ovalbumin and Salmonella-Infections--Animal

Ideal potential vaccine adjuvants to stimulate a Th1 immune response are urgently needed to control intracellular infections in clinical applications. Telocinobufagin (TBG), an active component of Venenum bufonis, exhibits immunomodulatory activity. Therefore, we investigated whether TBG enhances the Th1 immune response to ovalbumin (OVA) and formalin-inactivated Salmonella typhimurium (FIST) in mice. TBG augmented serum OVA- and FIST-specific IgG and IgG2a and the production of IFNγ by antigen-restimulated splenocytes. TBG also dramatically enhanced splenocyte proliferative responses to concanavalin A, lipopolysaccharide, and OVA and substantially increased T-bet mRNA levels and the CD3(+)/CD3(+)CD4(+)/CD3(+)CD8(+) phenotype in splenocytes from OVA-immunized mice. In in vivo protection studies, TBG significantly decreased the bacterial burdens in the spleen and prolonged the survival time of FIST-immunized mice challenged with live S. typhimurium. In vivo neutralization of IFNγ with anti-IFNγ mAbs led to a significant reduction in FIST-specific IgG2a and IFNγ levels and in anti-Salmonella effect in TBG/FIST-immunized mice. In conclusion, these results suggest that TBG enhances a Th1 immune response to control intracellular infections.

Topics: Animals; Bufanolides; Cytokines; Female; Formaldehyde; GATA3 Transcription Factor; Immunization; Immunoglobulin G; Mice, Inbred ICR; Nuclear Receptor Subfamily 1, Group F, Member 3; Ovalbumin; RNA, Messenger; Salmonella Infections, Animal; Salmonella typhimurium; Spleen; T-Box Domain Proteins; Th1 Cells

Invasive Salmonella infection is an important health problem that is worsening because of rising antimicrobial resistance and changing Salmonella serovar spectrum. Novel vaccines with broad serovar coverage are needed, but suitable protective antigens remain largely unknown. Here, we tested 37 broadly conserved Salmonella antigens in a mouse typhoid fever model, and identified antigen candidates that conferred partial protection against lethal disease. Antigen properties such as high in vivo abundance or immunodominance in convalescent individuals were not required for protectivity, but all promising antigen candidates were associated with the Salmonella surface. Surprisingly, this was not due to superior immunogenicity of surface antigens compared to internal antigens as had been suggested by previous studies and novel findings for CD4 T cell responses to model antigens. Confocal microscopy of infected tissues revealed that many live Salmonella resided alone in infected host macrophages with no damaged Salmonella releasing internal antigens in their vicinity. In the absence of accessible internal antigens, detection of these infected cells might require CD4 T cell recognition of Salmonella surface-associated antigens that could be processed and presented even from intact Salmonella. In conclusion, our findings might pave the way for development of an efficacious Salmonella vaccine with broad serovar coverage, and suggest a similar crucial role of surface antigens for immunity to both extracellular and intracellular pathogens.

Topics: Animals; Antigens, Bacterial; Antigens, Surface; CD4-Positive T-Lymphocytes; Cross Protection; Epitopes; Female; Macrophages; Mice; Mice, Inbred BALB C; Ovalbumin; Salmonella Infections, Animal; Salmonella typhi; Salmonella typhimurium; Salmonella Vaccines; Typhoid Fever

Inducible costimulator (ICOS) is expressed on activated T cells and plays a key role in sustaining and enhancing the effector function of CD4 T cells. Given the function of this molecule in sustaining T-cell responses, we reasoned that ICOS might play an important role in a prolonged infection model, such as Salmonella infection of mice. To test this hypothesis, wild-type (WT) and ICOS-deficient (ICOS-/-) mice were infected systemically with a Salmonella enterica serovar Typhimurium strain expressing the chicken ovalbumin gene (Salmonella-OVA). ICOS-/- mice exhibited greater splenomegaly than WT mice and showed delayed bacterial clearance. The acquired immune response in this model was slow to develop. Maximal T-cell responses to Salmonella-OVA were detected at 3 weeks postinfection in both WT and ICOS-/- mice. CD4 T-cell-dependent gamma interferon production and a class switch to immunoglobulin G2a were severely reduced in ICOS-/- mice. ICOS-/- mice also exhibited a substantial defect in antigen-specific CD8 T-cell responses. In vitro, the effect of anti-ICOS on CD8 T-cell division was greater when CD8 T cells rather than CD4 T cells expressed ICOS, suggesting that the in vivo effects of ICOS on CD8 T cells could be direct. Taken together, these studies show that ICOS plays a critical role in control of Salmonella infection in mice, with effects on antibody, Th1, and CD8 T-cell responses.

Topics: Animals; Antibodies, Bacterial; Antigens, Differentiation, T-Lymphocyte; CD4-Positive T-Lymphocytes; CD8-Positive T-Lymphocytes; Disease Models, Animal; Inducible T-Cell Co-Stimulator Protein; Mice; Ovalbumin; Salmonella Infections, Animal; Salmonella typhimurium; Splenomegaly; Th1 Cells

Ag presentation to CD8(+) T cells often commences immediately after infection, which facilitates their rapid expansion and control of infection. Subsequently, the primed cells undergo rapid contraction. We report that this paradigm is not followed during infection with virulent Salmonella enterica, serovar Typhimurium (ST), an intracellular bacterium that replicates within phagosomes of infected cells. Although susceptible mice die rapidly (approximately 7 days), resistant mice (129 x 1SvJ) harbor a chronic infection lasting approximately 60-90 days. Using rOVA-expressing ST (ST-OVA), we show that T cell priming is considerably delayed in the resistant mice. CD8(+) T cells that are induced during ST-OVA infection undergo delayed expansion, which peaks around day 21, and is followed by protracted contraction. Initially, ST-OVA induces a small population of cycling central phenotype (CD62L(high)IL-7Ralpha(high)CD44(high)) CD8(+) T cells. However, by day 14-21, majority of the primed CD8(+) T cells display an effector phenotype (CD62L(low)IL-7Ralpha(low)CD44(high)). Subsequently, a progressive increase in the numbers of effector memory phenotype cells (CD62L(low)IL-7Ralpha(high)CD44(high)) occurs. This differentiation program remained unchanged after accelerated removal of the pathogen with antibiotics, as majority of the primed cells displayed an effector memory phenotype even at 6 mo postinfection. Despite the chronic infection, CD8(+) T cells induced by ST-OVA were functional as they exhibited killing ability and cytokine production. Importantly, even memory CD8(+) T cells failed to undergo rapid expansion in response to ST-OVA infection, suggesting a delay in T cell priming during infection with virulent ST-OVA. Thus, phagosomal lifestyle may allow escape from host CD8(+) T cell recognition, conferring a survival advantage to the pathogen.

Topics: Animals; Antigen Presentation; CD8-Positive T-Lymphocytes; Cell Differentiation; Chronic Disease; Epitopes, T-Lymphocyte; Female; Immunologic Memory; Immunophenotyping; Listeria monocytogenes; Male; Mice; Mice, Inbred C57BL; Mice, Transgenic; Ovalbumin; Salmonella Infections, Animal; Salmonella typhimurium; Time Factors; Virulence

STM1 is an aro A(-) attenuated mutant of Salmonella enterica serovar Typhimurium, and is a well-characterised vaccine strain available to the livestock industry for the prevention of salmonellosis in chickens. This strain has potential for heterologous antigen delivery, and here we show that the strain can be used to deliver a model antigen, ovalbumin, to immune cells in vitro and in vivo. Two plasmid constructs expressing the ovalbumin gene were utilised, one of which uses a prokaryotic promoter and the other the CMV promoter (DNA vaccine). In vitro, STM1 carrying ovalbumin-encoding plasmids was able to invade dendritic cells and stimulate a CD8(+) cell line specific for the dominant ovalbumin epitope, SIINFEKL. In vivo, spleen cells were responsive to SIINFEKL after vaccination of mice with ovalbumin-encoding plasmids in STM1, and finally, humoral responses, including IgA, were induced after vaccination.

Topics: Animals; Antigens, Bacterial; Bacterial Vaccines; Cell Line; Genetic Vectors; In Vitro Techniques; Mice; Mice, Inbred C57BL; Ovalbumin; Plasmids; Salmonella Infections, Animal; Salmonella typhimurium

The present study was initiated to gain insight into the interaction between splenic dendritic cells (DC) and Salmonella enterica serovar Typhimurium in vivo. Splenic phagocytic cell populations associated with green fluorescent protein (GFP)-expressing bacteria and the bacterium-specific T-cell response were evaluated in mice given S. enterica serovar Typhimurium expressing GFP and ovalbumin. Flow cytometry analysis revealed that GFP-positive splenic DC (CD11c+ major histocompatibility complex class II-positive [MHC-II+] cells) were present following bacterial administration, and confocal microscopy showed that GFP-expressing bacteria were contained within CD11c+ MHC-II+ splenocytes. Furthermore, splenic DC and T cells were activated following Salmonella infection. This was shown by increased surface expression of CD86 and CD40 on CD11c+ MHC-II+ cells and increased CD44 and CD69 expression on CD4+ and CD8+ T cells. Salmonella-specific gamma interferon (IFN-gamma)-producing cells in both of these T-cell subsets, as well as cytolytic effector cells, were also generated in mice given live bacteria. The frequency of Salmonella-specific CD4+ T cells producing IFN-gamma was greater than that of specific CD8+ T cells producing IFN-gamma in the same infected animal. This supports the argument that the predominant source of IFN-gamma production by cells of the specific immune response is CD4+ T cells. Finally, DC that phagocytosed live or heat-killed Salmonella in vitro primed bacterium-specific IFN-gamma-producing CD4+ and CD8+ T cells as well as cytolytic effector cells following administration into naïve mice. Together these data suggest that DC are involved in priming naïve T cells to Salmonella in vivo.

Topics: Animals; CD4-Positive T-Lymphocytes; CD8-Positive T-Lymphocytes; Cells, Cultured; Dendritic Cells; Green Fluorescent Proteins; Interferon-gamma; Luminescent Proteins; Lymphocyte Activation; Mice; Mice, Inbred C57BL; Ovalbumin; Phagocytes; Salmonella Infections, Animal; Salmonella typhimurium; Spleen

The results show that CD4 T cells specific for a recombinant antigen expressed in Salmonella typhimurium proliferate normally in mice that express the susceptible form of the Ity gene at early times after infection but do not retain the capacity to produce gamma interferon later in the infection.

Topics: Adoptive Transfer; Animals; Carrier Proteins; Cation Transport Proteins; CD4-Positive T-Lymphocytes; Cell Division; Chickens; Disease Susceptibility; Immunity, Innate; Interferon-gamma; Membrane Proteins; Mice; Mice, Inbred BALB C; Mice, Transgenic; Ovalbumin; Receptors, Antigen, T-Cell; Salmonella Infections, Animal; Salmonella typhimurium

Topics: Adjuvants, Immunologic; Animals; Antigens; Bacterial Vaccines; CpG Islands; Cytokines; Drug Evaluation; Enzyme-Linked Immunosorbent Assay; Female; Gene Expression Regulation; Immunization; Listeriosis; Mice; Mice, Inbred BALB C; Oligodeoxyribonucleotides; Ovalbumin; Salmonella Infections, Animal; Salmonella typhimurium; Tularemia; Vaccines, DNA

Recombinant Salmonella typhimurium aroA aroD mutants which expressed ovalbumin were constructed. The two expression constructs used were based on either pUC18 or pBR322. The pBR322-based construct was more stable in vitro and in vivo than the pUC-based construct. Salmonellae containing the stable pBR322-based plasmid induced major histocompatibility complex (MHC) class I-restricted cytotoxic T lymphocytes (CTL), in contrast to salmonellae containing the pUC18-based expression construct. The priming of MHC class I-restricted CTL was increased by multiple immunizations. The study described in this report suggest that S. typhimurium delta aro mutants have the capacity to induce MHC class I-restricted CTL against carried antigens and that MHC class I-restricted CTL responses require stable in vivo expression of the target antigen. Further, the results indicate that the Salmonella typhi delta aro mutants currently undergoing evaluation in studies with humans may be good carriers of viral antigens with CTL determinants.

Topics: Animals; Antibodies, Bacterial; Antigens, Bacterial; Cloning, Molecular; Female; Gene Expression; Histocompatibility Antigens Class I; Mice; Mutation; Ovalbumin; Recombinant Proteins; Salmonella Infections, Animal; Salmonella typhimurium; T-Lymphocytes, Cytotoxic

A single intraperitoneal injection of ovalbumin in oil adjuvant in young lambs has been shown to result in the appearance in the intestinal lamina propria of antibody-containing cells, most of which contained antibody of IgA specificity. Intraperitoneal immunisation of lambs with a Salmonella typhimurium vaccine during the suckling period provided protection against postweaning challenge with live organisms. This response was shown to be associated with specific IgA antibody in intestinal secretion.

Topics: Animals; Animals, Suckling; Antibodies, Bacterial; Female; Immunization; Immunoglobulin A; Ovalbumin; Salmonella Infections, Animal; Salmonella typhimurium; Salmonella Vaccines; Sheep; Sheep Diseases

An intestinal immunisation procedure involving systemic priming and oral boosting was investigated in lambs with a view to providing vaccination control of enteritis in young animals. The procedure stimulated the appearance of antibody-containing cells of IgA specificity in the intestine and lambs immunised in this way with a bacterial vaccine were protected against subsequent challenge with live enteropathogenic bacteria. This immunisation regime therefore provides a useful method for the stimulation of IgA immunity in the intestine of ruminants and it is anticipated that it will have general application to a variety of enteric diseases.

Topics: Animals; Antibodies, Bacterial; Bacterial Infections; Enteritis; Female; Immunization; Immunization Schedule; Models, Biological; Ovalbumin; Salmonella Infections, Animal; Salmonella typhimurium; Sheep; Sheep Diseases

Topics: Animals; Carbon; Connective Tissue; Electrons; Histiocytes; Lymph Nodes; Macrophages; Mice; Microscopy; Microscopy, Electron; Mononuclear Phagocyte System; Ovalbumin; Pharmacology; Rabbits; Research; Salmonella Infections; Salmonella Infections, Animal; Salmonella typhimurium; Spleen; Tuberculosis; Tuberculosis, Cutaneous; Typhoid-Paratyphoid Vaccines