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1.
Chronic bovine brucellosis is characterized by persistent infection of the mammary gland. The interaction of live Brucella abortus with bovine mammary gland macrophages was studied in vitro. Opsonization of smooth B abortus strain 2308 and rough strain 45/20 was required for phagocytosis by mammary gland macrophages. When opsonized with specific antiserum, strains 2308 and 45/20 stimulated a considerable oxidative burst when phagocytized by mammary gland macrophages. Intracellular survival rates for strain 2308 were significantly higher than those for strain 45/20. After being phagocytized, B abortus localized in phagosomes and phagolysosomes of mammary gland macrophages.  相似文献   

2.
Biological properties of RB51; a stable rough strain of Brucella abortus   总被引：27，自引：0，他引：27  
A rifampin-resistant mutant of Brucella abortus, designated RB51, was derived by repeated passage of strain 2308 on Trypticase soy supplemented with 1.5% agar and varying concentrations rifampin or penicillin. The RB51 colonies absorbed crystal violet and RB51 cell suspensions autoagglutinated, indicating a rough type colonial morphology for this strain. No O-chain component was detected in lipopolysaccharide (LPS) extracted from RB51 on SDS-PAGE gels stained with silver. Western blot analysis with the monoclonal antibody BRU 38, which is specific for the perosamine homopolymer O-chain of smooth Brucella LPS, indicated that the LPS of RB51 is highly deficient in O-chain when compared with the parenteral smooth strain 2308 or rough strain 45/20. Biochemically, RB51 resembles parental strain 2308 in its ability to utilize erythritol. Intraperitoneal inoculation of RB51 into mice results in a splenic colonization which is cleared within four weeks post infection. RB51 does not revert to smooth colony morphology upon passage in vivo (mice) or in vitro. Mice infected with RB51 produce antibodies against B. abortus antigens including class 2 and 3 outer membrane proteins but not against the O-chain. Furthermore, rabbits, goats and cattle hyperimmunized with sonicates of RB51 develop antibodies to B. abortus cellular antigens but do not develop antibodies specific for the O-chain. Immunization of mice with 1 x 10(8) viable RB51 organisms confers significant protection against challenge with virulent B. abortus strain 2308.  相似文献   

3.
PHE1 is a htrA cycL double gene deletion mutant of virulent Brucella abortus strain 2308 (S2308) which has previously been evaluated in the murine and caprine models of bovine brucellosis. This report describes the results of studies conducted with this mutant in the natural bovine host. Six sexually mature, non-gravid heifers were inoculated via the conjunctival sac with 1 x 10(10) colony forming units (CFU) of either the parental S2308 or the htrA cycL gene deletion mutant, PHE1. At 4, 7 and 11 days post-inoculation, PHE1 was found to colonize the bovine host at lower levels than S2308. In a second experiment, eight heifers in mid-gestation were infected with 1 x 10(7) CFU of either strain via the conjunctival sac. The virulent S2308 caused abortions or weak calves in 4/4 cows, while all four cows infected with PHE1 had healthy calves. Furthermore, PHE1 exhibited decreased resistance to killing by cultured bovine neutrophils and macrophages compared to the parental strain. These studies demonstrate that the B. abortus htrA cycL gene deletion mutant PHE1 is highly attenuated in the bovine host when compared to the virulent parental S2308.  相似文献   

4.
OBJECTIVE: To determine the virulence of a Brucella abortus mutant, BA25, lacking a major 25 kd outer membrane protein (Omp25) in cattle. ANIMALS: 20 mixed-breed heifers in late gestation. PROCEDURE: 10 heifers were inoculated with 1 x 10(7) colony-forming units of the Omp25 mutant via the conjunctival sac, and an equal number were infected with the virulent parental strain B. abortus 2308. The delivery status of the dams was recorded, and colonization was assessed following necropsy. The ability of BA25 to replicate inside bovine phagocytes and chorionic trophoblasts was also evaluated in vitro because of the propensity of virulent brucellae to replicate inside these cells in vivo. RESULTS: The parental strain induced abortions in 5 of 10 inoculated cattle, whereas only 1 of 10 dams exposed to BA25 aborted. Brucella abortus strain 2308 colonized all of the cow-calf pairs and induced Brucella-specific antibodies in 100% of the dams. In contrast, BA25 was isolated by bacteriologic cultural technique from 30% of the calves and 50% of the inoculated dams (n = 10). Of the 10 heifers inoculated with BA25, 4 did not develop Brucella-specific antibodies nor were they colonized by the mutant strain. In bovine macrophages and chorionic trophoblasts, BA25 replicated in significantly lower numbers than the virulent parental strain (n = 3). CONCLUSIONS AND CLINICAL RELEVANCE: The 25 kd outer membrane protein may be an important virulence factor for B. abortus in cattle. The attenuation of the Omp25 mutant in cattle may involve the inability of BA25 to replicate efficiently in bovine phagocytes and chorionic trophoblasts.  相似文献   

5.
Brucella spp. are gram-negative intracellular bacterial pathogens that cause chronic infections. Brucella virulence factors include a type IV secretion system (T4SS) and its lipopolysaccharide (LPS), which are essential for persistence. However, the role of the virB-encoded T4SS has not been investigated in naturally rough Brucella species such as Brucella ovis. In this study, male 6-week old BALBc mice were infected with B. ovis, Brucella abortus, and their respective ΔvirB2 mutant strains. During early infection, B. ovis and B. abortus wild type strains were similarly recovered from spleen. Interestingly, in contrast to ΔvirB2 B. abortus that was recovered at similar levels when compared to the wild type strain, the ΔvirB2 B. ovis was markedly attenuated as early as 24h post infection (hpi). The ΔvirB2 B. ovis was unable to survive and multiply in murine peritoneal macrophages and extracellularly within the peritoneal cavity at 12 and 24 hpi with lower splenic colonization than the parental strain at 6, 12 and 24 hpi. In contrast, wild type B. abortus and ΔvirB2 B. abortus had a similar kinetics of infection in this model. As expected, the T4SS was essential for intracellular replication of smooth and rough strains in RAW macrophages at 48 hpi. These results suggest that T4SS is important for survival of B. ovis in murine model, and that a T4SS deficient B. ovis strain is cleared at earlier stages of infection when compared to a similar B. abortus mutant.  相似文献   

6.
Bovine T-lymphocyte lines reactive with Brucella abortus   总被引：1，自引：0，他引：1  
Bovine T-cell lines reactive with Brucella abortus were established by repeated stimulation with B abortus and mitomycin C-treated autologous antigen-presenting cells. Representative results were obtained, using 33 cell lines from 14 cows. Cultures responded to the virulent laboratory strain 2308, the vaccine strain 19, and the rough mutant strain RB51 in thymidine-incorporation assays. The cells in these cultures required antigen-presenting cells for their response to B abortus. Autologous antigen-presenting cells were optimal for most lines tested, although some T-cell lines could respond to B abortus in the presence of some, but not all, allogeneic antigen-presenting cells. The cell lines expressed cell surface markers characteristics of activated bovine T cels. Of the cell lines tested for expression of cluster-determinant (CD) 4 and CD8 cell surface antigens, no cells in any cultures expressed the bovine CD8 equivalent, but all cultures included CD4+ cells in variable amounts. Some cell lines consisted of up to 50% CD2+CD4-CD8- cells. None of the cell lines tested expressed surface immunoglobulin or other bovine B-cell markers. Thus, these long-term cell lines appear to include 2 T-lymphocyte subsets: the helper/inducer subset and a second subset expressing a phenotype similar to major histocompatibility complex-unrestricted cytolytic cells in other species.  相似文献   

7.
Lipopolysaccharide (LPS) fractions were obtained from smooth cultures of Brucella abortus strains 2308 and S-19 by butanol extraction procedures. The LPS from the initial butanol extraction contained 10 to 15% protein and was reduced to less than 1% protein by treatment with proteinase K. The LPS fractions were identified and characterized on the basis of the chemical analysis, sodium dodecyl sulfate gel electrophoresis, cesium chloride gradients, electron microscopy, and gel immunodiffusion. Results indicated that the butanol procedure is a reliable method in the extraction of LPS from Brucella abortus cells. Proteinase K-treated LPS containing less than 1% protein from strain 2308 was used to vaccinate BALB/cByJ mice. Immune and protective criteria for vaccinated and nonvaccinated mice were increased immunoglobulin (IgG and IgM) titers in sera of prechallenge-exposed mice, reduced colony-forming units/spleen, and splenomegaly in post-challenge-exposed mice. Results indicated that proteinase K-treated LPS was immunogenic as well as protective for mice.  相似文献   

8.
Forty-eight cattle were used in 4 experiments; 6-week-old calves in experiments 1-3 (n = 24) and 10-month-old heifers in experiment 4 (n = 24). In experiments 1-3, 7 groups of 3 calves each were inoculated SC with 5 strains of Brucella abortus: virulent strain 2308 (2 groups), vaccine strain 19 (2 groups), and mutant strains RB51. 19 delta 31K, and 19 delta SOD. Sera and lymph node tissues were examined at 2-week intervals for evidence of infection. At postinoculation (PI) week 12, 2 calves in each group were given dexamethasone for 5 days. Calves were then euthanatized and lymphoid tissue, spleen, liver, and bone marrow were examined for evidence of B abortus. Calves given strain 2308 had large numbers of bacteria in their lymph nodes, marked granulomatous lymphadenitis in the deep cortex, and loss of lymphoid cells in superficial cortical areas. In addition, they had high serum antibody titers at PI week 16. Calves given strain 19, or genetic mutants derived from strain 19, cleared bacteria from lymph nodes more rapidly, had less lymphoid destruction, and developed antibody titers that did not persist for 16 weeks. The RB51 strain (rough) was cleared most rapidly from lymphoid tissues and induced serum antibody responses only to the core of the lipopolysaccharide molecule. Treatment of calves with dexamethasone did not cause B abortus to reappear in tissues of any calves, nor did serum antibody titers increase.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

9.
Hybridomas producing antibodies to determinants associated with the lipopolysaccharide (LPS) of Brucella abortus and B melitensis were obtained by polyethylene glycol fusion of the SP2/0 myeloma cell line with B lymphocytes harvested from a Sprague-Dawley-derived rat previously immunized with whole B abortus strain 1119 organisms. Two clones, BRU38 and BRU28 , were selected for their ability to react with whole B abortus organisms and purified smooth-LPS ( f5p ). The BRU38 monoclonal antibodies were absorbed with live, rough strain 45/20 and smooth strains of B abortus and B melitensis organisms, whereas only smooth strains absorbed the antibody activity from BRU28 . Complete inhibition of the monoclonal's activity could be achieved with crude smooth-LPS, a purified f5p fraction, and a water-soluble acid degraded polysaccharide. Absorption of BRU38 and BRU28 with rough Brucella LPS, polysaccharide-B antigen, keto- deoxyoctanoic acid, or with several sugars and fatty acids known to be components of the Brucella LPS complex had no effect on the monoclonals. The data indicate that antigenic determinants are associated with the smooth LPS complex, probably with the O-side chain, and are expressed patchwise and in different quantities on several strains of B abortus and B melitensis. The B abortus rough strain 45/20 contains surface determinants which lead to the agglutination of smooth strain 1119 organisms. The potential use of monoclonals in competitive enzyme-linked immunosorbent assays for diagnostic purposes is discussed.  相似文献   

10.
Purified O chain of Brucella abortus was passively attached to polystyrene to differentiate antibody responses of cattle vaccinated with B abortus strain 19 from those of naturally infected cattle. In the indirect assay, using O polysaccharide as antigen, a single serum dilution was used and mouse monoclonal antibody to bovine L chain conjugated with horseradish peroxidase was the detection reagent. Measurable antibody was not found in sera of vaccinated cattle, except for 3 sera from cattle that were persistently infected with strain 19. Sera from 25 cattle infected with pathogenic strains contained antibody on the basis of results of indirect enzyme immunoassay, using smooth lipopolysaccharide or O chain as antigens, or results of competitive enzyme immunoassay, using the O-chain antigen. Results in sera from calves with experimentally induced Yersinia enterocolitica serotype 0:9 infection or inoculated with a low dose of B abortus strain 2308 were comparable with those in sera of cattle that were vaccinated with strain 19. The data correlated with those from competitive enzyme immunoassay, using one serum dilution and horseradish peroxidase-conjugated mouse monoclonal antibody to smooth lipopolysaccharide. On the basis of results of the indirect enzyme immunoassay, all sera (except those samples obtained before inoculation) contained antibody to smooth lipopolysaccharide.  相似文献   

11.
The outer membrane-peptidoglycan complex (OM-PG) from rough strains of Brucella abortus was tested for its ability to induce lymphocyte responsiveness in cattle. Six groups of heifers were immunized with varying doses and administration schedules of rough OM-PG and assayed for responsiveness of their lymphocytes in proliferation assays in vitro. All OM-PG preparations were emulsified in a commercial adjuvant for administration. Two other groups of heifers were immunized with strain 19 vaccine or adjuvant alone. Three groups of heifers received two inoculations of OM-PG antigens from a naturally-occurring rough strain at a 57-day interval. The doses of OM-PG given in these three groups were 400 micrograms, 1200 micrograms, and 4000 micrograms at each inoculation. The frequency of cows that responded in lymphocyte proliferation assays increased with the dose of OM-PG given. Two groups received single inoculations of OM-PG, either 2400 micrograms or 8000 micrograms. Although there were responsive cows in these immunization groups, their frequency was lower than in the groups receiving the same total dose in two inoculations. A sixth group of cows was inoculated with OM-PG from a rough transposon mutant of B. abortus, and the frequency of responsive cows in this immunization group was comparable to that of responsive cows immunized with the same dose of OM-PG from the spontaneous rough mutant. In comparisons of cows inoculated with strain 19 to those inoculated with OM-PG preparations, differences were observed in the relative responsiveness of their lymphocytes to whole cells and OM-PG in the in vitro lymphocyte proliferation assays. These differences suggested that lymphocytes stimulated by strain 19 vaccination have different specificities than those stimulated by immunization with OM-PG of rough mutant strains of B. abortus.  相似文献   

12.
Chorioallantoic membrane (CAM) explants were used to determine the in vitro growth and cytotoxic potential of 3 strains of Brucella abortus. Bovine CAM explants were inoculated with 2 x 10(7) colony-forming units of the pathogenic strain 2308, attenuated strain 19, or the rough strain RB51 of B abortus. After inoculation, the explants were harvested and examined at 2 or 4 hours, 12 or 14 hours, and 24 or 26 hours of incubation. Bacterial growth associated with each explant was determined by counting colony-forming units. The degree of cellular damage in each explant associated either with bacterial growth or bacterial toxins was evaluated by morphometric analysis after trypan blue staining. Significant differences were not detected in the numbers of bacteria of any strain of B abortus in the CAM explants at comparable time intervals. The rate of growth of the bacteria in CAM explants was higher between 2 and 12 hours after inoculation than between 12 and 24 hours after inoculation. Cytotoxic effects associated with strain 2308 were significantly (P less than 0.05) greater than that caused by other strains. Cytotoxic effects associated with strain 19 and rough strain RB51 were similar, and both were significantly (P less than 0.05) greater than the phosphate buffer solution control. Chorioallantoic membrane explants inoculated with a filtrate of heat-killed strain 2308 induced minimal cellular damage, compared with that caused by the viable bacteria. These results indicated that the number of B abortus in trophoblasts was independent of the degree of cellular damage.  相似文献   

13.
Brucella abortus strain RB51 is an attenuated rough strain, currently being used as the official live vaccine for bovine brucellosis in the USA and several other countries. In strain RB51, the wboA gene, encoding a glycosyltransferase required for the O-side chain synthesis, is disrupted by an IS711 element. Recently, we have demonstrated that strain RB51WboA, RB51 complemented with a functional wboA gene, remains rough but expresses low quantities of O-side chain in the cytoplasm. Mice vaccinated with strain RB51WboA develop greatly enhanced resistance against challenge with B. abortus virulent strain 2308. We have also demonstrated that overexpression of Cu/Zn superoxide dismutase (SOD) in strain RB51 (RB51SOD) significantly increases its vaccine efficacy against strain 2308 challenge. In this study, we constructed a new recombinant strain, RB51SOD/WboA, that over expresses SOD with simultaneous expression of O-side chain in the cytoplasm. We tested the vaccine potential of strains RB51SOD, RB51WboA, RB51SOD/WboA against challenge with virulent Brucella melitensis 16M and B. abortus 2308 in mice. In comparison with strain RB51, strain RB51SOD induced better protection against strain 2308, but not strain 16M, challenge. Similar to strain RB51WboA, vaccination with strain RB51SOD/WboA resulted in complete protection of the mice from infection with strain 2308. When challenged with strain 16M, mice vaccinated with either strain RB51WboA or strain RB51SOD/WboA were significantly better protected than those vaccinated with strain RB51 or RB51SOD. These results suggest that strains RB51WboA and RB51SOD/WboA are good vaccine candidates for inducing enhanced protection against B. melitensis infection.  相似文献   

14.
Lymphocytes from cattle were tested in a blastogenesis test with outer membrane proteins isolated from smooth strain 2308 and rough strain 45/20 of Brucella abortus. The titration assay developed for measuring blastogenesis to microbial antigens (Baldwin, Antczak and Winter, this issue, pp. 319-333) was used to assess the response to both group 2 (porins) (Douglas et al., 1984) and group 3 proteins (Verstreate et al., 1982). Blastogenesis was evaluated for distinguishing cattle infected with virulent B. abortus strain 2308 from unimmunized cattle, cattle vaccinated with attenuated strain 19, or inoculated with Escherichia coli 0116:H31, known to cause serological cross-reactions with B. abortus (Nielsen et al., 1980). Strain 45/20 porin was the most effective for this purpose and data analyses utilizing the titration assay were better than those relying on a single point assay. When compared with BASA, an antigen preparation used in other studies (Kaneene et al., 1978a), responses to porin provided a more specific index of infection with B. abortus. Reactions to 45/20 porin occurred, however, in some heifers vaccinated as adults with strain 19 or inoculated with E. coli 0116:H31. Furthermore, nonpregnant heifers had negligible or only transient blastogenesis responses to the porin during the first 14 weeks after infection even though they developed strong 0 antibody responses. We do not recommend the blastogenesis test in its present form as a useful adjunct to serological tests, and could allow measurement of cell mediated immune responses relevant to protective immunity.  相似文献   

15.
Although the immune response to Brucella abortus is multifaceted, the key event in contending with this pathogen appears to be the interaction of the organism with cells of the mononuclear phagocyte system. A cell culture system was developed which allowed the long-term maintenance of blood monocyte-derived macrophages in Teflon culture vessels in a relatively unstimulated state. The assay system was optimized for timing of bacteria-macrophage interaction and numbers of bacteria and macrophages used in each assay. Interaction of B. abortus strain 2308 with bovine mononuclear phagocytes from animals phenotypically resistant and susceptible to infection with B. abortus was investigated. This cell culture and assay system should provide a useful model for the investigation of intracellular parasitism in cattle.  相似文献   

16.
试验旨在探究ClpS基因在布鲁氏菌中的作用,分析比较ClpS基因突变对布鲁氏菌毒力的影响。利用同源重组技术,构建布鲁氏菌ClpS基因突变株,通过检测细菌生长曲线、细菌LPS合成能力及其在巨噬细胞内的存活能力和小鼠模型中的毒力,比较亲本株2308和突变株ΔClpS两者之间的差异。结果显示,在相同的培养条件下,亲本株2308和突变株ΔClpS的细菌浓度无明显差异,且两者提取的LPS银染结果基本一致,表明ClpS基因突变不影响布鲁氏菌生长速度,不影响细菌LPS合成;在细胞感染模型中,突变株ΔClpS在感染后72 h的胞内存活能力极显著低于亲本株2308（P<0.01）;小鼠感染试验显示,在感染后1周,亲本株2308感染组和突变株ΔClpS感染组小鼠脾脏重量及细菌含量无显著差异,但在感染后4周,突变株ΔClpS感染组的小鼠脾脏细菌含量为103.93 CFU/g脾脏,显著低于亲本株2308（106.68 CFU/g脾脏,P<0.01）,且突变株ΔClpS感染组的小鼠脾脏肿胀程度极显著低于亲本株2308（P<0.01）。综上所述,布鲁氏菌ClpS基因突变不影响细菌生长速度及细菌LPS合成能力,但ClpS基因突变可降低布鲁氏菌在小鼠脾脏内的定殖能力。  相似文献   

17.
The present study aimed to determine the role of ClpS gene,and to analyse the impact of ClpS mutation on the virulence of Brucella.A ClpS gene mutant strain,named ΔClpS was constructed by homologous recombination technology.The bacterial growth kinetics,the LPS synthesis ability and the survival ability of bacterial within macrophages as well as the virulence in mouse model were measured.In addition,the difference between parent strain 2308 and the mutant strain ΔClpS were compared.The results showed that under the same culture conditions,no difference in bacterial concentration was observed between 2308 and ΔClpS strains.The silver staining examination showed that the expression level of LPS extracted from two strains were similar,indicating ClpS gene mutation did not alter the growth rate and LPS synthesis ability of Brucella. In the cell infection assay,the survival ability of ΔClpS strain in cells was extremely significantly lower than that of 2308 strain at 72 h after infection (P<0.01).The results of mouse infection experiment showed that in the first week after infection,no significant difference in spleen weight and bacterial concentration between 2308 and ΔClpS strains infected mice was observed.However,at 4 weeks after infection,the bacterial concentration in spleen of ΔClpS infected mice was 103.93 CFU/g spleen,which was significantly lower than that of 2308 strain (106.68 CFU/g spleen,P<0.01).The spleen weight of ΔClpS infected mice was also remarkably lower than that of 2308 strain (P<0.01).In summary,the results suggested that the ClpS gene of Brucella did not play a role in Brucella growth rate and ability of LPS synthesis,whereas ClpS gene mutation decreased the ability of Brucella colonization in mouse spleen.  相似文献   

18.
In the studies reported here, protection induced by calfhood vaccination of bison with 1.2-6.1 x 10(10)CFU of Brucella abortus strain RB51 (SRB51) against a virulent strain of B. abortus was evaluated. Non-vaccinated and SRB51-vaccinated bison were intraconjunctivally challenged during midgestation with 3 x 10(7)CFU of virulent B. abortus strain 2308 (S2308). Maternal and fetal tissues were obtained within 24hour after abortion or parturition. Incidence of abortion was greater (P<0.05) in non-vaccinated as compared to SRB51-vaccinated bison (62% and 15%, respectively), with abortions occurring between 5 and 8 weeks after experimental challenge. Calves from bison vaccinated with SRB51 had a reduced (P<0.05) prevalence of fetal infection with S2308 as compared to calves from non-vaccinated bison (19% and 62%, respectively). Although the ability to recover the 2308 challenge strain from maternal tissues did not differ (P>0.05) between nonvaccinates and vaccinates (100% and 78%, respectively), calfhood vaccination with SRB51 reduced (P<0.05) recovery of S2308 from uterine or mammary gland tissues. In bison which did not abort, S2308 was routinely recovered in low numbers from maternal lymphatic tissues; particularly the parotid, bronchial, supramammary, and mandibular lymph nodes. The RB51 vaccine strain was not recovered at any time from maternal or fetal samples obtained at necropsy. Histological lesions associated with Brucella-induced abortions were suppurative placentitis, fetal broncho-interstitial pneumonia, and fetal histiocytic splenitis. The results of our studies suggest that calfhood vaccination of bison with SRB51 is efficacious in protecting against intramammary, intrauterine, and fetal infection following exposure to a virulent strain of B. abortus during pregnancy. As brucellosis is transmitted horizontally through fluids associated with the birth or abortion of an infected fetus, or vertically to the calf through the ingestion of milk containing B. abortus, our data suggest that calfhood vaccination with SRB51 will be beneficial in preventing transmission of brucellosis in bison.  相似文献   

19.
Brucella abortus strain RB51, a rough mutant of the B. abortus 2308 virulent strain, was recently approved in the United States as the official vaccine for brucellosis in cattle. Following recent evidence of unauthorized use of RB51 vaccine in Italy, where the use of vaccines for brucellosis is no longer allowed, the suitability of an RB51-specific polymerase chain reaction assay for identifying the RB51 strain among Brucella field isolates from cattle in Italy was investigated. The oligonucleotide primers used in this study, belonging to a six-primer cocktail for Brucella species previously described by other authors, allowed the amplification of a 364-base pair (bp) fragment specific for RB51 and its parent strain 2308, and a 498-bp product specific for B. abortus. In addition, unresolved bands ranging from 600 to 700 bp were observed from RB51 strain. Brucella abortus biovars 1, 2 and 4 have only one specific sensitive 498-bp band. The B. abortus biovars 3, 5 and 6 did not give any signal. The 498-bp product from a reference Brucella strain was sequenced and submitted to EMBL with the accession number AJ271969 while the 364-bp fragment from RB51 strain was submitted to EMBL database with accession number AJ271968. The sequence studies confirmed the specificity of the detected fragments. No amplification was obtained by testing DNA from strains antigenically related to Brucella, such as Yersinia enterocolitica O:9, Escherichia coli O:157, Salmonella urbana and Pasteurella multocida. The results of this study indicate that this technique, in combination with specific serological tests, could be a useful diagnostic method to verify the use of RB51 vaccine and can contribute to the creation of a databank of circulating strains.  相似文献   

20.
It was shown in this study that complement-resistant Brucella abortus used were unable to activate complement in the absence of specific antibody. Complement-resistant isolates possessed O-antigen, but complement-sensitive organisms used are O-antigen deficient. Since B. abortus LPS does not activate the alternative pathway of complement, we concluded that activation of bovine complement must be due to some other mechanism. In this study, it was shown that bovine C1 binds to the outer membrane proteins of B. abortus. Isolated outer membrane proteins of both smooth (O-antigen positive) and rough (O-antigen negative) B. abortus used bind to C1q. However, only rough isolates were killed by complement. All of the O-antigen positive B. abortus isolates were complement-resistant. We propose that O-antigen shields outer membrane proteins and blocks C1q binding.  相似文献   

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