弓形虫天然免疫影响因素的研究进展

弓形虫与宿主免疫系统之间存在着精妙的平衡,而弓形虫天然免疫在这个平衡中发挥着重要的作用,因此了解弓形虫天然免疫的影响因素对于控制疾病、开发有效的疫苗具有重要的意义。本文对影响天然免疫的8种主要因素进行了综述,主要包括IL-12、IFN-γ、NO、活性氧中间物、铁、色氨酸、p47GTP酶和抗炎性细胞因子。     

Duck MDA5 functions in innate immunity against H5N1 highly pathogenic avian influenza virus infections

Melanoma differentiation-associated gene 5 (MDA5) is an important intracellular receptor that recognizes long molecules of viral double-stranded RNA in innate immunity. To understand the mechanism of duck MDA5-mediated innate immunity, we cloned the MDA5 cDNA from the Muscovy duck (Cairina moschata). Quantitative real-time PCR analysis indicates that duck MDA5 mRNA was constitutively expressed in all sampled tissues. A significant increase of MDA5 mRNA was detected in the brain, spleen and lungs of ducks after infection with an H5N1 highly pathogenic avian influenza virus (HPAIV). We investigated the role of the predicted functional domains of MDA5. The results indicate the caspase activation and recruitment domain (CARD) of duck MDA5 had a signal transmission function through IRF-7-dependent signaling pathway. Overexpression of the CARD strongly activated the chicken IFN-β promoter and upregulated the mRNA expression of antiviral molecules (such as OAS, PKR and Mx), proinflammatory cytokines (such as IL-2, IL-6, IFN-α and IFN-γ, but not IL-1β and IL-8) and retinoic acid-inducible gene I (RIG-I)-like receptors (RLR) (RIG-I and LGP2) without exogenous stimulation. We also demonstrate the NS1 of the H5N1 HPAIV inhibited the duck MDA5-mediated signaling pathway in vitro. These results suggest that duck MDA5 is an important receptor for inducing antiviral activity in the host immune response of ducks.     

Aspects of the innate and adaptive immune responses to acute infections with BVDV

The immune response can be divided into innate and adaptive components that synergise to effect the clearance of pathogens. Recently, it has been realised that these arms of the immune system do not act independently, the magnitude and quality of the adaptive response is dependent on signals derived from the innate response. Here, we review the innate immune responses to bovine viral diarrhoea virus infections of cattle and relate these changes to immunosuppression and the subsequent development of the adaptive immune response.     

Interaction between innate immunity and porcine reproductive and respiratory syndrome virus

Innate immunity provides frontline antiviral protection and bridges adaptive immunity against virus infections. However, viruses can evade innate immune surveillance potentially causing chronic infections that may lead to pandemic diseases. Porcine reproductive and respiratory syndrome virus (PRRSV) is an example of an animal virus that has developed diverse mechanisms to evade porcine antiviral immune responses. Two decades after its discovery, PRRSV is still one of the most globally devastating viruses threatening the swine industry. In this review, we discuss the molecular and cellular composition of the mammalian innate antiviral immune system with emphasis on the porcine system. In particular, we focus on the interaction between PRRSV and porcine innate immunity at cellular and molecular levels. Strategies for targeting innate immune components and other host metabolic factors to induce ideal anti-PRRSV protection are also discussed.     

鸡球虫病免疫Ⅱ.免疫成功的要点和展望

采用免疫方法控制球虫病已经成为一种趋势，因为它可以从根本上免除球虫抗药性和肉蛋品药残带来的一系列问题。但是随着进入市场球虫病疫苗种类的增多也带来不少问题。球虫病疫苗有毒苗和弱毒苗之分，有三价、四价、五价、七价甚至八价之分。有商品肉鸡用的．也有种鸡用的。商家宣传也各有动人之处．令人眼花缭乱，不知何以适从?如果你了解了球虫和球虫病的重要特点，了解了球虫免疫的原理就能够释疑解惑，就能够理性地选择和正确使用球虫病疫苗。本文拟就上述几个方面介绍，以飨读者。     

Evolution of anaphylatoxins, their diversity and novel roles in innate immunity: insights from the study of fish complement

Anaphylatoxins are small molecules ( approximately 9 kDa) that are generated as a result of the activation of the complement system. These molecules play an important role in inflammation, and they are responsible for the activation of various innate and adaptive immune processes. The study of these important inflammatory molecules has been restricted to mammalian species so far. Recent studies have shown that teleost fish, unlike any other known animal species, contain multiple forms of the C3a anaphylatoxin, all of which are functionally active and play a prominent role in inducing superoxide production in fish leukocytes. The C5a anaphylatoxin has also been characterized in these animals, and like in mammals, it plays an important role in leukocyte chemotaxis and in triggering the respiratory burst of leukocytes. Interestingly, it has been shown that rainbow trout anaphylatoxins play an unexpected role in enhancing phagocytosis of particles. C5a and C3a receptors have recently been cloned and characterized in rainbow trout, suggesting that the duplication of these receptors from a common ancestor occurred before the emergence of teleosts. The studies derived from these molecules in teleost fish indicate that the basic structure and function of anaphylatoxins and their receptors, have been conserved for more than 300 million years.     

Cellular immunity against Theileria parva and its influence on parasite diversity

Theileria parva, a tick-borne parasite of African cattle, causes a fatal disease known as East Coast fever. Cattle that recover from the disease develop strong parasite-specific MHC-class I-restricted cytotoxic T-lymphocyte responses. Protection can be transferred between immune and na?ve calves in the CD8+ T cell fraction emanating from a responding lymph node. In vitro studies suggest that this response requires input from activated CD4+ T cells. The T parva life cycle involves developmental stages in mammalian and tick hosts and can lead to a number of different endemic scenarios for the disease. These range from a stable situation with high prevalence of herd infection, but low fatality rates, to a low prevalence/high fatality scenario. The impact on endemic stability is an important consideration for the design of vaccine implementation strategies. For subunit vaccines targeted at T parva schizonts, the principal issue in this regard is whether development of the piroplasm stage is blocked by immunity.     

Molecular approaches to elucidating innate and acquired immune responses to Babesia bovis, a protozoan parasite that causes persistent infection.

For many vector-transmitted protozoal parasites, immunological control of acute infection leads to a state of persistent infection during which parasitemias may cycle unnoticed in infected but otherwise clinically healthy animals. Achieving persistent infection is a strategy that favors parasitism, since both host and, therefore, parasite survive, and endemically infected animal populations provide a reservoir of parasites continually available for subsequent transmission. Examples of the major economically important protozoan pathogens that cause persistent infection in mammals include the related Theileria and Babesia parasites as well as Trypanosoma species. Control of acute infection and maintenance of clinical immunity against subsequent infection are determined by the interplay of innate and acquired immune responses. This review will focus on approaches taken to gain an understanding of the molecular basis for innate and acquired immunity against the hemoprotozoan parasite of cattle, Babesia bovis. Knowledge of mechanisms used by the parasite to survive within infected cattle from acute to persistent infection combined with definition of the correlates of protective immunity in cattle should be applicable to designing effective vaccines.     

Characterization of the innate and adaptive immunity to Salmonella enteritidis PT1 infection in four broiler lines

Four broiler lines were inoculated orally with Salmonella enteritidis phage type 1 at the age of 7 days (experiment A: lines 1 and 2) and at the age of 1 day (experiment B: lines 3 and 4). At various days post-infection chickens were sacrificed and the number of Salmonella in the caeca, liver, and spleen were determined. Furthermore, phagocytic activity, cellular immune responses, and humoral responses were determined using, respectively, single-cell suspensions of spleen or intestine and serum. In both experiments, similar trends were seen. Increased numbers of S. enteritidis were found in the caeca of lines 1 and 3, whereas at the same time a decreased colonization was found in the spleen and in the liver, as compared to lines 2 and 4. In the latter two lines, the phagocytic activity of the phagocytes was higher and the humoral responses were lower. Observations from this study suggest that lower activity of phagocytes and higher humoral activity prevent systemic S. enteritidis infection.     

Oxidative stress and innate immunity in feline patients with diabetes mellitus: the role of nutrition

This study was undertaken to test the hypothesis that oxidative stress is increased and neutrophil function is decreased in cats with diabetes mellitus (DM). Measures of oxidative stress and neutrophil function were evaluated in 20 control and 15 diabetic cats. Cats were then fed a diet designed specifically for feline diabetics (Purina DM Dietetic Management Feline Formula) for 8 weeks, after which all assays were repeated. Cats with DM had significantly less plasma superoxide dismutase (SOD) than control cats, consistent with a greater degree of oxidative stress in the DM group. Following 8 weeks of consuming a diabetes-specific diet glutathione peroxidase, an antioxidant enzyme increased significantly in both groups. Other parameters of oxidative stress, as well as neutrophil function, were similar between groups and did not change following dietary intervention. The DM cats were significantly older and heavier than the control cats, which may have contributed to differences in parameters of oxidative stress and levels of antioxidant enzymes between these groups, but the decreased level of SOD enzyme in the diabetic group would appear to support the continued development of targeted antioxidant supplementation for this cats with this disease.     

The involvement of the macrophage mannose receptor in the innate immune response to infection with parasite Trichinella spiralis

The macrophage mannose receptor (MR) is a pattern recognition receptor of the innate immune system that binds to microbial structures bearing mannose, fucose and N-acetylglucosamine on their surface. The MR can mediate endocytosis and phagocytosis, as well as activation of macrophages and antigen presentation. Since Trichinella spiralis antigens are rich in oligomannose residues, we investigated whether a mannose-recognizing receptor, such as the MR, participated in the host-parasite interaction. The results show that the MR (either on the surface of macrophages or in the purified form) recognizes and binds components of T. spiralis muscle larvae. The presence of parasites provoked activation of peritoneal macrophages, which was indicated by down-regulation of MR expression, and the stimulation of NO secretion. In vitro stimulation of macrophages with T. spiralis components resulted in increased NO and IL-6 production. However, while the MR was partially involved in stimulation of NO production, it did not mediate IL-6 secretion.     

Bulk milk ELISA and the diagnosis of parasite infections in dairy herds: a review

The bulk milk enzyme-linked immune sorbent assay (ELISA) is a rapid and inexpensive method of assessing herd exposure to pathogens that is increasingly being used for the diagnosis of parasite infections in dairy herds. In this paper, with the dairy herd health veterinarian in mind, we review the principles of the assay and the recent literature on the potential role of bulk milk ELISA for the diagnosis of ostertagiosis, fasciolosis, parasitic bronchitis due to cattle lung worm and neosporosis. It is generally accepted that assay results reflect exposure to the parasite rather than the presence of active infection. Bulk milk ELISA can be a useful tool for the veterinary practitioner as a component of a herd health monitoring programme or in the context of a herd health investigation. It can also play a role in regional or national surveillance programmes. However, the results need to be interpreted within the context of the herd-specific health management, the milk production pattern and the parasite life cycle.     

Lamb model in the study of immunity to enteropathogenic Escherichia coli infections

Three groups of ewes were vaccinated with formalin inactivated, whole cell, aluminum hydroxide adjuvanted bacterins prepared from capsulated enteropathogenic Escherichia coli (EEC). Lambs born to and suckling these ewes, compared with lambs of nonvaccinated control ewes, were highly resistant to homologous EEC challenge exposure. Lambs of ewes vaccinated with products prepared from K99 antigen-positive, noncapsulated E coli were highly resistant to heterologous EEC challenge exposure. In both cases, lambs of vaccinated ewes had significantly (P less than 0.005) less morbidity and mortality, fewer challenge inoculum-type E coli per rectal swab evaluation, and had superior weight gains over a 4-day period. Immunoglobulin assay of 122 lamb sera (collected 12 hours after birth) failed to reveal any correlation between serum immunoglobulin values and morbidity or mortality. When tested by plate agglutination technique, using whole cell antigens, or by reverse radial immunodiffusion, using purified capsular antigens, colostral whey samples of vaccinated ewes did not have increased capsular antibody titers. The K99 serum antibody values of K99 antigen-vaccinated ewes were markedly higher than were those of ewes vaccinated with other bacterins or of control ewes.     

Viral infections of the respiratory tract of calves: Local immunity

Local immunity is the first defence mechanism against viral respiratory infections in young calves. The great variety of different viruses which may infect the very young animal makes it necessary to develop effective local defences early in life. The best approach appears to be to increase the subjects' defences by using immunoadjuvants and interferon inducers. With this end in view we should increase our knowledge of the immune system of the calf respiratory tract, particularly with respect to specific immunoglobulins, and cells which mediate the immune response.

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Kurzfassung Die örtliche Immunität ist der erste Abwehrmechanismus gegen virale Erkrankungen der Atemwege beim jungen Kalb. Da sich diese sehr jungen Tiere mit den unterschiedlichsten Viren infizieren können, ist ein frühzeitiger Aufbau einer wirksamen örtlichen Abwehr unerlässlich; dieses Problem liesse sich vielleicht durch eine Steigerung der Abwehrkräfte bei den Tieren mit Immunitatsadjuvanten und Induktoren von Interferonbildung bewältigen. Die bisher vorliegenden Angaben über das Immunsystem der Atemwege beim Kalb (spezifische Immunglobuline, Immunzellen) müssen zu diesem Zweck noch vertieft werden.

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Resume L'immunité locale est le premier mécanisme de défense contre les affections réspiratoires virales du jeune veau. La grande diversité des virus pouvant infecter ces sujets très jeunes rend indispensable l'établissement précoce de défenses locales éfficaces; l'augmentation des défenses des sujets par l'emploi d'adjuvants de l'immunite et d'inducteurs d'interféron semble être le moyen d'aborder ce problème. Les données que nous possédons sur le système immunitaire de l'appareil réspiratoire du veau (immunoglobulines specifiques, cellules effectrices de l'immunité) doivent, dans ce but, être approfondies.

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Riassunto L'immunita locale e il primo meccanismo di difesa del giovane vitello contro le affezioni virali delle vie respiratorie. La grande diversità dei virus in grado di infettare soggetti molto giovani rende necessaria l'instaurazione precoce di difese locali efficaci; la soluzione migliore dovrebbe consistere nel potenziamento delle difese dei soggetti mediante adiuvanti dell'immunità e induttori di interferon. A tal fine e necessario approfondire i dati in nostro possesso sul sistema immunitario dell'apparato respiratorio del vitello (Immunoglobuline specifiche, immunociti).