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1.
The immunofluorescent antibody test and immunocytochemical method were employed to study the surface antigens of Angiostrongylus cantonensis obtained from infected rats, mice and guinea pigs. Positive results with intense fluorescence and brownish peroxidase staining were observed on the cuticular surface of A. cantonensis recovered from rats 22 days (late cerebral phase) and 34 days (lung phase) post-infection when tested with antisera against host (normal rat serum) antigens as well as crude extracts of A. cantonensis. However, host antigens were not observed on the surface of the nematode recovered from the brain of mice and guinea pigs 15 days post-infection. 相似文献
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T cells are required for an effective immune response against a wide range of pathogens and for the generation of immunological memory. T cell activation can be divided into two phases: an antigen-specific signal delivered through the T cell antigen receptor, and a costimulatory signal delivered through accessory molecules on the T cell surface. Following activation, T cells differentiate to acquire distinct effector functions depending on the costimulatory signal, cytokine environment, and the pathogen itself. Although CD28 has been identified as the dominant costimulatory molecule, several other molecules have been described as having a costimulatory function. This review will focus on recent evidence for the existence of alternate costimulatory molecules, and the differential roles they might play in the activation, development, and survival of T cells. 相似文献
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K B Tan 《Cytobios》1977,20(79-80):143-149
The uptake of simian virus 40 (SV40) by cells that are both non-permissive for virus replication and resistant to virus infection could be enhanced markedly by infecting the cells in presence of DEAE-dextran. Virus uptake by semi-permissive and permissive cells was also enhanced by DEAE-dextran. Optimum enhancement of virus uptake occurred at 100 microgram of DEAE-dextran per ml and under the conditions employed, the polycation was not toxic to cells. The increased cellular uptake of virus may result from the uptake of virus aggregates formed in the presence of DEAE-dextran. 相似文献
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Chytridiomycosis, the disease caused by Batrachochytrium dendrobatidis, is considered to be a disease exclusively of amphibians. However, B. dendrobatidis may also be capable of persisting in the environment, and non-amphibian vectors or hosts may contribute to disease transmission. Reptiles living in close proximity to amphibians and sharing similar ecological traits could serve as vectors or reservoir hosts for B. dendrobatidis, harbouring the organism on their skin without succumbing to disease. We surveyed for the presence of B. dendrobatidis DNA among 211 lizards and 8 snakes at 8 sites at varying elevations in Panama where the syntopic amphibians were at pre-epizootic, epizootic or post-epizootic stages of chytridiomycosis. Detection of B. dendrobatidis DNA was done using qPCR analysis. Evidence of the amphibian pathogen was present at varying intensities in 29 of 79 examined Anolis humilis lizards (32%) and 9 of 101 A. lionotus lizards (9%), and in one individual each of the snakes Pliocercus euryzonus, Imantodes cenchoa, and Nothopsis rugosus. In general, B. dendrobatidis DNA prevalence among reptiles was positively correlated with the infection prevalence among co-occurring anuran amphibians at any particular site (r = 0.88, p = 0.004). These reptiles, therefore, may likely be vectors or reservoir hosts for B. dendrobatidis and could serve as disease transmission agents. Although there is no evidence of B. dendrobatidis disease-induced declines in reptiles, cases of coincidence of reptile and amphibian declines suggest this potentiality. Our study is the first to provide evidence of non-amphibian carriers for B. dendrobatidis in a natural Neotropical environment. 相似文献
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Seasonal changes in the impact of parasites on hosts should result in seasonal changes in immune function. Since both ectoparasites and endoparasites time their reproduction to that of their hosts, we can predict that hosts have been selected to show an annual peak in their ability to raise an immune response during the reproductive season. We found large seasonal changes in immune function between the breeding and the nonbreeding season for a sample of temperate bird species. These changes amounted to a decrease in spleen mass from the breeding to the nonbreeding season by on average 18% across 71 species and a seasonal decrease in T-cell-mediated immunity by on average 33% across 13 species. These seasonal changes in immune function differed significantly among species. The condition dependence of immune function also differed between the breeding and the nonbreeding season, with individuals in prime condition particularly having greater immune responses during breeding. Analyses of ecological factors associated with interspecific differences in seasonal change of immune function revealed that hole-nesting species had a larger increase in immune function during the breeding season than did open nesters. Since hole nesters suffer greater reduction in breeding success because of virulent parasites than do open nesters, this seasonal change in immune function is suggested to have arisen as a response to the increased virulence of parasites attacking hole-nesting birds. 相似文献
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La Flamme AC MacDonald AS Pearce EJ 《Journal of immunology (Baltimore, Md. : 1950)》2000,164(5):2419-2426
The eggs of Schistosoma mansoni are strong inducers of a Th2 response, and previous work has shown that Ag-specific IL-6 is produced within 24 h after the injection of eggs into mice. Investigations to determine the role of IL-6 in orchestrating the early response to schistosome eggs have revealed that IL-12 is rapidly produced in lymph node cell cultures from egg-injected mice. This "early" IL-12 primes for the production of IL-6 and IFN-gamma, for in IL-12-/- mice egg injection fails to stimulate increased production of either of these cytokines. Furthermore, IL-6 also up-regulates IL-10 production which, together with IL-6, negatively regulates IL-12 and IFN-gamma production. Finally, IL-10 down-regulates the production of its inducer, IL-6. These data indicate that the anti-inflammatory role of IL-6 may be effected through negative regulation of type 1 (IFN-gamma) and type 1-associated (IL-12) cytokines either directly (by IL-6) or indirectly (through the induction of IL-10) and suggest that one mechanism by which eggs may support the development of Th2 responses is through the negative regulation of the type 1 response. 相似文献
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《BMJ (Clinical research ed.)》1977,1(6068):1048-1049
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Regualtion of the immune response to tumor antigens. I. Immunosuppressor cells in tumor-bearing hosts. 总被引:17,自引:0,他引:17
A/Jax mice were rendered immune to the syngeneic and transplantable methylcholanthrene-induced Sarcoma 1509a by the surgical removal of the tumor 7 days after implantation; subsequent injection i.v. transfer of 10(7) to 10(8) washed thymus or spleen cells of tumor-bearing animals (TBA) to immune animals significantly inhibited the rejection of the tumor; this suppressive effect was entirely abolished by the treatment of these lymphocytes with anti-theta serum or anti-thymocyte serum (ATS) and complement before adoptive transfer. On the other hand, an equal number of thymus or spleen cells of normal animals or of animals bearing an unrelated tumor had no suppressive effect. Treatment of normal syngeneic animals with ATS after tumor cell inoculation or splenectomy of TBA resulted in the suppression of the tumor growth. The serum of TBA had no effect on tumor growth in immune syngeneic mice. Together these results suggest that TBA possess immunosuppressor T cells regulating negatively their immune response to the tumor. 相似文献
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Adenovirus (AdV) is a common cause of respiratory illness in both children and adults. Respiratory symptoms can range from those of the common cold to severe pneumonia. Infection can also cause significant disease in the immunocompromised and among immunocompetent subjects in close quarters. Fortunately, infection with AdV in the normal host is generally mild. This is one reason why its initial use as a gene-therapy vector appeared to be so promising. Unfortunately, both innate and adaptive responses to the virus have limited the development of AdV vectors as a tool of gene therapy by increasing toxicity and limiting duration of transgene expression. This article will focus on the innate immune response to infection with wild-type AdV and exposure to AdV gene-therapy vectors. As much of the known information relates to the pulmonary inflammatory response, this organ system will be emphasized. This article will also discuss how that understanding has led to the creation of new vectors for use in gene therapy. 相似文献
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Canine adenovirus vectors for lung-directed gene transfer: efficacy, immune response, and duration of transgene expression using helper-dependent vectors
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A major hurdle to the successful clinical use of some viral vectors relates to the innate, adaptive, and memory immune responses that limit the efficiency and duration of transgene expression. Some of these drawbacks may be circumvented by using vectors derived from nonhuman viruses such as canine adenovirus type 2 (CAV-2). Here, we evaluated the potential of CAV-2 vectors for gene transfer to the respiratory tract. We found that CAV-2 transduction was efficient in vivo in the mouse respiratory tract, and ex vivo in well-differentiated human pulmonary epithelia. Notably, the in vivo and ex vivo efficiency was poorly inhibited by sera from mice immunized with a human adenovirus type 5 (HAd5, a ubiquitous human pathogen) vector or by human sera containing HAd5 neutralizing antibodies. Following intranasal instillation in mice, CAV-2 vectors also led to a lower level of inflammatory cytokine secretion and cellular infiltration compared to HAd5 vectors. Moreover, CAV-2 transduction efficiency was increased in vitro in human pulmonary cells and in vivo in the mouse respiratory tract by FK228, a histone deacetylase inhibitor. Finally, by using a helper-dependent CAV-2 vector, we increased the in vivo duration of transgene expression to at least 3 months in immunocompetent mice without immunosuppression. Our data suggest that CAV-2 vectors may be efficient and safe tools for long-term clinical gene transfer to the respiratory tract. 相似文献
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Gog J Woodroffe R Swinton J 《Proceedings. Biological sciences / The Royal Society》2002,269(1492):671-676
Conventional applications of metapopulation theory have suggested that increasing migration between patches is usually good for conservation. A recent analysis by Hess has pointed out a possible exception to this: when infectious disease is present, migration may promote disease spread and therefore increase local extinction. We extend Hess's model to discuss this problem: when infections have spilled over from more abundant alternative hosts. This is often the case for species of conservation concern, and we find that Hess's conclusions must be substantially modified. We use deterministic analytic and stochastic numerical approaches to show that movement between patches will rarely have a negative impact, even when the probability of external infection is low. 相似文献
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Parasite biodiversity and host defenses: chewing lice and immune response of their avian hosts 总被引:9,自引:0,他引:9
Antagonistic host-parasite interactions lead to coevolution of host defenses and parasite virulence. Such adaptation by parasites to host defenses may occur to the detriment of the ability of parasites to exploit alternative hosts, causing parasite specialization and speciation. We investigated the relationship between level of anti-parasite defense in hosts and taxonomic richness of two chewing louse suborders (Phthiraptera: Amblycera, Ischnocera) on birds. While Amblyceran lice tend to occur in contact with host skin, feed on host skin and chew emerging tips of developing feathers to obtain blood, Ischnoceran lice live on feathers and feed on the non-living keratin of feather barbules. We hypothesized that Amblyceran abundance and richness would have evolved in response to interaction with the immune system of the host, while Ischnoceran taxonomic richness would have evolved independently of immunological constraints. In an interspecific comparison, the abundance of Ischnocerans was positively related to host body size, while host body mass and Ischnoceran taxonomic richness accounted for the abundance of Amblycerans. Amblyceran taxonomic richness was predicted by the intensity of T-cell mediated immune response of nestling hosts, while the T-cell response of adults had no significant effect. In contrast, Ischnoceran taxonomic richness was not predicted by host T-cell responses. These results suggest that the taxonomic richness of different parasite taxa is influenced by different host defenses, and they are consistent with the hypothesis that increasing host allocation to immune defense increases Amblyceran biodiversity.Electronic Supplementary Material Supplementary material is available for this article at 相似文献
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We examine the constraints and the feasibility of field experiments involving the release of genetically modified (GM) pathogen-resistant mosquitoes, and whether there are alternatives to the research line based on the production of refractory strains. The production of a GM mosquito strain characterized instead by obligate primiparous and parous autogeny and by disrupted host seeking and biting behaviour could make the release more acceptable by the general public. Genetic transformation should act in this case to reverse some of the essential steps of the evolutionary process that gave rise to hematophagy. The replacement strategy could be based on the mass release of both sexes in a well defined ecological niche made temporarily empty of the natural population, thus avoiding the problems related to the need of sexual competitiveness of the released material. This option is encouraged by the growing evidence that competitive exclusion mechanisms influence the pattern of distribution of different taxa within Anopheles gambiae s.s. and by the fact that the plesiomorphic characteristics of vitellogenesis without a blood meal (autogeny), which exploits fat body reserve accumulated during larval life and food other than blood in adult life, persist as genetic variants in various hematophagous insect groups, and it has been found secondarily fixed in others showing stable reversions to primiparous and parous autogeny. If this has been the result of natural selection, then the artificial production of non-biting mosquito strains, by selection and/or transgenesis, should be feasible. 相似文献
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Interleukin 12: a potential link between nerve cells and the immune response in inflammatory disorders. 总被引:4,自引:0,他引:4
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L. A. Turka R. E. Goodman J. L. Rutkowski A. A. Sima A. Merry R. S. Mitra T. Wrone-Smith G. Toews R. M. Strieter B. J. Nickoloff 《Molecular medicine (Cambridge, Mass.)》1995,1(6):690-699
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Regulation of the immune response to tumor antigens. II. The nature of immunosuppressor cells in tumor-bearing hosts. 总被引:12,自引:0,他引:12
Immunosuppressor (IS) cells were found to be generated in tumor-bearing animals (TBA) within 24 hr after inoculation of tumor cells of the methylcholanthrene-induced Sarcoma 1509a and appeared to persist in the hosts as long as the tumor was progressing. However, IS cells disappeared with 5 days after extirpation of the tumor. Increasing doses of thymus cells of TBA increased the degree of suppression of tumor rejection in immune syngeneic animals. Ten million thymus cells of TBA were capable of suppressing significantly the tumor rejection. The IS cells were detected in the thymus, spleens, and draining lymph nodes, as well as in bone marrow of TBA, but could not be detected in the peripheral circulating blood. Since immunosuppressive activity of bone marrow cells from TBA was entirely abolished by the in vitro treatment of the cells with anti-theta serum and complement, the observed immunosuppression appears to be mediated by the T cell population. 相似文献
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J K Jancovich E W Davids A Seiler B L Jacobs J P Collins 《Diseases of aquatic organisms》2001,46(3):159-163
Ambystoma tigrinum virus (ATV) is a lethal virus originally isolated from Sonora tiger salamanders Ambystoma tigrinum stebbinsi in the San Rafael Valley in southern Arizona. USA. ATV is implicated in several salamander epizootics. We attempted to transmit ATV experimentally to fish and amphibians by injection, water bath exposure, or feeding to test whether ATV can cause clinical signs of infection or be recovered from exposed individuals that do not show clinical signs. Cell culture and polymerase chain reaction of the viral major capsid protein gene were used for viral detection. Salamanders and newts became infected with ATV and the virus was recovered from these animals, but virus could not be recovered from any of the frogs or fish tested. These results suggest that ATV may only infect urodeles and that fish and frogs may not be susceptible to ATV infection. 相似文献
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The network theory of the immune response proposed by Jerne has stimulated considerable interest, and a large body of evidence supporting this theory has been produced. However, the structure and function of the immune network have not been precisely defined. In this paper we develop several criteria to compare alternative systems on the basis of function and then examine mathematically the functional significance of two interactions involving suppressor regulation of effector lymphocytes in normal immune responses. The interactions examined in detail are suppressor regulation of the production of effector lymphocytes and suppressor regulation of the clearance of effector lymphocytes. The approach is one that has been used previously to predict and characterize function and design in biochemical and genetic control systems. The results of our analysis suggest that an immune system with suppressor regulation of the production of effector lymphocytes is equal or superior to a system without this form of regulation on the basis of all of the criteria examined in this study. Also, a system with regulation of the clearance of effector lymphocytes can be equal or superior to a system without this form of regulation on the basis of six criteria, but it is inferior to such a system on the basis of one criterion. Furthermore, a system with regulation of both production and clearance of effector lymphocytes is equal or superior to a system without regulation of production on the basis of all of the criteria and can be equal or superior to a system without regulation of clearance on the basis of six criteria, but it is inferior to such a system on the basis of one criterion. Similar conclusions hold for the comparison of systems in which regulation is exerted upon the production or clearance of effector molecules, such as antibodies or free radicals. 相似文献
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Canine adenovirus vectors: an alternative for adenovirus-mediated gene transfer 总被引:7,自引:0,他引:7
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Preclinical studies have shown that gene transfer following readministration of viral vectors is often inefficient due to the presence of neutralizing antibodies. Vectors derived from ubiquitous human adenoviruses may have limited clinical use because preexisting humoral and cellular immunity is found in 90% of the population. Furthermore, risks associated with the use of human adenovirus vectors, such as the need to immunosuppress or tolerize patients to a potentially debilitating virus, are avoidable if efficient nonhuman adenovirus vectors are feasible. Plasmids containing recombinant canine adenovirus (CAV) vectors from which the E1 region had been deleted were generated and transfected into a CAV E1-transcomplementing cell line. Vector stocks, with titers greater than or equal to those obtained with human adenovirus vectors, were free of detectable levels of replication-competent CAV and had a low particle-to-transduction unit ratio. CAV vectors were replication defective in all cell lines tested, transduced human-derived cells at an efficiency similar to that of a comparable human adenovirus type 5 vector, and are amenable to in vivo use. Importantly, 49 of 50 serum samples from healthy individuals did not contain detectable levels of neutralizing CAV antibodies. 相似文献