为后期无乳链球菌的疫苗研制与检测奠定了良好的基础。首先提取了无乳链球菌基因组DNA,从中成功扩增出长度为452bp的编码表面蛋白Rib N端的基因片段。将这一片段连入重组表达载体pET-26b,转化受体菌株BL21(DE3)后利用IPTG进行诱导,结果表达了分子质量约为18ku的外源蛋白。在低温表达条件下,对IPTG诱导浓度进行优化,结果表明,IPTG的最适诱导浓度为0.05mmol/L。将诱导后的菌体进行超声波破碎并进行SDS-PAGE检测,结果显示重组蛋白以包涵体形式存在,对其进行变性、复性处理,利用亲和凝胶纯化后获得了纯度较高的重组蛋白。将重组蛋白免疫新西兰兔制备多克隆抗体,经检测抗体效价达到1∶480 000。 相似文献
17.
Contagious mastitis pathogens continue to pose an economic threat to the dairy industry. An understanding of their frequency and transmission dynamics is central to evaluating the effectiveness of control programmes. The objectives of this study were twofold: (1) to estimate the annual herd-level incidence rates and apparent prevalences of Streptococcus agalactiae (S. agalactiae) in the population of Danish dairy cattle herds over a 10-year period from 2000 to 2009 inclusive and (2) to estimate the herd-level entry and exit rates (demographic parameters), the transmission parameter, β, and recovery rate for S. agalactiae infection. Data covering the specified period, on bacteriological culture of all bulk tank milk samples collected annually as part of the mandatory Danish S. agalactiae surveillance scheme, were extracted from the Danish Cattle Database and subsequently analysed. There was an increasing trend in both the incidence and prevalence of S. agalactiae over the study period. Per 100 herd-years the value of β was 54.1 (95% confidence interval [CI] 46.0-63.7); entry rate 0.3 (95% CI 0.2-0.4); infection-related exit rate 7.1 (95% CI 5.6-8.9); non-infection related exit rate 9.2 (95% CI 7.4-11.5) and recovery rate 40.0 (95% CI 36.8-43.5). This study demonstrates a need to tighten the current controls against S. agalactiae in order to lower its incidence. 相似文献
18.
奶牛乳腺炎无乳链球菌的分离鉴定 总被引：1，自引：0，他引：1
无乳链球菌是比较常见的导致奶牛乳腺炎的病原菌,该菌也是山羊、绵羊慢性乳房炎的病原菌之一,也能引起婴儿败血症、脑膜炎和肺炎等。人医临床上对该菌以B群链球菌相称。试验从内蒙古呼和浩特市周边5个牛场中患有乳房炎的病牛中采集120份乳样,通过分菌培养、形态学观察、生化试验,鉴定出14株无乳链球菌,同时对这14株菌进行了药物敏感试验、动物致病性试验等。试验结果发现,所分离到的无乳链球菌对青霉素类、氨基糖苷类药物高度敏感,对磺胺类、氟哌酸、喹诺酮类药物中度敏感。动物致病性试验对小鼠的致死率达到80%以上。 相似文献
19.
Bibek Ranjan Shome Mani Bhuvana Susweta Das Mitra Natesan Krithiga Rajeswari Shome Dhanikachalam Velu Apala Banerjee Sukhadeo B. Barbuddhe Krishnamshetty Prabhudas Habibar Rahman 《Tropical animal health and production》2012,44(8):1981-1992
Streptococci are one among the major mastitis pathogens which have a considerable impact on cow health, milk quality, and productivity. The aim of the present study was to investigate the occurrence and virulence characteristics of streptococci from bovine milk and to assess the molecular epidemiology and population structure of the Indian isolates using multilocus sequence typing (MLST) and pulsed-field gel electrophoresis (PFGE). Out of a total of 209 bovine composite milk samples screened from four herds (A–D), 30 Streptococcus spp. were isolated from 29 milk samples. Among the 30 isolates, species-specific PCR and partial 16S rRNA gene sequence analysis identified 17 Streptococcus agalactiae arising from herd A and 13 Streptococcus uberis comprising of 5, 7, and 1 isolates from herds B, C, and D respectively. PCR based screening for virulence genes revealed the presence of the cfb and the pavA genes in 17 and 1 S. agalactiae isolates, respectively. Similarly, in S. uberis isolates, cfu gene was present in six isolates from herd C, the pau A/skc gene in all the isolates from herds B, C, and D, whereas the sua gene was present in four isolates from herd B and the only isolate from herd D. On MLST analysis, all the S. agalactiae isolates were found to be of a novel sequence type (ST), ST-483, reported for the first time and is a single locus variant of the predicted subgroup founder ST-310, while the S. uberis isolates were found to be of three novel sequence types, namely ST-439, ST-474, and ST-475, all reported for the first time. ST-474 was a double locus variant of three different STs of global clonal complex ST-143 considered to be associated with clinical and subclinical mastitis, but ST-439 and ST-475 were singletons. Unique sequence types identified for both S. agalactiae and S. uberis were found to be herd specific. On PFGE analysis, identical or closely related restriction patterns for S. agalactiae ST-483 and S. uberis ST-439 in herds A and B respectively, but an unrelated restriction pattern for S. uberis ST-474 and ST-475 isolates from herds D and C respectively, were obtained. This signifies that the isolates of particular ST may exhibit related PFGE patterns suggesting detection of a faster molecular clock by PFGE than MLST. Since all the isolates of both the species belonged to novel sequence types, their epidemiological significance in global context could not be ascertained, however, evidence suggests that they have uniquely evolved in Indian conditions. Further research would be useful for understanding the role of these pathogens in bovine sub-clinical mastitis and implementing effective control strategies in India. 相似文献
20.
试验旨在研究无乳链球菌的生物学特性,为防治无乳链球菌引起的奶牛乳房炎提供理论依据。根据细菌分子生物学分离鉴定无乳链球菌,参考GenBank登录的牛源无乳链球菌16S rRNA、菌属特异性cfb （CAMP因子）、毒力基因和耐药基因序列,运用Oligo 6.0和Primer Premier 5.0软件设计14对引物,建立PCR快速检测方法,并进行20种常见抗生药物的耐药试验。结果显示,试验成功鉴定出17株牛源无乳链球菌,毒力基因与NCBI上已报道的无乳链球菌相应序列具有高度同源性,均≥99%;共检测到6种耐药基因;分离菌株对青霉素、红霉素、林可霉素、克林霉素、万古霉素、氨苄西林、新生霉素、磺胺异噁唑的耐药率均较高,耐药率依次为100.0%、94.1%、94.1%、94.1%、94.1%、82.3%、82.3%和47.1%,对青霉素严重耐药;而对氨基糖苷类、四环素类、头孢菌素类、喹诺酮类耐药率均较低,耐药率分别为15.7%、14.7%、7.7%和3.9%。本研究结果表明,建立的PCR快速检测方法灵敏可靠,云南地区无乳链球菌已对部分β-内酰胺类、大环内酯类、磺胺类等抗生素出现多重耐药性。 相似文献