Project description:Objective of the study is to find out the differentially regulated genes of Mycobacterium BCG strain in extended stationary phase comparison to log phase growth and resuscitation phase. Mycobacterium BCG culture was grown in Sauton medium at 37o C without shaking. Cells at A600 0.6-0.8 were harvested as log phase culture. The cells harvested after 5 months incubation at 37oC without shaking became non culturable and were harvested as extended stationary phase cells. The extended stationary phase cells were treated with resuscitation promoting factor (Rpf) from Micrococcus luteus and harvested after 8 days. Cells of this stage were treated as resuscitation phase cells. Gene expression profiling was carried out using Agilent microarray platform. Keywords: Extended stationary phase, Log phase growth and Resuscitation phase.
Project description:Objective of the study is to find out the differentially regulated genes of Mycobacterium BCG strain in extended stationary phase comparison to log phase growth and resuscitation phase. Mycobacterium BCG culture was grown in Sauton medium at 37o C without shaking. Cells at A600 0.6-0.8 were harvested as log phase culture. The cells harvested after 5 months incubation at 37oC without shaking became non culturable and were harvested as extended stationary phase cells. The extended stationary phase cells were treated with resuscitation promoting factor (Rpf) from Micrococcus luteus and harvested after 8 days. Cells of this stage were treated as resuscitation phase cells. Gene expression profiling was carried out using Agilent microarray platform. Keywords: Extended stationary phase, Log phase growth and Resuscitation phase. ⢠Organism: Mycobacterium tuberculosis BCG ⢠Slides: Agilentâs Mycobacterium tuberculosis custom array 4x44k (G2514F) AMADID No: 016013 ⢠Labeling kit: Ambion Message Amp II Bacteria a RNA Amplification Kit Cat# 1790 ⢠Labeling Method: T7 promoter based-linear amplification to generate labeled complementary RNA ⢠Total RNA and cRNA Purification Kit: Qiagenâs RNeasy minikit Cat#74104 ⢠Hybridization Kit: Agilentâs In situ Hybridzation kit 5184-3568 ⢠RNA quality was checked using Bioanalyzer. Hybridization protocol 825ng each of labeled control cRNA was mixed with 825ng of treated labelled cRNA, mixed with appropriate amount of blocking buffer and hybridization buffer (Agilent Technologies). The hybridization mix was applied on to the backings and hybridized to custom designed 60mer Mycobacterium tuberculosis microarray using sure hyb chambers at 65degC for 17 hours. Slides were washed with gene expression wash buffer 1 and 2 (Agilent Technologies) followed by Acetonitrile. Scan protocol Laser detection of Cyanine 3 and Cyanine 5 fluorescence is performed using a confocal scanning instrument containing two tuned lasers, which excite Cyanine dyes at the appropriate wavelengths. Description Slides were scanned at 5 micron resolution using Agilent scanner.Automated feature extraction was done using Agilentâs Feature Extraction Software. Data processing Analysis of feature extracted data was done using Agilentâs GeneSpring GX V 7.3.1 software. Pre-processing of the replicate experiment data was done to flag the outliers. Normalization of the data was done using per spot per chip intensity dependant lowess normalization and dye swap experiment was data transformed. Genes with log2 ratio of 1.29 and above in replicate experiments were considered as up regulated and 0.81 and below was considered down regulated. p-value was calculated by GeneSpring GX for each gene on the basis of replicate probes to indicate statistical significance. Biological significance of differentials were analyzed using Genotypics Biointerpreter - Web based tool for biological interpretation of given genelist.
Project description:Despite wide scale vaccination with Mycobacterium bovis BCG, the prevalence of tuberculosis remains high, reflecting the global variable efficacy of this vaccine against adult pulmonary TB. Characterisation of different immune responses to M. tuberculosis and M. bovis BCG would increase understanding of pathology following M. tuberculosis infection or reactivation, and would facilitate the rational design of a new vaccine. Gene expression profiling was conducted on samples from diluted whole blood cultures from three healthy donors following incubation with live mycobacteria for six days. Approximately 8,000 gene entities were at least two-fold up- or down- regulated by the mycobacteria, and both mycobacteria induced similar expression changes in approximately 2,300 genes. Strikingly, many genes exhibited qualitatively different expression patterns, with over 1,000 genes up-regulated in response to M. bovis BCG but not changed by M. tuberculosis. Gene Ontology analysis revealed that the genes which failed to upregulate in M. tuberculosis-infected cultures included a large proportion of genes with lysosomal function. The inhibited up-regulation of expression of IFN-γ-inducible protein 30, acid phosphatase 2, cathepsin B and GM2 ganglioside activator was verified in samples from six biologically independent donors by qRT-PCR. The failure to up-regulate these genes in response to M. tuberculosis may constitute an immune evasion mechanism, preventing intracellular killing and antigen presentation. Blood from three healthy BCG-vaccinated donors was diluted with growth medium and incubated alone or with live M. tuberculosis (H37Rv), M. bovis BCG for 6 days. RNA samples were pooled before hybridisation.
Project description:Despite wide scale vaccination with Mycobacterium bovis BCG, the prevalence of tuberculosis remains high, reflecting the global variable efficacy of this vaccine against adult pulmonary TB. Characterisation of different immune responses to M. tuberculosis and M. bovis BCG would increase understanding of pathology following M. tuberculosis infection or reactivation, and would facilitate the rational design of a new vaccine. Gene expression profiling was conducted on samples from diluted whole blood cultures from three healthy donors following incubation with live mycobacteria for six days. Approximately 8,000 gene entities were at least two-fold up- or down- regulated by the mycobacteria, and both mycobacteria induced similar expression changes in approximately 2,300 genes. Strikingly, many genes exhibited qualitatively different expression patterns, with over 1,000 genes up-regulated in response to M. bovis BCG but not changed by M. tuberculosis. Gene Ontology analysis revealed that the genes which failed to upregulate in M. tuberculosis-infected cultures included a large proportion of genes with lysosomal function. The inhibited up-regulation of expression of IFN-γ-inducible protein 30, acid phosphatase 2, cathepsin B and GM2 ganglioside activator was verified in samples from six biologically independent donors by qRT-PCR. The failure to up-regulate these genes in response to M. tuberculosis may constitute an immune evasion mechanism, preventing intracellular killing and antigen presentation.