Nine proteins encoded by Mycobacterium tuberculosis RD1 region are important protective antigens that become absent in long passaging of Mycobacterium tuberculosis. They only exist in pathogenic Mycobacteria and are absent in Bacille Calmette-Guerin and environmental Mycobacteria. With good immunogenicities, they may play an important role in the diagnosis and prevention of Mycobacterium tuberculosis. This article reviews recent studies on using RD1-encoded proteins as antigens in the diagnosis of active tuberculosis and tuberculous pleurisy.
Antigens, Bacterial ; isolation & purification ; metabolism ; Humans ; Mycobacterium tuberculosis ; physiology ; Tuberculosis ; diagnosis

Antigens, Bacterial ; metabolism ; Bacterial Adhesion ; physiology ; Biofilms ; growth & development ; Dental Caries ; microbiology ; Extracellular Matrix ; physiology ; Glucosyltransferases ; metabolism ; Humans ; Mouth ; microbiology ; Polysaccharides, Bacterial ; physiology ; Streptococcus mutans ; enzymology ; pathogenicity ; physiology ; Virulence ; Virulence Factors ; physiology

OBJECTIVEYersinia enterocolitica is an extracellular pathogen and its related antigens interact with the host immune system. We investigated the difference in immunological characteristics between a highly pathogenic and poorly pathogenic strain of Y. enterocolitica.

METHODSWe used SDS-PAGE and western blotting to characterize lipopolysaccharide (LPS), Yersinia outer membrane proteins (Yops), membrane proteins, and whole-cell proteins from poorly pathogenic Y. enterocolitica bio-serotype 2/O:9, isolated from China, and highly pathogenic bio-serotype 1B/O:8, isolated from Japan.

RESULTSThese two strains of Y. enterocolitica had different LPS immune response patterns. Comparison of their Yops also showed differences that could have accounted for their differences in pathogenicity. The membrane and whole-cell proteins of both strains were similar; immunoblottting showed that the 35 kD and perhaps the 10 kD proteins were immunogens in both strains.

CONCLUSIONThe major antigens of the two strains eliciting the host immune response were the LPS and membrane proteins, as shown by comparing protein samples with reference and purified preparations.

Animals ; Antigens, Bacterial ; genetics ; metabolism ; Bacterial Proteins ; genetics ; metabolism ; Blotting, Western ; Electrophoresis, Polyacrylamide Gel ; Female ; Gene Expression Regulation, Bacterial ; physiology ; Lipopolysaccharides ; metabolism ; Rabbits ; Yersinia enterocolitica ; classification ; metabolism

HepG2 cells were treated with Helicobacter pylori (Hp) at different concentrations and the cell killing and apoptosis of the cells were measured with MTT assay and Hoechst 33258 staining technique. The results showed that with the increment of cagA (+) Hp concentration, HepG2 cell killing and apoptosis rate increased in a concentration-dependent manner, but cagA (-) Hp did not significantly impacted on the proliferation and apoptosis of HepG2.
Antigens, Bacterial ; metabolism ; Apoptosis ; physiology ; Bacterial Proteins ; metabolism ; Carcinoma, Hepatocellular ; microbiology ; pathology ; Cell Line, Tumor ; Cell Proliferation ; Cell Survival ; physiology ; Helicobacter pylori ; immunology ; physiology ; Humans ; Liver Neoplasms ; microbiology ; pathology

Perivasculitis and endothelial cell abnormalities are prominent histopathologic features of syphilis. Various cutaneous lesions are the main clinical features of syphilis. We examined whether Treponema pallidum 47 kDa antigen regulates the expression of cell adhesion molecules on human dermal microvascular endothelial cells (HDMEC) and the regulation of T-lymphocytes binding to HDMEC. Using immunofluorescence flow cytometry and enzyme-linked immunosorbent assay (ELISA), we demonstrated that T. pallidum upregulated the expression of adhesion molecules, including intercellular adhesion molecule 1 (ICAM-1), vascular cell adhesion molecule 1 (VCAM-1) and E-selectin. The 47 kDa antigen of T. pallidum also activated endothelium as measured by the upregulation of the expression of adhesion molecules on HDMEC, and it also promoted an increased adherence of T-lymphocytes to HDMEC. The expressions of ICAM-1 and VCAM-1 on HDMEC and the adherence of T-lymphocytes to HDMEC were inhibited by treatment with anti-TNF-alpha antibody or anti-IL-1alpha antibody. These results show that T. pallidum or T. pallidum-specific 47 kDa antigen are capable of stimulating HDMEC to increase the expression of ICAM-1, VCAM-1 and E-selectin and thereby, promote the adherence of T-lymphocytes. The whole process may play an important role in the immunopathogenesis of syphilis and it is likely that TNF-alpha and IL-1alpha are involved.
Antigens, Bacterial/physiology* ; Antigens, Bacterial/chemistry ; Cell Adhesion Molecules/metabolism* ; Cells, Cultured ; Endothelium, Vascular/pathology ; Endothelium, Vascular/metabolism* ; Human ; Microcirculation ; Molecular Weight ; Skin/blood supply* ; T-Lymphocytes/metabolism* ; Treponema pallidum/pathogenicity ; Treponema pallidum/immunology*

OBJECTIVECytotoxin-associated protein (CagA) of H. pylori has been confirmed to be closely associated with gastric inflammation and tumorigenesis, but the mechanism behind it is little understood. In this study, we try to determine roles of CagA(+) strain in activating PI3K/Akt1 signaling pathway, and affecting expression of p21(WAF1/CIP1) and p27(KIP1), and also in releasing IL-8 in host cells.

METHODSAkt1 phosphorylation and IL-8 levels of CagA(+) and CagA⁻ strain infected AGS cells were detected by ELISAs. Two quantitative RT-PCRs were established to measure p21(WAF1/CIP1) and p27(KIP1) mRNA levels in the CagA(+) and CagA⁻ strain infected cells. LY294002, an inhibitor of PI3K/Akt pathway, was used to define effect of the pathway in IL-8 release.

RESULTSCagA(+) strain could induce an obvious elevation of Akt1 phosphorylation in the infected AGS cells while CagA? strain failed to do so. The CagA(+) H. pylori strain infected AGS cells showed significant drops both in p21(WAF1/CIP1) and p27(KIP1) mRNA levels, whereas the CagA⁻ H. pylori strain caused a remarkable increase in p21(WAF1/CIP1) mRNA without affecting p27(KIP1) gene transcription in the AGS cells. Both the CagA(+) and CagA⁻ H. pylori strains enabled AGS cells to produce close elevated levels of IL-8, and the LY294002 block resulted in unexpected elevations of IL-8 levels.

CONCLUSIONSCagA can activate PI3K/Akt1 pathway that plays an inhibitory role in IL-8 release in H. pylori infected AGS cells. Activation of PI3K/Akt1 pathway and subsequent negative regulation of p21(WAF1/CIP1) and p27(KIP1) expression might be involved in CagA-associated carcinogenesis.

Antigens, Bacterial ; genetics ; physiology ; Bacterial Proteins ; genetics ; physiology ; Cell Line ; Cyclin-Dependent Kinase Inhibitor p21 ; biosynthesis ; Cyclin-Dependent Kinase Inhibitor p27 ; Gastric Mucosa ; cytology ; enzymology ; microbiology ; Helicobacter pylori ; metabolism ; pathogenicity ; physiology ; Humans ; Interleukin-8 ; secretion ; Intracellular Signaling Peptides and Proteins ; metabolism ; Phosphatidylinositol 3-Kinases ; metabolism ; Phosphorylation ; Proto-Oncogene Proteins c-akt ; metabolism ; Reverse Transcriptase Polymerase Chain Reaction ; Signal Transduction ; Transcription, Genetic ; Virulence

BACKGROUNDChina is one of the countries with the highest incidence of H. pylori and more than 9090 isolates possessed the cagA gene. This study was to evaluate the biological activity of the H. pylori virulence factor cagA isolated from Chinese patients.

METHODScagA DNA fragments were amplified from the genomic DNA and subsequently cloned into the mammalian expression vector for cell transfection and DNA sequencing. cagA protein, phosphorylated-tyrosine cagA and the complex of cagA precipitated with SHP-2 were identified respectively by western blot in the crude cell lysate from conditionally immortalized gastric epithelial cells at 48 hours after transfection with cagA DNA. In addition, the ability of induction of scattering phenotype was examined after transient expression of cagA in AGS cells.

RESULTSThe C-terminal half of cagA contained only one repeated sequence and three tandem five-amino-acid motifs glutamic acid-proline-isoleucine-tyrosine-alanine (EPIYA). Moreover, the amino acid sequence of D2 region in repeated sequence was aspartic acid-phenylanaline-aspartic acid (D-F-D) which was significantly distinguished from the three repeated sequences and aspartic acid-aspartic adid-leucine (D-D-L) in the western standard strain NCTC11637. Western blot revealed that cagA became phosphorylated in tyrosine site and bound with SHP-2 after transient expression of cagA DNA in gastric epithelial cells. Transient expression of cagA in AGS cells showed that cagA was able to induce the elongation phenotype although to a lesser extent than western strains.

CONCLUSIONScagA perturbs cell signaling pathways by binding with SHP-2. However, significant difference exists in amino acid sequence and biological function of cagA in Chinese compared with those of western countries.

Amino Acid Sequence ; Antigens, Bacterial ; chemistry ; physiology ; Bacterial Proteins ; chemistry ; physiology ; Blotting, Western ; Cells, Cultured ; Gastric Mucosa ; Humans ; Intracellular Signaling Peptides and Proteins ; Molecular Sequence Data ; Phenotype ; Phosphorylation ; Protein Tyrosine Phosphatase, Non-Receptor Type 11 ; Protein Tyrosine Phosphatases ; metabolism ; Repetitive Sequences, Amino Acid ; Signal Transduction

BACKGROUNDThe prevalence of Helicobacter pylori (H. pylori) infection varies by geographic locations. Studies indicate that the infection rate of H. pylori was previously high in China but that rates had been declining worldwide over recent decades.

THE AIMS OF OUR STUDY WERE(1) to determine the current prevalence of H. pylori infection among children and adults residing in areas with high (Muping County, Shandong) and low (Yanqing County, Beijing) incidences of gastric cancer in China, and (2) to compare the prevalence for 2006 with the prevalence for the early 1990s.

METHODSUsing Warthin-Starry silver staining of gastric mucosal biopsy specimens and H. pylori stool antigen tests (HpSA), we tested a total of 2065 asymptomatic children aged 8 - 15 years and adults aged 40 - 79 years in the above two regions from May to July 2006. We evaluated 520 children and 526 adults from Muping, and 516 children and 503 adults from Yanqing. Subjects were selected randomly and H. pylori status was determined by HpSA in children and either HpSA or histology of gastric biopsies in adults. Data obtained in the early 1990s in the same two areas of China were also collected and studied.

RESULTSFor children, the prevalence of H. pylori infection was significantly higher in Muping (37.69%) than it was in Yanqing (25.58%, P < 0.001). In both regions, the prevalence of H. pylori increased with age but was not related to gender. A significant difference was observed between 8 - 9-years old and 10 - 11-years old (P < 0.05), but not between other adjoining age groups (P > 0.05). From 1991 to 2006 H. pylori prevalence among 8 - 10-year-old children decreased in Muping (60.00% vs 32.07%, P < 0.001), but not Yanqing (24.06% vs 19.10%, P > 0.05). In the adult group, H. pylori prevalence was 50.95% in Muping, which was significantly higher than the 41.35% positive rate in Yanqing (P < 0.01). But there were no statistically significant differences between different age groups of 40 - 49, 50 - 59, and 60 - 79 years, or between males and females. A significant decrease in H. pylori prevalence in both regions was observed when the results of 2006 were compared with the data obtained in 1990 in Muping (50.95% vs 73.78%, P < 0.001) and in 1992 in Yanqing (41.35% vs 55.35%, P < 0.01).

CONCLUSIONSAfter fifteen years, the prevalence of H. pylori infection among both children and adults remained significantly higher in areas with a high incidence of gastric cancer in China compared with that in areas with a low incidence of gastric cancer. H. pylori infection rates have decreased in the general Chinese population during recent years.

Adolescent ; Adult ; Age Distribution ; Aged ; Antigens, Bacterial ; Child ; China ; epidemiology ; Female ; Helicobacter Infections ; epidemiology ; immunology ; Helicobacter pylori ; immunology ; physiology ; Humans ; Male ; Middle Aged ; Prevalence ; Stomach Neoplasms ; epidemiology ; immunology ; microbiology

Streptococcus mutans is a common Gram-positive bacterium and plays a significant role in dental caries. Tobacco and/or nicotine have documented effects on S. mutans growth and colonization. Sortase A is used by many Gram-positive bacteria, including S. mutans, to facilitate the insertion of certain cell surface proteins, containing an LPXTGX motif such as antigen I/II. This study examined the effect of nicotine on the function of sortase A to control the physiology and growth of S. mutans using wild-type S. mutans NG8, and its isogenic sortase-defective and -complemented strains. Briefly, the strains were treated with increasing amounts of nicotine in planktonic growth, biofilm metabolism, and sucrose-induced and saliva-induced antigen I/II-dependent biofilm formation assays. The strains exhibited no significant differences with different concentrations of nicotine in planktonic growth assays. However, they had significantly increased (P≤0.05) biofilm metabolic activity (2- to 3-fold increase) as the concentration of nicotine increased. Furthermore, the sortase-defective strain was more sensitive metabolically to nicotine than the wild-type or sortase-complemented strains. All strains had significantly increased sucrose-induced biofilm formation (2- to 3-fold increase) as a result of increasing concentrations of nicotine. However, the sortase-defective strain was not able to make as much sucrose- and saliva-induced biofilm as the wild-type NG8 did with increasing nicotine concentrations. These results indicated that nicotine increased metabolic activity and sucrose-induced biofilm formation. The saliva-induced biofilm formation assay and qPCR data suggested that antigen I/II was upregulated with nicotine but biofilm was not able to be formed as much as wild-type NG8 without functional sortase A.
Amino Acid Motifs ; Aminoacyltransferases ; drug effects ; genetics ; Antigens, Bacterial ; drug effects ; Bacterial Adhesion ; drug effects ; Bacterial Proteins ; drug effects ; genetics ; Biofilms ; drug effects ; Cysteine Endopeptidases ; drug effects ; genetics ; Dose-Response Relationship, Drug ; Humans ; Mutation ; genetics ; Nicotine ; administration & dosage ; pharmacology ; Peptidoglycan ; drug effects ; genetics ; Saliva ; physiology ; Streptococcus mutans ; drug effects ; enzymology ; growth & development ; Sucrose ; pharmacology

OBJECTIVETo construct prokaryotic expression systems of ltB/ctB-lipL41/1 fusion genes, identify immunogenic and adjuvant activities of the products as well as to understand the frequencies of lipL41 gene that carrying and expressing in L. interrogans wild strains and specific antibody levels in sera from patients with leptospirosis.

METHODSPolymerase chain reaction (PCR) with linking primer was applied to construct the fusion genes ltB-lipL41/1 and ctB-lipL41/1. By routine molecular biological techniques, prokaryotic expression systems of the two fusion genes were constructed. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) was used to examine expression of the target recombinant proteins rLTB-rLipL41/1 and rCTB-rLipL41/1. Both western blot and Ganglioside-enzyme linked immunosorbent assay (GM-ELISA) were used while immunogenic and adjuvant activities of rLTB-rLipL41/1 and rCTB-rLipL41/1 were measured. PCR and MAT were performed to detect lipL41 gene and expression of the gene in 97 wild strains of L. interrogans, respectively. Antibodies against product of lipL41 gene in serum samples from 228 leptospirosis patients were detected by ELISA.

RESULTSIn comparison with reported corresponding sequences, the similarities of ltB-lipL41/1 and ctB-lipL41/1 fusion genes to nucleotide and putative amino acid sequence were 99.6%-99.9% and 99.8%-100%, respectively. Expression outputs of both rLTB-rLipL41/1 and rCTB-rLipL41/1, mainly presenting with inclusion body, consisting approximate 10% of the total bacterial proteins. Both rLTB-rLipL41/1 and rCTB-rLipL41/1 could combine rabbit anti-rLipL41/1 serum as well as bovine GM1, respectively. 87.6% of the L. interrogans wild strains(85/97) having lipL41 gene while 84.5% (82/97) of the wild strains with rLipL41/1 or rLipL41/2 antiserum were positive for MAT with titers of 1:4-1:128. 84.6% (193/ 228), 78.5% (179/228) from the patients' serum samples were positive for rLipL41/1 and rLipL41/2 antibodies, respectively.

CONCLUSIONltB-lipL41/1 and ctB-lipL41/1 fusion genes and their prokaryotic expression systems were successfully constructed in this study. The two expressed fusion proteins showed qualified immunogenic and adjuvant activities. lipL41 gene was extensively distributed and frequently expressed in different serogroups of L. interrogans. rLTB-rLipL41/1 or rCTB-rLipL41/1 seemed to have had good potential to serve as an antigen in L. interrogans genus-specific vaccine.

Amino Acid Sequence ; Animals ; Antibody Specificity ; Antigens, Bacterial ; biosynthesis ; chemistry ; genetics ; immunology ; Cattle ; Enzyme-Linked Immunosorbent Assay ; Escherichia coli Proteins ; genetics ; Genetic Engineering ; methods ; Humans ; Leptospira interrogans ; genetics ; physiology ; Leptospirosis ; immunology ; Polymerase Chain Reaction ; Recombinant Fusion Proteins ; biosynthesis ; chemistry ; genetics ; immunology ; Sequence Analysis, DNA