Objective To study the effect of Mycobacterium tuberculosis (Mtb) Pro-Pro-Glu-59 (PPE59) protein on the biological function of Mycobacterium smegmatis (Ms) and the regulation of host cell immune response. Methods PPE59 gene fragment was obtained by PCR amplification, cloned into pALACE, constructed into recombinant pALACE-PPE59 vector, and electro-transformed into Ms. Western blot was applied to analyse PPE59 expression and subcellular localization. The survival of Ms_Vec and Ms_PPE59 under low acid (pH=3 and pH=5) conditions and active surface pressure sodium dodecyl sulfate (SDS) conditions and their intracellular survival in macrophages were analyzed. ELISA was used to detect the cytokine (IL-1β, IL-6, IL-12, TNF-α and IL-10) expression levels of Ms_Vec and Ms_PPE59 infected macrophages. Results PPE59 protein localized to the cell wall of Ms can enhance the acid-resistance and anti-SDS effect of Ms, which is conducive to the survival of Ms in macrophages. PPE59 significantly decreased the secretion levels of pro-inflammatory cytokines (IL-1β, IL-6, IL-12 and TNF-α), and promoted the secretion levels of anti-inflammatory cytokine (IL-10). Conclusion PPE59 enhances the survival ability of Ms under low acid and SDS pressure and promotes its intracellular survival by regulating the cytokine secretion levels.
Mycobacterium smegmatis/metabolism* ; Macrophages/metabolism* ; Cytokines/metabolism* ; Mycobacterium tuberculosis/metabolism* ; Bacterial Proteins/metabolism* ; Animals ; Mice ; Antigens, Bacterial/metabolism*

To construct a recombinant Bacillus subtilis strain expressing SpaA and CbpB of Erysipelothrix rhusiopathiae for oral administration, we constructed the recombinant plasmid pDG1730-CBJA by fusion PCR and seamless cloning. The plasmid was introduced into B. subtilis KC strain by natural transformation, and the recombinant strain KC-spaA-cbpB was screened out on the plate containing spectinomycin (spe^r) and confirmed by PCR and starch degradation test. The SpaA and CbpB expressed by KC-spaA-cbpB were detected by Western blotting and indirect immunofluorescence assay, and the genetic stability of the recombinant strain in mice was determined. The plasmid pMAD-∆spe^r with knockout of spe^r was constructed and transformed into KC-spaA-cbpB. The spe^r-deleted mutant strain KC-spaA-cbpB: : ∆spe^r was screened and identified, and its immunogenicity in a mouse model was evaluated by oral immunization. The results showed that the recombinant strain KC-spaA-cbpB was stable in mice, expressing SpaA on the cell surface and CbpB on the spore surface. KC-spaA-cbpB: : ∆spe^r expressed SpaA and CbpB. The mice vaccinated with the spores of KC-spaA-cbpB: : ∆spe^r had higher levels of SpaA and CbpB-specific IgG in the serum that those vaccinated with the wild-type spores 42 days after vaccination by gavage (P < 0.01). The protective rate of mice immunized with the recombinant spores was 67.5%. The results indicated that a recombinant B. subtilis strain expressing SpaA and CbpB of E. rhusiopathiae was successfully constructed, and the recombinant strain laid a foundation for the development of oral live vector vaccines for swine erysipelas.
Animals ; Bacillus subtilis/immunology* ; Mice ; Erysipelothrix/immunology* ; Bacterial Proteins/immunology* ; Bacterial Vaccines/genetics* ; Erysipelothrix Infections/prevention & control* ; Immunization ; Mice, Inbred BALB C ; Plasmids/genetics* ; Immunogenicity, Vaccine ; Administration, Oral ; Antigens, Bacterial

Nearly a quarter of the world's population is infected with Mycobacterium tuberculosis and remains long-term asymptomatic infection. Rv2626c is a latent infection-related protein regulated by DosR of M. tuberculosis. In this study, the Rv2626c protein was prokaryotically expressed and purified, and its immunobiological characteristics were analyzed using RAW264.7 cells and mice as infection models. SDS-PAGE and Western blotting analysis showed that the Rv2626c-His fusion protein was mainly expressed in soluble form and specifically reacted with the rabbit anti-H37RV polyclonal serum. In addition, we found that the Rv2626c protein bound to the surface of RAW264.7 macrophages and up-regulated the production of NO. Moreover, the Rv2626c protein significantly induced the production of pro-inflammatory cytokines IFN-γ, TNF-α, IL-6 and MCP-1, and induced strong Th1-tendency immune response. These results may help to reveal the pathogenic mechanism of M. tuberculosis and facilitate the development of new tuberculosis vaccine.
Animals ; Mice ; Rabbits ; Mycobacterium tuberculosis/genetics* ; Tuberculosis ; Antigens, Bacterial ; Cytokines ; Immunity, Cellular

Objective To explore the aptamer specific binding blood group antigen-binding adhesin (BabA) of Helicobacter pylori (H.pylori) for blocking of H.pylori adhering host cell. Methods H.pylori strain was cultured and its genome was extracted as templates to amplify the BabA gene by PCR with designed primers. The BabA gene obtained was cloned and constructed into prokaryotic expression plasmid, which was induced by isopropyl beta-D-galactoside (IPTG) and purified as target. The single stranded DNA (ssDNA) aptamers that specifically bind to BabA were screened by SELEX. Enzyme-linked oligonucleotide assay (ELONA) was used to detect and evaluate the characteristics of candidate aptamers. The blocking effect of ssDNA aptamers on H.pylori adhesion was subsequently verified by flow cytometry and colony counting at the cell level in vitro and in mouse model of infection, respectively. Meanwhile, the levels of cytokines, interleukin 6 (IL-6), IL-8, tumor necrosis factor α (TNF-α), IL-10 and IL-4 in the homogenate of mouse gastric mucosa cells were detected by ELISA. Results The genome of H.pylori ATCC 43504 strains was extracted and the recombinant plasmid pET32a-BabA was constructed. After induction and purification, the relative molecular mass (M_r) of the recombinant BabA protein was about 39 000. The amino acid sequence of recombinent protein was consistent with BabA protein by peptide mass fingerprint (PMF). Five candidate aptamers were selected to bind to the above recombinent BabA protein by SELEX. The aptamers A10, A30 and A42 identified the same site, while A3, A16 and the above three aptamers identified different sites respectively. The aptamer significantly blocked the adhesion of H.pylori in vitro. Animal model experiments showed that the aptamers can block the colonization of H.pylori in gastric mucosa by intragastric injection and reduce the inflammatory response. The levels of IL-4, IL-6, IL-8 and TNF-α in gastric mucosal homogenates in the model group with aptamer treatment were lower than that of model group without treatment. Conclusion Aptamers can reduce the colonization of H.pylori in gastric mucosa via binding BabA to block the adhesion between H.pylori and gastric mucosal epithelial cells.
Animals ; Mice ; Helicobacter pylori/genetics* ; Interleukin-4 ; Interleukin-6 ; Interleukin-8 ; Tumor Necrosis Factor-alpha ; Stomach ; Oligonucleotides ; Adhesins, Bacterial/genetics* ; Blood Group Antigens

Animals ; Mice ; Chlamydia muridarum ; Mice, Inbred BALB C ; Antigens, Bacterial ; Chlamydia Infections

To prepare a lipid nanoparticle (LNP)-based subunit vaccine of Mycobacterium tuberculosis (Mtb) antigen EsxV and study its immunological characteristics, the LNP containing EsxV and c-di-AMP (EsxV: C: L) was prepared by thin film dispersion method, and its encapsulation rate, LNP morphology, particle size, surface charge and polyphase dispersion index were measured. BALB/c mice were immunized with EsxV: C: L by nasal drops. The levels of serum and mucosal antibodies, transcription and secretion of cytokines in lung and spleen, and the proportion of T cell subsets were detected after immunization. EsxV: C: L LNPs were obtained with uniform size and they were spherical and negatively charged. Compared with EsxV: C immunization, EsxV: C: L mucosal inoculation induced increased sIgA level in respiratory tract mucosa. Levels of IL-2 secreted from spleen and ratios of memory T cells and tissue-resident T cells in mice were also elevated. In conclusion, EsxV: C: L could induce stronger mucosal immunity and memory T cell immune responses, which may provide better protection against Mtb infection.
Animals ; Mice ; Mycobacterium tuberculosis ; Antigens, Bacterial ; Immunization ; Nanoparticles ; Vaccines, Subunit ; Mice, Inbred BALB C

To explore the protective immune effect induced by mucosal delivery heparin-binding hemagglutinin (HBHA)-a candidate vaccine antigen of Mycobacterium tuberculosis. Female C57BL/6 mice were between 6 and 8 weeks of age before experimental use. Thirty mice received different immunization strategies and were randomly divided into the control group, the early secreting antigen target-6 (ESAT-6) intranasal immunization group, the HBHA intranasal immunization group, the BCG priming PBS control group, or BCG priming HBHA boost group, 6 mice in each group. In order to analyzed the immune effect, the concentrations of plasma Interleukin-17A (IL-17A) and other cytokines were measured by ELISA. Quantitative real-time PCR analyses were performed to detect the relative quantity (RQ) mRNA of IL-17A in the lung. The lung tissue sections were stained to detect the formation of the tertiary lymphoid structures. The chemokines contributed to formation of the tertiary lymphoid structures were also measured. Flow cytometry was used to detect the frequency of Th1 and Th17 cells in the system. Sixty mice in the BCG priming PBS control group and the BCG priming HBHA boost group were sacrificed at different time points after infection to count the lung bacterial burden. The concentrations of plasma IL-17A and relative quantity of lung IL-17A mRNA were highest in the BCG priming HBHA boost group [(14.76±4.73) pg/mL,RQ (12.27±6.71)], which was significantly higher than the control group [(5.57±2.95) pg/mL,RQ (1.30±0.97)] (t=4.213, P<0.001; t=5.984, P<0.001), and also significantly higher than the BCG priming PBS control group [(6.81±2.18) pg/mL,RQ (1.44±1.16)] (t=3.646 P=0.001; t=6.185 P<0.001). Compared with the BCG priming PBS control group (0.38±0.38)% the frequency of spleen Th17 cells were also significantly increased (t=-0.280 , P=0.048) in the BCG-primary HBHA boost group (1.02±0.34)%. In addition, HBHA boosting could promote better formation of the tertiary lymphoid structures in the lung, and decrease the bacterial load on the early stage after BCG challenge. Collectively, mucosal delivery of HBHA can effectively enhance the protective effect after BCG vaccination, and it is a potential candidate vaccine component.
Animals ; Antigens, Bacterial ; Bacterial Proteins ; Female ; Humans ; Immunization, Secondary ; Interleukin-17 ; Lectins ; Mice ; Mice, Inbred C57BL ; Mycobacterium tuberculosis ; Tuberculosis/prevention & control* ; Tuberculosis Vaccines

The GapC protein of Streptococcus uberis located on the surface of bacteria is a protein with glyceraldehyde-3-phosphate dehydrogenase activity. It participates in cellular processes and exhibits a variety of biological activities. In addition, it has good antigenicity. The aim of this study was to predict the possible B-cell epitopes of the GapC protein and verify the immunogenicity of candidate epitope peptides. The gapC gene of S. uberis isolate RF5-1 was cloned into a recombinant expression plasmid pET-28a-GapC and inducibly expressed. The purified protein was used to immunize experimental rabbits to produce anti-GapC polyclonal antibodies. The three-dimensional structure and three-dimensional location of the GapC B-cell epitopes and the homology comparison of the GapC protein and its B-cell epitopes were carried out using bioinformatics softwares. The results showed that the 44-kDa GapC protein had a good immunological reactivity. Six linear and 3 conformational dominant B-cell epitopes against the GapC protein were selected and synthesized. Three dimensional analysis indicated that the selected peptides have better antigen epitope formation potential. Rabbit anti-GapC polyclonal antibodies were generated after immunized with the purified GapC protein, and the polyclonal antibodies were used to identify the epitope peptide by an indirect ELISA. The ELISA results showed that all of the 9 epitope peptides could react with anti-GapC polyclonal antibodies with varying titers. Among them, the epitope polypeptide ²⁶⁶AANDSYGYTEDPIVSSD²⁸² reacted with the polyclonal antibodies significantly stronger than with other epitope peptides. This study laid an experimental foundation for in-depth understanding of the immunological properties and utilizing effective epitopes of the GapC protein of S. uberis.
Animals ; Antigens, Bacterial/genetics* ; Bacterial Proteins/genetics* ; Epitopes, B-Lymphocyte/genetics* ; Mice ; Mice, Inbred BALB C ; Rabbits ; Streptococcus

This research and development of MenB meningococcal vaccines includes two technical routes: outer membrane vesicle (OMV) vaccines and recombinant protein vaccines. This article intends to review the development, production and application of MenB meningococcal OMV vaccines in order to provide a reference for the development of MenB meningococcal OMV vaccine in China.
Antigens, Bacterial ; Humans ; Meningococcal Infections/prevention & control* ; Meningococcal Vaccines ; Neisseria meningitidis, Serogroup B ; Serogroup ; Vaccines, Synthetic

The enterobacterial common antigen (ECA) is a polysaccharide composed of polysaccharide repeats that are located in the outer membrane of almost all Enterobacteriaceae bacteria and has diverse biological functions. ECA is synthesized by the synergistic action of multiple genes that are present in clusters on the genome of Enterobacteriaceae bacteria, forming the ECA antigen gene cluster, an important virulence factor that plays a role in host invasion and survival of Enterobacteriaceae in vivo. ECA also plays an important role in the maintenance of the bacterial outer membrane permeability barrier, flagella gene expression, swarming motility, and bile salts resistance. In addition, ECALPS, anchored in the core region of bacterial lipopolysaccharide, is an important surface antigen for bacteria, stimulating high levels of antibody production in the host and could be a target for vaccine research. This review summarizes ECA purification, genes involved in ECA biosynthesis, its immunological characteristics, biological functions and clinical applications.
Antigens, Bacterial/genetics* ; Enterobacteriaceae/genetics* ; Lipopolysaccharides ; Polysaccharides