噬菌体降低铜绿假单胞菌所致腐蛋的效果

铜绿假单胞菌是孵化过程中造成腐蛋的主要病原菌,拟尝试用裂解性噬菌体防治。选用腐蛋中筛选的铜绿假单胞菌PA-MH12,以此为宿主从河水中筛选到1株裂解性噬菌体MH12-Q,对其进行了生物学特性研究,体外进行了对铜绿假单胞菌所致腐蛋的防控效果试验。结果显示：噬菌体MH12-Q属于肌尾噬菌体科（Myoviridae）,效价可达到10¹³pfu·mL^-1,完全裂解效价（CLC）为10¹⁰pfu·mL^-1,最适生长温度为37℃,pH稳定性好,最适pH为6~8,且其在pH4~10的效价都能维持在较高的水平。最佳感染复数（OMOI）为0.001,感染宿主的潜伏期为30 min,爆发期为70 min。噬菌体MH12-Q可使高浓度铜绿假单胞菌的感染率从70%降低到40%。铜绿假单胞菌噬菌体MH12-Q的生物学性质适合生产应用,对孵化场腐蛋具有较好的防控作用,能够提高感染铜绿假单胞菌的鸡胚成活率。     

Assessment of elastase as a Pseudomonas aeruginosa virulence factor in experimental lung infection in mink

Anaesthetized mink were inoculated intratracheally with an elastase-producing Pseudomonas aeruginosa strain (PAO1) and two mutants derived from PAO1 with defective elastase formation (strains PAO1-E64 and PAO1-las-16). Survival times were prolonged in mink infected with the mutants, and microscopic examination of lungs showed that the elastase-positive wild type strain produced more pronounced tissue damage and haemorrhages than did the elastase-defective mutant strains. The strains PAO1 and PAO1-las-16 were also compared to three strains isolated from natural infection in mink which differed in elastase production. The mink strains with high or moderate elastase production produced more severe lung damage and were associated with a higher mortality than the other strains tested. The results indicate that P. aeruginosa may enhance the virulence of the bacterium in lung infections.     

Effect of infectious dose and season on development of hemorrhagic pneumonia in mink caused by Pseudomonas aeruginosa

Hemorrhagic pneumonia is an acute and fatal disease of farmed mink caused by Pseudomonas aeruginosa. The pathogenesis of this disease has not yet been resolved. Mink are the only animals known to be susceptible to acute, contagious, and fatal lung infections caused by P. aeruginosa. The purpose of this study was to investigate the correlation between dose-response and season of infection and to clarify whether Danish mink are carriers of P. aeruginosa on their nasal mucosa during the season for hemorrhagic pneumonia. To elucidate the pathogenesis of the disease, an infectious dose-response trial was carried out on adult mink and mink kits, both in the season for hemorrhagic pneumonia (November) as well as out of season (July). It proved difficult to infect mink via the intra-nasal route. Only 4 out of 60 infected mink developed clinical disease and were euthanized, all of them in November, illustrating that predisposing factors in the mink itself and not infectious dose might be crucial for disease development. We were able to culture P. aeruginosa from the nasal cavity of the clinically healthy experimental mink 8 d after inoculation. This indicated that the mink can carry P. aeruginosa on their nasal mucosa without developing the disease. It was not possible, however, to culture P. aeruginosa from the nasal cavity of clinically healthy mink obtained from farms in November, which indicates that the organism is not a normal part of the nasal mucosal flora of mink.     

致水貂出血性肺炎铜绿假单胞菌胞外产物生物活性及免疫保护力分析

胞外产物在细菌致病过程中发挥重要作用,为探索胞外产物在铜绿假单胞菌致病过程中的作用,首先从铜绿假单胞菌培养液提取其出其胞外产物,利用小鼠模型分析其致病性,并通过细胞证实了该产物对巨噬细胞功能的抑制作用,进一步测定其胞外产物的酶活性并利用LC-MSMS方法对铜绿假单胞菌胞外产物蛋白成分和功能进行分析。结果表明,铜绿假单胞菌胞外产物对小鼠有致病性,能够显著抑制巨噬细胞吞噬细菌活性,其具有淀粉酶、脂肪酶、蛋白酶、卵磷脂酶活性和溶血活性可能在这一过程中发挥关键作用。LC-MSMS分析鉴定所提纯的胞外产物中有153种蛋白成分,涉及多种酶类、细胞结构蛋白和功能性蛋白。用低剂量胞外产物免疫动物对于铜绿假单胞菌感染具有较明显的保护率,可达90%。本试验为揭示铜绿假单胞菌致病机理,研制新型疫苗奠定基础。     

Effect of Ostertagia circumcincta excretory/secretory products on gastrin release in vitro.

It has been suggested that parasite excretory/secretory (ES) products may be capable of direct stimulation of gastrin secretion and of contributing to the hypergastrinaemia typical of abomasal parasitism. Ostertagia circumcincta ES products were tested on an ovine antral mucosal preparation which had been developed for a pharmacological study of gastrin secretion in the sheep. Its responsiveness to chemical stimulation was established by stimulation with amino acids and amines: tryptophan (0.1-5 mM) and phenylalanine (10-100 mM) stimulated gastrin release (151-160 and 117-129%, respectively), whereas glycine (0.1-100 mM) was without effect; ammonium sulphate, but not sodium sulphate, stimulated gastrin release in concentrations from 1mM (122%) to 50mM (148%). ES products were prepared by incubation of exsheathed third-stage larvae (L3) or parasites recovered on Day 8 p.i. (L4), Day 12 p.i. (10% L4, 90% immature adults), Day 21 p.i. (5% L4, 30% immature adults, 65% adults), Day 22 p.i. (20% immature adults, 80% adults), Day 30 p.i. (adults) and Day 35 p.i. (adults), or a mixed-age parasite population. Worms were recovered from agar and incubated in either distilled water or Hank's balanced salt solution (HBSS) adjusted to pH 2.5, 3.5, 4.5, 5.0 or 7.4. HBSS pH 7.4 was also prepared with antibiotics, without glucose, and with antibiotics but without glucose. Survival of Day 21 and 35 worms and exsheathed L3 in water or in a series of HBSS adjusted to pH 2.5, 3.5, 4.5, 5.0 or 7.4 was assessed from the percentage of motile parasites. L3 slowly became immotile over several days except in HBSS pH 2.5, in which survival was reduced, whereas adult worms did not tolerate incubation at 37 degrees C in water or HBSS at pH 2.5, retained motility for about 2 days at pH 3.5, but survived well at pH 4.5 and above. Incubates prepared from all stages of O. circumcincta, both in media favourable and unfavourable for parasite survival, failed to stimulate consistently the secretion of gastrin by tissue from both parasite-naive and previously exposed sheep, whereas a considerable number of incubates were significantly inhibitory. The inhibitor may not be produced by the nematodes, but by contaminating abomasal or environmental microflora, as inhibitory activity was predominantly generated by prolonged incubation, it was less potent when glucose was omitted and was not present in media containing antibiotics. This study did not find evidence for a gastrin stimulant in O. circumcincta ES products, but did demonstrate the acid intolerance of adult worms and suggests that abomasal microbes may be capable of modulating the secretory activity of the host digestive tract.     

Monosaccharide inhibition of adherence by Pseudomonas aeruginosa to canine corneocytes

The effect of d -galactose, d -mannose, l -rhamnose and dextrose on the adhesion to canine corneocytes by three strains of Pseudomonas aeruginosa was studied in six healthy dogs. Canine corneocytes were collected from the inner aspect of the pinna using adhesive discs (D-Squame®). Half millimetre of bacterial suspension in phosphate-buffered saline (PBS) with or without the addition of a monosaccharide was placed over the corneocyte layer and incubated in moist chambers. Image analysis was used to quantify bacterial adherence to corneocytes. The three strains of Pseudomonas adhered well to canine corneocytes. All monosaccharides tested inhibited the adherence of Pseudomonas to canine corneocytes. The mean reduction in adhesion for individual sugars at a concentration of 0.1% was 40.2% (dextrose), 30.8% ( l -rhamnose), 25.6% ( d -galactose) and 19.4% ( d -mannose). When d -galactose, d -mannose and l -rhamnose were used in combination at 0.1% concentration, the mean reduction in adherence was 52.9%. The monosaccharides studied may have a potential role in the management of Pseudomonas infections in dogs.     

肉仔鸡绿脓杆菌感染的诊治

绿脓杆菌病是由绿脓假单胞菌引起的人和动物共患的传染病。绿脓杆菌是一种条件性病原菌,在自然界的土壤、水和空气中分布甚广,对人畜均有一定程度的危害。动物常见内脏器官脓肿,幼龄畜禽常表现为群体的急性暴发而导致大批死亡。此病虽然不常发。一旦发病也会造成严重的经济损失。     

Secretion of virulence factors by Escherichia coli.

In order to interact with their host, pathogenic strains of E. coli need to secrete some virulence factors which can modify the metabolism of host cells, contributing to disease. Since E. coli is a Gram-negative bacteria, this secretion process involves the crossing of both the inner and the outer membranes. E. coli uses mainly four secretion mechanisms called type I, type II, type III and type IV secretion systems. In the type I secretion system, the secretion machinery is composed of three proteins forming a channel through the inner and outer membranes. It is a one-step mechanism. The secretion signal is present in the carboxyterminal region of the secreted protein but without proteolytic cleavage. In E. coli, the best studied type I secreted protein is haemolysin. In type II and type IV secretion systems, the crossing of the inner membrane involves the sec machinery with the cleavage of an aminoterminal signal sequence. The crossing of the outer membrane involves the formation of a pore either by other proteins (type II) or by the carboxyterminal region of the protein (type IV). The A-B toxins, such as heat labile enterotoxin, are secreted by the first mechanism and members of the IgA proteases are secreted by the second. The type III secretion system involves at least 20 proteins including cytoplasmic, inner membrane and outer membrane proteins. The originality of this system is the ability to inject secreted bacteria into the cytosol of the host cells. Such a system is found in attaching and effacing E. coli and in diffusely adhering E. coli.     

袋鼠源铜绿假单胞菌分离鉴定

为确定袋鼠死亡原因,本研究采用Biolog快速鉴定系统、16SrRNA序列分析以及传统细菌鉴定方法对2株分离自北京动物园袋鼠肺脏的菌株进行形态学、培养特性、生化特性、小鼠致病性、系统发育分析等生物特性的鉴定和分析,结果表明2菌株均为铜绿假单胞菌,对昆明小鼠有强致病性。系统发育分析结果表明2株袋鼠源铜绿假单胞菌16SrRNA序列与ATCC10145模式株差异很小,同源性分别为99.9%和100%,并且位于系统发育树的同一分支。     

水貂铜绿假单胞菌检测方法研究进展

水貂出血性肺炎是由铜绿假单胞菌引起的威胁养貂业的重要疾病之一。为了解该病相关检测方法的最新研究进展,本文从病原学和分子生物学方面,介绍了细菌分离培养、生化试验、特异性抗原及其抗体检测、PCR技术和LAMP技术等。通过比较各种方法的优缺点和实用性,为临床兽医科技工作者快速、简便、准确、实用地诊断提供参考。     

Immunization of Mice and Chinchillas Against Pseudomonas aeruginosa

The possibility of production of an effective vaccine against Pseudomonas aeruginosa infections in fur-bearing animals was investigated. Twenty-three strains of Pseudomonas aeruginosa isolated from diseased chinchillas and mink were tested in mice for their immunogenic properties. Nineteen of these strains produced good immunity against homologous strains, and three of these produced also good immunity against heterologous strains. Of the remaining four strains two produced moderate immunity and two no immunity.

It was found that 0.05% or 0.5% formalin added to suspensions of Pseudomonas aeruginosa or ultrasonification of the suspension produced better results than 0.5% phenol, 0.3% alcohol or heat at 100°C for half an hour.

Chinchillas vaccinated with two doses of formolized Pseudomonas aeruginosa bacterins were immune for 36 weeks after the second dose, while all controls died within 48 hours after being challenged.

It was found that the protection afforded by the polyvalent bacterin extended beyond the strains included in the vaccine.

A field survey on 34 ranches which included over 7,700 chinchillas showed very promising and encouraging results.

     

肉鸽铜绿假单胞菌分离与鉴定

从南京某肉鸽养殖场死亡病鸽肝脏中分离到1株细菌,经分离培养、形态染色镜检、生化试验、药敏试验、实验动物致病性试验和16S rDNA基因片段PCR检测及基因测序试验,结果表明,该菌可以在普通营养琼脂和SS琼脂平板上生长,革兰染色镜检为革兰阴性菌,生化试验检测结果鉴定值为1 655,符合铜绿假单胞菌生化特性;药敏试验表明,该菌对磷霉素、环丙沙星和阿米卡星高度敏感,接种小鼠能导致其死亡并分离出同一细菌,16S rDNA基因片段测序后与GenBank中登录的铜绿假单胞菌同源性为99%。综合以上结果鉴定该分离菌为铜绿假单胞菌。     

华蟾毒精对小鼠树突状细胞分泌功能的影响

为了调查华蟾毒精(CBG)对树突状细胞分泌功能的影响,采用小鼠粒细胞巨噬细胞集落刺激因子(GM-NSF)和IL-4体外联合诱导培养小鼠骨髓细胞,获得树突状细胞(DCs)。经免疫磁珠分选法纯化获取CDllc+树突状细胞。试验组CDllc+树突状细胞中加入不同浓度CBG,空白对照组加等量RPMI-1640,阳性对照组加LPS。作用48 h后,采用酶联免疫吸附法(ELISA)检测培养上清液中细胞因子IL-12p70、IL-10及IL-1β含量。结果表明:在适量浓度10⁵0μg/mL范围内,CBG均以剂量依赖的方式上调DCs分泌IL-12p70和IL-1β水平,下调IL-10的分泌水平。说明CBG能够通过调控DCs分泌Th1、Th2型细胞因子的分泌,来诱导Th1型细胞免疫应答。