鸡白痢沙门氏菌脂多糖的保护性作用

用被动保护试验的方法,通过比较抗脂多糖（ＬＰＳ）血清组与ＬＰＳ中和抗鸡白痢血清组的ＬＤ５０,证明了ＬＰＳ的保护性作用。与攻菌对照组的ＬＤ５０相比,抗ＬＰＳ血清组有非常显著的差异（０．００２＞Ｐ＞０．００５）,ＬＰＳ中和抗鸡白痢血清组有显著差异（０．０２＞Ｐ＞０．０５）。试验证明,ＬＰＳ是鸡白痢沙门氏菌（Ｓａｌｍｏｎｅｌａｐｕｌｏｒｕｍ）菌体主要的保护性抗原之一。     

全血与血清平板凝集试验检测鸡白痢的对比

对北京油鸡两个品系216只母鸡,在17~49周期间每隔8周同时用全血和血清平板凝集试验进行鸡白痢检测对比分析。结果发现,血清检出阳性率高于全血检出阳性率,且血清检出阳性个体包含全血检出阳性个体;同时,检测结果也表明,33周龄鸡白痢阳性率达到最高,此后阳性率下降。因此,在鸡白痢净化过程中采用血清平板凝集法比全血平板凝集法检测更为敏感,在25~33周对北京油鸡群体增加一次鸡白痢净化更有助于加快净化进程。本研究可为其他地方品种种鸡鸡白痢检测工作提供参考。     

Temporal changes in the population genetics of Salmonella pullorum

Salmonella pullorum is the cause of pullorum disease, which is characterized by white diarrhea and a high mortality rate in poultry. During the 1990s, the serologic "pullorum" test has occasionally failed to detect infected birds during the early stage of disease. To determine if any recent genetic changes have taken place in S. pullorum to account for poor seroconversion sometimes observed in infected flocks, S. pullorum from 1990s outbreaks and strains isolated prior to the 1980s were typed by random amplified polymorphic DNA (RAPD). Of 40 S. pullorum isolates typed by this method, eight distinct DNA patterns were identified with one of three RAPD polymerase chain reaction primers. Sixty-two percent of S. pullorum isolates shared the same RAPD DNA pattern, and a major proportion of these strains were from recent flock infections. The RAPD patterns for S. pullorum were clearly distinct from the avian Salmonella group B isolates included in this analysis. The distribution of Salmonella virulence genes among avian Salmonella isolates was also examined. Eighty-five percent of the S. pullorum isolates had both the virulence plasmid gene, spvB, and the invasion gene, invA, with the same percentage positive for the Salmonella enteriditis fimbrial gene, sef. However, significant variability was observed among S. pullorum in their ability to invade avian epithelial cells, despite the presence of the Salmonella invasion gene in these isolates.     

缺失rfaH基因的鸡白痢沙门氏菌株的构建及鉴定

为研制可以鉴别检测基因缺失型鸡白痢疫苗与自然感染菌,本研究通过基因同源重组技术,利用高效自杀性载体系统,敲除鸡白痢沙门氏菌(S.pullorum)CVCC 79201株的rfaH基因,同时未引入任何抗生素抗性基因等外源DNA序列,经筛选获得重组S.pullorum(rSp)株。检测结果显示缺失菌由光滑型转变为粗糙型。rSp在普通琼脂培养基上传15代后,仍然保持粗糙型表型。动物试验结果表明,rSp免疫伊莎褐蛋鸡后,其抗血清可通过平板凝集试验与CVCC 79201免疫的血清相区分。本研究为S.pullorum缺失疫苗的研制提供了技术平台。     

鸡白痢沙门菌等位基因特异性PCR检测方法的建立

根据鸡白痢沙门菌与鸡伤寒沙门菌的rfbS基因在第237和第598位碱基的不同，设计和合成了等位基因特异性PCR引物，建立了快速检测鸡白痢沙门菌的PCR方法，并应用该方法对鸡白痢沙门菌临床分离样品进行了PCR鉴定。结果显示，该PCR方法能够特异性地鉴定鸡白痢沙门菌，检测灵敏度达100PgDNA。对35个经常规方法鉴定的鸡白痢沙门菌分离株应用等位基因特异性PCR方法进行鉴定，鉴定出33株鸡白痢沙门菌，符合率为94．3％。表明，建立的等位基因特异性PCR方法能够准确而快速地鉴定鸡白痢沙门菌。     

双重放大酶免疫传感器检测鸡白痢鸡伤寒沙门菌

为探求新型鸡白痢鸡伤寒沙门菌快速检测技术,本研究首次利用多壁碳纳米管与离子液体[BMIM] PF6修饰四通道丝网印刷碳电极,制成双重放大信号检测鸡白痢鸡伤寒沙门菌的酶免疫传感器.用原子力显微镜表征其表观形态,循环伏安法监测其电化学特性.结果表明,在优化的检测条件下,免疫电极对目标菌的线性响应范围为103～109 cfu· mL-1,检出限为3.93×102 cfu·mL-1(S/N=3),4℃放置28 d后,响应电流为初始值的90.15％,具有良好的稳定性、特异性、重现性和准确性.多壁碳纳米管与离子液体结合制备的鸡白痢鸡伤寒沙门菌酶免疫传感器实现了检测信号的双重放大,检测灵敏度高,离子液体有助于保持酶标抗体的活性,延长免疫电极的有效时间.依据该方法构建的酶免疫传感器为快速检测其它致病菌酶免疫传感器的研究提供了良好的参照模型.     

鸡白痢/禽伤寒沙门菌抗体检测试剂的比较与评估

对市面上现有鸡白痢/禽伤寒沙门菌抗体平板凝集检测试剂及其不同批次,微量凝集检测试剂和ELISA共4种检测试剂进行比较与评估。用4种试剂以及试剂A的不同批次检测来自11个种鸡场的1 650份血清,计算不同试剂检测种鸡场的抗体阳性率,2种试剂之间的阳性符合率、阴性符合率和总符合率,并以Kappa检验判断不同检测方法及其试剂之间的一致性程度。平板凝集试剂A的不同批次间以及平板凝集试剂A和B之间具有高度一致性(Kappa系数=0.714~0.746),但阳性符合率不足80%。平板凝集试剂A、微量凝集试剂C、ELISA试剂D之间仅具有中度或弱一致性(Kappa系数=0.392~0.542)。不同鸡白痢/禽伤寒沙门菌抗体检测试剂间存在差异,平板凝集试剂不同批次间也存在差异,提示试剂生产厂家应加强质量控制,同时研发敏感性、特异性、稳定性更好的替代试剂,而种鸡场在进行抗体监测时应固定使用1种检测试剂,避免影响检测结果的准确性和连续性。     

The slide agglutination test for the diagnosis of filariasis in camels

The slide agglutination test was adapted for the diagnosis of filariasis in camels, using an antigen prepared from the microfilariae by a simple lytic technique. The preliminary results were satisfactory as the test detected 86 per cent of the infected animals. Only 6 per cent of the healthy camels with no blood parasites or microfilariae in their blood gave positive results and no positive reactions were obtained from 18 animals suffering from Trypanosoma infection.     

鸡白痢沙门菌减毒候选疫苗株的环境应激评价及主要生物学特性测定

为评估鸡白痢沙门菌减毒候选疫苗株对环境应激及消毒剂的抵抗力,本研究对S6702△rfaG△csgA、S6702△rfaL△csgA、S6702△rfaG△csgA△ompR和S6702△rfaL△csgA△ompR等4种鸡白痢沙门菌双基因缺失株和三基因缺失株进行了生长曲线、生物被膜形成能力、药敏试验、环境应激试验及消毒剂的灭活效果的测定。结果显示,4株缺失株均丧失生物被膜形成能力并保留了与亲本株相似的药物敏感性。多基因缺失株对pH为4.0和8.0的培养条件较野生菌株和单基因缺失株更为敏感,呈现微耐酸和不耐碱的特性;所有菌株对54℃热处理和紫外线处理均敏感。消毒剂对实验菌株的杀灭效果显示,野生菌株和各基因缺失株均对0.01%的聚维酮碘溶液敏感,基因缺失株相比野生菌株过硫酸氢钾复合物更为敏感。因此,鸡白痢沙门菌减毒候选疫苗株对环境应激的抵抗力均有所降低,本研究为该菌后续候选疫苗株的进一步筛选奠定了基础。     

Salmonella pullorum in the common pheasant (Phasianus colchicus)

In 1996, pullorum disease due to Salmonella enterica serovar Gallinarum biovar pullorum (Salmonella pullorum) was diagnosed in pheasants on a gamebird rearing enterprise in south-west Scotland. The gross pathology and bacteriological findings are described, as are the results of screening for S pullorum on the site in 1997. The causal organism was readily isolated from the lung, liver, yolk sac and heart blood on direct culture, but less readily from the digestive tract or by the use of selective media. The bacteria recovered from the pheasants were identified as S pullorum phage type 7, a phage type previously associated with pheasants rather than domestic fowl, and the organisms were most probably introduced to the site by the movement of carrier pheasants.     

The selection of Salmonella gallinarum, Salmonella pullorum and Escherichia coli in chickens after chloramphenicol administration]

The effect of a chloramphenicol administration was examined on the selection of E. coli of the chicken intestinal flora, and of the infectious S. gallinarum and S. pullorum strains. On the other hand, an effort was made to detect the frequency of the resistance transmission of E. coli to above mentioned sensitive salmonella strains. Fourteen chicken, 12 infected and 2 negative controls were used. It was found that the enteric E. coli strains became resistant in a week's time. Besides, the strains that were used for infecting the chicken neither were selected through the chloramphenicol administered nor did they take the E. coli resistance, via R-factor transmission.