In order to develop a safer vaccine strain exploit Salmonella Pullorum vaccine strain as a live vaccine vector.Methods:AΔcrpΔasd mutant of S.pullorum C79-13 strain was constructed and it was developed E.coli donor strain mutant was generated through the two-step method introduced by χ7213 ( pREΔasd) was conjugated with the recipient of C 79-13Δcrp.The C79-13ΔcrpΔasd the transduction of recombinant suicide plasmid .Results:PCR and sequencing results showed that ΔsipBSL1344 was suc-cessfully constructed.The further study indicated that foreign DAP must be supplied for the ΔcrpΔasd mutant to grow,in addition,the asd gene was transmitted stably .Compared with C79-13 strain,the O antigens was identical to C79-13 strain,but the growth velocity was reduced significantly ,significantly reduced virulence .Conclusion: The ΔcrpΔasd mutant can accept asd+plasmid to construct host-vector balance lethal system , and this system can be used to express foreign gene efficiently and to develop potential oral multivalent vaccines.

Objective:To discuss the effects of recombinant IFN-α-IL-18 fusion protein on chicken lymphocyte histamine induced and the NF-κB p65 activation and nucleo-cytoplasmic transport.Methods: The healthy chickens blood was sterile adopted with anticoagulant,then separation of the chicken peripheral blood lymphocyte and divided into 10 groups:The yeast expression and purification protein IFN-α-IL-18,IL-18,IFN-α were added with 250 ng/ml,500 ng/ml and 1 000 ng/ml respectively while the control was only added RPMI1640 with 3 repetitions for each group.Then the histidine decarboxylase activity,histamine,IFN-γ,PI3K,MAPK and NF-κB p65 in cell nucleus were detected.Results: The recombinant IFN-α-IL-18 and IL-18 could significantly promote the activity of histidine decarboxylase (P<0.01),increase the contents of histamine (P<0.01),induce IFN-γ (P<0.01),improve the contents of PI3K (P<0.01) and the NF-κB p65 levels in nucleus (P<0.01),and the higher concentration of IFN-α had a similar effect to lymphocytes.The effects of IFN-α-IL-18,IL-18 and IFN-α on MAPK was acratia.Conclusion: IFN-α-IL-18 and IL-18 can stimulate chicken peripheral blood lymphocyte populations increased histamine contents significantly and promote the induction of IFN-γ.IFN-α-IL-18,IL-18 and IFN-α increase PI3K expression in lymphocyte associated with the NF-κB activation and NF-κB p65 nucleo-cytoplasmic transport.The study built foundation for the function of IFN-α-IL-18 and the exploration of the mechanism of controlling epidemic diseases.

Objective:To discuss the effects of recombinant IFN-α-IL-18 fusion protein on chicken lymphocyte transformation and the chicken nuclear factor kappa B ( NF-κB ) activity.Methods: The recombinant plasmids pPICZ-IFN-α, pPICZ-IL-18 and pPICZ-IFN-α-IL-18 were constructed,and transformed into P.Pastoris X-33 strain by electroporation.The recombinant proteins were ex-pressed under the induction of 1% methanol,and detected by SDS-PAGE and Western blot.The biological activities of the expressed products were detected by the lymphocyte transformation test,the NF-κB concentration in chicken lymphocyte and lymphocytic nucleus were detected at different times with ELISA.Results:SDS-PAGE and Western blot showed that the expressed products existed in super-natant,and the molecular weights were about 22 kD,23 kD and 43 kD,respectively.The expressed products IL-18 and IFN-α-IL-18 could stimulate chicken lymphocyte transformation (P<0.05),the biological activity of IFN-αstimulating lymphocyte transform was feeble (P>0.05).Compared with the control group,the total NF-κB concentration in chicken lymphocyte induced by IL-18 and IFN-α-IL-18 were increased (P<0.05),and the NF-κB in lymphocytic nucleus was increased significantly (P<0.01).Otherwise,the total NF-κB in lymphocyte induced by IFN-αincrease was limited (P>0.05),but the NF-κB in lymphocytic nucleus showed the remarkable increase ( P<0.05 ) .Conclusion: IFN-α-IL-18 and IL-18 can promote lymphocyte transformation significantly, the activity of IFN-αinduced lymphocyte transformation is imperfect.The biological activity of stimulating lymphocyte transformation is associated with the NF-κB expression,activation and nucleo-cytoplasmic transport.The study built foundation for the function of IFN-α-IL-18 fusion protein and the exploration of the role of controlling epidemic diseases.

Objective:In order to develop an oral live vaccine vector of swine that can stably carry exogenous genes.Methods:Mutant ΔcrpΔcyaΔasdC78-1 was constructed by the method of suicide plasmid pREasd-mediated bacteria homologous recombination on the basis of attenuated Salmonella choleraesuisΔcrpΔcyaC78-1.Complementary plasmid pYA3493 with asd was electrotransformed into the mutant,and thenΔcrpΔcyaΔasdC78-1(pYA3493) host-vector balanced lethal system was constructed.Its biological characteristics were analyzed further.Results:The results of PCR and sequencing showed thatΔcrpΔcyaΔasdC78-1(pYA3493) was constructed suc-cessfully.Biological characteristics showed that the serotype of ΔcrpΔcyaΔasdC78-1(pYA3493) was identical to ΔcyaΔasdC78-1 and vaccine strain C500 and it can stably carry theΔasd gene in vitro;its growth speed was a little slower than ΔcrpΔcyaC78-1 strain,but both of their growth speeds were significantly slower than vaccine strain C500;the biochemical characteristics of ΔcrpΔcyaΔasdC78-1 ( pYA3493 ) were basically the same with ΔcrpΔcyaC78-1 strain.Oral virulence test in mice showed that the virulence ofΔcrpΔcyaΔasdC78-1 ( pYA3493 ) was similar with ΔcrpΔcyaC78-1, but its median lethal dose is 412 times of vaccine strain C500.Conclusion:These results demonstrated that attenuated Salmonella choleraesuisΔcrpΔcyaΔasdC78-1(pYA3493) strain had the potential to be used as an oral live vaccine vector for expressing foreign genes efficiently.

Objective:In order to develop a safer vaccine strain exploit Salmonella typhimurium vaccine strain .A ΔsipB mutant of Salmonella typhimurium SL 1344 strain was constructed.Methods: Firstly, the recombinant suicide plasmid containing the missing 585 bp sipB ( PREΔsipB ) was built by homologous recombination , and screenned by two-step method.Results: PCR and sequencing results showed that SL 1344ΔsipB was successfully constructed.It was no significant changes compared with SL 1344.But compared with the parent strains SL 1344 , the mutant strain had obvious change in its virulence , oral challenge of bacteria in mice revealed that LD50 of the mutant strain was 1.70 ×108 CFU,the toxicity reduced about 1.4%.The protection rate induced by the sipB mutant was 50%,and the serum antibody peaked 14 d post-immunization.Conclusion:The SL1344ΔsipB mutant was constructed suc-cessfully,and genetic stability ,significantly reduced virulence.The study provides a new approach for further study of the relationship between the gene and pathogenicity of Salmonella typhimurium.It is likely that the ΔsipB mutant could be adapted to develope attenuated Salmonella vaccine.

In order to research immunogenicity of the recombinant rVP2-IL-2 fusion protein, we obtained the rVP2-IL-2 fusion protein using Pichia pastoris expression system, and then evaluated its potential to induce immune responses in chicken. The effect was determined in the form of protective anti-IBDV VP2 titers, antibodies (IgG1 and IgG2a), lymphocyte proliferation, the levels of interferon-gamma and interleukin-4 cytokines, and challenge experiment. Antibody titers and proliferation lymphocyte level suggested that the fusion protein could elicit specific humoral immune and cellular immune responses, antibody sub-type results indicated that the rVP2-IL-2 fusion protein induced secretion both of IgG1 and IgG2a. The seem result elicited from cytokines ELISA test, secretion of both of Th1 (gamma-IFN) and Th2 (IL-4) were induced by the rVP2-IL-2 fusion protein. Challenge experiment result shown that chicken immunized the rVP2-IL-2 fusion protein obtained 85% protection. These results confirm that the fusion protein enhances the protection against IBDV through both humoral and cell-mediated immunity, and thus could serve as a candidate for the development of IBDV subunit vaccine.
Animals ; Antibodies, Viral ; biosynthesis ; blood ; Chickens ; immunology ; Immunoglobulin G ; blood ; Interleukin-2 ; biosynthesis ; genetics ; Pichia ; genetics ; metabolism ; Recombinant Fusion Proteins ; biosynthesis ; genetics ; immunology ; Th1 Cells ; immunology ; Th2 Cells ; immunology ; Vaccines, Subunit ; immunology ; Viral Structural Proteins ; biosynthesis ; genetics ; Viral Vaccines ; immunology

Objective To analyze the biological characteristics of a mutant strain of Salmonella ty-phimurium SL1344 with sseK2-deletion (SL1344△sseK2) in order to provide reference for further study of safe and effective live vaccines. Methods The mutant strain SL1344△sseK2 with a deletion of 1047 bp in sseK2 gene was constructed through a two-step allelic exchange using recombinant suicide plasmid. Its com-plemented strain, SL1344C△sseK2, was also constructed. Biological and immunological characteristics of the mutant strain were detected. Results PCR, double-enzyme digestion and sequencing analysis showed that the mutant strain SL1344△sseK2 and the complemented strain SL1344C△sseK2 were successfully con-structed. The serotype of the mutant strain was 1,4,[5],12:i:1,2, identical to the parent strain SL1344. In addition, the mutant strain showed no significant change in biochemical characteristics or growth rate and was genetically stable in vitro. Compared with the parent strain SL1344, the virulence of SL1344△sseK2 was attenuated in BALB/ c mice. The median lethal dose of SL1344△sseK2 for 6-week-old BALB/ c mice was 3. 44×108 colony-forming units (CFU), which was 1620 times lower than that of SL1344. Oral immuniza-tion with SL1344△sseK2 protected 62. 5％ of the mice against challenge with wild Salmonella typhimurium strains on 17 d after vaccination. The levels of serum IgG antibody peaked on 14 d after immunization. No significant difference in biological characteristics was observed between the complemented and the parent strains, indicating that the mutant strain was basically complemented to the wild-type strain.Conclusions The mutant strain SL1344△sseK2 was constructed successfully and genetically stable with sig-nificantly attenuated virulence and good immunogenicity. This study suggested that sseK2 gene played an im-portant role in regulating the virulence of SL1344, which might provide reference for further study of its func-tion and for assessing its potential as a candidate live attenuated vaccine.

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

Objective To explore the effect of EZH2 on Hcy-induced cholesterol accumulation of foam cells. Methods THP-1 foam cells were divided into control group ,100 μmol/L Hcy group and folic acid group. Lipid droplet in foam cells was tested by Oil red O. TC and TG contents in cells were determined by enzymic meth od. H3K27me3 level and EZH2 protein expression were detected by Western-blot. EZH2 mRNA expression was assayed by q-PCR. H3K27me3 level and TC and TG contents were examined followed by overexpression or knock- down of EZH2. Results After administration of Hcy,TC and TG contents in foam cells were increased (P <0.05). H3K27me3 level and EZH2 expression were also increased(P<0.05). Overexpression of EZH2 caused the expansion of H3K27me3 level,and the TC and TC contents were also increased(P<0.05). Conclusion Regula-tion of H3K27me3 by EZH2 might be involved in Hcy-induced accumulation of cholesterol in foam cells.

Objective To study the sequence structure of Salmonella typhimurium Ssek3 gene and to express it at protein level in a prokaryotic expression system .Methods Sequence of Ssek3 gene was ob-tained from Salmonella typhimurium SL1344 strain.Bioinformatics methods were used for systematic analy-sis .A prokaryotic expression system for expressing Sse3k gene was constructed and the expressed protein was purified by Ni-NTA affinity chromatography .Results Sequence analysis showed that the Ssek3 gene of Sal-monella typhimurium was 1008 bp in length, encoding a protein of 335 amino acids and 72 amino acid resi-dues.The molecular weight, molecular formula and isoelectric point of Ssek3 protein was 37.89×103, C1700 H2629 N463 O497 S12 and 6.7, which indicated that it was a stable and hydrophilic protein .Ssek3 protein was a membrane protein without signal peptide or transmembrane region , containing five N-glycosylation sites , three O-glycosylation sites , 33 phosphorylation sites , 22 linear B-cell epitopes , 11 T-cell epitopes and 21 di-sulfide bonds.The secondary structure of Ssek3 protein contained 114 α-helices (Hh) (34.03％), 72 ex-tended chain (Ee) (21.49％), 30β-sheets (Tt) (8.96％) and 119 random coils (Cc) (35.52％).Re-sults of SDS-PAGE showed that the fusion protein Ssek 3 expressed in the prokaryotic expression system was a secretory protein with a molecular weight of about 40×103 .Conclusion The Ssek3 gene of Salmonella typh-imurium is successfully cloned , sequenced and expressed in this study , which will lay a foundation for fur-ther studying the role of Ssek3 protein in host cells during Salmonella typhimurium infection.