Differential expression of mycobacterial proteins following phagocytosis by macrophages

Abstract

Mycobacterium tuberculosis resides within the macrophages of the host, but the molecular and cellular mechanisms of survival are poorly understood. Recent evidence suggests that the attenuated vaccine strain Mycobacterium bovis BCG is both a deletion and regulatory mutant, yet retains both its immunoprotective and intra-macrophage survival potential. In an attempt to define M. bovis BCG genes expressed during interaction with macrophages, the patterns of protein synthesis were examined by both one-and twodimensional gel electrophoresis of BCG while inside the human leukaemic macrophage cell line THP-1. This study demonstrated that BCG expresses proteins while resident inside macrophages that are not expressed during in vitro growth in culture media or under conditions of heat shock. Western blotting analysis revealed that some of the differentially expressed proteins are specifically recognized by human M. tuberculosis-infected sera. Proteome analysis by two-dimensional electrophoresis and MS identified six abundant proteins that showed increased expression inside macrophages : 16 kDa α-crystallin (HspX), GroEL-1 and GroEL-2, a 317 kDa hypothetical protein (Rv2623), InhA and elongation factor Tu (Tuf). Identification of proteins by such a strategy will help elucidate the molecular basis of the attenuation and the vaccine potential of BCG, and may provide antigens that distinguish infection with M. tuberculosis from vaccination with BCG.

Endocytosis of Mycobacterium tuberculosis Heat Shock Protein 60 Is Required to Induce Interleukin-10 Production in Macrophages*

“…Among the M. tuberculosis heat shock proteins, the Mtbhsp60 (Cpn60.1, Rv3417c) is known to be a very potent stimulator of cytokine production in macrophages and is believed to be an important virulence factor for M. tuberculosis (26). Up-regulation of Rv3417c expression inside the macrophages suggests that Mtbhsp60 might offer a survival advantage to the bacteria within the host (79).…”

Expression of Th1-mediated immunity in mouse lungs induces aMycobacterium tuberculosistranscription pattern characteristic of nonreplicating persistence

“…29 and K. McDonough, personal communication). rv2623, which is also up-regulated on ingestion of Mycobacterium bovis bacillus Calmette-Guérin by cultured macrophages (18), encodes a protein of unknown function that contains an ATP-binding motif and shares homology with the family of prokaryotic universal stress proteins (29,30). sodA and sodC, which encode superoxide dismutases, were selected because superoxide dismutase activity decreases during nonreplicating persistence in the Wayne model (31).…”

“…Thus, mice incapable of making IFN-␥ (7,8) or NOS2 (9,10) or of generating NO (9,11) cannot control growth of tubercle bacilli in the lung. On the pathogen's side, much is known about the modulation of transcription in response to environmental changes during M. tuberculosis growth in vitro (12,(13)(14)(15) or when tubercle bacilli are ingested by macrophages in culture (16)(17)(18). However, there is little, if any, knowledge concerning shifts in transcription patterns of tubercle bacilli responding to defense mechanisms in a host animal.…”

Comparative proteome analysis of Mycobacterium tuberculosis grown under aerobic and anaerobic conditions

“…Identification of proteins that are upregulated during latency is important in order to study the mechanisms of latency and to identify vaccine targets as well as targets for drug development. There are several reports on the proteomes of mycobacterial strains where cytosolic proteins, as well as cell wall proteins and culture filtrate proteins, have been identified (Boon et al, 2001;Jungblut et al, 1999;Mattow et al, 2001;Monahan et al, 2001;Rosenkrands et al, 2000;Sonnenberg & Belisle, 1997;Wong et al, 1999;Yuan et al, 1996).…”