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Updated: May 29, 2026
Demonstrating a Multi-drug Resistant Mycobacterium tuberculosis Amplification Microarray
Published on: April 25, 2014
PPE_MPTR genes are differentially expressed by Mycobacterium tuberculosis in vivo
Silvia Soldini1, Ivana Palucci, Antonella Zumbo
1Istituto di Microbiologia, Università Cattolica del Sacro Cuore, L.go A. Gemelli, 8, 00168 Rome, Italy.
Abstract:
The PPE_MPTR protein sub-family is unique to mycobacteria and comprises proteins found only in MTB complex and in few other pathogenic mycobacteria. Very little is known about the precise function of PPE_MPTR, as well as on the expression pattern and the transcriptional regulation of their structural genes. In the present work, real time RT-PCR techniques were used to determine the expression profile of PPE_MPTR genes of Mycobacterium tuberculosis during infection in vivo and in different culture conditions. The PPE_MPTR genes showed a similar expression profile in axenic cultures, with a significant increase of gene expression following exposure to environmental signals such as SDS, isoniazid and ethambutol. The PPE_MPTR genes were expressed in lung and spleen tissues infected by M. tuberculosis, and levels of expression were similar to those of genes encoding M. tuberculosis virulence factors such as hbhA and mpt64. Levels and pattern of gene expression in host tissues were different for each PPE_MPTR gene under study. The results of this study indicate that PPE_MPTR genes are differentially regulated in the lung and spleen tissues during M. tuberculosis infection, suggesting that each gene responds independently to the different and complex environmental signals encountered in host tissues.
Insights
The PPE_MPTR genes in Mycobacterium tuberculosis are expressed during infection and respond to environmental signals. Their differential regulation in host tissues suggests unique roles in tuberculosis pathogenesis.
Area of Science:
- Microbiology
- Molecular Biology
- Tuberculosis Research
Background:
- The PPE_MPTR protein subfamily is unique to mycobacteria, particularly the Mycobacterium tuberculosis complex.
- The precise function, expression patterns, and transcriptional regulation of PPE_MPTR genes remain largely unknown.
- Understanding these genes is crucial for deciphering Mycobacterium tuberculosis pathogenesis.
Purpose of the Study:
- To investigate the expression profile of PPE_MPTR genes in Mycobacterium tuberculosis.
- To analyze gene expression under various in vitro culture conditions and during in vivo infection.
- To elucidate the transcriptional regulation and potential roles of PPE_MPTR genes.
Main Methods:
- Real-time reverse transcription PCR (RT-PCR) was employed to quantify gene expression.
- Expression levels were analyzed in axenic cultures exposed to environmental stressors (SDS, isoniazid, ethambutol).
- Gene expression was assessed in lung and spleen tissues from M. tuberculosis-infected hosts.
Main Results:
- PPE_MPTR genes exhibited similar expression patterns in axenic cultures, with increased expression upon exposure to SDS, isoniazid, and ethambutol.
- These genes were expressed in infected lung and spleen tissues, with expression levels comparable to known virulence factors (hbhA, mpt64).
- Expression levels and patterns varied distinctly among different PPE_MPTR genes within host tissues.
Conclusions:
- PPE_MPTR genes are differentially regulated in lung and spleen tissues during M. tuberculosis infection.
- Each PPE_MPTR gene appears to respond independently to the complex and varied signals within host environments.
- These findings suggest specialized functions for individual PPE_MPTR genes in the context of host-pathogen interactions.
