肉毒梭菌毒力以其毒素灭活疫苗的效力试验

肉毒梭菌毒素毒力强,可以作为灭鼠的药物,现将肉毒梭菌C株菌液上清适当稀释,进行小鼠毒力试验。结果表明,肉毒梭菌C株菌液上清对小鼠的最小致死量为5.0×10~4MLD/ml,可以作为草原、牧场、其他养殖场灭鼠的参考依据。将毒素灭活制备疫苗,进行免疫小鼠,对小鼠具有保护力,可以抵抗致死量毒素的攻击。     

C型肉毒梭菌毒素杀灭高原鼠兔的初步试验研究

生物毒素灭鼠是值得探索的一条途径。用细菌毒素进行灭鼠,国内外未见报导。肉毒梭菌毒素是目前已知生物毒素中毒性最强者。为寻求新的灭鼠途径,1985年9—11月,我们先后在青海省海南州共和县铁卜加、果洛州甘德县、达日县等地进行了C型肉毒梭菌毒素对青藏高原的主要害鼠高原鼠兔[Ochotona curzoniae(Hodgson)]的毒力测定、毒饵的保存期、适口性以及现场灭鼠试验,获得了初步成功。现报告于下:     

肉毒素防治草原鼠害试验与示范

用A、C、D型肉毒梭菌毒素农药进行草原害鼠灭治试验,灭效分别为73.6%、93.5%和90.4%。四川省累计推广C型肉毒毒素灭鼠242万hm2次,平均效果90%以上。     

运用生物毒素杀灭地面鼠的报告

用Ｃ型肉毒梭菌毒素杀灭地面鼠效果显著,灭鼠率达到９２５０％～９７２０％。     

加快C型肉毒梭菌毒素的开发促进畜牧业经济跨越式发展

牧草、牲畜是畜牧业生产的两大要素。C型肉毒梭菌毒素是目前较佳的一个优质、高效、无残留和二次中毒的草原灭鼠药品，对保护天然草地，促进畜牧业快速、健康发展有着重要意义，西藏生物药品制造厂作为目前全区唯一一家生产生物制品的厂家，已着手试制生产C型肉毒梭菌毒素杀鼠素，它的生产将大大推进西藏天然草地的保护。     

鸭十种常见中毒性疾病的防治

肉毒梭菌毒素中毒：本病是由肉毒梭菌毒素引起的一种疾病，多发生于夏秋季节，由于天气干旱少雨、湖泊水浅，鸭群在放牧时，吞食了一些腐败的含有大量肉毒梭菌、绿脓杆菌等的鱼类和小动物尸体，或投喂了被肉毒梭菌污染的饲料，而引起中毒。     

一例犬肉毒梭菌中毒的诊疗体会

肉毒梭菌毒素中毒简称肉毒中毒，是由于人或动物摄人含有肉毒梭菌毒素的食物（或饲料）后引发的一种人和多种动物共患的中毒性疾病。早在1820年Kerber首先描述了人的肉毒梭菌中毒，1922年和1927年分别有人报道了鸡、牛的肉毒梭菌中毒症Ⅲ。近年来，在宠物门诊病例中，该病也是时有发生。笔者在临诊中曾发现一起犬感染肉毒梭菌中毒病例，现报告如下：     

水鸭肉毒梭菌毒素中毒的诊断

水鸭肉毒梭菌毒素中毒的诊断梁国明（广东省湛江市兽医诊断室５２４０３８）肉毒梭菌毒素中毒是由于摄入肉毒梭菌毒素引起人畜以及多种动物发生的中毒性疾病。１９９５年我市某水鸭养殖场的水鸭发生一起症状与肉毒梭菌毒素中毒相似的疫病，但以零星发病死亡出现。为探明原...     

鸭肉毒梭菌中毒症治疗

鸭肉毒梭菌中毒症治疗杜劲松邵武和平镇牧医站３５４０００鸭肉毒梭菌中毒症是由于鸭食入含有肉毒梭菌的饲料或食物，而发生的一种急性中毒性疾病。肉毒梭菌外毒素是神经性毒素，非毒蛋白和血凝素等的复合体，在小肠中被胰蛋白酶降解，释放出神经性毒素，被小肠吸收后选择...     

一起犬肉毒梭菌毒素中毒的调查分析和启示

肉毒梭菌毒素中毒是细菌性毒素型食肉中毒之一。肉毒梭菌是一种腐败寄生菌，在自然界分布很广。肉毒梭菌在适宜的条件下，形成外毒素（肉毒毒素），它的毒力是现今已知的化学毒物以及细菌毒素中毒性量强烈的一种。口服0．0001mg就可毙命，其毒力比氰化物还要大一万倍。     

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。     

Proteases of Clostridium botulinum. VI. The role of trypsin, Clostridium botulinum proteases and protease inhibitors in the formation and activation of toxin in growing cultures of Clostridium botulinum

In this study the influence of bovine serum protease inhibitors, trypsin and proteases produced by different types of Clostridium botulinum has been investigated. Trypsin and botulinum proteases had the capability of increasing the toxicity in growing cultures in Clostridium botulinum types A, B and E. Trypsin increased the toxin level to a greater extent than proteases from Clostridium botulinum types A, B, C and F. Protease inhibitors did not influence the toxin formation to any extent compared with the controls. The combined effects of proteases and protease inhibitors on the development of toxin in Clostridium botulinum type B were also investigated by adding proteases and protease inhibitors to the same culture at different time intervals. Protease inhibitors did not reduce the toxicity of the cultures as compared to the controls. Altogether a complex relationship seems to exist between protoxin, toxin, proteases and inhibitors in the culture, and the order and time sequence of addition seem to be of importance. The results obtained in this investigation indicate that proteases of Clostridium botulinum play a part in the formation and/or activation of toxin in growing cultures of proteolytic strains such as Clostridium botulinum types A and B. As to the activation of protoxin and progenitor toxin produced by non-proteolytic Clostridium botulinum types B and E, botulinum proteases showed a marked capability of increasing the toxicity in these cultures. Trypsinization may be valuable for the detection of Clostridium botulinum types A and B in foods, as well as for type E, where it is commonly used.     

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.     

Tonsils--place of botulinum toxin production: results of routine laboratory diagnosis in farm animals

Since a case of a veterinarian was reported, who was likely to be infected/intoxicated by Clostridium botulinum during the handling of a diseased animal, tonsils in animals were tested for botulinum neurotoxin and bacterial forms of neurotoxic Clostridium botulinum during routine botulism laboratory examinations including standard samples (intestinal tract and liver) from 48 cattle, 11 horses, and 14 goats. Ten out of 60 samples from tonsils contained free botulinum toxin, and 12 out of 59 were positive for live toxin producing bacteria. In 32 out of 162 intestinal samples toxin was detected. Toxin producing bacteria were found in 37 samples. Eight of 56 liver samples contained free toxin, and 15 out of 43 toxigenic bacteria. Samples from 10 slaughter pigs were all negative, whereas from slaughter cattle tonsils had a high incidence of toxin (7 of 10) or toxigenic bacteria (2 of 8). The results are discussed in the context of effects on animal health and botulism as zoonosis.     

Clostridium botulinum type D intoxication in a dairy herd in Ontario

Thirty-four Holstein cows died after exposure to Clostridium botulinum type D toxin, presumably from contaminated haylage. The presence of type D toxin in ruminal contents was confirmed by mouse inoculation. This is the first confirmation by direct toxin isolation of C. botulinum type D toxin in cattle in North America.     

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).     

Susceptibility of Foxes to Clostridium Botulinum Type C and E Toxins

Investigations were performed to determine the exact susceptibility of foxes to Clostridium botulinum type C and E toxins.Doses of 5 mill. MLD type C toxin mixed with the feed did not cause symptoms of botulism in either cubs or adult foxes. Subcutaneous injections of 300,100(0 MLD or more were fatal to cubs, while 750,000 MLD caused the death of all adults.Regarding type E toxin, doses of 1 mill. MLD affected neither cubs nor adults on oral administration. Subcutaneously injected doses of 5,000 MLD or more killed all cubs, while 10,000 MLD was required to produce lethal effect on adult animals.The conclusion made is that foxes are highly resistant to both type C and E Clostridium botulinum toxins following oral application. It is further revealed that foxes are 60–70 times more susceptible to type E than to type C toxin when injected subcutaneously.     

Botulism as a sequel to open castration in a horse

Clostridium botulinum and type-B C botulinum toxin were isolated from a necrotic wound that developed subsequent to castration in a 2-year-old Thoroughbred gelding. The horse had clinical signs of botulism and was successfully treated with wound debridement, C botulinum type-B antitoxin, potassium penicillin, and supportive care.     

Determination of the median toxic dose of type C botulinum toxin in lactating dairy cows.

Because of the difficulty in identifying botulinum toxin in cattle, it is hypothesized that cattle are sensitive to levels of toxin below the detection limits of current diagnostic techniques (the mouse protection bioassay and the immunostick enzyme-linked immunosorbent assay [ELISA] for type C botulinum toxin). Using an up-down method for toxicologic testing, the median toxic dose (MTD50) for cattle was determined. Four lactating Holstein cows were dosed at 0.125 or 0.25 ng/kg with Clostridium botulinum type C toxin and failed to develop clinical signs of botulism during the 7-day observation period. Three cows given 0.50 ng/kg of toxin developed clinical signs of botulism. From these results, the MTD50 was calculated at 0.388 ng/kg (3.88 mouse lethal doses/kg) using the trim-logit method. These results suggest that cattle are 12.88 times more sensitive to type C botulinum toxin than a mouse on a per kilogram weight basis. The mouse protection bioassay and the immunostick ELISA for type C botulinum toxin failed to identify the presence of the toxin in the serum, blood, and milk samples taken from all 7 animals.     

Outbreak of botulism in a dairy herd in Turkey

In this study, the clinical findings and results of haematological and biochemical analyses of 26 cattle with botulism were evaluated. The most important clinical signs in the affected cattle included: decreased appetite, ataxia, difficulty to rise, loss of tongue tone, salivation and bradycardia. A definitive diagnosis of botulism was based on demonstration of the preformed toxin in ruminal and intestinal contents and feed materials including poultry litter, by mouse inoculation test. This study is the first confirmation, by direct toxin isolation, of Clostridium botulinum type C and Clostridium botulinum type D in cattle, in Turkey.