Death of a neonatal lamb due to Clostridium perfringens type B in New Zealand     

JS Munday  H Bentall  D Aberdein  M Navarro  FA Uzal  S Brown 《New Zealand veterinary journal》2020,68(4):242-246

ABSTRACT

Case history and clinical findings: A flock of 20 sheep was kept within three paddocks on a single property. None of the animals in the flock had been vaccinated against any disease for at least three years. Abdominal bloating and haemorrhagic diarrhoea were observed in Lamb 1 at 24 hours-of-age. The lamb subsequently died within an hour of the onset of clinical signs. Lamb 2 was 3-days-old when observed to be recumbent with opisthotonus. The lamb was treated with dextrose, vitamins B1 and B12, and penicillin G, but died 4 hours later.

Pathological findings: Examination of Lamb 1 revealed markedly increased gas within the peritoneum and within dilated loops of intestine. The intestines were dark red and contained large quantities of haemorrhagic fluid. Histology of the intestines revealed peracute mucosal necrosis with minimal accompanying inflammation. The intestinal lumen contained cell debris, haemorrhage, and myriad large Gram-positive bacilli. The intestines of Lamb 2 did not appear bloated or reddened. However, multiple fibrin clots were visible within the pericardial sac. Histopathological examination revealed small foci of necrosis within the mucosa of the distal intestine. The necrotic foci were often associated with large numbers of large Gram-positive bacilli.

Immunohistochemsitry and molecular biology: Intestinal samples from Lamb 1 were processed for Clostridium perfringens immunohistochemistry, which revealed large numbers of intralesional, positively immunostained rods. Fragments corresponding to the expected sizes for genes encoding alpha, beta, and epsilon C. perfringens typing toxins were amplified by PCR from DNA extracted from formalin-fixed sections of intestine.

Diagnosis: Lamb dysentery due to C. perfringens type B.

Clinical relevance: C. perfringens bacteria have a worldwide distribution, but disease due to C. perfringens type B has only been diagnosed in a small number of countries and has never been reported in New Zealand or Australia. C. perfringens type B produce both beta toxin and epsilon toxins, therefore both haemorrhagic enteritis and systemic vascular damage can develop. As many animals are exposed to C. perfringens without developing disease, there must be additional unknown factors that resulted in disease in these particular sheep. Vaccines that specifically protect against C. perfringens type B are available and may be recommended for use in smaller non-commercial flocks, as in the present case.  相似文献   

种间关系对中条山油松人工林天然更新及群落稳定性的影响          下载免费PDF全文

裴顺祥  法蕾  杜满义  郭嘉  辛学兵 《林业科学研究》2022,35(1):150-157

[目的]为了揭示种间关系对中条山油松人工林天然更新及群落稳定性的影响,为油松人工林经营管理提供理论依据.[方法]基于中条山油松人工林群落样地调查数据,分析油松人工林下主要植物的种间关联性、生态位重叠及群落稳定性,并在此基础上探讨种间关联和生态位理论在油松人工林天然更新障碍及群落稳定性形成机制中的作用.[结果]中条山油松...  相似文献   

Analysis of the mucosal microenvironment: factors determining successful responses to mucosal vaccines     

Husband AJ  Bao S  Beagley KW 《Veterinary immunology and immunopathology》1999,72(1-2):135-142

The predominance of IgA antibodies in mucosal sites reflects a combination of high rate IgA isotype switching among precursor cells in induction sites, their selective localisation in mucosal effector tissues and vigorous proliferation of these cells after extravasation. Each of these steps leading to IgA expression at the mucosa is under cytokine control. This paper will address the role of cytokines in induction and expression of IgA responses, the contribution of various precursor cell subsets and their differential responses to cytokine signals and strategies for manipulating cytokine expression. With respect to IgA antibody production in the gut whereas IL-4 and TGF-beta have been implicated in isotype switching of precursor cells to IgA commitment, their subsequent localisation, proliferation and effector activity expression is dependent on IL-5 and IL-6 expression locally. Most IgA plasma cells in the intestine derive from cells of the B2 lineage in the Peyer's patch, but a subpopulation of cells derived from the peritoneal cavity (B1 cells) also contribute to the IgA plasma cell population in the intestinal lamina propria. Whereas IgA+ cells of the B2 lineage are IL-6 dependent but IL-5 independent, B1-derived IgA+ cells are IL-5 dependent and IL-6 independent. On the other hand, cell mediated immune responses in the gut are highly dependent on IFN-gamma production by both Th1 CD4 cells and CD8 cells and in enteric Salmonella infection IFN-gamma production is essential but antibody has little effect on this process.Therapeutic interventions based on the information emerging from these studies will lead to improved vaccination responses and correction of immunodeficiencies especially in young animals.  相似文献   

Interleukin-6 expression in gut of parasite challenged sheep     

Shen J  Bao S  McClure SJ  Emery DL  Husband AJ 《Veterinary immunology and immunopathology》2000,76(1-2):163-168

Following challenge with Trichosirongylus colubrifonizis, increased numbers of T-cells and immunoglobulin responses are seen in the intestine of sheep immunised by repeated infection with live worms. IL-6 mRNA expression in the small intestine from T. colubriformis-immunised and naive sheep was determined by in situ hybridisation, whereas CD4(+), IgA(+), IgG(+) cells in the gut were evaluated by immunohistochemistry. There was constitutive expression of IL-6 mRNA by cells in the naive gut, and the number of these cells was increased by parasite challenge. There were corresponding increases in numbers of CD4(+) and TCR gamma/delta(+) T-cells and IgG(+) B-cells. Our data are consistent with a role for IL-6, perhaps produced by CD4(+) and/or TCR gamma/delta(+) T-cells or B-cells, in B-cell terminal differentiation. Infiltration of B-cells, particularly IgG(+) B-cells, may reflect parasite immunity in the host.  相似文献   

国有苗圃所有制结构调整之我见     

周国平  李发凯 《江西林业科技》2001,(Z1)

所有制结构的调整是国有苗圃发展壮大的出路所在.笔者从必要性,战略方向,基本途径等三个方面阐述了看法.  相似文献   

3种阔叶树育苗技术及苗木生长规律研究初探   总被引：2，自引：0，他引：2  

刘志强  肖水清  邹元熹  肖才发 《江西林业科技》2001,(3):14-15

通过对闽楠，蓝果树，东京野茉莉的育苗试验，研究苗木生长规律，掌握生理生物学特性。  相似文献   

Analysis of embedded gas detection system based on nano-porphyrin arrays     

LUO Xiao gang  BAI Xing hong  HOU Chang jun  HUO Dan qun  FA Huan bao  YANG Mei 《保鲜与加工》2011,(12):48-53

In view of the necessity of gas detection in environment, an embedded gas detection system is designed based on the basic principles of chromatography change of chemical reaction between nano-porphyrin arrays and micro-gas, which takes ARM9 S3C2440A as the core and nano-porphyrin array as the sensors. The overall program, the circuit organization and control software of the main function module such as spectrum signal acquisition, processing and monitoring are presented. With energy conservation differential equation, the control model of temperature and flow rate in the sample chamber is established, which can precisely control the detection conditions of chemical sensors. Some typical trace gases such as ammonia, enanthaldehyde, cyclohexane and hexanal are tested by the system, and the results show that the system can achieve rapid and accurate detection of trace volatile gas.  相似文献   

阔叶红松林山杨伐根分解过程中真菌动态研究     

法蕾  赵秀海 《北京林业大学学报》2006,(Z2)

山杨是长白山阔叶红松林中的常见阔叶树种,择伐后的伐根很多.山杨伐根在多种真菌的作用下逐渐分解,不断地向周围释放养分,构成保证森林生态系统稳定循环的一个重要环节.随分解的不断进行,山杨伐根上的真菌的种类和数量都呈现出一定的变化趋势.真菌数量高峰出现在伐后的第5年,而种类高峰则出现在伐后的第7年.这一时间上的交错现象是由真菌的不同分解能力引起的.分解能力强的主要分解菌将难于分解的木质素、纤维素等分解为易于利用的小分子物质,为其他真菌提供了营养来源,便于其他真菌的定殖.另外,伐根上的真菌数量还与伐根桩径呈正相关关系.  相似文献   

The mucosal immune system. Current topics in veterinary medicine and animal science,vol. 12, 1981: Editor F.J. Bourne. Martinus Nijhoff,The Hague,ix, 560 pp., Cloth Dfl. 165/US$73.00, ISBN 90-247-2528-3     

Alan Husband 《Veterinary microbiology》1983,8(2):215-218

  相似文献   

Transport of serum IgA into bile of sheep infected with Fasciola hepatica     

R F Sheldrake  A J Husband  D L Watson  I A Barger  J C Boray 《Veterinary immunology and immunopathology》1988,18(1):29-39

Sheep infected with Fasciola hepatica were studied for their ability to transport intravenously injected radiolabelled IgA from serum to bile. The results show that there was an apparent reduction in the selectivity of transport of IgA into bile in infected animals compared with uninfected controls. However, in infected animals the biliary flow rate was approximately twice that of uninfected animals, and the total amount of radiolabelled IgA transported was similar irrespective of infection status. The possible relevance of the elevated biliary flow rate is discussed with respect to the pharmacokinetics of drugs used for the chemotherapy of helminth infections in sheep.  相似文献