拟态弧菌毒力因子的分子生物学研究进展

拟态弧菌的致病作用与其在生长繁殖过程中产生的毒力因子密切相关。该菌的毒力因子主要有外毒素、内毒素及黏附素等,其中外毒素是其重要的毒力因子,它包括毒性酶、肠毒素、溶血素和铁载体等。各毒力因子不仅在生物学活性上具有协同作用,而且在分子水平上也是相互影响,受毒力岛上调控基因调节。本文主要对拟态弧菌毒力因子的分子生物学特性及其致病机理进行了综述。     

胸膜肺炎放线杆菌毒素分子致病机理研究进展

胸膜肺炎放线杆菌是引起猪传染性胸膜肺炎的一种重要病原菌。该病具高度传染性，给养猪业造成巨大的经济损失,本文就病原、毒素成分，毒素分子结构，分子致病机理的研究作了综述。     

畜禽硒缺乏症的临床——病理特征及其发病机理

本课题根据实验病理学原则和分组对比的方法,通过用低硒基础日粮分别加硒(0.2ppm)或不加硒,对雏禽、仔猪进行饲喂,取得畜禽硒缺乏症病例复制的成功。经对实验过程的临诊观察及多种项目的检测,得到了系统的基础资料和大量数据。并在渗出性素质的表现、平滑肌损害、胰腺的病变特征以及对淋巴器官与免疫功能和对生殖器官与生殖激素的影响等方面,发现一些新现象,提出一些新观点。研究结果为明确该病的临床病理特征、澄清动物种属间的异同,提供了客观依据。综合实验结果,系统地论述了发病机理并设计、绘制了示意图,取得理论研究的重要成果。实验结果还提示:不同种属畜禽对低硒营养的耐受力及其反应性不尽相同;而机体本身对硒的体内代谢过程,具有一定的调节能力。     

大豆菌核病研究进展

由核盘菌(Sclerotinia sclerotiorum (Lib.) de Bary)引起的大豆菌核病是一种世界性分布的重要病害,严重威胁大豆产业的安全生产和发展。为了更有效地预防和控制大豆菌核病的发生和发展,本文归纳了大豆菌核病的病原生物学特性、病害循环、致病机理、抗病育种以及综合防治等方面的最新研究,指出了深入挖掘优良抗性资源并探究大豆-核盘菌的互作机制,为后期开发高效的综合防治技术奠定基础。     

关于水稻稻曲病的田间管理与防治

笔者通过对水稻稻曲病的发病规律以及常规田间管理,总结其综合防治技术,以期对水稻稻曲病的预防能够起到参考借鉴。     

Soluble interferon-γ receptors encoded by poxviruses

Poxviruses encode a broad range of proteins that counteract the formidable attack of the immune response initiated in the host after infection, among which are proteins that mimic the extracellular binding domain of host cytokine receptors and are secreted from virus-infected cells. A soluble interferon-γ receptor (IFN-γR) is produced early after infection and efficiently blocks the binding of IFN-γ to cellular receptors, thus inhibiting both the anti-viral and immune functions of IFN-γ. An IFN-γR is highly conserved among members of the poxvirus family, suggesting a major role in viral pathogenesis. The highly species-specific nature of the IFN system enables questions concerning the evolutionary relationship between poxviruses and their hosts to be addressed. The IFN-γR encoded by myxoma virus, a natural pathogen of rabbits, is specific for rabbit IFN-γ. However, the IFN-γR encoded by orthopoxviruses (vaccinia, cowpox, camelpox, ectromelia) shows a novel, broad species specificity suggesting that these viruses have evolved in several species. The implications for the unknown origin and natural host(s) of vaccinia virus are discussed.     

BVD virus antigens in tissues of persistently viraemic, clinically normal cattle: implications for the pathogenesis of clinically fatal disease

The cellular events involved in precipitation of the clinically fatal outcome of an infection with bovine viral diarrhoea virus (BVDV) remain unresolved, though it is now known that this course of the infection, Mucosal Disease (MD), only occurs in calves persistently infected with non-cytopathic BVDV. In studies aimed at elucidating the pathogenesis of MD, the distribution of BVDV antigens and infectious virus in tissues of persistently infected, clinically normal calves was investigated. Virus antigen was detected in most tissues, in epithelial and immune cells. No signs of an inflammatory response were detected and cytopathological changes were subtle or absent. The infection may nevertheless create a cell-environment which will enhance replication of cytopathic virus. Variations in the clinical, pathomorphologies and virological appearance of MD-cases may depend on both the host-reactions, including virus-induced immunopathology, and the virus-strain combinations in a putative mixed infection.     

Monitoring expression of selected Plasmodiophora brassicae genes during clubroot development in Arabidopsis thaliana

The expression of 12 cDNAs from Plasmodiophora brassicae , among them two novel sequences, was determined during clubroot development on Arabidopsis thaliana . The aim was to find cDNAs expressed at distinct stages of pathogenesis. The relative amount of infection with active plasmodia could be estimated using Pb Actin cDNA as an internal standard. Two cDNAs, Pb Brip9 and Pb CC249, were strongly expressed at stages of disease development corresponding to the occurrence of sporulating plasmodia. Therefore, it should be possible in the future to find more cDNAs which could be used as markers for certain stages of clubroot development.     

Mechanisms involved in the biological control ofBotrytis cinerea incited diseases

Mechanisms involved in the biological suppression of infection and inoculum potential ofBotrytis cinerea are numerous and variable and the involvement of two or more mechanisms has been demonstrated in several systems. Reported combinations include antibiosis with enzyme degradation ofB. cinerea cell walls; competition for nutrients followed by interference with pathogenicity enzymes of the pathogen or with induced resistance; and alteration of plant surface wettability combined with antibiosis. Since germinatingB. cinerea conidia are dependent on the presence of nutrients, competition for nutrients is regarded as important in systems where biocontrol is involved. Conidial viability and germination capacity are also potentially affected by the presence of antibiotics produced by biocontrol agents and present in the phyllosphere. Slower in action are mechanisms involving induced resistance in the host plant and production of hydrolytic enzymes that degradeB. cinerea cell walls. The latter has been demonstrated much more convincinglyin vitro than in the phyllosphere. Biocontrol in established lesions and reduction of sporulation on necrotic plant tissues is a means to minimize the pathogen inoculum.Abbreviations BCA bio-control agent - Bc Botrytis cinerea - PG polygalacturonase - PL Pectin lyase - PME Pectin methyl esterase - PR pathogenesis related - VPD vapour pressure deficit