Assessment of the serodiagnostic potential of nine novel proteins from Mycobacterium tuberculosis.

To identify antigens that would improve the accuracy of serological diagnosis of active tuberculosis, we cloned the genes encoding nine potentially immunogenic secreted or surface-associated proteins of Mycobacterium tuberculosis. Recombinant proteins were reacted with sera from HIV-negative individuals with extrapulmonary tuberculosis (EP-TB) or HIV-positive individuals with pulmonary tuberculosis (TBH). Specific and high level antibody responses were obtained for four recombinant proteins, of which antigen GST-822 was recognized by 60% of EP-TB and 42% of TBH and antigen MBP-506 was recognized by 45% of EP-TB and 61% of TBH.

Identification of novel immunogenic Mycobacterium tuberculosis peptides that stimulate mononuclear cells from immune donors.

Proteins which are secreted or associated with the cell envelope of Mycobacterium tuberculosis may contain protective T-cell epitopes. Prior to this study, a recombinant clone bank of enzymatically active M. tuberculosis-alkaline phosphatase fusions, were screened for immunogenicity in a murine T-cell model.

Mycobacterium tuberculosis efpA encodes an efflux protein of the QacA transporter family.

The Mycobacterium tuberculosis H37Rv efpA gene encodes a putative efflux protein, EfpA, of 55,670 Da. The deduced EfpA protein was similar in secondary structure to Pur8, MmrA, TcmA, LfrA, EmrB, and other members of the QacA transporter family (QacA TF) which mediate antibiotic and chemical resistance in bacteria and yeast. The predicted EfpA sequence possessed all transporter motifs characteristic of the QacA TF, including those associated with proton-antiport function and the motif considered to be specific to exporters.

New vectors for the in vitro generation of alkaline phosphatase fusions to proteins encoded by G+C-rich DNA.

Phagemid vectors were constructed to allow fusions of alkaline phosphatase to proteins encoded by G+C-rich DNA, by engineering a BstBI site (TT/CGAA) in front of a phoA gene that lacks an encoded signal peptide. Three vectors (pJDT1, pJDT2 and pJDT3), each with phoA in a different reading frame with respect to the BstBI site, were produced; a lacP region is present in each plasmid upstream of the BstBI site. The presence of the BstBI site allows the random cloning of G+C-rich DNA digested with a number of restriction enzymes that generate cohesive ends.