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Fulltext Study of Mycobacterium tuberculosis complex genotypic diversity in Malaysia reveals a predominance of ancestral East-African-Indian lineage with a Malaysia-specific signature

Ismail F, Couvin D, Farakhin I, Abdul Rahman Z, Rastogi N, Suraiya S

PLoS One, 2014;9(12):e114832.
PMID: 25502956 DOI: 10.1371/journal.pone.0114832

Tuberculosis (TB) still constitutes a major public health problem in Malaysia. The identification and genotyping based characterization of Mycobacterium tuberculosis complex (MTBC) isolates causing the disease is important to determine the effectiveness of the control and surveillance programs.

Matched MeSH terms: Mycobacterium tuberculosis/genetics*; Tuberculosis/genetics*
Fulltext Genome sequence analysis of multidrug-resistant Mycobacterium tuberculosis from Malaysia

Tan JL, Simbun A, Chan KG, Ngeow YF

Sci Data, 2020 05 05;7(1):135.
PMID: 32371951 DOI: 10.1038/s41597-020-0475-x

Mycobacterium tuberculosis (MTB) is commonly used as a model to study pathogenicity and multiple drug resistance in bacteria. These MTB characteristics are highly dependent on the evolution and phylogeography of the bacterium. In this paper, we describe 15 new genomes of multidrug-resistant MTB (MDRTB) from Malaysia. The assessments and annotations on the genome assemblies suggest that strain differences are due to lineages and horizontal gene transfer during the course of evolution. The genomes show mutations listed in current drug resistance databases and global MTB collections. This genome data will augment existing information available for comparative genomic studies to understand MTB drug resistance mechanisms and evolution.

Matched MeSH terms: Mycobacterium tuberculosis/genetics*
Molecular epidemiology of tuberculosis in Malaysia

Dale JW, Nor RM, Ramayah S, Tang TH, Zainuddin ZF

J Clin Microbiol, 1999 May;37(5):1265-8.
PMID: 10203468

Molecular typing with IS6110 was applied to Mycobacterium tuberculosis isolates from all parts of Malaysia. The degree of clustering increased with patient age, suggesting that reactivation may contribute to clustering. Identical banding patterns were also obtained for isolates from widely separate regions. Therefore, the use of clustering as a measure of recent transmission must be treated with caution. Strains related to the Beijing family were common in Peninsular Malaysia but were less common in Sabah and Sarawak, while a distinct group of strains comprised nearly 40% of isolates from East Malaysia but such strains were rare in Peninsular Malaysia. Single-copy strains, common in South and Southeastern Asia, constituted nearly 20% of isolates from the peninsula but were virtually absent in East Malaysia. The marked geographical difference in the prevailing strains indicates not only a restricted dissemination of M. tuberculosis but also a considerable degree of stability in the banding patterns.

Matched MeSH terms: Mycobacterium tuberculosis/genetics*
Fulltext Genome Analysis of the First Extensively Drug-Resistant (XDR) Mycobacterium tuberculosis in Malaysia Provides Insights into the Genetic Basis of Its Biology and Drug Resistance

Kuan CS, Chan CL, Yew SM, Toh YF, Khoo JS, Chong J, et al.

PLoS One, 2015;10(6):e0131694.
PMID: 26110649 DOI: 10.1371/journal.pone.0131694

The outbreak of extensively drug-resistant tuberculosis (XDR-TB) has become an increasing problem in many TB-burdened countries. The underlying drug resistance mechanisms, including the genetic variation favored by selective pressure in the resistant population, are partially understood. Recently, the first case of XDR-TB was reported in Malaysia. However, the detailed genotype family and mechanisms of the formation of multiple drugs resistance are unknown. We sequenced the whole genome of the UM 1072388579 strain with a 2-kb insert-size library and combined with that from previously sequenced 500-bp-insert paired-end reads to produce an improved sequence with maximal sequencing coverage across the genome. In silico spoligotyping and phylogenetic analyses demonstrated that UM 1072388579 strain belongs to an ancestral-like, non-Beijing clade of East Asia lineage. This is supported by the presence of a number of lineage-specific markers, including fadD28, embA, nuoD and pks7. Polymorphism analysis showed that the drug-susceptibility profile is correlated with the pattern of resistance mutations. Mutations in drug-efflux pumps and the cell wall biogenesis pathway such as mmpL, pks and fadD genes may play an important role in survival and adaptation of this strain to its surrounding environment. In this work, fifty-seven putative promoter SNPs were identified. Among them, we identified a novel SNP located at -4 T allele of TetR/acrR promoter as an informative marker to recognize strains of East Asian lineage. Our work indicates that the UM 1072388579 harbors both classical and uncommon SNPs that allow it to escape from inhibition by many antibiotics. This study provides a strong foundation to dissect the biology and underlying resistance mechanisms of the first reported XDR M. tuberculosis in Malaysia.

Matched MeSH terms: Mycobacterium tuberculosis/genetics*; Extensively Drug-Resistant Tuberculosis/genetics
Fulltext Whole-genome sequencing to establish relapse or re-infection with Mycobacterium tuberculosis: a retrospective observational study

Bryant JM, Harris SR, Parkhill J, Dawson R, Diacon AH, van Helden P, et al.

Lancet Respir Med, 2013 Dec;1(10):786-92.
PMID: 24461758 DOI: 10.1016/S2213-2600(13)70231-5

BACKGROUND: Recurrence of tuberculosis after treatment makes management difficult and is a key factor for determining treatment efficacy. Two processes can cause recurrence: relapse of the primary infection or re-infection with an exogenous strain. Although re-infection can and does occur, its importance to tuberculosis epidemiology and its biological basis is still debated. We used whole-genome sequencing-which is more accurate than conventional typing used to date-to assess the frequency of recurrence and to gain insight into the biological basis of re-infection.
METHODS: We assessed patients from the REMoxTB trial-a randomised controlled trial of tuberculosis treatment that enrolled previously untreated participants with Mycobacterium tuberculosis infection from Malaysia, South Africa, and Thailand. We did whole-genome sequencing and mycobacterial interspersed repetitive unit-variable number of tandem repeat (MIRU-VNTR) typing of pairs of isolates taken by sputum sampling: one from before treatment and another from either the end of failed treatment at 17 weeks or later or from a recurrent infection. We compared the number and location of SNPs between isolates collected at baseline and recurrence.
FINDINGS: We assessed 47 pairs of isolates. Whole-genome sequencing identified 33 cases with little genetic distance (0-6 SNPs) between strains, deemed relapses, and three cases for which the genetic distance ranged from 1306 to 1419 SNPs, deemed re-infections. Six cases of relapse and six cases of mixed infection were classified differently by whole-genome sequencing and MIRU-VNTR. We detected five single positive isolates (positive culture followed by at least two negative cultures) without clinical evidence of disease.
INTERPRETATION: Whole-genome sequencing enables the differentiation of relapse and re-infection cases with greater resolution than do genotyping methods used at present, such as MIRU-VNTR, and provides insights into the biology of recurrence. The additional clarity provided by whole-genome sequencing might have a role in defining endpoints for clinical trials.
FUNDING: Wellcome Trust, European Union, Medical Research Council, Global Alliance for TB Drug Development, European and Developing Country Clinical Trials Partnership.

Matched MeSH terms: Mycobacterium tuberculosis/genetics*; Tuberculosis/genetics*
Immunoinformatics study on highly expressed Mycobacterium tuberculosis genes during infection

Nguyen Thi le T, Sarmiento ME, Calero R, Camacho F, Reyes F, Hossain MM, et al.

Tuberculosis (Edinb), 2014 Sep;94(5):475-81.
PMID: 25034135 DOI: 10.1016/j.tube.2014.06.004

The most important targets for vaccine development are the proteins that are highly expressed by the microorganisms during infection in-vivo. A number of Mycobacterium tuberculosis (Mtb) proteins are also reported to be expressed in-vivo at different phases of infection. In the present study, we analyzed multiple published databases of gene expression profiles of Mtb in-vivo at different phases of infection in animals and humans and selected 38 proteins that are highly expressed in the active, latent and reactivation phases. We predicted T- and B-cell epitopes from the selected proteins using HLAPred for T-cell epitope prediction and BCEPred combined with ABCPred for B-cell epitope prediction. For each selected proteins, regions containing both T- and B-cell epitopes were identified which might be considered as important candidates for vaccine design against tuberculosis.

Matched MeSH terms: Mycobacterium tuberculosis/genetics*; Tuberculosis/genetics*
Analysis of differentially expressed proteins in late-stationary growth phase of Mycobacterium tuberculosis H37Rv

Ang KC, Ibrahim P, Gam LH

Biotechnol Appl Biochem, 2014 Mar-Apr;61(2):153-64.
PMID: 23826872 DOI: 10.1002/bab.1137

Mycobacterium tuberculosis is a causative agent of tuberculosis (TB). The ability of M. tuberculosis to be quiescent in the cell has caused the emergence of latent infection. A comprehensive proteomic analysis of M. tuberculosis H37Rv over three growth phases, namely mid-log (14-day culture), early stationary (28-day culture), and late stationary (50-day culture), was performed in order to study the change in proteome from the mid-log phase to late-stationary phase. Combination methods of two-dimensional electrophoresis (2-DE) and tandem mass spectrometry were used to generate proteome maps of M. tuberculosis at different growth phases. Ten proteins were detected differentially expressed in the late-stationary phase compared with the other two phases. These proteins were SucD, TrpD, and Rv2161c, which belong to metabolic pathway proteins; FadE5, AccD5, DesA1, and Rv1139c are proteins involved in cell wall or lipid biosynthesis, whereas TB21.7 and Rv3224 are conserved hypothetical proteins with unknown function. A surface antigen protein, DesA1, was not detectable in the late-stationary phase, although present in both log and early-stationary phases. The changes in the expression levels of these proteins were in line with the growth environment changes of the bacteria from mid-log phase to late-stationary phase. The information gathered may be valuable in the intervention against latent TB infection.

Matched MeSH terms: Mycobacterium tuberculosis/genetics*
Near miss diagnosis of childhood tuberculosis

Norlijah O, Intan HI, Feizel AM, Kasim MS, Noh LM

Southeast Asian J. Trop. Med. Public Health, 2006 Sep;37(5):953-7.
PMID: 17333739

Tuberculosis (TB) remains a public health problem in Malaysia. We describe three atypical cases of serious tuberculosis in children. The potential diagnostic pitfall in these cases is highlighted by its unusual presentation in a setting of culture-negative infection. A positive polymerase chain reaction (PCR) in each case assists in gauging the diagnosis in concordance with appropriate clinical findings.

Matched MeSH terms: Mycobacterium tuberculosis/genetics
Fulltext Sequence comparison of six human microRNAs genes between tuberculosis patients and healthy individuals

Amila A, Acosta A, Sarmiento ME, Suraiya S, Zafarina Z, Panneerchelvam S, et al.

Int J Mycobacteriol, 2015 Dec;4(4):341-6.
PMID: 26964819 DOI: 10.1016/j.ijmyco.2015.06.009

MicroRNAs (miRNAs) play an important role in diseases development. Therefore, human miRNAs may be able to inhibit the survival of Mycobacterium tuberculosis (Mtb) in the human host by targeting critical genes of the pathogen. Mutations within miRNAs can alter their target selection, thereby preventing them from inhibiting Mtb genes, thus increasing host susceptibility to the disease.

Matched MeSH terms: Mycobacterium tuberculosis/genetics
Detection of Mycobacterium tuberculosis in bronchoalveolar lavage from patients with sputum smear-negative pulmonary tuberculosis using a polymerase chain reaction assay

Liam CK, Chen YC, Yap SF, Srinivas P, Poi PJ

Respirology, 1998 Jun;3(2):125-9.
PMID: 9692522

The objective of this study was to evaluate the utility of a polymerase chain reaction (PCR) assay in detecting Mycobacterium tuberculosis in bronchoalveolar lavage (BAL) specimens of patients suspected of having active pulmonary tuberculosis (TB) but who were sputum smear-negative. Patients undergoing investigation for suspected pulmonary TB at the University Hospital, Kuala Lumpur, and who were sputum smear-negative underwent fibreoptic bronchoscopy and BAL. One portion of each lavage specimen was submitted for smear examination for acid-fast bacilli and mycobacterial culture and the other portion assayed by PCR for the presence of a 562-base pair DNA segment belonging to the insertion sequence IS986, unique to the M. tuberculosis complex. As controls, lavage specimens from patients with other lung lesions were also similarly tested. The PCR assay gave a positivity rate of 80.9% (55 of 68) compared with 8.8% of smear examination and 7.4% of culture for detecting M. tuberculosis in BAL specimens. The assay was positive in two of 45 BAL specimens from 35 control subjects. The PCR assay was more sensitive than smear and culture in detecting M. tuberculosis in BAL specimens of patients with sputum smear-negative pulmonary TB.

Matched MeSH terms: Mycobacterium tuberculosis/genetics
Insertion sequence typing of Mycobacterium tuberculosis: characterization of a widespread subtype with a single copy of IS6110

Fomukong NG, Tang TH, al-Maamary S, Ibrahim WA, Ramayah S, Yates M, et al.

Tuber. Lung Dis., 1994 Dec;75(6):435-40.
PMID: 7718832 DOI: 10.1016/0962-8479(94)90117-1

DNA fingerprinting with the insertion sequence IS6110 (also known as IS986) has become established as a major tool for investigating the spread of tuberculosis. Most strains of Mycobacterium tuberculosis have multiple copies of IS6110, but a small minority carry a single copy only. We have examined selected strains from Malaysia, Tanzania and Oman, in comparison with M. bovis isolates and BCG strains carrying one or two copies of IS6110. The insertion sequence appears to be present in the same position in all these strains, which suggests that in these organisms the element is defective in transposition and that the loss of transposability may have occurred at an early stage in the evolution of the M. tuberculosis complex.

Matched MeSH terms: Mycobacterium tuberculosis/genetics*
Fulltext In Silico identification of M. TB proteins with diagnostic potential

Calero R, Mirabal M, Bouza J, Guzmán MV, Carrillo H, López Y, et al.

BMC Immunol, 2013;14 Suppl 1:S9.
PMID: 23458073 DOI: 10.1186/1471-2172-14-S1-S9

TB, caused by Mycobacterium tuberculosis (MTB), is one of the major global infectious diseases. For the pandemic control, early diagnosis with sensitive and specific methods is fundamental. With the advent of bioinformatics' tools, the identification of several proteins involved in the pathogenesis of TB (TB) has been possible. In the present work, the MTB genome was explored to look for molecules with possible antigenic properties for their evaluation as part of new generation diagnostic kits based on the release of cytokines. Seven proteins from the MTB proteome and some of their combinations suited the computational test and the results suggested their potential use for the diagnosis of infection in the following population groups: Cuba, Mexico, Malaysia and sub-Saharan Africa. Our predictions were performed using public bioinformatics tools plus three computer programs, developed by our group, to facilitate information retrieval and processing.

Matched MeSH terms: Mycobacterium tuberculosis/genetics*
An overview of the phenotypic and genotypic characteristics of multidrug-resistant Mycobacterium tuberculosis isolates from four Asian countries

Ang CF, Ong CS, Rukmana A, Pham Thi KL, Yap SF, Ngeow YF, et al.

J Med Microbiol, 2008 Aug;57(Pt 8):1039-1040.
PMID: 18628510 DOI: 10.1099/jmm.0.47850-0
Matched MeSH terms: Mycobacterium tuberculosis/genetics*
Human tuberculosis and Mycobacterium tuberculosis complex: A review on genetic diversity, pathogenesis and omics approaches in host biomarkers discovery

Kanabalan RD, Lee LJ, Lee TY, Chong PP, Hassan L, Ismail R, et al.

Microbiol Res, 2021 May;246:126674.
PMID: 33549960 DOI: 10.1016/j.micres.2020.126674

Mycobacterium tuberculosis complex (MTBC) refers to a group of mycobacteria encompassing nine members of closely related species that causes tuberculosis in animals and humans. Among the nine members, Mycobacterium tuberculosis (M. tuberculosis) remains the main causative agent for human tuberculosis that results in high mortality and morbidity globally. In general, MTBC species are low in diversity but exhibit distinctive biological differences and phenotypes among different MTBC lineages. MTBC species are likely to have evolved from a common ancestor through insertions/deletions processes resulting in species speciation with different degrees of pathogenicity. The pathogenesis of human tuberculosis is complex and remains poorly understood. It involves multi-interactions or evolutionary co-options between host factors and bacterial determinants for survival of the MTBC. Granuloma formation as a protection or survival mechanism in hosts by MTBC remains controversial. Additionally, MTBC species are capable of modulating host immune response and have adopted several mechanisms to evade from host immune attack in order to survive in humans. On the other hand, current diagnostic tools for human tuberculosis are inadequate and have several shortcomings. Numerous studies have suggested the potential of host biomarkers in early diagnosis of tuberculosis, in disease differentiation and in treatment monitoring. "Multi-omics" approaches provide holistic views to dissect the association of MTBC species with humans and offer great advantages in host biomarkers discovery. Thus, in this review, we seek to understand how the genetic variations in MTBC lead to species speciation with different pathogenicity. Furthermore, we also discuss how the host and bacterial players contribute to the pathogenesis of human tuberculosis. Lastly, we provide an overview of the journey of "omics" approaches in host biomarkers discovery in human tuberculosis and provide some interesting insights on the challenges and directions of "omics" approaches in host biomarkers innovation and clinical implementation.

Matched MeSH terms: Mycobacterium tuberculosis/genetics*
Nested PCR for the rapid detection of TB from pleural fluid at HUKM Malaysia

Salleh SA, Hussin S, Rahman MM

Pak J Biol Sci, 2008 Jul 01;11(13):1728-32.
PMID: 18819627

The aim of the present study is rapid detection of tuberculosis from pleural effusion of suspected patients. Molecular technique Nested Polymerase Chain Reaction (PCR) was used for the purpose. A total of 67 pleural fluid collected at Hospital University Kebangsaan Malaysia during May 2005 to October 2006 were sent to Microbiology Laboratory enrolled in the study. Detection rate of Mycobacterium tuberculosis in pleural effusion was 0% by acid-fast bacilli (AFB) staining and 1.5% by culture on Lowenstein-Jensen medium. Mycobacterium tuberculosis was detected by PCR in 9% of the cases. PCR of pleural fluid had 19% sensitivity and 96% specificity, compared to AFB staining (0% sensitivity and 100% specificity) and culture (4% sensitivity and 100% specificity). PCR also has 67% Positive Predictive Value (PPV) and 72% Negative Predictive Value (NPV) in detecting Mycobacterium tuberculosis. Culture ofpleural fluid has 100% PPV and 71% NPV while AFB staining has 0% PPV and 31% NPV. This preliminary study showed that PCR is a rapid method for detection of Mycobacterium tuberculosis in pleural fluid but its sensitivity is not up the marked.

Matched MeSH terms: Mycobacterium tuberculosis/genetics*
Fulltext DNA Electrochemical Biosensor Based on Iron Oxide/Nanocellulose Crystalline Composite Modified Screen-Printed Carbon Electrode for Detection of Mycobacterium tuberculosis

Mat Zaid MH, Che-Engku-Chik CEN, Yusof NA, Abdullah J, Othman SS, Issa R, et al.

Molecules, 2020 Jul 24;25(15).
PMID: 32722334 DOI: 10.3390/molecules25153373

Death from tuberculosis has resulted in an increased need for early detection to prevent a tuberculosis (TB) epidemic, especially in closed and crowded populations. Herein, a sensitive electrochemical DNA biosensor based on functionalized iron oxide with mercaptopropionic acid (MPA-Fe3O4) nanoparticle and nanocellulose crystalline functionalized cetyl trimethyl ammonium bromide (NCC/CTAB) has been fabricated for the detection of Mycobacterium tuberculosis (MTB). In this study, a simple drop cast method was applied to deposit solution of MPA-Fe3O4/NCC/CTAB onto the surface of the screen-printed carbon electrode (SPCE). Then, a specific sequence of MTB DNA probe was immobilized onto a modified SPCE surface by using the 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide/N-hydroxysuccinimide (EDC/NHS) coupling mechanism. For better signal amplification and electrochemical response, ruthenium bipyridyl Ru(bpy)32+ was assigned as labels of hybridization followed by the characteristic test using differential pulse voltammetry (DPV). The results of this biosensor enable the detection of target DNA until a concentration as low as 7.96 × 10-13 M with a wide detection range from 1.0 × 10-6 to 1.0 × 10-12 M. In addition, the developed biosensor has shown a differentiation between positive and negative MTB samples in real sampel analysis.

Matched MeSH terms: Mycobacterium tuberculosis/genetics
Restriction fragment length polymorphism analysis of Mycobacterium tuberculosis isolated from countries in the western pacific region

Park YK, Bai GH, Kim SJ

J Clin Microbiol, 2000 Jan;38(1):191-7.
PMID: 10618086

A total of 422 Mycobacterium tuberculosis isolates from eight countries were subjected to IS6110 and IS1081 DNA fingerprinting by means of restriction fragment analysis to characterize M. tuberculosis strains from each country. Chinese, Mongolian, Hong Kong, Filipino, and Korean isolates had comparatively more copies of IS6110 (proportion with eight or more copies; 95% +/- 5%), while Thai, Malaysian, and Vietnamese isolates had fewer copies (proportion with eight or more copies, 60% +/- 4%). We found a number of novel IS1081 types in this study. One IS1081 type was present in 56% of Filipino isolates, had a specific 6.6-kb PvuII fragment in its IS6110 DNA fingerprint, and was termed the "Filipino family." The IS1081 types of Thai isolates had interposing characteristics between the characteristics of northeastern Asian and southeastern Asian IS1081 types. A 1.3-kb single-copy IS6110 fragment was found only in Vietnamese M. tuberculosis isolates. Although M. tuberculosis isolates from each country had comparatively similar characteristics depending on the classification factor, each country's isolates showed characteristic DNA fingerprints and differed slightly from the isolates from the other countries in either the mode number of IS6110 copies or the distribution of IS1081 types.

Matched MeSH terms: Mycobacterium tuberculosis/genetics*
Fulltext Proof of concept in utilizing in-trans surface display system of Lactobacillus plantarum as mucosal tuberculosis vaccine via oral administration in mice

Mustafa AD, Kalyanasundram J, Sabidi S, Song AA, Abdullah M, Abdul Rahim R, et al.

BMC Biotechnol, 2018 10 11;18(1):63.
PMID: 30309359 DOI: 10.1186/s12896-018-0461-y

BACKGROUND: Tuberculosis is one of the most common and deadliest infectious diseases worldwide affecting almost a third of the world's population. Although this disease is being prevented and controlled by the Bacille Calmette Guérin (BCG) vaccine, the protective efficacy is highly variable and substandard (0-80%) in adults. Therefore, novel and effective tuberculosis vaccine that can overcome the limitations from BCG vaccine need to be developed.
RESULTS: A novel approach of utilizing an in-trans protein surface display system of Lactobacillus plantarum carrying and displaying combination of Mycobacterium tuberculosis subunit epitope antigens (Ag85B, CFP-10, ESAT-6, Rv0475 and Rv2031c) fused with LysM anchor motif designated as ACERL was constructed, cloned and expressed in Esherichia coli Rossetta expression host. Subsequently the binding capability of ACERL to the cell wall of L. plantarum was examined via the immunofluorescence microscopy and whole cell ELISA where successful attachment and consistent stability of cell wall binding up to 4 days was determined. The immunization of the developed vaccine of L. plantarum surface displaying ACERL (Lp ACERL) via the oral route was studied in mice for its immunogenicity effects. Lp ACERL immunization was able to invoke significant immune responses that favor the Th1 type cytokine response of IFN-γ, IL-12 and IL-2 as indicated by the outcome from the cytokine profiling of spleen, lung, gastrointestinal tract (GIT), and the re-stimulation of the splenocytes from the immunized mice. Co-administration of an adjuvant consisting of Lactococcus lactis secreting mouse IL-12 (LcIL-12) with Lp ACERL was also investigated. It was shown that the addition of LcIL-12 was able to further generate significant Th1 type cytokines immune responses, similar or better than that of Lp ACERL alone which can be observed from the cytokine profiling of the immunized mice's spleen, lung and GIT.
CONCLUSIONS: This study represents a proof of concept in the development of L. plantarum as a carrier for a non-genetically modified organism (GMO) tuberculosis vaccine, which may be the strategy in the future for tuberculosis vaccine development.

Matched MeSH terms: Mycobacterium tuberculosis/genetics; Tuberculosis/genetics
Genomic plasticity between human and mycobacterial DNA: A review

Danjuma L, Ling MP, Hamat RA, Higuchi A, Alarfaj AA, Marlina, et al.

Tuberculosis (Edinb), 2017 12;107:38-47.
PMID: 29050770 DOI: 10.1016/j.tube.2017.03.006

Mycobacterium tuberculosis has a remarkable ability of long-term persistence despite vigorous host immunity and prolonged therapy. The bacteria persist in secure niches such as the mesenchymal stem cells in the bone marrow and reactivate the disease, leading to therapeutic failure. Many bacterial cells can remain latent within a diseased tissue so that their genetic material can be incorporated into the genetic material of the host tissue. This incorporated genetic material reproduces in a manner similar to that of cellular DNA. After the cell division, the incorporated gene is reproduced normally and distributed proportionately between the two progeny. This inherent adoption of long-term persistence and incorporating the bacterial genetic material into that of the host tissue remains and is considered imperative for microbial advancement and chemotherapeutic resistance; moreover, new evidence indicates that the bacteria might pass on genetic material to the host DNA sequence. Several studies focused on the survival mechanism of M. tuberculosis in the host immune system with the aim of helping the efforts to discover new drugs and vaccines against tuberculosis. This review explored the mechanisms through which this bacterium affects the expression of human genes. The first part of the review summarizes the current knowledge about the interactions between microbes and host microenvironment, with special reference to the M. tuberculosis neglected persistence in immune cells and stem cells. Then, we focused on how bacteria can affect human genes and their expression. Furthermore, we analyzed the literature base on the process of cell death during tuberculosis infection, giving particular emphasis to gene methylation as an inherited process in the neutralization of possibly injurious gene components in the genome. The final section discusses recent advances related to the M. tuberculosis interaction with host epigenetic circuitry.

Matched MeSH terms: Mycobacterium tuberculosis/genetics*; Latent Tuberculosis/genetics*
Fulltext Selection of phage-displayed human antibody fragments specific for CD1b presenting the Mycobacterium tuberculosis glycolipid Ac2SGL

Camacho F, Sarmiento ME, Reyes F, Kim L, Huggett J, Lepore M, et al.

Int J Mycobacteriol, 2016 06;5(2):120-7.
PMID: 27242221 DOI: 10.1016/j.ijmyco.2015.12.002

OBJECTIVE/BACKGROUND: The development of new tools capable of targeting Mycobacterium tuberculosis (Mtb)-infected cells have potential applications in diagnosis, treatment, and prevention of tuberculosis. In Mtb-infected cells, CD1b molecules present Mtb lipids to the immune system (Mtb lipid-CD1b complexes). Because of the lack of CD1b polymorphism, specific Mtb lipid-CD1b complexes could be considered as universal Mtb infection markers. 2-Stearoyl-3-hydroxyphthioceranoyl-2'-sulfate-α-α'-d-trehalose (Ac2SGL) is specific for Mtb, and is not present in other mycobacterial species. The CD1b-Ac2SGL complexes are expressed on the surface of human cells infected with Mtb. The aim of this study was to generate ligands capable of binding these CD1b-Ac2SGL complexes.
METHODS: A synthetic human scFv phage antibody library was used to select phage-displayed antibody fragments that recognized CD1b-Ac2SGL using CD1b-transfected THP-1 cells loaded with Ac2SGL.
RESULTS: One clone, D11-a single, light-variable domain (kappa) antibody (dAbκ11)-showed high relative binding to the Ac2SGL-CD1b complex.
CONCLUSION: A ligand recognizing the Ac2SGL-CD1b complex was obtained, which is a potential candidate to be further tested for diagnostic and therapeutic applications.

Matched MeSH terms: Mycobacterium tuberculosis/genetics

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