共查询到18条相似文献，搜索用时 934 毫秒
1.
虽然旋毛虫抗肿瘤的分子机制仍不清楚,但旋毛虫具有抗肿瘤的效应却已被许多实验所证实。小鼠感染旋毛虫后对肿瘤细胞在体内的增殖或对移植进体内的肿瘤生长的抑制作用,其可能的机理是旋毛虫感染机体后激发宿主免疫网络系统促使机体产生多种免疫活性细胞因子,发挥特异性和非特异性抗肿瘤免疫功能;或者是由于寄生虫本身就具有能够分泌排泄一些抗肿瘤活性物质而发挥抗肿瘤效应;或者是由于寄生虫感染诱导肿瘤的基因表达发生变化而产生了抗肿瘤的效应。 相似文献
2.
《动物医学进展》2021,42(10)
羊链球菌病又称羊败血性链球菌病,是由C群马链球菌兽疫亚种引起的一种急性热性败血性传染病,病死率高达80%。人与发病羊只接触或食用被该菌污染的食品也可导致发病。近年来对羊链球菌病研究的热点之一是该菌的致病力及其致病机制。羊链球菌感染引起羊只发病的过程主要包括感染、黏附宿主细胞、入侵宿主细胞、损伤细胞和免疫逃避等过程。羊链球菌的毒力因子具有附着和侵袭机体细胞的作用,使细菌在羊只体内大量聚集,进而干扰机体的正常免疫功能引起疾病。论文综述了链球菌对宿主细胞的黏附作用以及链球菌对宿主的免疫逃避的机制,并阐述了链球菌在入侵机体细胞过程中发挥主要作用的毒力因子的种类、结构及其作用机制。通过对毒力因子的综述,为抑制毒力因子和防控羊链球菌病提供参考。 相似文献
3.
4.
一氧化氮抗寄生虫感染的研究进展 总被引：4，自引：1，他引：3
一氧化氮 (NO)在寄生虫感染过程中具有抑制或杀伤寄生虫与对宿主机体产生病理损伤的双重作用。机体内 NO的产生及抗寄生虫作用受细胞因子严格调节 ,巨噬细胞经 IFN-γ等细胞因子或脂多糖 L PS刺激后能大量表达 i N-OS,产生的 NO对球虫、弓形虫、锥虫、疟原虫、肝片吸虫、血吸虫等均有杀伤作用 ,NOS抑制剂的阻断则进一步表明 NO在寄生虫感染中的重要作用。近年来 ,关于 NO抗寄生虫感染、作用机制、NO合酶抑制剂和细胞因子影响等的研究报道日渐增多。文章就有关研究进展进行了综述 相似文献
5.
巴贝斯虫(Babesia)是一种寄生于宿主红细胞的顶复门寄生虫,硬蜱为其传播媒介。由于巴贝斯虫感染后可以引起人或动物严重的临床症状,甚至造成死亡,给畜牧业和人类健康带来了极大威胁。本文主要综合国内外近年的研究成果,从巴贝斯虫入侵红细胞并对红细胞造成的影响,宿主感染后机体免疫状态的变化,以及共感染等方面进行综述,旨在为巴贝斯虫相关研究提供参考。 相似文献
6.
3．1细胞因子抗寄生虫作用机制3．1．1激活巨噬细胞细胞因子主要是调节机体细胞免疫发挥抗虫作用,保护机体不被感染,巨噬细胞（MФ）是主要功能的承担者。寄生虫侵入机体,首先接触的肠道上皮组织,肠道上皮中的细胞有15％是淋巴细胞, 相似文献
7.
基质金属蛋白酶(MMPs)是一类锌依赖的内源蛋白酶,能降解几乎所有的细胞外基质。研究发现,寄生虫存在MMPs,且感染宿主后可引起宿主MMPs表达改变,从而破坏宿主组织屏障,利于寄生虫入侵,调节寄生虫感染后疾病的发展与转归等。鉴于MMPs在寄生虫疾病中的重要地位,本文重点综述了寄生虫疾病中宿主和寄生虫各自MMPs的研究现状,为寄生虫疾病中基质金属蛋白酶功能的系统性研究提供参考。 相似文献
8.
宿主感染寄生虫的一个显著表现是在感染期间不能发生有效的免疫反应。花生四烯酸代谢物可能在这一现象中起重要作用。大量的研究证据表明，寄生虫释放花生四烯酸代谢物；寄生虫花生四烯酸代谢物抑制宿主免疫细胞功能，从而有利于寄生虫的入侵和生存；寄生虫也激发宿主细胞产生花生四烯酸代谢物。 相似文献
9.
丝氨酸蛋白酶抑制剂在寄生虫入侵宿主的过程中发挥着关键作用,能够参与到入侵宿主、免疫逃避、炎症反应、凝血系统和细胞迁徙等过程。为了探讨两种丝氨酸蛋白酶抑制剂(Ts Ad SPI和Ts Ka SPI)对巨噬细胞所分泌炎性细胞因子的调节作用,应用实时荧光定量PCR技术对两种SPIs分别处理的小鼠巨噬细胞进行TNF-α、IL-1β、IL-6、IL-12、IL-10、TGF-βmRNA表达水平的检测。结果显示,Ts Ad SPI和Ts Ka SPI均可不同程度的抑制LPS活化的小鼠巨噬细胞促炎性细胞因子TNF-α、IL-1β、IL-6和IL-12 mRNA的表达水平。并且两种SPI均可不同程度的促进巨噬细胞抗炎性细胞因子IL-10和TGF-β的表达。表明这两种旋毛虫SPI可通过调节宿主巨噬细胞影响入侵时宿主的免疫应答。 相似文献
10.
动物肠道菌群与病原微生物感染关系的研究进展 总被引：2，自引：2，他引：0
动物肠道内寄居着大量微生物,通常被称为共生菌群。它们对动物的生长、代谢和免疫状态至关重要,还与许多疾病的发生密切相关。病毒、细菌和寄生虫感染都会使机体的肠道菌群发生紊乱,表现在益生菌丰度减少而有害菌丰度增加。其机制包括引发宿主的炎症反应和抑制机体的免疫细胞两方面。同样肠道菌群也会调控病原菌的感染,如肠道菌群对不同的病毒会产生颉颃或促进作用,对细菌和寄生虫分别产生抑制和促进作用。肠道菌群抑制病原菌的机制包括与病原菌竞争代谢产物和诱导宿主的免疫反应。肠道菌群促进病毒感染的机制包括3点,分别为提高病毒的稳定性及其与靶细胞的黏附作用、抑制机体免疫系统和刺激靶细胞的增殖。肠道菌群促进寄生虫感染的可能机制包括降低Th2细胞因子(如IL-4和IL-13)并提高调节性T细胞的表达频率。肠道菌群、病原微生物和宿主不断相互作用,形成一个动态的平衡关系,并在感染过程中不断进化。作者主要综述了病毒、细菌和寄生虫感染对动物肠道菌群的组成和丰度的影响,动物肠道菌群如何影响病毒、细菌和寄生虫的感染进程并分析相关机制,以期了解疾病的发病机理,为疫苗佐剂的研发及制定更有效的预防和治疗策略提供新视角和理论依据。 相似文献
11.
Meyerhoff RR Nighot PK Ali RA Blikslager AT Koci MD 《Comparative immunology, microbiology and infectious diseases》2012,35(1):63-69
The inducible nitric oxide synthase (iNOS) enzyme has long been recognized as a key mediator of innate immune responses to infectious diseases across the phyla. Its role in killing or inactivating bacterial, parasitic, and viral pathogens has been documented in numerous host systems. iNOS, and its innate immune mediator NO has also been described to have negative consequence on host tissues as well; therefore understanding the pathogenesis of any infectious agent which induces iNOS expression requires a better understanding of the role iNOS and NO play in that disease. Previous studies in our laboratory and others have demonstrated evidence for increased levels of iNOS and activity of its innate immune mediator NO in the intestine of turkeys infected with astrovirus. To begin to characterize the role iNOS plays in the innate immune response to astrovirus infection, we identified, characterized, developed tkiNOS specific reagents, and demonstrated that the intestinal epithelial cells induce expression of iNOS following astrovirus infection. These data are the first to our knowledge to describe the tkiNOS gene, and demonstrate that astrovirus infection induces intestinal epithelial cells to express iNOS, suggesting these cells play a key role in the antiviral response to enteric infections. 相似文献
12.
Unique characteristics of local responses in host resistance to mucosal parasitic infections 总被引：5，自引：0，他引：5
D Befus T Lee P Ernst T Egwang P McElroy J Gauldie J Bienenstock 《Veterinary parasitology》1986,20(1-3):175-194
13.
Kuehn CC Oliveira LG Santos CD Augusto MB Toldo MP do Prado JC 《Veterinary parasitology》2011,177(3-4):242-246
DHEA, a steroid hormone synthesized from cholesterol by cells of the adrenal cortex, plays an essential role in enhancing the host's resistance to different experimental infections. Receptors for this hormone can be found in distinct immune cells (especially macrophages) that are known to be the first line defense against Trypanosoma cruzi infection. These cells operate through an indirect pathway releasing nitric oxide (NO) and cytokines such TNF-α and IL-12 which in turn trigger an enhancement of natural killer cells and lymphocytes which finally secrete pro and anti-inflammatory cytokines. The effects of pre- and post-infection DHEA treatment on production of IL-12, TNFα and NO were evaluated. T. cruzi infected macrophages post treated with DHEA displayed enhanced concentrations of TNF-α, IL-12 and NO. Probably, the mechanisms that induced the production of cytokines by infected cells are more efficient when the immune system has been stimulated first by parasite invasion, suggesting that the protective role of DHEA is greater when administered post infection. 相似文献
14.
Innes EA Wright S Bartley P Maley S Macaldowie C Esteban-Redondo I Buxton D 《Veterinary immunology and immunopathology》2005,108(1-2):29-36
Infection with the protozoan parasite Neospora caninum is thought to be a major cause of reproductive failure in cattle worldwide. Cattle infected with the parasite are three to seven times more likely to abort compared to uninfected cattle. The parasite may be transmitted to cattle through the ingestion of oocysts that are shed in the faeces of acutely infected dogs (definitive host of N. caninum) or by congenital infection from mother to foetus via the placenta. Interestingly, transplacental transmission can occur over consecutive pregnancies and congenitally infected heifers can transmit the parasite to their own offspring. This repeated vertical transmission observed in naturally infected cattle suggests that cattle do not easily develop effective immunity to the parasite, presenting a significant challenge to the development of a control strategy based on vaccination. Neosporosis is a disease of pregnancy and studying the bovine maternal and foetal immune responses during pregnancy will help us to understand the change in the balance between the parasite and the host that may result in disease of the foetus. Studies in non-pregnant cattle and in murine models of infection have shown the importance of T-helper 1-type immune responses involving pro-inflammatory cytokines, such as IFNgamma and IL-12, in limiting intracellular multiplication of the parasite. During pregnancy, changes occur in the immune system allowing the mother to accept the foetal allograft. Research in other species has stressed the crucial role of T-helper 2-type cytokines at the materno-foetal interface in maintaining the pregnancy and regulating the potentially damaging effect of Th-1 responses. Studies in cattle have shown that cell proliferation and IFNgamma responses may be significantly down-regulated around mid-gestation. This may mean that cattle are less able to cope with N. caninum infection at this time and are more likely to transmit the parasite to the foetus. Another important factor is the gestational age and hence immuno-competence of the foetus at the time of infection. Early in gestation, N. caninum infection of the placenta and subsequently the foetus usually proves fatal, whereas infection occurring in mid to late pregnancy may result in the birth of a congenitally infected but otherwise healthy calf. Studies of foetal immune responses have shown that at 14 weeks of gestation, lymphocytes only respond to mitogen, while by 24 weeks (mid-gestation), they respond to antigen by proliferating and releasing IFNgamma. Clearly, there are several factors influencing the outcome of N. caninum infection in pregnancy: the timing, quantity and duration of parasitaemia, the effectiveness of the maternal immune response and the ability of the foetus to mount an immune response against the parasite. The challenge is to design a vaccine that will prevent foetal infection by N. caninum. This is likely to involve a fine balancing act with the immune system that will allow intervention in a manner that will tip the host-parasite balance in favour of the host without compromising the pregnancy. 相似文献
15.
Young AR Barcham GJ McWilliam HE Piedrafita DM Meeusen EN 《Veterinary immunology and immunopathology》2012,145(1-2):362-367
Galectins are increasingly recognised as important mediators of immune homeostasis and disease regulation, but comparatively little is known about their role in parasite infection. This study investigates the interaction between two ovine galectins, galectin-11 and galectin-14, and the parasitic liver fluke, F. hepatica. Galectin-14 was found in eosinophils infiltrating the tissue surrounding infected bile ducts and secreted in the connective tissue, while galectin-11 was specifically induced in epithelial cells of bile ducts from infected sheep. Strong nuclear staining was observed for galectin-11. Both galectins were found to be secreted into the bile fluid of parasite infected sheep, and were also detected in the excretory/secretory products of adult flukes, following their removal from the ovine host. Recombinant galectin-14, but not recombinant galectin-11, was found to bind specifically to the surface tegument of adult flukes in a carbohydrate dependent manner. This study shows for the first time that both galectin-14 and galectin-11 are produced in liver tissue after chronic liver fluke infection and that they can directly interact with the parasite in the bile ducts. Galectin-11 may also be involved in epithelial cell turnover and cancerogenesis. 相似文献
16.
Although rainbow trout fry mortality syndrome caused by the bacterium Flavobacterium psychrophilum is widespread in fish farms it is difficult to reproduce infection of rainbow trout in the laboratory using immersion exposure with bacterial suspensions. It has therefore been speculated that ectoparasites could act as enhancers of bacterial infections under natural conditions. In the present study rainbow trout fry were exposed to infections with F. psychrophilum (immersion for 30 min or 10 h) alone, exposed to the ectoparasitic monogenean Gyrodactylus derjavini alone or exposed to both pathogens in combination. Infection levels and host mortality were subsequently monitored to elucidate if the ectoparasitic monogeneans could enhance infection of fish with the bacterium. Immersion of fish in bacterial suspensions alone did not result in infection. Only one fish became infected with the bacterium and this fish belonged to the combination exposure group. The parasite populations increased differently in the various groups and it was found that host mortality was correlated to gyrodactylid infection levels (r=0.94) but not to bacterial exposure. The results emphasise the pathogenicity of the parasite G. derjavini, the relative resistance of intact fish to direct exposure to F. psychrophilum but provide only a weak indication of a possible enhancement of bacterial invasion due to ectoparasitic infections. It cannot be excluded that higher parasite burdens and/or prolonged immersion (more than 10 h) in bacterial suspensions may result in bacterial invasion. 相似文献
17.
Glass EJ 《Research in veterinary science》2001,70(1):71-75
The tick-borne protozoan parasite, Theileria annulata, causes an overwhelming disease in Friesian cattle, imported to improve productivity, in a large area of the world. The parasite invades bovine macrophages and induces aberrant changes which seem pivotal in triggering disease in na?ve susceptible animals: parasite infected cells acquire dendritic cell features and over-activate CD4+ and CD8+ T cells. Elevated levels of interferon-gamma (IFN-gamma) are induced and B cells are developmentally arrested in the light zone of germinal centres. Infected macrophages are refractory to the effects of IFN-gamma and indeed flourish in its presence. High levels of pro-inflammatory cytokines, as evinced by high acute phase protein responses, probably also play a role in pathology. However, animals can become immune to further challenge. Cellular immune responses involving macrophages, natural killer cells and CD8+ T cells play a major role in recovery and subsequent maintenance of immunity. The main target for immunity appears to be the parasite infected macrophage, as attenuated cell lines can protect and are used as vaccines. Cloned lines selected for low cytokine production protect with no associated pathological reactions. Theileria annulata causes a relatively mild disease in an indigenous breed of cattle, which is associated with lower acute phase protein responses (controlled by macrophage cytokines). Thus the initial host-parasite interactions must determine the balance between immunity and pathogenesis. New generation vaccines to T. annulata should both induce active immunity and suppress pathology. 相似文献
18.
寄生虫金属蛋白酶研究进展 总被引：2，自引：0，他引：2
金属蛋白酶（Metalloproteinase）是虫体活性中心依赖于金属离子的一类蛋白酶，在寄生虫中其分布非常广泛，功能涉及寄生虫营养摄取、细胞分化、对宿主的入侵以及免疫逃避等许多方面，一些金属蛋白酶还具有比较强的免疫原性。寄生虫金属蛋白酶的功能和作用的阐明，将为寄生虫病的免疫诊断和治疗以及新型生物制剂的开发开辟新的思路。本文综述了寄生虫金属蛋白酶的最新研究进展。 相似文献