OBJEVTIVETo study the effect of spvB/spvC gene on Salmonella virulence and the Host immune.

METHODSSTM.211, STM.211-Delta;spvB, STM.211-Delta;spvC, STM.211-Delta;spvB.spvC and PBS were infected with 0.2 mL 10(5) CFU corresponding strain respectively by intraperitoneal. We observed the mental status, movement, diarrhea, weight, pelage changed hair of the infected mouse. Then the level of IL-10, IL-12, IFN-γ were detected by ELISA. Finally, we observe the pathological changes of liver and spleen with the general view and the microscope.

RESULTSInfection symptoms of STM.211, STM.211-Delta;spvB and STM.211-Delta;spvC were significantly worse than PBS group, but there was no significant difference between STM.211-spvB.spvC group and PBS group. The secretion of IFN-γ and IL-12 of STM.211, STM.211-Delta;spvB, STM.211-Delta;spvC group were significantly lower than those in the STM.211-Delta;spvB.spvC group (P<0.05), but IL-10 secretion was significantly higher than STM.211-Delta;spvB.spvC group (P<0.05). There were no statistical significance among the STM.211, STM.211-Delta;SpvB, STM.211-Delta;spvC groups (P>0.05).

CONCLUSIONSSalmonella virulence can be affected obviously by spvB combined with spvC gene, but not by spvB or spvC. spvB/spvC gene can inhibit the TH1 cytokines (IFN-γ and IL-12) secretion but promote the TH2 cytokines (IL-10) expression, leading immune response trend to TH2 shift. It shows that spvB/spvC gene can help the bacteria evade the host immune defenses, leading to aggravation of infection.

Animals ; Cytokines ; immunology ; Interleukin-12 ; Mice ; Salmonella ; genetics ; pathogenicity ; Salmonella Infections ; immunology ; Virulence ; Virulence Factors ; genetics

Salmonella enterica Gallinarum (SG) causes fowl typhoid (FT), a septicemic disease in avian species. We constructed deletion mutants lacking the stress sigma factor RpoS, the nitric oxide (NO)-detoxifying flavohemoglobin Hmp, and the SsrA/SsrB regulator to confirm the functions of these factors in SG. All gene products were fully functional in wild-type (WT) SG whereas mutants harboring single mutations or a combination of rpoS, hmp, and ssrAB mutations showed hypersusceptibility to H2O2, loss of NO metabolism, and absence of Salmonella pathogenicity island (SPI)-2 expression, respectively. A triple-deletion mutant, SGDelta3 (SGDeltarpoSDeltahmpDeltassrAB), was evaluated for attenuated virulence and protection efficacy in two-week-old Lohmann layer chickens. The SGDelta3 mutant did not cause any mortality after inoculation with either 1 x 10(6) or 1 x 10(8) colony-forming units (CFUs) of bacteria. Significantly lower numbers of salmonellae were recovered from the liver and spleen of chickens inoculated with the SGDelta3 mutant compared to chickens inoculated with WT SG. Vaccination with the SGDelta3 mutant conferred complete protection against challenge with virulent SG on the chickens comparable to the group vaccinated with a conventional vaccine strain, SG9R. Overall, these results indicate that SGDelta3 could be a promising candidate for a live Salmonella vaccine against FT.
Administration, Oral ; Animals ; Bacterial Proteins/*genetics/immunology ; *Chickens ; Female ; Poultry Diseases/*immunology/microbiology ; Salmonella Infections, Animal/*immunology/microbiology ; Salmonella Vaccines/administration & dosage/genetics/*immunology ; Salmonella enterica/immunology/*physiology ; Vaccines, Attenuated/administration & dosage/genetics/immunology ; Virulence

To date, efforts to treat autoimmune diseases have primarily focused on the disease symptoms rather than on the cause of the disease. In large part, this is attributed to not knowing the responsible auto-antigens (auto-Ags) for driving the self-reactivity coupled with the poor success of treating autoimmune diseases using oral tolerance methods. Nonetheless, if tolerogenic approaches or methods that stimulate regulatory T (Treg) cells can be devised, these could subdue autoimmune diseases. To forward such efforts, our approach with colonization factor antigen I (CFA/I) fimbriae is to establish bystander immunity to ultimately drive the development of auto-Ag-specific Treg cells. Using an attenuated Salmonella vaccine expressing CFA/I fimbriae, fimbriae-specific Treg cells were induced without compromising the vaccine's capacity to protect against travelers' diarrhea or salmonellosis. By adapting the vaccine's anti-inflammatory properties, it was found that it could also dampen experimental inflammatory diseases resembling multiple sclerosis (MS) and rheumatoid arthritis. Because of this bystander effect, disease-specific Treg cells are eventually induced to resolve disease. Interestingly, this same vaccine could elicit the required Treg cell subset for each disease. For MS-like disease, conventional CD25+ Treg cells are stimulated, but for arthritis CD39+ Treg cells are induced instead. This review article will examine the potential of treating autoimmune diseases without having previous knowledge of the auto-Ag using an innocuous antigen to stimulate Treg cells via the production of transforming growth factor-beta and interleukin-10.
Animals ; Antigens, Bacterial/*immunology ; Arthritis, Rheumatoid/immunology/prevention & control ; Autoantigens/*immunology ; Fimbriae Proteins/*immunology ; Humans ; Multiple Sclerosis/immunology/prevention & control ; Salmonella/*immunology ; T-Lymphocytes, Regulatory/*immunology ; *Vaccination

Although the confirmative diagnosis of typhoid fever is by culture of the causative organism, usually from blood, a serological test is still necessary to provide a more rapid method of diagnosis. The indirect fluorescent antibody test, using a Salmonella typhi Vi antigen and a FITC-conjugated rabbit anti-human polyvalent immunoglobulin, was evaluated for the diagnosis of typhoid fever. Serum specimens were collected from patients with febrile diseases on admission. Of the 32 patients with titers of 1:64 or more, 22 were confirmed to have typhoid fever by blood culture and 7 had fever of undetermined origin that was considered to be typhoid fever clinically. Three patients were diagnosed to have salmonellosis other than typhoid fever. Of the 121 patients with titers of 1:32 or less, 105 patients had non-typhoidal febrile disease, 15 patients had fever of undetermined origin, and one patient was confirmed to have typhoid fever by blood culture. When a Vi antibody titer of 1:64 or more was taken as serological evidence for the diagnosis of typhoid fever, the sensitivity and specificity were 95.7% and 97.2%, respectively. The incidence of positive test results following fever onset was 70.0% within 1 week of fever onset, 88.9% from 1 to 2 weeks, and 100% after 2 weeks. In conclusion, the Vi-indirect fluorescent antibody test(Vi-IFAT) can be employed as a useful serologic test in the diagnosis of typhoid fever.
Antigens, Bacterial/*analysis ; Fluorescent Antibody Technique/*standards ; Human ; Salmonella typhi/immunology ; Sensitivity and Specificity ; Typhoid Fever/*diagnosis

Salmonella enterica serovar Choleraesuis strain C500 is a live, attenuated vaccine that has been used in China for over 40 years to prevent piglet paratyphoid. The objective of this study was to evaluate the potential of attenuated Salmonella enterica serovar Choleraesuis C500 strain with a delta asd mutant as an effective live vaccine vector by the Asd+ balanced-lethal host-vector system. Here, we compared the characteristics of S. enterica serovar Choleraesuis delta asdC500 strain with the parent C500 strain, including phenotype, growth rate, virulence, safety, and expression for heterologous antigen. The mean generation times of delta asdC500 mutant, the vector control delta asdC500 (pYA3493), and the parent avirulent C500 vaccine strain in Luria broth were 30.7, 28.1, and 27.9 min, respectively. The fermentation patterns of theses three strains on different carbohydrates, and the levels of production of H2S, were similar. The O and H antigens of delta asdC500 mutant, delta asdC500 (pYA3493) and delta asdC500 (pYA-F1P2) were 6,7:C:1,5, identical to the parent strain C500. By the method of Reed and Muench, groups of mice were challenged by the intraperitoneal route with different amounts of delta asdC500 (pYA3493) or the parent C500 strain, and the virulence of delta asdC500 (pYA3493) with LD50 of 1.1 x 10(7) CFU was a little lower than C500 with LD50 of 4.4 x 10(6) CFU. All piglets inoculated with delta asdC500 (pYA3493) or C500 survived, and no signs of disease were observed during the entire experimental period. No major differences were found in these two groups. In addition, the recombinant pYA-F1P2 plasmid was very stable in the recombinant delta asdC500 (pYA-F1P2) strain, which expressed secretorily a large amount of the recombinant filamentous hemagglutinin type I domain and pertactin region 2 domain antigen (rF1P2) of Bordetella bronchiseptica. In this study, we have shown that the delta asdC500 mutant had a series of biological characteristics similar to the parent vaccine strain C500. Furthermore, the strain could express secretorily a large amount of heterologous antigen. It is likely that this Salmonella expression and delivery system could be easily adapted to develop multivalent recombinant Salmonella vaccines against infectious agents using the Asd+ balanced-lethal host-vector system.
Amino Acid Oxidoreductases ; genetics ; Animals ; Bacterial Proteins ; genetics ; Gene Deletion ; Genetic Vectors ; Mice ; Mutation ; Salmonella Vaccines ; genetics ; immunology ; Salmonella enterica ; genetics ; immunology ; pathogenicity ; Swine ; Transduction, Genetic ; Vaccines, Attenuated ; genetics ; immunology ; Vaccines, Synthetic ; genetics ; immunology ; Virulence

Mice and 3-day-old chickens were orally inoculated with the recombinant attenuated Salmonella typhimurium strain ZJ111 carrying pcDNA3-F expression plasmid encoding the fusion protein of Newcastle disease virus (NDV). The results showed that ZJ111/pcDNA3-F was relatively safe. The recombinant plasmid pcDNA3-F was stable within the host stain ZJ111 in vitro and in vivo as shown by restriction enzyme analysis and PCR identification of the F gene. In an experimental vaccination study, 3-day-old chickens were orally immunized with ZJ111/pcDNA3-F with a dose of 108 cfu per chicken and boosted two weeks later. At week 4 post boosting, all chickens were challenged with a lethal dose of a virulent NDV strain F48 E9. The results showed that oral vaccination with ZJ111/pcDNA3-F induced stronger humoral and cellular immune responses than intramuscular immunization with naked pcDNA3-F plasmid. It also exhibited higher protection rate than the latter (66.7% vs 50%). This study indicates that the DNA vaccine using attenuated Salmonella typhimurium as delivery carrier had good safety, stability and immunogenicity and exhibited good potential of low cost and convenience for poultry disease control.
Animals ; Chickens ; Immunity, Cellular ; immunology ; Immunity, Humoral ; immunology ; Mice ; Newcastle Disease ; immunology ; virology ; Plasmids ; Polymerase Chain Reaction ; Salmonella typhimurium ; genetics ; metabolism ; Vaccines, DNA ; adverse effects ; genetics ; immunology

The fusion protein (F) gene of Newcastle disease virus was amplified by polymerase chain reaction (PCR) from the recombinant plasmid pVAX1-F, and subcloned into eukaryotic expression vector pmcDNA3. 1+. The F gene was identified by sequencing. The recombinant plasmid was transformed into attenuated Salmonella typhimurium SL7207, and the recombinant was designated as SL7207 (pmcDNA3. 1-F). In vitro and in vivo experiments showed that the plasmid stability of pmcDNA3. 1-F was apparently higher than that of pcDNA3. 1-F in SL7207. In order to compare the immune response induced by these two re combinant bacteria, BALB/c mice were immunized orally with them at the dosage of 2 x 10(9) CFU respectively. Both SL7207(pcDNA3. 1-F) and SL7207(pmcDNA3. 1-F) initiated F-specific serum and mucosal antibodies in immunized mice. Furthermore, 4-day-old SPF chickens were immunized with SL7207(pcDNA3. 1-F) and SL7207(pmcDNA3. 1-F) at the dosage of 5 x 10(9) CFU and boosted two weeks later with the same dosage. Humoral and intestinal mucosal immune responses were observed and their levels were significantly higher than that of negative and positive controls. The result of protective efficacy showed that the chickens immunized with SL7207(pmcDNA3. 1-F) had the protective rate of 70.0%, higher than that of the SL7207 (pcDNA3. 1-F) with 50.0%. In summary, the DNA vaccine delivered by attenuated Salmonella typhimurium has good immunogenicity. A novel mucosal DNA vaccine has been developed and could be useful for controlling the infection and epidemic of Newcastle disease in the poultry.
Animals ; Chickens ; Female ; Immunization ; Mice ; Mice, Inbred BALB C ; Newcastle disease virus ; immunology ; Plasmids ; Salmonella typhimurium ; genetics ; Vaccines, Attenuated ; immunology ; Vaccines, DNA ; immunology ; Viral Vaccines ; immunology

Hepatitis C virus (HCV) core protein is considered to be an attractive candidate for development of protective HCV vaccines. However, this protein may attenuate the induction of systemic immune responses due to its immunomodulatory properties. In this study, we constructed a HCV core gene-containing eukaryotic expression plamid pCI-C, and an in vivo-inducible prokaryotic expression plasmid pZW-C, and transformed the recombinant plasmids into an attenuated Salmonella typhimurium aroA strain SL7207. The resulting bacterial strains SL7207/pCI-C and SL7207/pZW-C were used to orally immunize BALB/c mice, and the immune responses specific to HCV core protein were assessed. Immunization with the recombinant bacteria SL7207/pCI-C led to a persistent drop in percentage of CD3 CD4 T cells, and induced a weak anti-core IgG production. Splenocytes from SL7207/pCI-C immunized mice developed a relatively weak proliferation response and inferior cytotoxic activity compared to those from the mice immunized with bacteria SL7207/pZW-C. Boost immunization with SL7207/ pCI-C yielded limited improvement in immune strength, while the boost with bacteria SL7207/pZW-C significantly enhanced the immune response. These results suggest that de novo synthesis of native HCV core protein may blunt the induction of immune responses. Attenuated S. typhimurium carrying HCV core protein could efficiently activate systemic cellular and humoral responses, and may be a promising strategy for the development of core-based HCV vaccines.
Animals ; Hepacivirus ; genetics ; immunology ; Mice ; Plasmids ; genetics ; Salmonella typhimurium ; genetics ; metabolism ; Vaccines, DNA ; immunology ; Viral Core Proteins ; genetics ; immunology ; Viral Hepatitis Vaccines ; genetics ; immunology

The immunologic reactivity of a lipopolysaccharide (LPS)-protein complex isolated from a potassium thiocyanate extract of a Pasteurella multocida (capsular type A and somatic type 3) strain was evaluated in mice. The LPS-protein complex provided 100% protection in mice against a challenge with the homologous strain. However, when the complex was fractionated into LPS and protein moieties by phenol-water treatment, both components lacked immunogenicity. The complex and extracted components were mitogenic for mouse B lymphocytes with the protein moiety the most active. Although immune serum against the LPS-protein complex protected mice against challenge thereby indicating a role for humoral immunity, the LPS-protein complex of P. multocida was also found to induce cell-mediated immunity. This cell-mediated immunity was demonstrated in mice immunized with the complex by: (1). mitogenic responses of T lymphocytes, (2). induction of delayed type hypersensitivity reaction in the hind footpads, and (3). enhanced resistance to challenge infection with Salmonella enteritidis.
Animals ; Antibodies, Bacterial/blood/immunology ; Bacterial Proteins/chemistry/*immunology ; Chemical Fractionation ; Hypersensitivity, Delayed ; Immune Sera/immunology ; Immunity, Cellular ; Immunization, Passive ; Lipopolysaccharides/chemistry/*immunology ; Lymphocyte Activation ; Mice ; Pasteurella Infections/immunology/*prevention & control ; Pasteurella multocida/*chemistry/immunology ; Salmonella Infections, Animal/immunology/prevention & control ; Salmonella enteritidis/growth & development/immunology ; Spleen/cytology/immunology/microbiology

Salmonella choleraesuis C500 strain was an attenuated vaccine strain to prevent piglet paratyphoid, attenuated by chemical method. Although the vaccine has good immunogenicity, it remains some residual virulence. In order to develop a safer vaccine strain and exploit C500 as a live vaccine vector for mucosal immunization, delta crp delta asd double deletion mutant was constructed. Firstly, the recombination suicide vector with 320 bp-deleted crp (cAMP receptor protein) gene and sacB (sucrose-sensitive gene) gene was constructed and conjugated with C500. The unmarked crp deleted strain without resistance was selected by two-step method and crp deletion on the genome was determined by PCR. Then the asd (beta-aspartic semialdehyde dehydrogenase) gene was further deleted in the delta crp strain by the same method. Foreign DAP (diaminopimelic acid) must be supplied for delta crp delta asd mutant to grow. The phenotype, growth properties and virulence in mice of delta crp mutant were further characterized. In conclusion, the delta crp delta asd double-deletion mutant was successfully constructed. The delta crp delta asd mutant can be used as a live vector to express foreign genes and to develop potential oral multivalent vaccines.
Amino Acid Oxidoreductases ; genetics ; Animals ; Antibodies, Bacterial ; biosynthesis ; Bacterial Proteins ; genetics ; Cyclic AMP Receptor Protein ; genetics ; Gene Deletion ; Mice ; Mutation ; Salmonella ; genetics ; immunology ; pathogenicity ; Salmonella Vaccines ; genetics ; immunology ; Swine ; Transduction, Genetic ; Vaccines, Attenuated ; genetics ; immunology ; Virulence