Alteration of protective and serologic responses in BALB/c mice vaccinated with chemically modified versus nonmodified proteins of Brucella abortus 19

Abstract

A study was conducted to determine whether the covalent chemical modification of BruceUla abortus 19 salt-extractable proteins (BCSP) and BCSP derivatives would modulate the immune responses in BALB/c mice. Salt-extractable proteins BCSP 0-70 and BCSP 70-100 were modified with acetoacetic anhydride, and recombinant proteins rBCSP20 (20 kDa), rBCSP31 (31 kDa), and rBCSP45 (45 kDa) were modified with succinic and dodecanoyl anhydrides. Four weeks after mice were vaccinated with the different preparations, principal and control mice were challenge exposed with a virulent culture of B. abortus 2308, and mice were necropsied 2 weeks later. Serum samples were obtained immediately before mice were challenge exposed and at necropsy. Sera were tested for specific immunoglobulin M (IgM) and G (IgG) antibodies by using an enzyme-linked immunosorbent assay. Acylation decreased the immune responses (increased IgG antibodies and reduced spleen CFU and splenomegaly) induced by both BCSP 0-70 and BCSP 70-100. Modification of the recombinant proteins by dodecanoyl and succinic anhydrides had no effect on the protection induced; however, the IgG serologic responses to the homologous and heterologous proteins were altered. Monophosphoryl lipid A markedly enhanced the immunogenicity of BCSP 0-70.

Simultaneous Identification of Antibodies toBrucella abortusandStaphylococcus aureusin Milk Samples by Flow Cytometry

“…In the absence of repeated serological follow-up of the animals, it is difficult to interpret the meaning of the antibody level (mean channel value) differences observed in the present study. In particular, the high antibody levels reported in Table 3 them was not included among the objectives of the present study, the changes in antibody isotype (2,15,21) and titer (2) occurring during B. abortus infection are approaching clinical relevance. By using two isotype-specific secondary antibodies, one labelled with fluorescein and the other labelled with phycoerythrin, the DCT can be used to study antibodies of two different isotypes simultaneously.…”

Variation of Brucella abortus 2308 infection in BALB/c mice induced by prior vaccination with salt-extractable periplasmic proteins from Brucella abortus 19

“…Some diseases occur only when the balances are disrupted either by failure of the host's immune surveillance system or because the microbe develops special factors or attributes that enable it to circumvent the host's defenses. In that context, Brucella infection of the host animal and the putative disease and immunity induced are thought to be due to specific virulence factors produced by Brucella species constitutively or in response to the host defenses (6,8,9,17,25,37,38,41,57). The severity of the disease produced and the subsequent immune responses induced are dependent on the biochemical nature of the bacterial factors involved and their interactions (2, 3, 10, 12, 14-16, 21-25, 30-37, 40-43, 54, 57, 59, 60).…”

“…More recently, how-ever, studies were directed at the use of outer membrane proteins (including porins), cell surface proteins, polysaccharides, and LPS (2, 10, 12, 23, 24, 30-34, 41, 53, 54, 59, 60). We have been able to show that some of the Brucella cell surface proteins (BCSP) are immunogenic (37,40,51,53) and that others may serve as virulence factors in the disease process (20,37,38,57).…”

“…The periplasmic proteins BCSP70 (4,5,38,40,51,53,54) and BCSP100 (37) were isolated from B. abortus 19 by differential ammonium sulfate precipitation at 70 and 100% saturation, respectively, from supernatant fluid of a high-salt extract of B. abortus. Three subfractions, BCSP20, BCSP31, and BCSP45, were isolated from protein BCSP70 and have been studied (4, 7, 20, 37-39, 45, 46, 49, 53, 57).…”

“…The objective of the study was to determine the efficacy of vaccines prepared from subfractions of BCSP100 relative to that of nonfractionated BCSP100 and BCSP70 vaccines with monophosphoryl lipid A (MPL) from Salmonella typhimurium Re mutant strain as an immune response modifier (37,53,54).…”