Isoelectric Characterization of Clostridium Botulinum Type C Toxin

The physico-chemical laws controlling natural pH gradients that have been developed by stationary electrolysis have been described in earlier papers by Svensson (2, 3). As demonstrated by Svensson (4) the resolving power attained by this method is better than 0.2 pH unit. In a later paper (5) the same author described the use of synthetic carrier ampholytes, and it was shown that a still better resolving power could be produced.     

C型肉毒梭菌毒素防治草原鼠害的试验报告

选用甘肃省畜牧兽医研究所研制生产的C型肉毒梭菌毒素灭鼠剂在宁夏固原市原州区进行了试验.结果表明,试验的总平均灭鼠率为81.7%,其效果较好;随着毒饵浓度的增加,灭鼠率并没有相应地提高;小麦毒饵的灭鼠效果较洋芋毒饵好.     

The Inhibition of Clostridium Botulinum Type B and E in Salami Sausage

Vegetative cells and spores of Clostridium botulinum type B and E were inoculated into salami sausages with and without the preservatives sodium nitrite and sodium benzoate. The growth and toxin production of Clostridium botulinum type B and E were inhibited in this type of salami sausages, even without any addition of preservatives. The use of a starter culture with pH-lowering components has both technological and hygienic advantages.     

Susceptibility of mink to Clostridium botulinum type E toxin

Experiments aiming at elucidation of the toxicity of Clostridium botulinum type E for mink are described. The observations indicate that amounts in the order of 2 x10^s intraperitoneal MLD (mice) or approximately 200 MLD per g of type E toxin will kill a mink after oral administration. The symptoms observed in the animals were atypical as there was an unusually short period between administration of the toxin and the onset of symptoms and deaths of the animals. Similar results were obtained when Clostridium botulinum type E toxin was fed to Swiss mice. When mice were protected by subcutaneous injections of type E antitoxin prior to feeding the animals survived without showing any symptoms.Subcutaneous injection of type E toxin in amounts of the order of 2 x10^s intraperitoneal MLD (mice) killed mink, and typical symptoms of botulism were observed. This quantity corresponds to ap-proximately 2 intraperitoneal MLD (mice) per g.Comparison is made with previous observations obtained in similar experiments made with Clostridium botulinum type C toxin. It is shown that mink arc substantially less susceptible to type E than to type C toxin when the toxins are given by mouth. On this basis previous results in reports on outbreaks of botulism in mink caused by Clostridium botulinum type E may be regarded as questionable.     

Susceptibility of mink to Clostridium botulinum type C toxin

Investigations to determine the exact susceptibility of mink to Clostridium botulinum type C toxin clearly showed that mink were considerably less resistant to this toxin than has previously been described. Mink weighing approximately 900 g were killed by 360 MLD when toxin was mixed into the feed. By subcutaneous injection, the lethal dose was determined to be in the range of 18 to 36 MLD.When comparing the susceptibility per g of body weight after parenteral application of the toxin, mink proved to be less resistant than mice to this type of toxin. Continued feeding tests in mink with suspected material is pointed out as a preferable method for practical demonstrations of Clostridium botulinum type C toxin in cases where the toxin content in the suspected material is very low (1 MLD per g or less).     

Proteases of Clostridium Botulinum: II. The Relationship Between Growth Medium and the Production of Proteases by Clostridium Botulinum Types A,B, C,D, E and F

The present investigation was carried out in order to find a suitable medium for the production of proteolytic enzymes from different types of Clostridium botulinum. Proteolytic activity was found in Clostridium botulinum types A, B, C, D and F, while supernatants of Clostridium botulinum type E did not possess any proteolytic activity at all.Skim milk medium possessed the greatest ability for the production of proteolytic enzymes from the different cultures of Clostridium botulinum tested, while Robertson’s meat broth produced lowest amounts. Highest titres were usually found after 4–5 days of incubation and, after this period, the level of proteolytic activity decreased.     

Clostridium perfringens Type C Enterotoxemia

Forms of enteric disease caused by Clostridium perfringens type C are critically reviewed with emphasis on practical aspects and recent research findings. Available data indicate that more animal species may be fatally infected by type C of this organism than by any other type of C. perfringens. Fatal cases have been recorded in pigs, cattle, sheep, horses and humans. Newborn animals are typically the most susceptible, possibly related to aspects of bacterial colonization, intestinal digestive functions, and to some other, unexplained, factors. Both beta toxin and the bacterial cells are required to initiate pathogenesis at the tips of jejunal villi, and subsequent massive adherence of these cells to necrotic mucosa is a characteristic feature. Although major lesions occur in the intestine, death is due to toxemia. The disease can be effectively controlled by vaccination of the dam. Epizootiology of this disease is a possible area for further studies.     

一种致命的隐形杀手:肉毒杆菌与肉毒毒素

2013年8月,因肉毒杆菌污染,问题奶粉再次进入公众视野。肉毒杆菌(Clostridium botulinum)是一种革兰阳性粗短杆菌,严格厌氧,有A～G 7个亚型,每个亚型都可产生一种剧毒的大分子外毒素,即肉毒毒素(botulinum toxin)。这种毒素可引起人和动物发生以松弛性麻痹为主症的肉毒中毒(botulism),虽然并不常见,但却是一种致命的中毒性疾病。本文综述了肉毒杆菌生物学特征、肉毒毒素结构与毒性、肉毒中毒临床表现以及检验鉴定等,并介绍了食品安全生产中肉毒杆菌与肉毒毒素的安全风险与控制措施。     

几种培养基对A型产气荚膜杆菌产毒效果的比较

本文以四种培养基，对同一A型产气荚膜杆菌分离株G3的生长曲线和培养液pH值变化进行了测定，并比较了四种培养基的产毒效果。结果表明：A型产气荚膜杆菌在四种培养基上的生长内线基本一致，但pH值变化有差异，其中以疱肉培养液的pH值变化幅度最小，且其毒素产量最多，活性最高。由此可见，疱肉培养基可作为A型产气荚膜杆菌的产毒培养基。     

奶牛和乳制品中的肉毒杆菌

本文回顾了全球范围内牛的肉毒中毒事件和因食用乳及乳制品引发的人的肉毒中毒事件,分析了肉毒污染的可能原因.重点阐述了乳及乳制品中的肉毒毒素或肉毒杆菌引起人肉毒中毒或感染肉毒杆菌及引发乳品加工链中肉毒污染的风险,并对如何防控乳及乳制品发生肉毒污染提出了建议举措.     

艰难梭菌毒素及致病基因的研究进展

艰难梭菌是一种革兰阳性厌氧芽胞梭菌,是人类肠道感染的主要致病菌,以肠道病理损伤及菌群失调为主的感染性疾病.使用抗菌药物后可导致艰难梭菌过度生长,分泌大量毒素A(肠毒素)和毒素B(细胞毒素),通过毒素介导致病.毒素A启动细胞损伤后,毒素B即可侵入肠黏膜,引起细胞病变,导致一系列与感染相关的临床表现.少数强毒株艰难梭菌还可以产生二元毒素,该毒素可以导致细胞骨架破坏,增强毒素A和毒素B的作用导致严重病变.研究发现,人和动物艰难梭菌之间具有同源性,成为人类感染艰难梭菌的传染源.对艰难梭菌产生毒素的致病机理进行综述,为治疗艰难梭菌感染提供依据.     

重组C型肉毒梭菌毒素的表达与免疫保护性分析

本研究旨在获得重组C型肉毒梭菌毒素蛋白,并评价其免疫保护性。将麦芽糖蛋白（MBP）和C型肉毒梭菌毒素重链C末端（CH_C）的编码基因序列进行优化和串联,获得基因片段GMBPCH_C。将GMBPCH_C克隆至pET28a-（＋）后转化大肠杆菌BL21（DE3）感受态细胞,分别在15和37℃两种温度条件下诱导表达。利用Ni-IDA亲和层析方法对可溶性表达的目的蛋白进行纯化,从而获得重组蛋白rMBPCH_C。将rMBPCH_C与Montanide ISA 201佐剂混合制备成疫苗,免疫4只家兔,剂量为100 μg/只。根据《中华人民共和国兽药典》（2015年版）规定的方法检测一免后21 d及二免后14 d家兔血清的中和抗体效价。同时,在二免后14 d对家兔进行攻毒。结果表明,rMBPCH_C在37℃的诱导温度下,主要以包涵体的形式表达;在15℃的诱导温度下,可溶性表达的比例可达50%。一次免疫后,免疫组4只家兔血清对C型肉毒梭菌天然毒素（简称天然毒素）的中和效价均可达到1（0.1 mL血清中和1个小鼠最小致死量（MLD）的天然毒素）。二免后,家兔血清的中和抗体效价可达到4~8。用10个家兔MLD的天然毒素攻毒后,免疫组家兔得到了100%（4/4）的保护,而用1个家兔MLD的天然毒素攻毒后,对照组家兔100%（2/2）死亡。以上结果说明,rMBPCH_C具有良好的免疫原性,从而为C型肉毒梭菌病基因工程亚单位疫苗的研制提供了重要的试验数据。     

产气荚膜梭菌主要致死性毒素的研究进展

产气荚膜梭菌作为危害各国家畜养殖业的主要致病菌之一,受到国内外研究者的普遍关注.产气荚膜梭菌的主要致病因子是菌体产生的外毒素.近年来,国内外对其致病机理进行了深入研究,建立起简便、快速的检测方法,并且在防治手段方面取得了巨大突破.对产气荚膜梭菌的主要致死性毒素类型、致病机理、检测技术及其防治措施等方面的研究进展进行了阐述.     

艰难梭菌毒素致病机理的研究进展

艰难梭菌是一种革兰氏阳性厌氧芽胞梭菌,是人类肠道感染的主要致病菌,其主要致病因素为毒素A(肠毒素)和毒素B(细胞毒素).毒素A引发细胞损伤后,毒素B即可侵入肠黏膜,引起细胞病变,导致一系列与感染相关的临床表现.同时,艰难梭菌毒素也是引起猪、鸡等畜禽发生腹泻的重要因素,因此探讨艰难梭菌毒素对机体的损伤作用,有利于揭示艰难梭菌的致病机理,为其防控提供理论依据.     

貉肉毒梭菌中毒的诊治

2006年8月,台前县某养貉专业户饲养的42只貉因进食腐败鱼片导致肉毒梭菌中毒并出现死亡.此病以运动中枢神经和延脑麻痹为主要症状,死亡率高,现报告供参考.     

E型产气荚膜梭菌ι毒素重组质粒的构建与表达

ι毒素是是公认的引起羔羊、犊牛和家兔患肠毒血症的主要毒素,为了减小其给畜牧业带来重大损失,论文就ι毒素蛋白的构建与表达进行研究,以期对其所引起疾病的预防及疫苗的研发提供参考。通过E型产气荚膜梭菌基因组,利用PCR方法获得大小为1 377bp的iota a基因和2 640bp的iota b基因;随后将目的基因同pET-28a质粒连接构建重组载体,并将重组载体转化E.coli BL21,用IPTG诱导表达,并通过SDS-PAGE、Western blot进行分析,发现Ia、Ib蛋白均成功进行了可溶性表达;最后利用Ni-NTA层析柱对重组蛋白进行纯化,获得了目的蛋白。     

Susceptibility of Clostridium perfringens of animal origin to fifteen antimicrobial agents

The minimal inhibitory concentrations of fifteen antibacterial agents were determined by agar-dilution method against 121 strains of Clostridium perfringens isolated from pigs, cattle and poultry. All strains, regardless of host of origin, were susceptible to avoparcin, furazolidone, monensin, nitrovin, penicillin G, ronidazole and tiamulin and resistant to flavomycin. Poultry strains were also susceptible to carbadox, chloramphenicol, erythromycin and virginiamycin. Bacitracin-resistant poultry strains were susceptible to all tested antibacterial agents except tetracycline, but the bacitracin-resistant cattle strains were polyresistant. Porcine strains were susceptible to bacitracin and bovine strains to carbadox. Carbadox-resistant porcine strains were resistant to erythromycin, lincomycin and tetracycline and susceptible to chloramphenicol. Resistance to erythromycin was associated with resistance to lincomycin. High level erythromycin-lincomycin-resistant strains were susceptible to virginiamycin, but the intermediate level erythromycin-lincomycin-resistant cattle strains were resistant to virginiamycin. Resistance to chloramphenicol or erythromycin-lincomycin was always associated with resistance to tetracycline but the reverse was not always true.     

C、D型二价产气荚膜梭菌抗毒素血清的制备及保护效果评价

为治疗产气荚膜梭菌感染引起的疾病,研究制备了产气荚膜梭菌多价高效抗毒素血清。试验采用C、D型产气荚膜梭菌标准菌株,制备了高浓度外毒素和灭活疫苗,作为免疫原多次免疫绵羊,通过间接ELISA法监测绵羊抗体水平变化,采用小鼠中和试验检验绵羊抗毒素血清保护效果。结果表明:制备的高效价抗C、D型产气荚膜梭菌毒素血清每0.1 m L血清能中和400个C型毒素对小鼠的MLD和600个D型毒素MLD,有良好的应用前景。