Acute and chronic phases of Toxoplasma gondii infection in mice modulate the host immune responses

Murine antibody responses to soluble proteins are generally restricted to the immunoglobulin G1 (IgG1) isotype. When mice were infected with Toxoplasma gondii Beverley and concomitantly immunized with a soluble unrelated protein antigen, a modification in the isotypic distribution of antibodies directed against this nonparasite antigen was observed, with a preferential production of IgG2a. Interestingly, when mice were immunized with a soluble protein antigen during the chronic phase (day 40) of infection with T. gondii Beverley, a similar modification in the isotypic distribution of antiprotein antibodies was observed

Purification, partial characterization, and identification of a skin-reactive protein antigen of Mycobacterium bovis BCG.

An immunogenic and skin-reactive protein called P64 was purified from Sauton zinc-deficient culture filtrate of Mycobacterium bovis BCG by using successively hydrophobic chromatography on phenyl-Sepharose, ion exchange on DEAE-Sephacel, and molecular sieving on Sephadex G-200. The final P64 preparation was found to be homogeneous based on several analyses. Protein P64 was a constituent of BCG cells since it was present in soluble cellular extract from normally grown BCG cells. It represented 8 to 9% of the soluble proteins of the extract and appeared as the major soluble protein antigen of BCG. This protein was found to have a molecular weight of 64,000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, but in molecular sieving it eluted at a volume corresponding to a molecular weight of 246,000. An abnormal UV spectrum was observed for this protein. Its amino acid composition showed an abundance of acidic amino acids (or their amides). Aromatic amino acids represented only 3% of the total amino acid residues. The NH2-terminal amino acid sequence of this protein (10 amino acids) was determined. Its sugar content measured with the phenol-sulfuric acid test was lower than 0.3% (wt/wt.) Isolated P64 was tested by various crossed-immunoelectrophoresis techniques and was shown to correspond to antigen 82 in the reference system for BCG antigens. The protein antigen P64 elicited a delayed cutaneous reaction in guinea pigs sensitized with either living or heat-killed BCG. Its potency in skin reaction was, respectively, two- and threefold that of the BCG purified protein derivative. The two types of sensitization used for skin test reactions promoted significant immunoglobulin G antibody production against the protein antigen P64 in guinea pigs 7 weeks after sensitization.Journal Articleinfo:eu-repo/semantics/publishe

Detection of lytic antimycobacterial antibodies by immune lysis of liposomes sensitized to tuberculin.

Two procedures were used in order to incorporate purified protein derivative tuberculin (PPD) from M. tuberculosis, strain H37Rv, into calcein-containing liposomes: formation of multilamellar vesicles (MLV) in a PPD solution or exposure of preformed MLV to this solution. Immune lysis of these PPD-sensitized MLV was studied in the presence of a hyperimmune anti-M. tuberculosis sheep serum using a specific pathogen-free rabbit serum as a source of complement. A 50% release of encapsulated calcein was observed spectrofluorometrically after 30 min and remained unchanged up to 2 h. The release of calcein in the absence of complement or of anti-H37Rv serum or by liposomes which did not contain PPD never exceeded 1-2%. Liposomes formed in PPD solution were more sensitive to anti-H37Rv serum than preformed liposomes exposed to PPD. Trials with human sera from ten tuberculous patients revealed the presence of specific lytic immunoglobulins. In the presence of sera from skin test negative, non-tuberculous subjects, calcein release was significantly lower. This opens the way to a new method for the study of the humoral immunity in tuberculosis.Journal ArticleResearch Support, Non-U.S. Gov'tinfo:eu-repo/semantics/publishe

Isoelectrophoretic characterization of protein antigens present in mycobacterial culture filtrates and recognized by monoclonal antibodies directed against the Mycobacterium bovis BCG antigen 85 complex

SCOPUS: ar.jFLWNAinfo:eu-repo/semantics/publishe