OBJECTIVETo identify antigenic proteins secreted by Streptococcus suis (S. suis) type 2 strain SC84.

METHODSTwo-dimensional electrophoresis (2-DE), western-blot assay and matrix-assisted laser desorption/ionization-time of flight-mass spectrometry (MALDI-TOF-MS) analysis were performed to search and identify antigenic proteins secreted by S. suis strain SC84, which triggered an outbreak of the disease in Sichuan province,China, in 2005.

RESULTSA total number of 14 western blot spots were found on PVDF membrane. 11 spots which could be found the existence of matching protein on coomassie G-250-stained 2-DE gel were identified by MALDI-TOF MS. The 11 proteins, all located at extra-cellular or cell wall, were classified into 8 kinds of proteins. Among of them, muramidase-released protein (MRP), suilysin (Sly) and extra-cellular factor (EF) were the known antigenic proteins, but several proteins such as putative 5'-nucleotidase, ribo-nucleases G and E, and predicted metal-loendo-peptidase were newly found antigenic proteins. All the identified protein were found to have had the coding gene in genomic of S. suis strain 05ZYH33, isolated from patients in Sichuan province, China in 2005.

CONCLUSIONThe newly found proteins could be used as voluntary antigens for detection and vaccination of S. suis.

Bacterial Proteins ; analysis ; immunology ; Humans ; Proteomics ; Streptococcal Infections ; Streptococcus suis ; immunology ; isolation & purification ; metabolism

Autophagy is a housekeeping process that maintains cellular homeostasis through recycling of nutrients and degradation of damaged or aged cytoplasmic constituents. Over the past several years, accumulating evidence has suggested that autophagy can function as an intracellular innate defense pathway in response to infection with a variety of bacteria and viruses. Autophagy plays a role as a specialized immunologic effector and regulates innate immunity to exert antimicrobial defense mechanisms. Numerous bacterial pathogens have developed the ability to invade host cells or to subvert host autophagy to establish a persistent infection. In this review, we have summarized the recent advances in our understanding of the interaction between antibacterial autophagy (xenophagy) and different bacterial pathogens.
Animals ; Autophagy/*physiology ; Bacterial Infections/*immunology/metabolism ; Humans ; Immunity, Innate/physiology ; Reactive Oxygen Species/metabolism

OBJECTIVESNeonates are vulnerable to various infections because of their immature immune responses. Toll-like receptors could induce immune responses, both the innate and the acquired immune responses. The aim of the present study was to investigate the changes of TLR2 and TLR4 in neonatal infections, and to determine their roles in anti-infection immune reaction.

METHODSA total of 200 infants were divided into six groups: sepsis group (n = 21), bacterial pneumonia group (n = 70), bacterial meningitis group (n = 17), urinary tract infection group (n = 38), congenital syphilis group (n = 11) and non-infection group (n = 48). The TLR mRNA was determined by RT-PCR. The protein expression of TLR and the percentage of TLR positive cells were evaluated through flow cytometric analysis.

RESULTS1. The TLR2 mRNA expression increased significantly in the sepsis group (6.14 +/- 0.80), most significantly in the Gram positive sepsis group (6.43 +/- 0.74). TLR2 mRNA expression was also significantly higher in the bacterial pneumonia group (5.49 +/- 0.62), the bacterial meningitis group (5.61 +/- 0.60) and the congenital syphilis group (5.89 +/- 0.38). TLR2 protein expression was the highest in the sepsis group and significantly increased in the bacterial pneumonia group, bacterial meningitis group and the congenital syphilis groups as well, all were higher than the TLR2 protein expression of the non-infectious group (1.27 +/- 0.75). The TLR2 protein expression in the Gram positive bacterial sepsis group was 2.54 +/- 0.68, that of Gram negative bacterial sepsis group was 1.25 +/- 0.51 (P < 0.05). The percentage of TLR2 positive cells in the neonatal infection group was (70.95 +/- 20.15)%, which did not differ significantly from that of non-infection group. 2. The mRNA expression of TLR4 was the highest in the sepsis group (6.20 +/- 1.59), while that in the Gram negative bacterial sepsis group was 6.78 +/- 1.79, higher than that of the Gram positive bacterial sepsis group, 5.39 +/- 0.78, (t = 2.29, P = 0.037). TLR4 mRNA expression increased significantly in the bacterial pneumonia group (5.33 +/- 1.07), the bacterial meningitis group (5.87 +/- 0.70) and the urinary tract infection group (5.38 +/- 0.91). There were no significant differences in TLR4 protein expression among these groups. The percentage of TLR4 positive cells in the neonatal infection groups was (0.71 +/- 0.31)%, higher than that of non- infection group (0.29 +/- 0.36)%. 3. In the Gram positive bacterial sepsis group, the mRNA expression of TLR2 (6.43 +/- 0.74) was higher than the mRNA expression of TLR4 (5.39 +/- 0.78), (t = 1.56, P = 0.024). In the Gram negative bacterial sepsis group, the mRNA expression of TLR4 (6.78 +/- 0.79) was significantly higher than the mRNA expression of TLR2 (5.64 +/- 0.68) (t = 2.63, P = 0.011). In the sepsis group, the TLR2 protein expression was significantly higher than the expression of TLR4 (t = 1.06, P = 0.044). The percentage of TLR4 positive cells was lower than the percentage of TLR2 positive cells among all these groups, P < 0.01. 4. Correlation analysis on gestational age and the mRNA expression, the protein expression and the percentage of TLR2 and TLR4 positive cells among all these groups did not show any statistical significance.

CONCLUSIONSThe mRNA and the protein expression of TLR2 and the mRNA expression of TLR2 increased significantly in the studied neonatal infection groups, especially in the severe sepsis groups. The mRNA expression of TLR2 increased mainly in the Gram positive bacterial infection groups, and the mRNA expression of TLR4 increased in the Gram negative bacterial infection groups, suggesting that both the TLR2 and TLR4 signal pathway took part in the immune mechanism of neonatal infection, providing new idea and experimental basis for further understanding of immune mechanism of neonatal infection.

Gram-Negative Bacterial Infections ; immunology ; Gram-Positive Bacterial Infections ; immunology ; Humans ; Infant, Newborn ; Meningitis, Bacterial ; immunology ; Pneumonia, Bacterial ; immunology ; Sepsis ; immunology ; microbiology ; Syphilis, Congenital ; immunology ; Toll-Like Receptor 2 ; immunology ; metabolism ; Toll-Like Receptor 4 ; immunology ; metabolism ; Urinary Tract Infections ; immunology ; microbiology

The inflammasome is an emerging new pathway in innate immune defense against microbial infection or endogenous danger signals. The inflammasome stimulates activation of inflammatory caspases, mainly caspase-1. Caspase-1 activation is responsible for processing and secretion of IL-1β and IL-18 as well as for inducing macrophage pyroptotic death. Assembly of the large cytoplasmic inflammasome complex is thought to be mediated by members of NOD-like receptor (NLR) family. While functions of most of the NLR proteins remain to be defined, several NLR proteins including NLRC4 have been shown to assemble distinct inflammasome complexes. These inflammasome pathways, particularly the NLRC4 inflammasome, play a critical role in sensing and restricting diverse types of bacterial infections. Here we review recent advances in defining the exact bacterial ligands and the ligand-binding receptors involved in NLRC4 inflammasome activation. Implications of the discovery of the NAIP family of inflammasome receptors for bacterial flagellin and type III secretion apparatus on future inflammasome and bacterial infection studies are also discussed.
Animals ; Bacteria ; immunology ; Bacterial Infections ; immunology ; metabolism ; CARD Signaling Adaptor Proteins ; immunology ; metabolism ; Caspase 1 ; metabolism ; Flagellin ; immunology ; metabolism ; Humans ; Immunity, Innate ; immunology ; Macrophages ; immunology ; metabolism ; microbiology ; Neuronal Apoptosis-Inhibitory Protein ; immunology ; metabolism

The inflammasome is a multi-protein complex that induces maturation of inflammatory cytokines interleukin (IL)-1beta and IL-18 through activation of caspase-1. Several nucleotide binding oligomerization domain-like receptor family members, including NLRP3, recognize unique microbial and danger components and play a central role in inflammasome activation. The NLRP3 inflammasome is critical for maintenance of homeostasis against pathogenic infections. However, inflammasome activation acts as a double-edged sword for various bacterial infections. When the IL-1 family of cytokines is secreted excessively, they cause tissue damage and extensive inflammatory responses that are potentially hazardous for the host. Emerging evidence has shown that diverse bacterial pathogens or their components negatively regulate inflammasome activation to escape the immune response. In this review, we discuss the current knowledge of the roles and regulation of the NLRP3 inflammasome during bacterial infections. Activation and regulation of the NLRP3 inflammasome should be tightly controlled to prevent virulence and pathology during infections. Understanding the roles and regulatory mechanisms of the NLRP3 inflammasome is essential for developing potential treatment approaches against pathogenic infections.
Bacterial Infections/immunology/metabolism/pathology/prevention & control ; Carrier Proteins/*metabolism ; Caspase 1/metabolism ; Humans ; Inflammasomes/immunology/*metabolism ; Interleukin-1beta/metabolism ; Signal Transduction

This article reviews the production, metabolism, and clinical application of procalcitonin (PCT). PCT is a useful indicator to differentiate bacterial infection and virus infection. Also, it can be used to determine the infection severity and prognosis.
Animals ; Bacterial Infections ; immunology ; Calcitonin ; genetics ; metabolism ; Calcitonin Gene-Related Peptide ; Humans ; Protein Precursors ; genetics ; metabolism ; Virus Diseases ; metabolism

The aim of this study was to investigate the expression of MHCⅠ gene in different tissues of Rana dybowskii under the stress of Aeromonas hydrophila (Ah), and to provide evidence for revealing the anti-infective immune response mechanism of amphibians. The experimental animal model of Aeromonas hydrophila infection was first constructed, and the pathological changes were observed by HE staining. The MHCⅠ gene α1+α2 peptide binding region of Rana dybowskii was cloned by RT-PCR and analyzed by bioinformatics. Real-time PCR was used to detect the transcription level of MHCⅠ in different tissues under Ah stress. After Ah infection, the skin, liver and muscle tissues showed signs of cell structure disappearance and texture disorder. The MHCⅠ gene α1+α2 peptide binding region fragment was 494 bp, encoding 164 amino acids, and homology with amphibians. Above 77%, the homology with mammals was as low as 14.96%, indicating that the α1+α2 region of MHC gene was less conserved among different species. The results of real-time PCR show that the liver, spleen and kidney of the experimental group were under Ah stress. The transcript levels of MHCⅠ gene in skin and muscle tissues were higher than those in the control group at 72 h, but the time to peak of each tissue was different (P<0.01), indicating that the response time of MHCⅠ gene in different tissues was different under Ah stress. This study provides a reference for further exploring the immune function of MHC molecules in anti-infection.
Aeromonas hydrophila ; Animals ; Gene Expression Profiling ; Gene Expression Regulation ; immunology ; Gram-Negative Bacterial Infections ; immunology ; Liver ; metabolism ; Ranidae ; genetics ; immunology ; microbiology ; Skin ; metabolism

To compare immunological characteristics of Extracellular fibrinogen-binding protein (Efb) and Clumping factor A (CfA) of Staphylococcus aureus, we constructed two prokaryotic expression vector pET28a-Efb and pET28a-ClfA. After prokaryotical expression and purification, Efb and ClfA were used to immunize experimental animal. After the second immunization the antisera were collected and the antibody titers, the bacteria binding activity and adhesion inhibition activity of these antisera were detected by enzyme linked immunosorbent assay, adhesion inhibition assay and challenge. Both Efb and ClfA had Fibrinogen binding activity whereas the former had better Fibronectin binding activity. The bacteria binding capability of antisera of rabbits immunized with ClfA was better than that with Efb (P < 0.01). Both antisera of Efb and ClfA could inhibit adherence activity of Staphylococcus aureus to Fibrinogen and Fibronectin adherence compare to the control group (P < 0.01), and Efb had better adhesion inhibition activity than ClfA. The antibody titer of immunized group could reach 1:40 500. After the second immunization, both Efb and ClfA had good protective efficacy. This result constitutes a good foundation for Staphylococcus aureus subunit vaccine development.
Animals ; Antibodies, Bacterial ; blood ; Bacterial Adhesion ; Bacterial Proteins ; immunology ; Cattle ; microbiology ; Coagulase ; immunology ; Enzyme-Linked Immunosorbent Assay ; Fibrinogen ; metabolism ; Genetic Vectors ; Immune Sera ; immunology ; Immunization ; Rabbits ; Staphylococcal Infections ; immunology ; Staphylococcus aureus

OBJECTIVETo construct a recombinant Lactobacillus acidophilus that expresses high levels of Helicobacter pylori (Hp) adhesin Hp0410.

METHODSThe gene fragment encoding Hp0410 was amplified by PCR from the DNA of H. pylori NCTC11639 strain and cloned into the shuttle plasmid pMG36e to construct pMG36e-Hp0410, which was transformed into Lactobacillus acidophilus by electroporation. The target protein was confirmed with SDS-PAGE and silver nitrate staining and analyzed by Western blotting. The stability of the recombinant plasmid was assessed by drawing the growth curve of the recombinant Lactobacillus acidophilus.

RESULTSA 750-bp fragment was inserted into the pMG36e plasmid and transformed into Lactobacillus lactis. The transformed bacterium expressed the target protein with a relative molecular mass of about 34 kD. Western blotting confirmed that the expressed proteins could be recognized by the serum of patients with Hp infection. The recombinant plasmid pMG36e-Hp0410 exhibited good stability in the presence or absence of erythromycin.

CONCLUSIONSThe recombinant Lactobacillus acidophilus with high constitutive expression of Hp0410 has been constructed successfully.

Adhesins, Bacterial ; biosynthesis ; genetics ; immunology ; Bacterial Vaccines ; biosynthesis ; Helicobacter Infections ; prevention & control ; Humans ; Lactobacillus acidophilus ; genetics ; metabolism ; Plasmids ; Recombinant Proteins ; biosynthesis ; genetics ; immunology ; Vaccines, Attenuated ; biosynthesis

The antigenicity of Photobacterium damselae (Ph. d.)subsp. piscicida, cultured in four different growth media[tryptone soya broth (TSB), glucose-rich medium (GRM),iron-depleted TSB (TSB+IR-), and iron-depleted GRM(GRM+IR-)] was compared by enzyme-linked immuno-sorbent assay (ELISA) and Western blot analysis usingsera obtained from sea bass (Dicentrarchus labrax) raisedagainst live or heat-killed Ph. d. subsp. piscicida. Theantigenic expression of Ph. d. subsp. piscicida was found todiffer depending on the culture medium used. A significantlyhigher antibody response was obtained with iron-depletedbacteria by ELISA compared with non-iron depletedbacteria obtained from the sera of sea bass raised againstlive Ph. d. subsp. piscicida. The sera from sea bass raisedagainst live bacteria showed a band at 22kDa in bacteriacultured in TSB+IR- or GRM+IR- when bacteria thathad been freshly isolated from fish were used for thescreening, while bands at 24 and 47kDa were observedwith bacteria cultured in TSB or GRM. When bacteriawere passaged several times on tryptic soya agar prior toculturing in the four different media, only bands at 24 and47kDa were recognized, regardless of the medium used toculture the bacteria. It would appear that the molecularweight of Ph. d. subsp. piscicida antigens change in thepresence of iron restriction, and sera from sea bassinfected with live bacteria are able to detect epitopes onthe antigens after this shift in molecular weight.
Animals ; Antibodies, Bacterial/blood ; Antigens, Bacterial/immunology/*metabolism ; Bass/blood/*immunology ; Blotting, Western/veterinary ; Cell Count/methods ; Culture Media ; Enzyme-Linked Immunosorbent Assay/veterinary ; Fish Diseases/immunology/*microbiology ; Molecular Weight ; Pasteurella Infections/immunology/microbiology/*veterinary ; Photobacterium/*immunology