OBJECTIVETo investigate the limited digestion of recombinant staphylococcal enterotoxin C2 (SEC2-His)in different conditions.

METHODSThe purified recombinant SEC2-His was treated with different reagents and the cleavage of rSEC2 molecule was observed by SDS-PAGE.

RESULTThe cleavage occurred in positions Cys93-Cys110 of the disulfide loop. Complete auto-cleavage of recombinant SEC2 was observed in solution at 37degrees within 24 hrs, and that was accelerated under alkaline conditions. The auto-cleavage of the recombinant protein was inhibited in the presence of beta-ME (2%), PMSF (5-10 mmol/L), imidazole (1 mol/L) or crude E.coli lysate. Non-specific degradation of recombinant SEC2 was promoted with the increasing of the concentration of H(2)O(2).

CONCLUSIONThe recombinant SEC2-His is broken down in special site of protein, which may be associated with the protein structure.

Amino Acid Sequence ; Enterotoxins ; chemistry ; genetics ; Molecular Sequence Data ; Protein Conformation ; Protein Stability ; Recombinant Fusion Proteins ; chemistry ; genetics

Escherichia coli heat-labile enterotoxin (LT) is composed of catalytic A and non-catalytic homo-pentameric B subunits and causes diarrheal disease in human and animals. In order to produce a nontoxic LT for vaccine and adjuvant development, two novel derivatives of LT were constructed by a site-directed mutagenesis of A subunit; Ser63 to Tyr63 in LTS63Y and Glu110, Glu112 were deleted in LT delta 110/112. The purified mutant LTs (mLTs) showed a similar molecular structural complex as AB5 to that of wild LT. In contrast to wild-type LT, mLTs failed to induce either elongation activity, ADP-ribosyltransferase activity, cAMP synthesis in CHO cells or fluid accumulation in mouse small intestine in vivo. Mice immunized with mLTs either intragastrically or intranasally elicited high titers of LT-specific serum and mucosal antibodies comparable to those induced by wild-type LT. These results indicate that substitution of Ser63 to Tyr63 or deletion of Glu110 and Glu112 eliminate the toxicity of LT without a change of AB5 conformation, and both mutants are immunogenic to LT itself. Therefore, both mLTs may be used to develop novel anti-diarrheal vaccines against enterotoxigenic E. coli.
Amino Acid Substitution ; Animal ; Bacterial Toxins/toxicity* ; Bacterial Toxins/metabolism ; Bacterial Toxins/immunology* ; Bacterial Toxins/genetics ; CHO Cells ; Cyclic AMP/metabolism ; Enterotoxins/toxicity* ; Enterotoxins/metabolism ; Enterotoxins/immunology* ; Enterotoxins/genetics ; Enzyme-Linked Immunosorbent Assay ; Escherichia coli*/metabolism ; Escherichia coli*/genetics ; Female ; Hamsters ; IgA, Secretory/blood ; Ileum/metabolism ; Immunity, Mucosal ; Mice ; Mice, Inbred BALB C ; Mutagenesis, Site-Directed ; NAD+ ADP-Ribosyltransferase/metabolism ; Recombinant Proteins/toxicity ; Recombinant Proteins/metabolism ; Recombinant Proteins/immunology ; Recombinant Proteins/chemistry

BACKGROUND: ChromID Clostridium difficile agar (IDCd; bioMerieux SA, France) is a recently developed chromogenic medium for rapid and specific isolation of C. difficile. We compared the performance of IDCd with that of Clostridium difficile Selective Agar (CDSA). METHODS: A total of 530 fresh stool specimens were collected from patients with clinical signs compatible with C. difficile infection, and cultures for C. difficile were performed on IDCd and CDSA. C. difficile colonies were identified by spore staining, odor, use of an ANI identification test kit (bioMerieux SA), and multiplex PCR for tcdA, tcdB, and tpi. RESULTS: The concordance rate between IDCd and CDSA was 90.6% (480/530). The positivity rates on IDCd on days 1 and 2 (55.6% and 85.0%, respectively) were significantly higher than those on CDSA (19.4% and 75.6%, respectively) (P<0.001 for day 1 and P=0.02 for day 2), but the detection rates on IDCd and CDSA on day 3 were not different (89.4% vs. 82.8%, P=0.0914). On day 3, the recovery rates for non-C. difficile isolates on IDCd and CDSA were 30.2% (160/530) and 22.1% (117/530), respectively (P=0.0075). Clostridium spp. other than C. difficile were the most prevalent non-C. difficile isolates on both media. CONCLUSIONS: The culture positivity rates on IDCd and CDSA were not different on day 3 but IDCd may allow for rapid and sensitive detection of C. difficile within 2 days of cultivation.
Agar/*chemistry ; Bacterial Proteins/genetics ; Bacterial Toxins/genetics ; Clostridium difficile/genetics/*isolation & purification ; DNA, Bacterial/analysis ; Enterocolitis, Pseudomembranous/diagnosis/microbiology ; Enterotoxins/genetics ; Feces/*microbiology ; Humans ; Multiplex Polymerase Chain Reaction ; Reagent Kits, Diagnostic ; Triose-Phosphate Isomerase/genetics

BACKGROUND: Enzyme immunoassay (EIA) capable of detecting both toxin A and toxin B is strongly recommended for the diagnosis of Clostridium difficile associated disease. Therefore, we evaluated two different EIAs for the detection of C. difficile toxin A/B. METHODS: For a total of 228 stool specimens we performed bacteriologic cultures for C. difficile and examined for toxin A and toxin B using enzyme linked fluorescent immunoassay (ELFA; VIDAS CDAB, Bio-Merieux sa, France) and ELISA (C.DIFFICILE TOX A/B II, TECHLAB, USA). We also performed PCR assays for toxin A and B genes in 117 C. difficile isolates that grew from the stool cultures and compared the results with those obtained with the two different EIAs. RESULTS: The concordance rate between ELFA and ELISA was 85.5% (195/228). Using the culture and PCR results as the standard, the sensitivity/specificity of the ELFA and ELISA were 65.0%/72.1% and 71.8%/70.3%, and for positive/negative predictive values were 78.4%/69.6% and 71.8%/70.3%, respectively (P value >0.05). No differences were observed between the results of ELFA and ELISA with toxin A- toxin B+ strains of C. difficile. CONCLUSIONS: The sensitivity of the ELISA was slightly higher than that of ELFA for toxin A and toxin B, but the specificity and positive predictive value of the ELFA were rather higher than those of the ELISA, although no statistical differences were observed. A bacteriologic culture and PCR assay for toxin genes are recommended in case the both EIAs are negative.
Bacterial Proteins/*analysis/genetics/immunology ; Bacterial Toxins/*analysis/genetics/immunology ; Clostridium difficile/genetics/isolation & purification/*metabolism ; Enterotoxins/*analysis/genetics/immunology ; Enzyme-Linked Immunosorbent Assay/*methods ; Feces/microbiology ; Fluorescent Dyes/chemistry ; Humans ; Reagent Kits, Diagnostic

It has been well established that bacterial superantigens lead to the induction and aggravation of chronic inflammatory skin diseases. We investigated the clinical significance of serum specific immunoglobulin E (lgE) to the staphylococcal superantigens staphylococcal enterotoxin A (SEA), staphylococcal enterotoxin B (SEB), and toxic shock syndrome toxin (TSST)-1 in patients with chronic urticaria (CU), focusing on the differences in these prevalences between aspirin-intolerant CU (AICU) and aspirin-tolerant CU (ATCU) patients. Aspirin sensitivity was confirmed by oral aspirin provocation test. There were 66 patients AICU and 117 patients ATCU in the study. Serum IgE antibodies specific for SEA, SEB, and TSST-1 were measured by the ImmunoCAP test and the patients were compared with 93 normal controls (NC). The prevalences of serum specific IgE to staphylococcal superantigens were significantly higher in CU than in NC patients (IgE to SEA, 13.7% vs. 5.4%; IgE to SEB, 12.0% vs. 4.3%; IgE to TSST-1, 18.0% vs. 6.5%; p<0.05, respectively). The patients with specific IgE to SEA, SEB, and TSST-1 had higher serum total IgE levels and higher rates of atopy. Significant associations were noted between the prevalence of specific IgE to SEA and SEB and the HLA DQB1*0609 and DRB1*1302 alleles in the AICU group. We confirmed that a sub-population of patients with CU possesses serum IgE antibodies to SEA, SEB, and TSST- 1. Particularly, the IgE immune response to TSST-1 is associated with aspirin sensitivity in CU patients.
Adolescent ; Adult ; Aged ; Anti-Inflammatory Agents, Non-Steroidal/pharmacology ; Antigens/*chemistry ; Aspirin/pharmacology ; Bacterial Toxins/metabolism ; Chronic Disease ; Enterotoxins/metabolism ; Female ; Humans ; Immunoglobulin E/*chemistry/metabolism ; Male ; Middle Aged ; Phenotype ; Staphylococcus/*genetics/immunology ; Superantigens/metabolism ; Urticaria/*immunology

OBJECTIVETo express a fusion protein of Neisseria gonorrhoeae with a mucosal adjuvant.

METHODSThe gene coding Loop VI-VIII(PL678) of porin, an out-membrane protein of Neisseria gonorrhoeae, was obtained by PCR. It was inserted into a plasmid fused with subunit B of heat labile enterotoxin. The recombinant was transformed in E. coli. The expression of fusion protein was analysed by ELISA, SDS-PAGE and Western-blot.

RESULTFusion protein with LTB was successfully expressed, and displayed both the ability of binding GM1 and the reactogenicity with polyclonal antibodies against Neisseria gonorrhoeae.

CONCLUSIONThe expression of fusion protein laid a foundation for the study of the intramolecular vaccine against Neisseria gonorrhoeae.

Bacterial Outer Membrane Proteins ; biosynthesis ; Bacterial Toxins ; biosynthesis ; Bacterial Vaccines ; immunology ; Enterotoxins ; biosynthesis ; Escherichia coli ; genetics ; Escherichia coli Proteins ; Neisseria gonorrhoeae ; chemistry ; immunology ; Polymerase Chain Reaction ; Recombinant Fusion Proteins ; biosynthesis ; Vaccines, Synthetic ; immunology

Staphylococcus aureus is a major etiological pathogen of bovine mastitis, which triggers significant economic losses in dairy herds worldwide. In this study, S. aureus strains isolated from the milk of cows suffering from mastitis in Korea were investigated by spa typing and staphylococcal enterotoxin (SE) gene profiling. Forty-four S. aureus strains were isolated from 26 farms in five provinces. All isolates grouped into five clusters and two singletons based on 14 spa types. Cluster 1 and 2 isolates comprised 38.6% and 36.4% of total isolates, respectively, which were distributed in more than four provinces. SE and SE-like toxin genes were detected in 34 (77.3%) isolates and the most frequently detected SE gene profile was seg, sei, selm, seln, and selo genes (16 isolates, 36.3%), which was comparable to one of the genomic islands, Type I nuSabeta. This is a first report of spa types and the prevalence of the recently described SE and SE-like toxin genes among S. aureus isolates from bovine raw milk in Korea. Two predominant spa groups were distributed widely and recently described SE and SE-like toxin genes were detected frequently.
Animals ; Cattle ; Cluster Analysis ; DNA, Bacterial/chemistry/genetics ; Enterotoxins/chemistry/*genetics ; Female ; Genotype ; Mastitis, Bovine/epidemiology/genetics/*microbiology ; Microsatellite Repeats ; Milk/*microbiology ; Polymerase Chain Reaction/veterinary ; Prevalence ; Republic of Korea/epidemiology ; Staphylococcal Infections/epidemiology/microbiology/*veterinary ; Staphylococcus aureus/classification/genetics/*isolation & purification