Escherichia coli-Derived Outer Membrane Vesicles Deliver Galactose-1-Phosphate Uridyltransferase and Yield Partial Protection against Actinobacillus pleuropneumoniae in Mice.

In our previous studies, we have identified several in vivo-induced antigens and evaluated their potential as subunit vaccine candidates in a murine model, in which the recombinant protein GalT showed the most potent immunogenicity and immunoprotective efficacy against Actinobacillus pleuropneumoniae. To exploit a more efficient way of delivering GalT proteins, in this study, we employed the widely studied E. coli outer membrane vesicles (OMVs) as a platform to deliver GalT protein and performed the vaccine trial using the recombinant GalT-OMVs in the murine model. Results revealed that GalT-OMVs could elicit a highly-specific, IgG antibody titer that was comparable with the adjuvant GalT group. Significantly higher lymphocyte proliferation and cytokines secretion levels were observed in the GalT-OMVs group. 87.5% and 50% of mice were protected from a lethal dose challenge using A. pleuropneumoniae in active or passive immunization, respectively. Histopathologic and immunohistochemical analyses showed remarkably reduced pathological changes and infiltration of neutrophils in the lungs of mice immunized with GalT-OMVs after the challenge. Taken together, these findings confirm that OMVs can be used as a platform to deliver GalT protein and enhance its immunogenicity to induce both humoral and cellular immune responses in mice.

Molecular studies on galactose 1 phosphate uridylyl transferase from normal and mutant subjects. An immunological approach.

The mutant forms of uridylyl transferase of eight galactosemic patients and two 'Rennes' variants were characterized with regard to the presence and level of immunoreactive protein, the apparent subunit molecular weight and the isoelectric point. Semi-purified haemolysates were studied by various electrophoretic techniques, then proteins were electrophoretically transferred on to nitrocellulose filters. They were treated with specific anti-transferase antibodies, and then with radioiodinated protein A, followed by autoradiography. We have found that: in all cases, a cross-reacting material was detectable, with a molecular subunit size of 46 000, indistinguishable from that of controls. a biochemical heterogeneity of the mutant enzyme was found: the amount of apparent immunologically reactive protein varied from 20 to 100% of that of controls; electrophoretic experiments performed on two 'Rennes' variants showed an increased negative charge.

Purification of normal and inactive galactosemic galactose-1-phosphate uridylyltransferase from human red cells.

A rapid method is described for the purification of galactose-1-phosphate uridylyltransferase (EC 2.7.7.12) from human red blood cells by the use of DEAE-cellulose and two steps of affinity chromatography on a "uridine-aminohexyl" agarose column. The enzyme consists of two identical subunits of 31,000 molecular weight as determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis. Chromatography on Sephadex G-200 chromatography gave a molecular weight of 69,000 for the native enzyme, it being eluted from the column with bovine serum albumin. Cross-linking of the enzyme with dimethylsuberimidate followed by analysis of the products by sodium dodecyl sulfate polyacrylamide gel electrophoresis caused the near-disappearance of the 31,000 molecular weight subunit and the appearance of a protein with a molecular weight of about 65,000 without the appearance of higher polymers.