BCG Vaccination Induces Robust CD4+ T Cell Responses to Mycobacterium tuberculosis Complex-Specific Lipopeptides in Guinea Pigs.

A new class of highly antigenic, MHC-II-restricted mycobacterial lipopeptides that are recognized by CD4-positive T lymphocytes of Mycobacterium tuberculosis-infected humans has recently been described. To investigate the relevance of this novel class of mycobacterial Ags in the context of experimental bacille Calmette-Guérin (BCG) vaccination, Ag-specific T cell responses to mycobacterial lipid and lipopeptide-enriched Ag preparations were analyzed in immunized guinea pigs. Lipid and lipopeptide preparations as well as complex Ag mixtures, such as tuberculin, mycobacterial lysates, and culture supernatants, all induced a similar level of T cell proliferation.

Membrane-associated DegP in Bordetella chaperones a repeat-rich secretory protein.

The chaperone/protease DegP belongs to the HtrA superfamily and is involved in protein quality control in the periplasm of Gram-negative bacteria. In Escherichia coli, typical substrates are unfolded or misfolded globular proteins that trigger the rearrangement of inactive DegP hexamers into substrate-sequestering 12- or 24-mers 'cages' for refolding or degradation. In Bordetella pertussis, DegP(Bp) facilitates, in addition, the secretion of FHA, a long β-helical adhesin that passes through the periplasm in an extended conformation.

Partial redundancy in the synthesis of the D-arabinose incorporated in the cell wall arabinan of Corynebacterineae.

The major cell wall carbohydrate of Corynebacterineae is arabinogalactan (AG), a branched polysaccharide that is essential for the physiology of these bacteria. Decaprenylphosphoryl-D-arabinose (DPA), the lipid donor of D-arabinofuranosyl residues of AG, is synthesized through a series of unique biosynthetic steps, the last one being the epimerization of decaprenylphosphoryl-beta-D-ribose (DPR) into DPA, which is believed to proceed via a sequential oxidation-reduction mechanism. Two proteins from Mycobacterium tuberculosis (Rv3790 and Rv3791) have been shown to catalyse this epimerization in an in vitro system.