中国牛种布鲁氏菌疫苗株A19 SNP位点的研究

为鉴别我国牛种布鲁氏菌疫苗株A19与野生菌株,运用生物信息学方法结合基因测序,对疫苗株A19基因组单核苷酸多态性(SNP)位点分析筛选,选取其中部分SNP位点,通过与布鲁氏菌常见种、生物型标准参考菌株和疫苗株基因组SNP位置核苷酸测序比较,验证SNP位点的A19特异性。结果表明,共筛选获得A19基因组29个SNP位点,验证ClpX G825-C825、LysR A605-C605、Omp2b G503-A503这3个SNP位点为A19(或S19)特异,揭示了A19基因组SNP位点分布情况,为疫苗株A19与野生菌株鉴别提供了分子依据。     

牛布鲁菌强毒株544与猪型疫苗株S2基因组差异筛选与鉴定

应用代表性差异分析技术(Representational difference analysis,RDA)对流产布鲁菌强毒株544和疫苗株S2进行基因组差异分析。经过3轮差减杂交,对差异片段进行Southern-blot验证,BLAST分析和PCR鉴定,最终获得疫苗株S2特有的3条差异片段与已测序的所有猪布鲁菌(Brucella suis)同源性均为100%,只在弱毒株S2基因组中检测出,而在强毒株544中不存在,为建立布鲁菌自然感染菌与疫苗株的基因鉴别诊断方法奠定了基础。     

中国山羊痘弱毒疫苗AV41株基因组分子标记的比较分析

为鉴别我国山羊痘病毒（GTPV）弱毒疫苗AV41株与牛结节性皮肤病病毒（LSDV）野毒株，运用生物信息学方法将AV41株基因组全序列与GenBank中已发表的LSDV、GTPV和绵羊痘病毒（SPPV）基因组进行比较，筛选AV41株基因组分子标记。采用我国不同厂家来源的AV41株疫苗测序验证分子标记相关序列，并与我国LSDV野毒株相应位置序列比较。结果显示，通过基因组比较分析共筛选获得分子标记19 个，经测序确认其中7 个为AV41株基因组独特分子标记，包括DNA ligase基因2433A2434、Kelch-like protein基因1831A1832、GTPV_gp020基因G203A、GTPV_gp021基因C681T、DNA-binding viron core protein基因C47T、RNA polymerase subunit 基因T64C和Myristylated protein基因C746A，而我国LSDV野毒株相应位置序列未见上述变化。本研究揭示了AV41株基因组独特分子标记分布情况，可用于我国牛结节性皮肤病疫情防控中与LSDV野毒株的分子鉴别。     

绵羊iNOS基因突变与布鲁杆菌侵染率的关系分析

探究绵羊诱导型一氧化氮合酶（iNOS）基因多态性与布鲁菌易感性的关系。使用虎红平板血清凝集试验检测哈萨克羊布鲁菌患病情况。参考GenBank中绵羊iNOS基因序列,针对其15、16、17外显子及其邻近内含子片段设计引物,PCR扩增出目的基因片段。采用SSCP凝胶电泳检测不同基因型分型,DNA测序进行多态性检测,分析其SNPs与哈萨克羊布鲁菌易感性之间的关系。经检测发现阳性羊数67只,占比29.00%。在哈萨克羊iNOS基因的exon 15片段上有F15-C29002T和F15-G29076A两个多态位点。在exon 16片段上有F16-A30045G位点。在exon 17片段上有F17-T31213G位点。卡方检验表明,F15-C29002T和F15-G29076A多态位点与布鲁菌易感性的相关性不显著（P>0.05）,F16-A30045G和F17-T31213G多态位点与布鲁菌易感性的相关性极显著（P<0.01）。哈萨克羊iNOS基因F15-C29002T和F15-G29076A与布鲁菌易感性没有相关性,F16-A30045G和F17-T31213G与布鲁菌易感性存在相关...     

粗糙型布鲁菌M111菌壳的安全性和免疫原性

以粗糙型布鲁菌M111株和重组裂解质粒制备出布鲁菌菌壳,利用小鼠模型对布鲁菌菌壳、布鲁菌M111活菌和福尔马林灭活菌的安全性和免疫原性进行比较研究。结果显示,与布鲁菌弱毒菌株M111比较而言,布鲁菌菌壳具有更好的安全性,免疫小鼠后能产生与弱毒菌株相似的血清抗体水平、脾CD3+和CD4+T淋巴细胞反应,甚至产生更高水平的IFN-γ。这些结果表明,布鲁菌菌壳具有与弱毒菌株相似的体液免疫和细胞免疫能力,将来可能作为预防布鲁菌感染的新型候选疫苗,但布鲁菌菌壳疫苗的有效性和特异性免疫机制还有待深入研究。     

表达Omp31基因重组牛布鲁菌的构建及鉴定

为提高布鲁菌疫苗株的免疫保护效果,本试验以牛布鲁菌疫苗株S19为研究对象,将羊布鲁菌Omp31基因克隆、扩增并插入至广宿主质粒pBBR1MCS-2中,构建重组质粒pBBR1MCS-Omp31;通过电转化的方式转入S19感受态细胞中,经抗性基因筛选和PCR验证,获得重组牛布鲁菌S19-Omp31株;该重组菌株连续传25代未发现重组质粒和Omp31基因丢失,表明其遗传稳定性良好;进一步经SDS-PAGE检测可见约26 000相对分子质量的目的条带,采用Western blot法检测显示目的蛋白可与His单克隆抗体及Omp31蛋白高免血清反应。本研究构建的重组牛布鲁菌S19-Omp31株能够稳定表达目的基因,为进一步开展S19-Omp31株的免疫效果评价奠定基础。     

布鲁菌S19疫苗株znuA单基因及bp26/znuA双基因缺失株的构建及鉴定

通过等位基因交换,分别敲除牛流产型布鲁菌减毒活疫苗S19株和缺失株S19-Δbp26的znuA基因,构建了布鲁菌znuA基因单缺失株S19-ΔznuA和bp26、znuA基因双缺失株S19-Δbp26-ΔznuA,对获得的2种缺失株进行形态学、生长特性、稳定性和基因测序验证。结果表明,S19株和S19-Δbp26株的znuA基因均成功缺失,生长特性表示2种缺失株与亲本株生长基本无差异;体外连续传至20代,菌落PCR鉴定及基因测序结果显示2种缺失株均遗传稳定。牛流产型布鲁菌单缺失株S19-ΔznuA和双缺失株S19-ΔznuA-Δbp26的成功构建为布鲁菌新型疫苗的研发、布鲁菌感染动物过程中ZnuA蛋白的作用机理及其与Bp26蛋白之间关系的研究奠定了基础。     

羊种布鲁菌分离株bp26及omp10基因的分子进化与变异分析

为了解羊种布鲁菌内蒙古分离株和疫苗株的遗传变异情况,对羊种布鲁菌分离株B1、B2、B3、B4以及疫苗株M5、S2、A19的bp26及omp10基因进行了扩增、克隆和序列分析,并与国内外的代表性毒株进行了序列比对。结果显示:4株分离株的bp26序列长度均为900bp,开放阅读框为753bp,与疫苗株M5同源性为100%,疫苗株S2和A19的同源性为99.99%;分析发现所有序列中共有4处变异,A19 bp26基因的CDS区第304位A→G和第405位C→T突变,S2 bp26基因的第498位C→T和727位G→A突变;其中304位的A→G的变异导致其编码的氨基酸发生了从天冬酰胺(N)到天冬氨酸(D),727位G→A的变异导致氨基酸发生了缬氨酸(V)到异亮氨酸(I)的变化;而分离株和疫苗株M5未发生变异。4株分离株的omp10序列长度均为513bp,开放阅读框为396bp,同源性为99.99%,与疫苗株S2和A19同源性为100%;分析发现疫苗株M5的omp10基因序列发生了1处变异,第144位C→T,但没有引起氨基酸改变,其他菌株没有发生变异。     

猪瘟病毒野毒株和兔化弱毒疫苗株RT-PCR-RFLP鉴别检测方法的建立

本研究旨在建立猪瘟病毒野毒株和兔化弱毒疫苗株RT-PCR-RFLP鉴别检测方法。根据Shimen株设计1对特异性引物,建立猪瘟病毒RT-PCR-RFLP检测方法;对20份疑似猪瘟临床样品进行检测,并对检出的山东8株流行野毒株和2株疫苗株PCR产物进行克隆与序列分析,验证上述方法。结果RT-PCR扩增片段为825bp,产物经RFLP分析,野毒株的PCR产物能被ApaⅠ酶切为322bp和503bp 2个片段,兔化弱毒疫苗株则不能被酶切,检测出RNA的最低浓度为0.028 6μg.mL-1;8株流行野毒株都含GGGCCC序列(ApaⅠ酶切位点),2株疫苗株相应序列为GAGCCC,不能被ApaⅠ酶切;8株流行野毒株属于基因2群,2株疫苗株与HCLV遗传关系近,为基因1群。建立了可鉴别猪瘟病毒野毒株和兔化弱毒疫苗株RT-PCR-RFLP检测方法,为猪瘟的防控提供有效手段。     

羊布鲁菌体内诱导基因的筛选与初步鉴定

本研究利用体内诱导表达抗原技术(IVIAT)来筛选和鉴定羊布鲁菌特异的体内诱导抗原,为筛选新的毒力分子,诊断靶标、疫苗候选抗原和药物靶点提供科学依据。通过收集临床上羊布鲁菌阳性血清,吸附后作为探针,构建羊布鲁菌16M基因组表达文库,进行体内诱导抗原的筛选,同时利用RT-PCR验证筛选得到的基因,对筛选得到的基因进行测序比对及生物信息学分析。结果显示:利用临床上感染布鲁菌的羊阳性血清作为探针,通过体内诱导抗原技术成功地从羊布鲁菌的基因组中筛选得到了14个体内诱导表达的基因。这些基因主要参与布鲁菌的糖代谢、tRNA修饰、离子转运和跨膜运输等生物过程,这些分子有的已经被证实是布鲁菌的药物靶点和毒力分子,有的可能与布鲁菌的毒力和免疫相关,可以作为疫苗候选抗原和诊断标识。体内诱导抗原技术(IVIAT)成功地应用到布鲁菌候选抗原和诊断标识的筛选和鉴定研究中,利用该技术成功获得14个体内诱导基因,这些基因将为布鲁菌疫苗的研制和诊断产品的研发提供候选抗原和诊断标识。     

Development of a new PCR assay to identify Brucella abortus biovars 5, 6 and 9 and the new subgroup 3b of biovar 3

One hundred twenty-nine Brucella field strains isolated from cattle in Cantabria, Spain, from March 1999 to February 2003, were analysed by using the AMOS-ERY PCR assay and by Southern blot hybridisation with a probe from insertion sequence IS711. Most of the field isolates produced only the ery band in the AMOS-ERY assay and showed a hybridisation pattern identical to that exhibited by reference strains of biovars 5, 6 and 9 of Brucella abortus, but different from strain Tulya, belonging to biovar 3 of B. abortus. However, typing of these strains by standard methods demonstrated that they belonged to biovar 3 of B. abortus. These results indicated that B. abortus biovar 3 was not genetically homogeneous and at least could be divided in two. In one class, that we called biovar 3a, would be the Tulya strain, while the local field strains would belong to biovar 3b. Cloning and nucleotide sequencing of a DNA fragment containing an IS711 copy exclusive of the B. abortus field strains from biovar 3b and reference strains from biovars 5, 6 and 9, revealed the existence of a 5.4 kb deletion close to an IS711 copy. Based on these data, we designed a new primer, which together with the IS711 AMOS primer produced a PCR fragment of 1.7 kb only from the isolates of biovars 3b, 5, 6 and 9 of B. abortus. No amplification products were produced with these primers from strains of the rest of species and biovars of Brucella and from bacteria phylogenetically close to Brucella analysed in this work. Addition of this primer to the AMOS-ERY PCR primer cocktail allows the positive distinction of B. abortus biovars 3b, 5, 6 and 9 from the rest of Brucella species and biovars.     

Identification of Brucella abortus strain 19 by decreased ability to utilize erythritol as determined by gas liquid chromatography

A method to identify Brucella abortus strain 19 by erythritol utilization using gas liquid chromatography (GLC) was developed. A total of 69 strains of B. abortus (41 virulent field strain isolates and 28 strain 19 isolates) were tested. Following incubation of the isolate with a standard amount of erythritol, the erythritol present in the cell suspension was acetylated and measured by GLC. Field strains of B. abortus utilized an average of 90.9% of the erythritol, whereas vaccine strains utilized an average of 42.4%. This difference in erythritol utilization will allow a more rapid identification of B. abortus strain 19.     

Isolation of Brucella abortus and Brucella abortus, strain 19, from cattle.

Tissues from 104 cows in herd were examined for brucellae. Brucella abortus, strain 19, was isolated from 22 cows, a field strain of B abortus, biotype 1, was isolated from 9 cows, and both strains were isolated from 2 cows.     

Biotypes of Brucella abortus and their value in epidemiologic studies of infected cattle herds.

Four Texas cattle herds containing cows infected with either Brucella abortus biotype 1, 2, or 4 were studied to determine the probability of transmission of Brucella between adjacent cattle herds, the most probable means by which Brucella was introduced into the herds, and the relative frequency of strain 19 isolation from vaccinated cattle. A total of 1,935 cattle in the four herds were tested for brucellosis; 339 reactors were identified, and isolations of B abortus were made from 143. The biotype of B abortus was used to determine that purchased cattle or reentry of bred heifers into the herds was probably responsible for introducing B abortus and that the biotype was not readily transmitted to adjacent herds. Three (9%) of 32 B abortus isolations from adult-vaccinated cattle were strain 19. The data supported the hypothesis that biotypes can be useful in determining the source of B abortus for cattle and in differentiating field and vaccine strain infections in adult-vaccinated cattle.     

Genomic fingerprinting and development of a dendrogram for Brucella spp. isolated from seals, porpoises, and dolphins.

Genomic DNA from reference strains and biovars of the genus Brucella was analyzed using pulsed-field gel electrophoresis (PFGE). Fingerprints were compared to estimate genetic relatedness among the strains and to obtain information on evolutionary relationships. Electrophoresis of DNA digested with the restriction endonuclease XbaI produced fragment profiles for the reference type strains that distinguished these strains to the level of species. Included in this study were strains isolated from marine mammals. The PFGE profiles from these strains were compared with those obtained from the reference strains and biovars. Isolates from dolphins had similar profiles that were distinct from profiles of Brucella isolates from seals and porpoises. Distance matrix analyses were used to produce a dendrogram. Biovars of B. abortus were clustered together in the dendrogram; similar clusters were shown for biovars of B. melitensis and for biovars of B. suis. Brucella ovis, B. canis, and B. neotomae differed from each other and from B. abortus, B. melitensis, and B. suis. The relationship between B. abortus strain RB51 and other Brucella biovars was compared because this strain has replaced B. abortus strain 19 for use as a live vaccine in cattle and possibly in bison and elk. These results support the current taxonomy of Brucella species and the designation of an additional genomic group(s) of Brucella. The PFGE analysis in conjunction with distance matrix analysis was a useful tool for calculating genetic relatedness among the Brucella species.     

Characterization of Brucella abortus strain 19 isolated from human and bovine tissues and fluids

One hundred isolates of Brucella abortus, which were recovered from bovine and human tissues or fluids, were identified as strain 19 by conventional bacteriologic methods. Each isolate was examined using a Warburg respirometer to determine oxidative rates on substrates of D- and L-alanine, L-glutamic acid, d(+)-galactose, D-ribose, and i-erythritol. These results were compared with those of repository (seed) cultures of strain 19 used for making antigens and vaccines. Except on the substrate of i-erythritol, each of the 100 isolates oxidized these substrates with rates different from the repository cultures and indistinguishable from those of field strains of B abortus. Thus, oxidatively, i-erythritol was the only substrate useful to help distinguish between strain 19 and virulent strains of B abortus biotype 1.     

DNA homology of Brucella abortus strains 19 and 2308

The restriction endonuclease digestion DNA patterns from Brucella abortus strains 19 and 2308 were examined with 11 restriction enzymes (AvaI, BamHI, BglII, BstEII, DdeI, EcoRI, HindIII, KpnI, PstI, XbaI, and SalI). The DNA electrophoretic banding patterns between the 2 strains were highly similar, using this restriction enzyme analysis. Differences were not discernable between B abortus strains 19 and 2308 in any of the restriction banding patterns examined. Methylation at CCGG or GATC sites was not detectable on the basis of digestion with isoschizomers (HpaII and MspI, and DpnI, Sau3AI and MboI). Homology between B abortus strains 19 and 2308 was assessed, using solution-hybridization techniques followed by S1 nuclease assays. Results of these reassociation experiments indicated 98.6 to 99.3% homology between B abortus strains 19 and 2308 with 13.5 to 18.6% homology between B abortus (strains 19 and 2308) and the E coli HB101 control. We concluded that any DNA differences between the 2 B abortus strains are small and will require analysis at the DNA sequence level.     

Restriction endonuclease analysis of Brucella abortus

The restriction endonuclease profiles of bacterial DNA from Brucella abortus isolates were evaluated. It was not possible to distinguish between vaccine strain 19 and virulent (biotype 1 and biotype 2) strains of B abortus. Restriction endonuclease analysis is therefore not a suitable epidemiological tool in bovine brucellosis investigations. The genetic homogeneity of the Brucella genus was reinforced by these findings.     

Brucella suis identification and biovar typing by real-time PCR

Fast and accurate identification of Brucella suis at the biovar level is an important issue for public health laboratories because some of the biovars that infect suidae (boars and pigs) are pathogenic for humans while others are not. Since classical biovar typing methods are often time-consuming, hard to standardize and require high-level biosafety containment, methodological improvements are desirable. This article describes new single nucleotide polymorphism (SNP) signatures for the rapid identification and biovar characterization of B. suis. These SNPs were included together with previously described ones in real-time PCR assays applicable to low-biosafety conditions. Allelic profiles unique for each B. suis biovar were defined and the most relevant signatures were determined on a collection of 137 field strains of worldwide origin characterized previously. Biovars assigned with both present and classical methods were globally consistent except for some biovar 3 field strains which matched the allelic profile of biovar 1.     

Levamisole potentiation of antigen specific lymphocyte blastogenic response in Brucella abortus exposed but nonresponsive cattle

Incubation of Brucella abortus (field strain) infected and strain 19 vaccinated bovine peripheral blood lymphocytes with B. abortus antigen and levamisole caused a consistently significant increase in [3H] thymidine uptake when compared to cultures without levamisole. Levamisole did not potentiate B. abortus-induced blastogenic response of lymphocytes from non-exposed cattle. A dose response study showed that 10 micrograms/culture induced maximum potentiation of B. abortus-induced lymphocyte stimulation. Using the 10 micrograms/well concentration of levamisole, further studies were conducted to determine the net potentiation of the blastogenic responses in lymphocytes from B. abortus (field strain) infected cattle. B. abortus strain 19 vaccinated but nonresponsive and non-exposed cattle. Levamisole significantly potentiated the B. abortus-induced lymphocyte blastogenesis in lymphocytes from unresponsive cattle.