Abortus Lipopolysaccharide Research Articles

Induction of immune and adjuvant immunoglobulin G responses in mice by Brucella lipopolysaccharide.

The immunogenic and adjuvant properties of Brucella abortus and Escherichia coli lipopolysaccharides (LPSs) were studied in endotoxin-responsive, athymic, and euthymic BALB/c mice and in responsive C3H/HeAu mice and congenic nonresponsive C3H/HeJ mice. Consistent with previous reports, E. coli LPS did not stimulate significant primary or secondary antibody responses in C3H/HeJ mice and induced the production of immunoglobulin M (IgM) and low levels of IgG in C3H/HeAu mice. In contrast, B. abortus smooth and rough LPS stimulated primary and secondary antibody responses and induced the production of IgM and high levels of IgG in both responsive and nonresponsive strains of C3H/He mice and in nude mice. When used as adjuvant, B. abortus LPS augmented the IgG plaque-forming-cell response of C3H/HeAu and BALB/c euthymic mice to the T-dependent antigen sheep erythrocytes. E. coli LPS augmented only the IgM plaque-forming-cell response in the same mouse strains. Neither B. abortus nor E. coli LPS was adjuvant for C3H/HeJ or nude mice. The dichotomy between the antibody and adjuvant responses of both C3H/HeJ mice and athymic mice to B. abortus LPS may be a function of the true thymus independence and dependence of these responses. In addition, the refractiveness of C3H/HeJ and nude mice to B. abortus LPS as adjuvant, but not as mitogen or polyclonal B cell activator, clearly dissociates these phenomena.

Comparative assessment of antibody isotypes to [formula omitted] by primary and secondary binding assays

Bovine isotypes IgM, IgG 1, IgG 2, and IgA, affinity purified via Brucella abortus lipopolysaccharide (LPS) attached covalently to agarose beads, were assessed for their antibody activity in various serological tests. In an enzyme linked immunosorbent test, using LPS as the antigen attached to a plastic matrix and goat anti-heavy chain specific IgG fractions conjugated to horseradish peroxidase, the limiting amount of antibody of each isotype detectable was 155 ng for IgM; 190 ng for IgG 1; 220 ng for IgG 2 and approximately 700 ng for IgA. In a hemolysis in gel test using LPS attached to bovine erythrocytes as the antigen, and guinea pig complement, the least amounts of detectable antibody were IgM:5500 ng; IgG 1:60 ng; IgG 2:4850 ng; IgA was not reactive. However, as preformed immune complexes all four isotypes were capable of activating bovine complement. For the indirect hemagglutination assay, both fresh sheep and chicken erythrocytes were sensitized with antigen. The least amounts of antibody detectable with LPS-coated sheep erythrocytes were IgG 2: 625 ng; IgG 1: 3750 ng; IgA: 4250 ng; and IgM: not reactive. Using LPS-coated chicken erythrocytes, only IgG 2 was reactive to a limit of 1250 ng. Using isotypes as the antibody in an antibody-dependent cell-mediated cytotoxicity assay, normal bovine mononuclear cells as effector cells and chicken erythrocytes sensitized with LPS as target cells, only IgG 2 was reactive. Specific activity was retained to approximately 1000 ng. The implication of these results in terms of diagnosis and protective immunity in brucellosis will be discussed.

Affinity purification of bovine antibodies to Brucella abortus Lipopolysaccharide.

Alkali-treated lipopolysaccharide from Brucella abortus S1119.3 coupled to agarose beads by cyanogen bromide activation resulted in an immunoadsorbent with which a large amount of B. abortus-specific antibodies could be purified. The method described gave alkali-treated lipopolysaccharide binding efficiencies of up to 98%. There was little loss of alkali-treated lipopolysaccharide from the column after several pH shifts, allowing the immunoadsorbent to be regenerated and used repeatedly.

Enzyme immunoassay of the antibody response to Brucella and Yersinia enterocolitica 09 infections in humans.

An enzyme immunoassay, with phenol-water extracted lipopolysaccharide (LPS) from Brucella abortus as antigen, was used to detect the class-specific antibody response in sera from 173 patients with B. abortus, B. melitensis or B. suis infection. Sera from 30 patients with salmonellosis, yersiniosis or tularaemia and from 25 healthy individuals served as controls. The B. abortus LPS antigen permitted a safe diagnosis of acute and chronic brucellosis with high IgM and rising IgG titres in sera collected in the acute stage of the disease, and with elevated IgG titres only in the chronic stage. The B. abortus LPS antigen also permitted a specific diagnosis with the exception of the high titres estimated in sera from patients with Yersinia enterocolitica 09 infection. The problem with that well-known reciprocal cross-reactivity was overcome by using two additional antigens: Y. enterocolitica 09 native and periodate oxidized and borohydride reduced LPS preparations. In sera from patients with brucellosis high titres were estimated against all three antigens, whereas in sera from patients with yersiniosis caused by serotype 09 high titres were measurable only with the B. abortus and the Y. enterocolitica native LPS antigens. These data suggest that the B. abortus and Y. enterocolitica 09 LPS share one antigenic determinant resistant to periodate oxidation and borohydride reduction, and that in addition the Y. enterocolitica 09 LPS has a determinant which is sensitive to periodate oxidation and borohydride reduction.

Ethylenediaminetetraacetic acid (disodium salt)-labile bovine immunoglobulin M Fc binding to Brucella abortus: a cause of nonspecific agglutination.

It was demonstrated by a radioimmunoassay procedure that Brucella abortus agglutinins from noninfected cattle sera, absorbed to B. abortus antigen and eluted with ethylenediaminetetraacetic acid (EDTA), was immunoglobulin M that bound to that bacterium by its Fc portion. The EDTA-eluted immunoglobulin M agglutinated intact B. abortus cells but not erythrocytes treated with B. abortus lipopolysaccharide. The specificity of the EDTA-eluted immunoglobulin was for B. abortus, although a small titer to Yersinia enterocolitica serotype O:9 was observed. In contrast, immunoglobulin M purified from the serum of a cow injected 7 days previously with heat-killed B. abortus bound to the antigen by its Fab portion, was not labile to EDTA treatment, cross-reacted extensively with Y. enterocolitica serotype O:9, and agglutinated various other bacterial antigens and normal erythrocytes.

Immune and mitogenic responses by BALB/c, C3H/HeJ, and nude mice to Brucella abortus bacterin and lipopolysaccharide.

The immunogenic and mitogenic properties of Brucella abortus 1119-3 bacterin (BA) and biologically active B. abortus lipopolysaccharide (BA-LPS) were studied using normal and athymic (nude) BALB/c and C3H/HeJ mice. Although BA stimulated 2-mercaptoethanol-sensitive (2-ME-S) primary and secondary antibody responses in all mice, nude mice, in contrast to normal BALB/c and C3H/HeJ mice, did not make substantial 2-mercaptoethanol-resistant (2-ME-R) antibody responses. Similarly, all mice injected with BA-LPS made 2-ME-S primary responses, and the secondary response of thymus-bearing mice contained a substantial 2-ME-R component. Collectively, these observations suggest that although both BA and BA-LPS can stimulate thymus-independent 2-ME-S antibody synthesis, thymus-derived cells are required for optimal immune responses containing a 2-ME-R component. The antibody responses of normal BALB/c and C3H/HeJ mice to BA and BA-LPS were qualitatively and quantitatively similar. Both BA and BA-LPS were mitogenic for spleen cells from normal and nude BALB/c and C3H/HeJ mice but not for thymus cells from normal BALB/c or C3H/HeJ mice, suggesting that both preparations are B-cell mitogens.