DNA immunization effectively induces humoral and cell-mediated immunity to numerous infectious diseases. To investigate the potential use of DNA-based vaccine for induction of bovine rotavirus (BRV) ...specific immune responses, I characterized the immune responses induced by plasmids encoding 2 important neutralizing antigens, VP4 and VP7, in a murine model. Immunization with plasmids encoding VP4 protein did not induced detectable BRV-specific antibody responses in mice. However, it induced BRV-specific cell-mediated immune responses characterized by an increased number of BRV-specific cytokine secreting cells in the spleens of immunized mice. In addition, the immunized animals were primed for both antibody and cellular immune responses following BRV boost. However, plasmids encoding VP4 did not boost the BRV-specific immune responses in the BRV-primed mice. The BRV-VP7 is also considered an important antigen for inducing protective immunity against rotaviruses. However, this study indicated that the VP7, either by itself or in the context of viral particle, was poorly immunogenic in mice. This project then explored several approaches to enhance the immunogenicity of the VP7 protein when expressed by the plasmid. These approaches included: (i) enhancing the level of gene expression by modifying the expression cassette of the plasmids; (ii) changing the cellular localization of the plasmid-expressed protein; (iii) co-administration of plasmids encoding VP4 and VP7; (iv) creating plasmids encoding a deletion mutant of VP7; and (v) construction of plasmids encoding chimeric proteins of VP7 and complement C3d or bovine herpes virus-1 glycoprotein D (BHV-1 gD). The results from these studies demonstrated that cellular localization and nature of the VP7 antigen could greatly influence the immunogenicity of the plasmid-expressed antigen and the pattern of immune responses in immunized mice. Plasmids encoding membrane-bound VP7 induced the best BRV-specific immune responses, following BRV boost or in BRV-primed mice, when compared with the authentic and the secretory versions. In addition, the plasmid encoding a deletion mutant VP7, induced predominantly BVR-specific IL-4 production. Strategies that had previously been shown to enhance the immunogenicity of protein antigens were also examined. However, different outcomes were observed when these strategies were applied to plasmid immunization. First, addition of the C3d gene into the expression cassette which encoded antigen-C3d chimeras inhibited the induction of both humoral and cell-mediated, antigen-specific immune responses. Secondly, co-expression of the gD molecule as a gD-VP7 chimera enhanced the level of BRV-specific antibody responses following viral boost or in the BRV-primed mice. These results with the gD protein suggested an alternative approach for improving the immunogenicity of poorly immunogenic antigens. None of the plasmids used in this study induced BRV-specific antibody responses following a primary immunization. However, immunological activity was evident following BRV administration, either prior to or following plasmid immunization. Each plasmid induced a distinct pattern of immune responses in both naive and BRV-primed mice. These investigations demonstrated specific ways that DNA immunization could be modified to modulate the outcome of BRV-specific immune responses. (Abstract shortened by UMI.)
Activation of the immune system is regulated through several mechanisms, within the system itself and by other body systems, in order to maintain disease resistance, and prevent immune-mediated ...disorders within the host. It is well accepted that the immunological, physiological, behavioral, and psychological state of an animal are closely linked and the factors affecting one feature of the network can influence the rest of the system. In recent years, our understanding of the interactions between the neuroendocrine network (i.e. the hypothalamicpituitary-adrenal axis, HPA) and immune-mediated inflammatory reactions has expanded enormously. This article outlines the nature of the immuno-neuroendocrine network and the implications of these interactions on swine health management strategies. In addition, various factors including stress, nutrition, genetics, the cost of immune activation and disease resistance will be explored under the context of the immune-neuroendocrine network.
Polynucleotide immunization has been described as the Third Revolution in Vaccinology. Early studies suggest the potential benefits of this form of immunization including: long-lived immunity, a ...broad-spectrum of immune responses (both cell mediated immunity, and humoral responses) and the simultaneous induction of immunity to a variety of pathogens through the use of multivalent vaccines. Using a murine model, we studied methods to enhance and direct the immune response to polynucleotide vaccines. We demonstrated the ability to modulate the magnitude and direction of the immune response by co-administration of plasmid encoded cytokines and antigen. Also, we clearly demonstrated that the cellular components (cytosolic, membrane-anchored, or extracellular) to which the expressed antigen is delivered determines the types of immune responses induced. Since induction of immunity at mucosal surfaces (route of entry for many pathogens) is critical to prevent infection, various methods of delivering polynucleotide vaccines to mucosal surfaces have been attempted and are described. Expansion of studies in various species, using natural models, should be extremely helpful in demonstrating the universality of this approach to immunization and more importantly, accurately identify parameters that are critical for the development of protective immunity.
Classical swine fever virus (CSFV), serum neutralizing antibody titers of 854 sows were determined using a neutralizing peroxidase linked assay (NPLA). Blood samples were collected one-week ...post-partum from 1st-6th parity sows, from 30 swine fever-free farms. The farms were divided according to their vaccination programs, 10 farms for each program. Program a sows had been vaccinated 3 weeks pre-partum (288 samples). Program B sows had been vaccinated 3 weeks post-partum (276 samples). Program C sows had been vaccinated 3 times/year (290 samples). The means log2 CSFV antibody titer of the sows in programs A, B, C were 6.59+-1.88, 5.72+-2.04 and 6.61+-2.04 respectively. Serum samples from 1 week old (1,924 samples) and 3 week old piglets (1,809 samples) born to the sows using the vaccination programs (A, B, C), from the 15 farms were collected and their CSFV maternal derived antibody titres were determined. The mean log2 of the maternal derived, antibody titers in the piglets was seen to decrease with a half-life of approximately two weeks. The correlation between serum neutralizing antibody titers in the sows and their piglets was demonstrated by r**(2)=0.22. Our results showed that all the three vaccination programs provided the protective levels of antibody. Furthermore, it suggests that the profiles of the CSFV specific, neutralizing antibody titers in the sows can be used as a guideline for planning a classical swine fever vaccination program for their piglets.
Immunization with naked plasmid DNA effectively induces both humoral and cell-mediated immunity to vaccine antigens and can confer protection against numerous infectious diseases. To explore the ...potential use of DNA immunization to induce rotavirus-specific immune responses, we used plasmid DNA encoding the VP4 gene of bovine rotavirus (BRV). Intrasmuscular injection of the plasmid encoding the VP4 gene into C57BI/6 mice induced cell-mediated immunity as measured by cytokine production. Although DNA immunization did not induce a detectable BRV-specific antibody response, DNA-immunized animals were primed for antibody production and a cellular immune response. Following viral inoculation, the immunized animals displayed an enhanced number of BRV-specific antibody-secreting cells and cytotoxic activity. The immune response induced by DNA immunization alone or followed by viral inoculation was biased toward IFN-gamma production (Th1-like). CD4+ lymphocytes were the major source of IFN-gamma production in the spleen following DNA immunization. In contrast, a balanced cytokine production was observed in the spleens of animals receiving whole virus. These experiments showed that DNA immunization with a gene encoding the VP4 protein of BRV stimulated a Th1-like immune response in mice, and this bias in the immune response persisted following exposures to whole virus.
Semiquantitative analysis of IL-10 production in broncho-alveolar lavage leukocytes of PRRSV infected pigs Permsak Thanawang(Chulalongkorn University, Bangkok (Thailand). Faculty of Veterinary Sciences); Chanida Yamkleebbua(Chulalongkorn University, Bangkok (Thailand). Faculty of Veterinary Sciences); Kritkong Shiyun(Chulalongkorn University, Bangkok (Thailand). Faculty of Veterinary Sciences) ...
Wētchasān sattawaphāet,
31 Mar 2004
Journal Article
Recenzirano
Semi-quantitative analysis of the interleukin 10(IL-10) in bronchoalveolar lavage cells (BALC), from pigs challenged with porcine reproductive and respiratory syndrome virus (PRRSV), was undertaken ...in this study. Twenty-one, three weeks old, crossbred pigs from a PRRSV-free commercial farm were separated into three groups, a control, non-infected group (3 pigs/group), and 2 groups (9 pigs/group), the first inoculated with a Thai-isolated European (O2SB3) strain and the second a Thai-isolated, North American (O1NP1) PRRSV strain. BALC were isolated from three infected pigs and one control on days 5, 9 and 15 post infection (DPI). The levels of IL-10 production in BALC were assessed by RT-multiplex PCR and immunofluorescent assay (IFA). In addition, the BALC were stained and subjected to a differential count. Both groups of PRRSV-infected pigs showed significant upregulation of the increase in IL-10 gene expression and IL-10 positive cells in the BALC after 9 DPI. Both PRRSV strains induced comparable levels of IL-10 production in the infected pigs. Furthermore, the enhanced IL-10 production was observed concurrently with an increased lymphocyte population in BALC.
