Pathogenesis Of Mycobacterium Tuberculosis Research Articles

Host-Directed Therapies for Tuberculosis.

Host-directed therapies are a relatively new and promising approach to treatment of tuberculosis. Modulation of specific host immune pathways, including those that impact inflammation and immunopathology, can limit mycobacterial infection and pathology, both in cell culture and in animal models. This review explores a range of host pathways and drugs, some already approved for clinical use that have the potential to provide new adjunctive therapies for tuberculosis. Drugs targeting host processes may largely avoid the development of bacterial antibiotic resistance, a major public health concern for tuberculosis. However, these drugs may also have generally increased risk for side effects on the host. Understanding the specific mechanisms by which these drugs act and the relationship of these mechanisms to Mycobacterium tuberculosis pathogenesis will be critical in selecting appropriate host-directed therapy. Overall, these host-directed compounds provide a novel strategy for antituberculosis therapy.

Regulation of L-type Voltage Gated Calcium Channel CACNA1S in Macrophages upon Mycobacterium tuberculosis Infection.

We demonstrated earlier the inhibitory role played by Voltage Gated Calcium Channels (VGCCs) in regulating Mycobacterium tuberculosis (M. tb) survival and pathogenesis. In this report, we investigated mechanisms and key players that regulate the surface expression of VGCC-CACNA1S by Rv2463 and M. tb infection in macrophages. Our earlier work identified Rv2463 to be expressed at early times post infection in macrophages that induced suppressor responses to dendritic cells and macrophages. Our results in this study demonstrate a role of MyD88 independent TLR pathway in mediating CACNA1S expression. Dissecting the role for second messengers, we show that calcium homeostasis plays a key role in CACNA1S expression during M. tb infection. Using siRNAs against molecular sensors of calcium regulation, we show an involvement of ER associated Stromal Interaction Molecules 1 and 2 (STIM1 and STIM2), and transcription factor pCREB, towards CACNA1S expression that also involved the MyD88 independent pathway. Interestingly, reactive oxygen species played a negative role in M. tb mediated CACNA1S expression. Further, a cross-regulation of ROS and pCREB was noted that governed CACNA1S expression. Characterizing the mechanisms governing CACNA1S expression would improve our understanding of the regulation of VGCC expression and its role in M. tb pathogenesis during M. tb infection.

ESX/type VII secretion systems of mycobacteria: Insights into evolution, pathogenicity and protection

Pathogenesis of Mycobacterium tuberculosis depends on the secretion of key virulence factors, such as the 6 kDa early secreted antigenic target ESAT-6 (EsxA) and its protein partner, the 10 kDa culture filtrate protein CFP-10 (EsxB), via the ESX-1 secretion system. ESX-1 represents the prototype system of the recently named type VII secretion systems that exist in a range of actinobacteria. The M. tuberculosis genome harbours a total of five gene clusters potentially coding for type VII secretion systems, designated ESX-1 - ESX-5, with ESX-4 being the most ancient system from which other ESX systems seem to have evolved by gene duplication and gene insertion events. The five ESX systems show similarity in gene content and gene order but differ in function. ESX-1 and ESX-5 are both crucial virulence determinants of M. tuberculosis, but with different mechanisms. While ESX-1 is implicated in the lysis of the host cell phagosomes, ESX-5 is involved in secretion of the mycobacteria specific PE and PPE proteins and cell wall stability. Research on type VII secretion systems has thus become a large and competitive research topic that is tightly linked to studies of host-pathogen interaction of pathogenic mycobacteria. Insights into this matter are of relevance for redrawing the patho-evolution of M. tuberculosis, which might help improving current strategies for prevention, diagnostics and therapy of tuberculosis as well as elucidating the virulence mechanisms employed by this important human pathogen.

The Uptake of Trehalose Glycolipids by Macrophages Is Independent of Mincle

Trehalose glycolipids play an important role in the pathogenesis of Mycobacterium tuberculosis and are used as adjuvants for vaccines; however, much still remains unanswered about the mechanisms through which these glycolipids exert their immunomodulatory potential. Recently, the macrophage-inducible C-type lectin Mincle was determined to be the receptor for trehalose glycolipids, yet the role played by Mincle in glycolipid uptake is unknown. Accordingly, we developed several fluorescent trehalose glycolipid reporter systems that can be used to study the uptake of soluble trehalose glycolipids and glycolipid-coated particles by macrophages. Our studies revealed that, although Mincle is essential for the activation of macrophages by trehalose glycolipids, the receptor does not play a role in the uptake of these glycolipids or of glycolipid-coated particles.

A novel antimycobacterial compound acts as an intracellular iron chelator.

Efficient iron acquisition is crucial for the pathogenesis of Mycobacterium tuberculosis. Mycobacterial iron uptake and metabolism are therefore attractive targets for antitubercular drug development. Resistance mutations against a novel pyrazolopyrimidinone compound (PZP) that is active against M. tuberculosis have been identified within the gene cluster encoding the ESX-3 type VII secretion system. ESX-3 is required for mycobacterial iron acquisition through the mycobactin siderophore pathway, which could indicate that PZP restricts mycobacterial growth by targeting ESX-3 and thus iron uptake. Surprisingly, we show that ESX-3 is not the cellular target of the compound. We demonstrate that PZP indeed targets iron metabolism; however, we found that instead of inhibiting uptake of iron, PZP acts as an iron chelator, and we present evidence that the compound restricts mycobacterial growth by chelating intrabacterial iron. Thus, we have unraveled the unexpected mechanism of a novel antimycobacterial compound.

Role of pattern recognition receptors in Mycobacterium tuberculosis infection

IntroductionTuberculosis (TB) is considered a major worldwide health problem with 10million new cases diagnosed each year. The present understanding of TB immunology has become greater and more refined since the identification of Mycobacterium tuberculosis (MTB) as an etiologic agent of disease and the recognition of new signaling pathways modulating infection. Understanding the mechanisms through which the cells of the immune system recognize MTB can be an important step in designing novel therapeutic approaches, as well as improving the limited success of current vaccination strategies. A great challenge in chronic disease is to understand the complexities, mechanisms and consequences of host interactions with pathogens. Innate immune reactions, along with the involvement of distinct inflammatory cytokines and cells, have been shown to play an important role in the host defense against MTB. Several classes of pattern recognition receptors (PRRs) are involved in the recognition of MTB, including Toll-Like Receptors (TLRs), C-type lectin receptors (CLRs) and Nod-like receptors (NLRs) linked to inflammasome activation. Among the TLR family, TLR1, TLR2, TLR4 and TLR9 and their downstream proteins play critical roles in the initiation of the immune response in the pathogenesis of MTB. Materials and ResultsIn this study, the expression of TLR 2 and 4 was tested in PBMC from a TB patient’s blood by staining cells for flow cytometry. The results showed that infection with MTB causes up-regulation of TLR2 and 4, but not TLR8. ConclusionsUnderstanding cross-talk between these signaling pathways in the pathophysiology of TB has an impact in designing novel strategies and in the development of vaccinations and immunotherapy regimes for this disease. Defects in TLR signaling pathways regulated by TB may affect the pathogenesis of MTB and need to be elucidated in future studies.

Discovery of Mycobacterium tuberculosis α-1,4-Glucan Branching Enzyme (GlgB) Inhibitors by Structure- and Ligand-based Virtual Screening

GlgB (α-1,4-glucan branching enzyme) is the key enzyme involved in the biosynthesis of α-glucan, which plays a significant role in the virulence and pathogenesis of Mycobacterium tuberculosis. Because α-glucans are implicated in the survival of both replicating and non-replicating bacteria, there exists an exigent need for the identification and development of novel inhibitors for targeting enzymes, such as GlgB, involved in this pathway. We have used the existing structural information of M. tuberculosis GlgB for high throughput virtual screening and molecular docking. A diverse database of 330,000 molecules was used for identifying novel and efficacious therapeutic agents for targeting GlgB. We also used three-dimensional shape as well as two-dimensional similarity matrix methods to identify diverse molecular scaffolds that inhibit M. tuberculosis GlgB activity. Virtual hits were generated after structure and ligand-based screening followed by filters based on interaction with human GlgB and in silico pharmacokinetic parameters. These hits were experimentally evaluated and resulted in the discovery of a number of structurally diverse chemical scaffolds that target M. tuberculosis GlgB. Although a number of inhibitors demonstrated in vitro enzyme inhibition, two compounds in particular showed excellent inhibition of in vivo M. tuberculosis survival and its ability to get phagocytosed. This work shows that in silico docking and three-dimensional chemical similarity could be an important therapeutic approach for developing inhibitors to specifically target the M. tuberculosis GlgB enzyme.

EspR, a regulator of the ESX-1 secretion system in Mycobacterium tuberculosis, is directly regulated by the two-component systems MprAB and PhoPR.

The regulatory mechanisms that control the ESX-1 secretion system, a key player in the pathogenesis of Mycobacterium tuberculosis, have not been fully elucidated. However, factors that regulate the ESX-1 substrate EspA usually affect ESX-1 function. Previous studies showed that espA is directly regulated by the nucleoid-associated protein EspR and the two-component system (TCS) MprAB. The PhoPR TCS also activates espA, but the direct target of PhoP was unknown. In this report, we reveal that EspR is directly regulated by MprA and PhoP-Rv, but not by PhoP-Ra. PhoP-Rv and MprA binding sites in the espR promoter were determined by gel-shift and DNase I footprinting assays, which identified a PhoP-protected region centred approximately 205 bp before the espR start codon and that encompasses MprA Region-1, one of two MprA-protected regions. MprA Region-2 is located approximately 60 bp downstream of MprA Region-1 and overlaps a known EspR binding site. Nucleotides essential for the binding of PhoP and/or MprA were identified through site-directed DNA mutagenesis. Our studies also indicate that MprA Region-2, but not MprA Region-1/PhoP region, is required for the full expression of espR. Recombinant strains carrying mutations at MprA Region-2 exhibited lower transcription levels for espR, espA and espD, and had reduced EspR and EspA levels in cell lysates. These findings indicate that EspR may mediate the regulatory effect of PhoPR and MprAB, and provide more insight into the mechanisms underlying ESX-1 control.

Rv0494 is a starvation-inducible, auto-regulatory FadR-like regulator from Mycobacterium tuberculosis.

Fatty acid metabolism plays an important role in the survival and pathogenesis of Mycobacterium tuberculosis. Lipids are assumed to be the major source of energy during dormancy. Here, we report the characterization of a starvation-inducible, lipid-responsive transcriptional regulator, Rv0494, divergently transcribed from the Rv0493c probable operon. The striking difference in the transcriptional regulatory apparatus between mycobacteria and other well-studied organisms, such as Escherichia coli, is the organization of mycobacterial promoters. Mycobacterial promoters have diverse architectures and most of these promoters function inefficiently in E. coli. In this study, we characterized the promoter elements of Rv0494 along with the sigma factors required for transcription initiation. Rv0494 promoter activity increased under nutrient starvation conditions and was transcribed via two promoters: the promoter proximal to the translational start site was active under standard growth conditions, whilst both promoters contributed to the increased activity seen during starvation, with the major contribution from the distal promoter. Furthermore, Rv0494 translation initiated at a codon located 9 bp downstream of the annotated start codon. Rv0494 bound to its upstream sequence to auto-regulate its own expression; this binding was responsive to long-chain fatty acyl-CoA molecules. We further report Rv0494-mediated transcriptional regulation of the Rv2326c gene - a probable transmembrane ATP-binding transporter encoding gene.

Mycobacterium tuberculosis metabolism.

Metabolism underpins the physiology and pathogenesis of Mycobacterium tuberculosis. However, although experimental mycobacteriology has provided key insights into the metabolic pathways that are essential for survival and pathogenesis, determining the metabolic status of bacilli during different stages of infection and in different cellular compartments remains challenging. Recent advances-in particular, the development of systems biology tools such as metabolomics-have enabled key insights into the biochemical state of M. tuberculosis in experimental models of infection. In addition, their use to elucidate mechanisms of action of new and existing antituberculosis drugs is critical for the development of improved interventions to counter tuberculosis. This review provides a broad summary of mycobacterial metabolism, highlighting the adaptation of M. tuberculosis as specialist human pathogen, and discusses recent insights into the strategies used by the host and infecting bacillus to influence the outcomes of the host-pathogen interaction through modulation of metabolic functions.

An overview to understand the role of PE_PGRS family proteins in Mycobacterium tuberculosis H37 Rv and their potential as new drug targets.

Tuberculosis has long been the scourge of humanity, claiming millions of lives. The family of PE_PGRS gene has been attributed to the Mycobacterium tuberculosis pathogenesis over the past few decades. The gene of PE_PGRS family proteins are most often clustered in a region of the genome often as overlapping genes and role in cell surface markers, adhesion and invasion of defense cells of the host (macrophage and dendritic cells). The proline-glutamic acid (PE) domain is responsible for the cellular localization of these proteins on bacterial cells. This gene family shows immense genetic variability in terms of multiple insertion-deletions and single-nucleotide polymorphisms as seen in PE_PGRS9, PE_PGRS17, PE_PGRS18, and PE_PGRS33. In spite of variability, there are indications of shared epitopes in these proteins. Few of these gene sequences that have been studied from evolutionary perspective show indication of positive selection and also landmarks of recent evolutionary events. Many of these proteins show calcium-binding motifs and consequently seen to be responsible in inhibition of phagolysosome formation via a calmodulin-kinase-dependent pathway. A number of PE_PGRS genes were tested for its expression with different growth conditions in vitro and in vivo, among which the contrast in expressivity was seen vividly in PE_PGRS16 (upregulated) and PE_PGRS26 (downregulated) in bacteria persisting in macrophages. Similarly, PE_PGRS33 has been indicated in macrophagial necrosis by a tumor necrosis factor-α-induced pathway. These PE_PGRS family genes may be an interesting subject for research and development. Their fibronectin-binding and calcium-binding property may be strongly implicated in immunopathogenesis of virulent M. tuberculosis strain. In this review, an attempt has been made to evaluate and present data for better understanding of in vivo pathogen functions, for understanding the physiological significance of PE_PGRS gene family, and their potential as new drug targets.

Double-Strand DNA Break Repair in Mycobacteria.

Discontinuity of both strands of the chromosome is a lethal event in all living organisms because it compromises chromosome replication. As such, a diversity of DNA repair systems has evolved to repair double-strand DNA breaks (DSBs). In part, this diversity of DSB repair systems has evolved to repair breaks that arise in diverse physiologic circumstances or sequence contexts, including cellular states of nonreplication or breaks that arise between repeats. Mycobacteria elaborate a set of three genetically distinct DNA repair pathways: homologous recombination, nonhomologous end joining, and single-strand annealing. As such, mycobacterial DSB repair diverges substantially from the standard model of prokaryotic DSB repair and represents an attractive new model system. In addition, the presence in mycobacteria of a DSB repair system that can repair DSBs in nonreplicating cells (nonhomologous end joining) or when DSBs arise between repeats (single-strand annealing) has clear potential relevance to Mycobacterium tuberculosis pathogenesis, although the exact role of these systems in M. tuberculosis pathogenesis is still being elucidated. In this article we will review the genetics of mycobacterial DSB repair systems, focusing on recent insights.

Reciprocal regulation of reactive oxygen species and phospho-CREB regulates voltage gated calcium channel expression during Mycobacterium tuberculosis infection.

Our previous work has demonstrated the roles played by L-type Voltage Gated Calcium Channels (VGCC) in regulating Mycobacterium tuberculosis (M. tb) survival and pathogenesis. Here we decipher mechanisms and pathways engaged by the pathogen to regulate VGCC expression in macrophages. We show that M. tb and its antigen Rv3416 use phospho-CREB (pCREB), Reactive Oxygen Species (ROS), Protein Kinase C (PKC) and Mitogen Activated Protein Kinase (MAPK) to modulate VGCC expression in macrophages. siRNA mediated knockdown of MyD88, IRAK1, IRAK2 or TRAF6 significantly inhibited antigen mediated VGCC expression. Inhibiting Protein Kinase C (PKC) or MEK-ERK1/2 further increased VGCC expression. Interestingly, inhibiting intracellular calcium release upregulated antigen mediated VGCC expression, while inhibiting extracellular calcium influx had no significant effect. siRNA mediated knockdown of transcription factors c-Jun, SOX5 and CREB significantly inhibited Rv3416 mediated VGCC expression. A dynamic reciprocal cross-regulation between ROS and pCREB was observed that in turn governed VGCC expression with ROS playing a limiting role in the process. Further dissection of the mechanisms such as the interplay between ROS and pCREB would improve our understanding of the regulation of VGCC expression during M. tb infection.

Mycobacterium tuberculosis Rv3402c enhances mycobacterial survival within macrophages and modulates the host pro-inflammatory cytokines production via NF-kappa B/ERK/p38 signaling.

Intracellular survival plays a central role in the pathogenesis of Mycobacterium tuberculosis, a process which depends on an array of virulence factors to colonize and replicate within the host. The M. tuberculosis iron regulated open reading frame (ORF) rv3402c, encoding a conserved hypothetical protein, was shown to be up-regulated upon infection in both human and mice macrophages. To explore the function of this ORF, we heterologously expressed the rv3402c gene in the non-pathogenic fast-growing Mycobacterium smegmatis strain, and demonstrated that Rv3402c, a cell envelope-associated protein, was able to enhance the intracellular survival of recombinant M. smegmatis. Enhanced growth was not found to be the result of an increased resistance to intracellular stresses, as growth of the Rv3402c expressing strain was unaffected by iron depletion, H2O2 exposure, or acidic conditions. Colonization of macrophages by M. smegmatis expressing Rv3402c was associated with substantial cell death and significantly greater amount of TNF-α and IL-1β compared with controls. Rv3402c-induced TNF-α and IL-1β production was found to be mediated by NF-κB, ERK and p38 pathway in macrophages. In summary, our study suggests that Rv3402c delivered in a live M. smegmatis vehicle can modify the cytokines profile of macrophage, promote host cell death and enhance the persistence of mycobacterium within host cells.

Tuberculosis alters pancreatic enzymes in the absence of pancreatitis.

BackgroundLipases and phospholipases are thought to contribute to the pathogenesis of Mycobacterium tuberculosis (MTB) infection. Genes coding for lipases, phospholipases and amylase are present in MTB, enabling the bacteria to produce these enzymes.ObjectiveTo compare serum lipase and amylase activity levels in patients with tuberculosis (TB) against those of healthy controls.MethodsSerum lipase and amylase activity levels were measured in 99 patients and 143 healthy controls using the Vitros 250 Chemistry analyser. Reference ranges for serum lipase and amylase were 23–300 U/L and 30–110 U/L, respectively.ResultsLipase was higher in patients with MTB than in controls (81.5 IU/L versus 66.5 IU/L, p = 0.006). Similarly, amylase was higher in the MTB patient group (76 IU/L versus 60 IU/L, p < 0.001). The Pearson correlation coefficient for lipase versus amylase (R) was higher in the controls (R = 0.351, p < 0.0001) compared with MTB patients (R = 0.217, p = 0.035). Amongst MTB patients, lipase activity correlated positively with erythrocyte sedimentation rate (ESR) (R = 0.263, p = 0.013), but not with haemoglobin concentration or treatment duration. A weak inverse correlation was noted between ESR and treatment duration (R = -0.222, p = 0.028).ConclusionPancreatic enzyme levels differ between MTB patients and normal controls; however, this difference still lies within the normal range. The concomitant increase of lipase with ESR, an inflammatory marker, could conceivably suggest a causal relationship. Further research is necessary to characterise MTB-derived enzymes for diagnostic and therapeutic utility.

Cyclic AMP Signaling in Mycobacteria.

All cells must adapt to changing conditions, and many use cyclic AMP (cAMP) as a second messenger to sense and respond to fluctuations in their environment. cAMP is made by adenylyl cyclases (ACs), and mycobacteria have an unusually large number of biochemically distinct ACs. cAMP is important for gene regulation in mycobacteria, and the ability to secrete cAMP into host macrophages during infection contributes to Mycobacterium tuberculosis pathogenesis. This article discusses the many roles of cAMP in mycobacteria and reviews what is known about the factors that contribute to production, destruction, and utilization of this important signal molecule. Special emphasis is placed on cAMP signaling in M. tuberculosis complex bacteria and its importance to M. tuberculosis during host infection.

Cell death paradigms in the pathogenesis of Mycobacterium tuberculosis infection

Cell death or senescence is a fundamental event that helps maintain cellular homeostasis, shapes the growth of organism, and provides protective immunity against invading pathogens. Decreased or increased cell death is detrimental both in infectious and non-infectious diseases. Cell death is executed both by regulated enzymic reactions and non-enzymic sudden collapse. In this brief review we have tried to summarize various cell death modalities and their impact on the pathogenesis of Mycobacterium tuberculosis.

An immunomodulatory role for the Mycobacterium tuberculosis region of difference 1 locus proteins PE35 (Rv3872) and PPE68 (Rv3873)

The pathogenesis of Mycobacterium tuberculosis involves the coordinate action of multiple bacillary components that modulate host immune responses to ensure its survival. One such group of factors is the multigenic PE_PPE protein family, several members of which have been implicated in host immune evasion. Here we investigate the function of the PE-PPE gene pair PE35 (Rv3872)-PPE68 (Rv3873), located in the region of difference 1, encoding a specialized mycobacterial secretion system that is deleted in all vaccine strains of Mycobacterium bovis BCG. We report that this gene pair is co-operonic in M. tuberculosis, and demonstrate that its gene products interact with each other. Stimulation of THP-1 macrophages with recombinant PE35 and PPE68, singly or in combination, led to a dose-dependent increase in levels of the anti-inflammatory cytokine interleukin (IL)-10 and the chemokine monocyte chemoattractant protein-1, and caused a reciprocal decrease in levels of the proinflammatory cytokine IL-12. PE35/PPE68-stimulated production of IL-10 and monocyte chemoattractant protein-1 was observed to be dependent on toll-like receptor 2, as receptor blockade caused a significant reduction in their levels. Pharmacological inhibition indicated that this induction involved activation of the mitogen-activated protein kinase signalling axis. In a transwell migration assay, culture supernatants from PE35/PPE68-treated THP-1 cells were observed to stimulate the migration of monocytes. Our findings suggest that the PE35-PPE68 gene pair plays an important immunomodulatory role in regulating the pathophysiology of M. tuberculosis. TLR2 physically interacts with PPE68 by anti bait coimmunoprecipitation (View interaction) PE35 binds to PPE68 by pull down (View interaction) PE35 physically interacts with PPE68 by anti tag coimmunoprecipitation (View interaction) TLR2 physically interacts with PE35 by anti bait coimmunoprecipitation (View interaction) PPE68 and PE35 physically interact by dihydrofolate reductase reconstruction (View interaction).

PknE, a Serine/Threonine Protein Kinase of Mycobacterium tuberculosis Initiates Survival Crosstalk That Also Impacts HIV Coinfection

Serine threonine protein kinases (STPK) play a major role in the pathogenesis of Mycobacterium tuberculosis. Here, we examined the role of STPK pknE, using a deletion mutant ΔpknE in the modulation of intracellular signaling events that favor M. tuberculosis survival. Phosphorylation kinetics of MAPK (p38MAPK, Erk½ and SAPK/JNK) was defective in ΔpknE compared to wild-type infected macrophages. This defective signaling dramatically delayed and reduced the phosphorylation kinetics of transcription factors ATF-2 and c-JUN in ΔpknE infected macrophages. MAPK inhibitors instead of reducing the phosphorylation in ΔpknE infected macrophages, revealed crosstalks with Erk½ signaling influenced by SAPK/JNK and p38 pathways independently. Modulations in intra cellular signaling altered the expression of coreceptors CCR5 and CXCR4 in ΔpknE infected macrophages. In conclusion, pknE plays a role in MAPK crosstalks that enables intracellular survival of M. tuberculosis. This survival strategy also impacts HIV/TB coinfection.

Mycobacterium tuberculosis Pili promote adhesion to and invasion of THP-1 macrophages.

Central to the paradigm of the pathogenesis of Mycobacterium tuberculosis is its ability to attach to, enter, and subsequently survive in host macrophages. However, little is known regarding the bacterial adhesins and invasins involved in this interaction with host macrophages. Pili are cell-surface structures produced by certain bacteria and have been implicated in adhesion to and invasion of phagocytes in several species. M. tuberculosis pili (MTP) are encoded by the Rv3312A (mtp) gene. In the present study, we assessed the ability of a Δmtp mutant and an mtp-complemented clinical strain to adhere to and invade THP-1 macrophages in comparison with the parental strain by determining colony-forming units. Both adhesion to and invasion of macrophages, although not reaching significance, were markedly reduced by 42.16% (P = 0.107) and 69.02% (P = 0.052), respectively, in the pili-deficient Δmtp mutant as compared with the wild-type. The pili-overexpressing complemented strain showed significantly higher levels of THP-1 macrophage adhesion (P = 0.000) and invasion (P = 0.040) than the mutant. We, thus, identified a novel adhesin and invasin of M. tuberculosis involved in adhesion to and invasion of macrophages.