Intranasal administration of proteoliposome-derived cochleates from Vibrio cholerae O1 induce mucosal and systemic immune responses in mice.

Conservative estimates place the death toll from cholera at more than 100,000 persons each year. A particulate mucosal vaccine strategy combining antigens and immune stimulator molecules from Vibrio cholerae to overcome this problem is described. Proteoliposomes extracted from V. cholerae O1 were transformed into cochleates (AFCo2, Adjuvant Finlay cochleate 2) through a calcium inducible rotary dialysis method. Light microscopy was carried out and tubules of 16.25+/-4.57 microm in length were observed. Western blots were performed to verify the immunochemical properties of the main AFCo2 incorporated antigens, revealing full recognition of the outer membrane protein U (OmpU), lipopolysaccharide (LPS), and mannose-sensitive hemagglutinin (MSHA) antigens. AFCo2 were administered by the intranasal route using a two or three dose schedule and the immune response against V. cholerae antigens was assessed. Three AFCo2 doses were required to induce significant (p<0.05), antigen specific IgA in saliva (1.34+/-0.135) and feces (0.60+/-0.089). While, two or three doses of AFCo2 or proteoliposomes induce similar specific IgG and vibriocidal activity responses in sera. These results show for the first time that AFCo2 can be obtained from V. cholerae O1 proteoliposomes and have the potential to protect against the pathogen when administered intranasally.

Mucosal immunization using proteoliposome and cochleate structures from Neisseria meningitidis serogroup B induce mucosal and systemic responses.

Most pathogens either invade the body or establish infection in mucosal tissues and represent an enormous challenge for vaccine development by the absence of good mucosal adjuvants. A proteoliposome-derived adjuvant from Neisseria meningitidis serogroup B (AFPL1, Adjuvant Finlay Proteoliposome 1) and its derived cochleate form (Co, AFCo1) contain multiple pathogen-associated molecular patterns as immunopotentiators, and can also serve as delivery systems to elicit a Th1-type immune response. The present studies demonstrate the ability of AFPL1and AFCo1 to induce mucosal and systemic immune responses by different mucosal immunizations routes and significant adjuvant activity for antibody responses of both structures: a microparticle and a nanoparticle with a heterologous antigen. Therefore, we used female mice immunized by intragastric, intravaginal, intranasal or intramuscular routes with both structures alone or incorporated with ovalbumin (OVA). High levels of specific IgG antibody were detected in all sera and in vaginal washes, but specific IgA antibody in external secretions was only detected in mucosally immunized mice. Furthermore, antigen specific IgG1 and IgG2a isotypes were all induced. AFPL1 and AFCo1 are capable of inducing IFN-gamma responses, and chemokine secretions, like MIP-1alpha and MIP-1beta. However, AFCo1 is a better alternative to induce immune responses at mucosal level. Even when we use a heterologous antigen, the AFCo1 response was better than with AFPL1 in inducing mucosal and systemic immune responses. These results support the use of AFCo1 as a potent Th1 inducing adjuvant particularly suitable for mucosal immunization.

Analysis of the antigen binding site of anti-deoxycholate monoclonal antibody using a novel affinity labeling reagent, acyl adenylate.

Large-scale analysis of protein-protein interaction sites is especially needed in the postgenomic era. The combination of affinity labeling with mass spectrometry is a potentially useful high-throughput screening method for this purpose. However, reagents in current use are not ideal as some cause damage to the target molecule and others have poor solubility in physiologic aqueous buffers. In this paper, we describe a novel affinity labeling reagent, acyl adenylate, which is highly soluble in aqueous solutions and reacts in a pH-dependent manner. The adenylate of deoxycholic acid reacts with amino groups on the side chain of a lysine residue and at the N-terminus of proteins/peptides. The reactivity and stability of this reagent were investigated, and it was confirmed that, after formation of a reversible ligand-protein complex under weakly acidic conditions, derivatization with acyl adenylate occurred at the target site under weakly alkaline condition. We further demonstrated the utility of this reagent for affinity labeling using a monoclonal antibody with high affinity for deoxycholic acid. Competitive ELISA indicated that deoxycholic acid was labeled around the antibody ligand binding site, thus enabling the structural elucidation of the ligand-protein interaction. In addition, LC/ESI-MS/MS analysis of the labeled peptide obtained by enzymatic digestion and affinity extraction allowed the identification of the structure surrounding the antigen binding site.

Immune responses to orally administered PLGA microparticles: influence of oil vehicles and surfactive agents.

Lipid vehicles and surfactive agents have been successfully used to increase oral absorption and availability of free and encapsulated proteins. In order to investigate if these vehicles could also enhance the serum IgG responses elicited after the oral administration of protein antigens, free bovine serum albumin (BSA) was orally administered to Balb/c mice in different vehicles: a 0.3% sodium bicarbonate aqueous solution, and ethyl oleate/0.3% sodium bicarbonate o/w emulsion (1:9 v/v containing 0.01 microM sodium deoxycholate and 1% poloxamer 188) or ethyl oleate containing the previously described surfactive agents. The immune response elicited by the free antigen was enhanced by the use of these substances, especially when the free protein was administered as an oil suspension containing the surfactive agents. However, when protein loaded 1 microm PLGA particles were orally administered, the use of these enhancers did not result in an improvement of the serum IgG responses, and only the suspension of the spheres in ethyl oleate containing the poloxamer and the bile salt elicited a similar immune response to that achieved with their suspension into an aqueous solution without any enhancer, which suggests that these enhancers are not capable of increasing the absorption of particulated antigens.

Creation and properties of histocompatibility antigen-cell conjugates. I. Preparation and immunological properties of rat histocompatibility antigens.

A necessary step in the induction of unresponsiveness to transplantation antigens is the preparation and presentation of tissue antigens in a suitable form. A method is presented for obtaining rat histocompatibility antigen in a soluble, "heptenic" form suitable for coupling to a tolerogencie carrier. Lewis and ACI spleen cell membranes are solubilized with deoxycholate and purified by Lens culinaris affinity chromatography. The ultracentrifuged, solubilized preparation of rat histocompatibility (HC) antigen is unable to initiate immunity, but is able to react specifically with the product of an already established immune response. The HC antigen preparation is neither immunogenic nor tolerogenic alone. However, an antibody response to allogeneic cells can be prevented when these rat HC preparations are chemically coupled to tolerogenic carrier as described in the accompanying paper.

Radioimmunoassay of serum-conjugated deoxycholic acid.

A specific, sensitive, and reliable radioimmunoassay for serum-conjugated deoxycholic acid has been developed with antiserum obtained after immunization of rabbits with deoxycholic acid--bovine serum albumin conjugate. The displacement curve of glyco [3H] deoxycholic acid was linear on a logit-log plot from 7.5 to 320 pmol of unlabeled glycodeoxycholic acid. At 50% displacement of bound label, the cross-reactivity of taurodeoxycholic acid was 100%, deoxycholic acid 30%, taurocholic acid 3%, and glycocholic acid 2%. No cross-reactivity was observed with free cholic acid, conjugated or free chenodeoxycholic acids and conjugated or free lithocholic acids. Fasting serum-conjugated deoxycholic acid concentrations in 10 healthy volunteers ranged from 0.18 to 0.92 mumol/1. Over a period of 5 hours following 0.5 g oral cholate administration the serum-conjugated deoxycholic acid concentration did not change in 5 fasting healthy persons, whereas an initial increase of serum cholic acid was observed.