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奶牛乳房炎是奶牛养殖业最常见的疾病之一,严重影响奶牛泌乳量和奶品质,增加奶牛淘汰率。饲养条件、环境因素及病原菌等都可诱发奶牛乳房炎,其中金黄色葡萄球菌(Staphylococcus aureus)导致的奶牛乳房炎最难治愈。金黄色葡萄球菌是一种具有高致病性、高耐药性且能通过自身分泌的酶、毒力因子介导免疫逃避作用的致病菌,其在宿主体内长期存活可导致长期慢性奶牛乳房炎的发生。笔者首先从奶牛乳腺免疫防御方面揭示奶牛乳腺在金黄色葡萄球菌入侵时所产生的一系列免疫防御手段;其次从金黄色葡萄球菌依靠自身表达的毒力因子、生物膜、表面蛋白及进化过程中产生小菌落变种、持留菌等不断增强其致病性和高耐药性方面进行阐述,揭示金黄色葡萄球菌高致病性和高耐药性的原因,以及金黄色葡萄球菌导致的奶牛乳房炎难以治愈的原因;最后进一步阐明金黄色葡萄球菌是如何在宿主强大的免疫防御作用下存活,以及通过荚膜多糖和纤维连接蛋白在乳腺定植并逃避吞噬,分泌中性粒细胞丝氨酸蛋白酶抑制蛋白、葡萄球菌蛋白A、产生细胞外囊泡等毒力因子逃避机体的免疫吞噬作用,揭示金黄色葡萄球菌具有高度环境适应力及众多免疫逃避手段。笔者从以上三方面对金黄色葡萄球菌... 相似文献
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奶牛乳腺炎是危害奶牛养殖业最常见的疾病之一,给奶牛生产造成巨大的经济损失。其乳腺防御机理、发病机理虽取得了一定的研究成果,但深层次的一些问题仍然未能弄清楚,在这方面还需继续进行大量的研究工作。现就国内外奶牛乳腺自我防御方面的一些机理进行讨论,从乳汁血液当中的免疫活性细胞、体液因子、细胞因子等对乳腺防御方面的功能作详尽的叙述,尤其对泌乳周期中各种白细胞群的分布、功能以及影响奶牛围产期阶段免疫机能下降的一些因素作了分析,对了解和预防奶牛乳腺炎的发生具有一定的参考和应用价值。 相似文献
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分泌性免疫球蛋白A(SIgA)是由J链连接成的二聚体免疫球蛋白A(IgA)与分泌片段结合后形成的复合物。肠道内的SIgA是肠道黏膜免疫中的重要环节之一。SIgA可维持肠道黏膜内环境稳态,调控肠道内源微生态,并在黏膜上皮通过干扰病原体与上皮细胞受体结合,阻止病原体附着宿主细胞,影响病原菌毒力及免疫排异,从而阻止病原体的传播和进一步的感染,因而在免疫防御中起着非常重要的作用。营养因子(如脂肪酸、氨基酸、维生素等)在机体受到病原菌入侵或应激的情况下,可显著促进肠道SIgA的分泌,提高机体对病原菌的抵抗能力,在一定程度上改善应激动物的生产性能。 相似文献
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产肠毒素大肠杆菌(enterotoxigenic E.coli, ETEC)是引起新生和断奶仔猪腹泻(post-weaning diarrhea, PWD)的最重要的病原之一。ETEC进入肠道后与肠上皮细胞的相互作用既是该细菌致病的前提条件,也是激发宿主免疫反应的基础。本研究旨在分析ETEC感染猪肠上皮细胞后IL-17细胞因子表达变化,同时探索细胞因子在抵抗ETEC感染中的免疫防御机制。本研究采用猪肠上皮细胞系IPEC-J2和产肠毒素大肠杆菌标准株(C83901)为主要研究材料,通过RT-PCR、ELISA、免疫荧光及免疫印迹的方法分析了IL-17细胞因子及肠黏膜免疫防御相关基因在感染前后的变化。同时,进一步研究了IPEC-J2细胞中相关IL-17细胞因子刺激对肠黏膜防御相关基因的调控作用。结果表明,除IL-17D未检测到外,C83901能促进所有IL-17细胞因子mRNA的转录,尤其能显著上调IL-17A、IL-17C在基因和蛋白水平的表达。ETEC感染或者体外添加IL-17A/IL-17C有利于IPEC-J2细胞中黏蛋白(mucin-2)、紧密连接蛋白(claudin-1、 claudin-2)及防御素pBD-2的表达。结果提示,ETEC感染后,肠上皮细胞通过调节IL-17细胞因子的表达进而增强肠黏膜屏障功能以抵抗该细菌的入侵。 相似文献
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昆虫的先天免疫系统包括细胞免疫与体液免疫,它们共同作用于入侵的微生物,保护机体免受各种病原物的侵染。在漫长的进化中,病原微生物也发展了一系列策略应对昆虫的细胞与体液免疫。已有研究表明,病原物主要采取杀死血细胞,抑制细胞吞噬及结节形成,分泌毒力因子或利用体表的脂类成分等策略逃避昆虫细胞免疫;通过分泌蛋白酶降解抗菌肽,利用病原物细胞表面缺乏免疫诱导因子或抑制宿主抗菌肽的表达等策略应对昆虫体液免疫。本文结合相关研究成果,综述病原物抵抗昆虫免疫反应的一系列策略,阐释宿主昆虫同病原物之间免疫与抗免疫的动态互作过程。 相似文献
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为探讨羊胎盘转移因子注射液(goat placental transfer factor injection,GPTF)对动物非特异性免疫功能的影响,采用巨噬细胞吞噬鸡红细胞试验、碳廓清试验以及诱导靶细胞释放免疫介质试验,评价羊胎盘转移因子注射液对动物非特异性免疫调节的作用。结果显示,羊胎盘转移因子注射液具有促进巨噬细胞吞噬鸡红细胞功能、提高受试小鼠免疫系统廓清指数和吞噬指数以及增加巨噬细胞一氧化氮(NO)和白细胞介素-1(IL-1)分泌量的作用。试验结果表明,羊胎盘转移因子注射液具有增强动物机体非特异性免疫力的作用。 相似文献
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人与动物的微生物群落在黏膜器官分布最多。近年来的研究表明，噬菌体可黏附于黏膜表面从而抵抗病原菌的侵袭；同时，噬菌体还可跨黏膜转位进入机体，并随血液迁移至其他部位的组织器官，进一步引起机体的免疫反应，包括促炎和抗炎反应，从而对机体整体免疫产生影响。机体免疫系统可通过吞噬作用或产生特异性抗体来清除这些进入体内的噬菌体。目前，关于噬菌体转位及进入机体后与免疫系统互作的研究还比较缺乏。本文综述了近些年噬菌体黏附于黏膜并跨黏膜转位进入循环系统以及噬菌体进入机体后对整体免疫影响的研究进展，以期为今后更广泛深入地研究提供参考。 相似文献
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Bob Goodband Mike Tokach Steve Dritz Joel DeRouchey Jason Woodworth 《畜牧与生物技术杂志(英文版)》2014,(3):251-261
Immune system activation begins a host of physiological responses. Infectious agents are recognized by monocytes and macrophages which in turn stimulate cytokine production. It is the hormone-like factors called cytokines that orchestrate the immune response. The classic responses observed with immune system activation and cytokine production include： anorexia, fever, lethargy, recruitment of other immune cells, and phagocytosis. While production of immune system components is known to require some amino acids, increases in amino acid requirements are more than offset by the associated decrease in protein accretion and increased muscle protein degradation that also accompanies immune system activation. However, the biggest impact of cytokine production is a decrease in feed intake. Therefore, as feed intake decreases, the energy needed to drive protein synthesis is also decreased. This suggests that diets should still be formulated on a similar calorie：lysine ratio as those formulated for non-immune challenged pigs. The evidence is sparse or equivocal for increasing nutrient requirements during an immune challenge. Nutritionists and swine producers should resist the pressure to alter the diet, limit feed, or add expensive feed additives during an immune challenge. While immune stimulation does not necessitate changes in diet formulation, when pigs are challenged with non-pathogenic diarrhea there are potential advantages on gut health with the increased use of crystalline amino acids rather than intact protein sources （i.e., soybean meal）. This is because reducing crude protein decreases the quantity of fermentable protein entering the large intestine, which lowers post weaning diarrhea. It also lowers the requirement for expensive specialty protein sources or other protein sources such as soybean meal that present immunological challenges to the gut. The objective of this review is two-fold. The first is to discuss immunity by nutrition interactions, or lack thereof, and secondly, to review amino acid re 相似文献
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Immune system activation begins a host of physiological responses. Infectious agents are recognized by monocytes and macrophages which in turn stimulate cytokine production. It is the hormone-like factors called cytokines that orchestrate the immune response. The classic responses observed with immune system activation and cytokine production include: anorexia, fever, lethargy, recruitment of other immune cells, and phagocytosis. While production of immune system components is known to require some amino acids, increases in amino acid requirements are more than offset by the associated decrease in protein accretion and increased muscle protein degradation that also accompanies immune system activation. However, the biggest impact of cytokine production is a decrease in feed intake. Therefore, as feed intake decreases, the energy needed to drive protein synthesis is also decreased. This suggests that diets should still be formulated on a similar calorie:lysine ratio as those formulated for non-immune challenged pigs. The evidence is sparse or equivocal for increasing nutrient requirements during an immune challenge. Nutritionists and swine producers should resist the pressure to alter the diet, limit feed, or add expensive feed additives during an immune challenge. While immune stimulation does not necessitate changes in diet formulation, when pigs are challenged with non-pathogenic diarrhea there are potential advantages on gut health with the increased use of crystalline amino acids rather than intact protein sources (i.e., soybean meal). This is because reducing crude protein decreases the quantity of fermentable protein entering the large intestine, which lowers post weaning diarrhea. It also lowers the requirement for expensive specialty protein sources or other protein sources such as soybean meal that present immunological challenges to the gut. The objective of this review is two-fold. The first is to discuss immunity by nutrition interactions, or lack thereof, and secondly, to review amino acid requirement estimates for nursery pigs. 相似文献
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中性粒细胞是机体先天性免疫系统中的重要组成成分,是外周血中数量最多的免疫细胞,在非特异性免疫中至关重要,是构成机体内抵御微生物入侵的第一道防线。近年来,人们发现中性粒细胞除了经典的通过胞吞作用吞噬病原微生物、释放嗜天青颗粒及产生并分泌抑菌杀菌物质外,还具有抵抗微生物入侵的新机制--中性粒细胞细胞外诱捕网（neutrophil extracellular traps,NETs）。该机制主要通过活性氧和肽酰基精氨酸脱亚氨酶4等影响因子刺激中性粒细胞形成以DNA为骨架的网状结构,内含有多种蛋白酶,能非特异性捕获杀伤病原体,还能在机体某些疾病的产生和发展中起到协同作用。作者就NETs的形成、影响因素及与病原、疾病的相互关系作一概述,为进一步研究中性粒细胞的功能提供依据。 相似文献