Use of the omp50 gene for identification of Campylobacter species by PCR

We studied the prevalence of the omp50 gene and the Omp50 protein in Campylobacter strains. Immunodetection assays and DNA-DNA hybridizations showed that most C. coli strains tested were negative and most C. jejuni and C. lari strains tested were positive. A PCR assay was developed, using the omp50 gene as a species-specific target. We propose a combination of a hippurate test and an omp50 assay to perform identification of Campylobacter species.     

Presence of autoantibodies to apolipoprotein A-1 in patients with acute coronary syndrome further links autoimmunity to cardiovascular disease

Anti-apolipoprotein A-1 (Apo A-1) autoantibodies were described in autoimmune disorders such as systemic lupus erythematosus (SLE) and antiphospholipid syndrome (APS) and might be involved in the genesis of arterial and venous thrombotic events. To investigate the presence of these autoantibodies in patients with acute coronary syndrome (ACS) without other features of autoimmunity, we set up an enzyme-linked immunosorbent assay (ELISA) for anti-Apo A-1 antibodies. We used it to investigate their prevalence in ACS as compared to SLE and APS and correlated them to plasma Apo A-1 and serum amyloid A protein (SAA) concentrations. The prevalence of anti-Apo A-1 autoantibodies in the healthy control group was 1% (1/92), but was significantly higher in other groups: 21% (11/53) in ACS group (P=0.001), 13% (12/92) in SLE and/or APS group (P=0.005). Multiple linear regression revealed a significant correlation between plasma Apo A-1 (r=-0.72, P=0.013), plasma SAA concentration (r=0.76, P=0.0066) and anti-Apo A-1 IgG titre in ACS patients. The presence of anti-Apo A-1 autoantibodies in patients with ACS highlights an additional link between autoimmunity, inflammation and atherosclerosis.     

Comparative toxicity,protective, histamine sensitizing and leucocytosis promoting activities in mice ofBordetella pertussis culture fluid,bacterial cells and cell extracts

Bordetella pertussis bacterial cells, bacterial extracts, and concentrated culture supernatant fluid were comparatively examined for histamine sensitizing and leucocytosis promoting activities, toxicity (mouse weight gain test), immunoprotective potency and lipopolysaccharide bioassay. The activity of histamine sensitizing factor always paralleled that of leucocytosis promoting factor. In contrast, important differences were demonstrated regarding the toxicity and protective activity of the three preparations. Culture supernatant was more toxic and less protective than either bacterial cells or cell extract. Although the latter had lower protective potency than whole cells, its lower toxicity might lead to its consideration as a possible potential vaccine.     

Epitope mapping of the Brucella melitensis BP26 immunogenic protein: usefulness for diagnosis of sheep brucellosis

Sequencing of bp26, the gene encoding the Brucella sp. immunogenic BP26 periplasmic protein, was performed in the reference strains of Brucella abortus, B. suis, and B. ovis. The three bp26 sequences were almost identical to that published for B. melitensis 16M bp26, and only minor nucleotide substitutions, without modifying the amino acid sequence, were observed between species. The bp26 genes of the seven B. abortus biovar reference strains and B. abortus S19 and RB51 vaccine strains were also sequenced. Again, only minor differences were found. Surprisingly, the bp26 nucleotide sequence for B. abortus S19 was almost identical to that found for B. melitensis 16M and differed from the sequence described previously by others (O. L. Rossetti, A. I. Arese, M. L. Boschiroli, and S. L. Cravero, J. Clin. Microbiol. 34:165-169, 1996) for the same B. abortus strain. The epitope mapping of BP26, performed by using a panel of monoclonal antibodies and recombinant DNA techniques, allowed the identification of an immunodominant region of the protein interesting for the diagnosis of B. melitensis and B. ovis infection in sheep. A recombinant fusion protein containing this region of BP26 reacted indeed, in Western blotting, as the entire recombinant BP26 against sera from B. melitensis- or B. ovis-infected sheep while it avoided false-positive reactions observed with sera from Brucella-free sheep when using the entire recombinant BP26. Thus, use of this recombinant fusion protein instead the entire recombinant BP26 could improve the specific serological diagnosis of B. melitensis or B. ovis infection in sheep.     

Virus overrides the propensity of human CD40L-activated plasmacytoid dendritic cells to produce Th2 mediators through synergistic induction of IFN-{gamma} and Th1 chemokine production

Depending on the activation status, plasmacytoid dendritic cells (PDC) and myeloid DC have the ability to induce CD4 T cell development toward T helper cell type 1 (Th1) or Th2 pathways. Thus, we tested whether different activation signals could also have an impact on the profile of chemokines produced by human PDC. Signals that induce human PDC to promote a type 1 response (i.e., viruses) and a type 2 response [i.e., CD40 ligand (CD40L)] also induced PDC isolated from tonsils to secrete chemokines preferentially attracting Th1 cells [such as interferon-gamma (IFN-gamma)-inducible protein (IP)-10/CXC chemokine ligand 10 (CXCL10) and macrophage inflammatory protein-1beta/CC chemokine ligand 4 (CCL4)] or Th2 cells (such as thymus and activation-regulated chemokine/CCL17 and monocyte-derived chemokine/CCL22), respectively. Activated natural killer cells were preferentially recruited by supernatants of virus-activated PDC, and supernatants of CD40L-activated PDC attracted memory CD4(+) T cells, particularly the CD4(+)CD45RO(+)CD25(+) T cells described for their regulatory activities. It is striking that CD40L and virus synergized to trigger the production of IFN-gamma by PDC, which induces another Th1-attracting chemokine monokine-induced by IFN-gamma/CXCL9 and cooperates with endogenous type I IFN for IP-10/CXCL10 production. In conclusion, our studies reveal that PDC participate in the selective recruitment of effector cells of innate and adaptive immune responses and that virus converts the CD40L-induced Th2 chemokine patterns of PDC into a potent Th1 mediator profile through an autocrine loop of IFN-gamma.     

Murine Immunoprotective Activity of Klebsiella pneumoniae Cell Surface Preparations: Comparative Study with Ribosomal Preparations

Cell surface preparations and ribosomal preparations were extracted from Klebsiella pneumoniae. Agar gel diffusion with antisera to cell surface preparations or ribosomal preparations indicated common antigenic components among the preparations. Lipopolysaccharide and capsular polysaccharide were identified in the cell surface preparations. These results and the previous identification of lipopolysaccharide and capsular polysaccharide in ribosomal preparations suggest that these antigens are responsible for the immunochemical cross-reactivity observed among these two bacterial extracts. Active protection could be induced in mice by these two preparations. On a dry-weight basis, cell surface preparations provided better immunoprotective activity than did ribosomal preparations. However, the 50% protective dose of both preparations is practically the same on the basis of their capsular polysaccharide content. These results are consistent with the hypothesis that the immunoprotective moiety of ribosomal preparations is the contaminating cell surface antigens. Furthermore, the low level of nucleotidic components detected in purified cell surface preparations led us to infer that the immunoprotective activity of capsular polysaccharide may not be dependent on the adjuvant activity of ribonucleic acid. The involvement of capsular polysaccharide in the immunoprotective capacity of cell surface preparations is demonstrated either by using a degradation of this antigen by K. pneumoniae bacteriophage K2-associated glycanase or by using a preparation extracted from a noncapsulated mutant of K. pneumoniae. Nevertheless, the low protective ability of purified capsular polysaccharides is in contrast to its greater activity when induced in bacterial cell surface preparations. The protective activity of K. pneumoniae capsular polysaccharide may be dependent on its association with other surface antigenic components present in cell surface preparations or may be dependent on its native form in the bacterial cell surface.