Demonstration of expression of six proteins of the mammalian cell entry (mce1) operon of Mycobacterium tuberculosis by anti-peptide antibodies, enzyme-linked immunosorbent assay and reverse transcription-polymerase chain reaction

Polyclonal rabbit antibodies were generated to synthetic peptides correspon ding to predicted B-cell epitopes of six proteins of the mce1 operon of Myc obacterium tuberculosis. Antipeptide antibodies reacted with Mce1A and Mce1 E fusion proteins in sonicates of recombinant Escherichia coli as well as w ith distinct bands in sonicates, but not in culture fluids of M. tuberculos is and M. bovis bacillus Calmette-Guerin (BCG). Polyvalent rabbit antibodie s generated by immunization with sonicates of BCG bacilli reacted with synt hetic peptides from the six Mce1 proteins on the solid phase in enzyme-link ed immunosorbent assay (ELISA), albeit with different frequencies. The Mce1 A peptide (p124-140) reacted most frequently, with seven of the nine antibo dies tested, while the Mce1F peptide (p329-343) reacted with two. Used as a control, 20 polyclonal rabbit antibodies to 12 isolated proteins of M. tub erculosis and M. bovis BCG did not react with any of the six synthetic pept ides, except in one case, mRNA expression of the six mce1A-mce2F genes of M . tuberculosis was demonstrated by reverse transcription-polymerase chain r eaction (RT-PCR). These data indicate that all Mce1A-Mce1F proteins of the mce1 operon are expressed by in vitro-grown M. tuberculosis and M. bovis BC G.