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Diagnostic Microbiology and Infectious... Jan 2024Efforts are underway globally to develop effective vaccines and drugs against M. tuberculosis (Mtb) to reduce the morbidity and mortality of tuberculosis. Improving...
Molecular detection of pre-ribosomal RNAs of Mycobacterium bovis bacille Calmette-Guérin and Mycobacterium tuberculosis to enhance pre-clinical tuberculosis drug and vaccine development.
Efforts are underway globally to develop effective vaccines and drugs against M. tuberculosis (Mtb) to reduce the morbidity and mortality of tuberculosis. Improving detection of slow-growing mycobacteria could simplify and accelerate efficacy studies of vaccines and drugs in animal models and human clinical trials. Here, a real-time reverse transcription PCR (RT-PCR) assay was developed to detect pre-ribosomal RNA (pre-rRNA) of Mycobacterium bovis bacille Calmette-Guérin (BCG) and Mtb. This pre-rRNA biomarker is indicative of bacterial viability. In two different mouse models, the presence of pre-rRNA from BCG and Mtb in ex vivo tissues showed excellent agreement with slower culture-based colony-forming unit assays. The addition of a brief nutritional stimulation prior to molecular viability testing further differentiated viable but dormant mycobacteria from dead mycobacteria. This research has set the stage to evaluate pre-rRNA as a BCG and/or Mtb infection biomarker in future drug and vaccine clinical studies.
Topics: Animals; Mice; Humans; Mycobacterium bovis; Mycobacterium tuberculosis; BCG Vaccine; RNA Precursors; Tuberculosis; Vaccine Development; Biomarkers
PubMed: 37931386
DOI: 10.1016/j.diagmicrobio.2023.116106 -
Journal of Biomedical Science Dec 2023Mycobacterium tuberculosis is the causative agent of tuberculosis (TB), and its pathogenicity is associated with its ability to evade the host defense system. The...
A secreted form of chorismate mutase (Rv1885c) in Mycobacterium bovis BCG contributes to pathogenesis by inhibiting mitochondria-mediated apoptotic cell death of macrophages.
BACKGROUND
Mycobacterium tuberculosis is the causative agent of tuberculosis (TB), and its pathogenicity is associated with its ability to evade the host defense system. The secretory form of the chorismate mutase of M. tuberculosis (TBCM, encoded by Rv1885c) is assumed to play a key role in the pathogenesis of TB; however, the mechanism remains unknown.
METHODS
A tbcm deletion mutant (B∆tbcm) was generated by targeted gene knockout in BCG to investigate the pathogenic role of TBCM in mice or macrophages. We compared the pathogenesis of B∆tbcm and wild-type BCG in vivo by measuring the bacterial clearance rate and the degree of apoptosis. Promotion of the intrinsic apoptotic pathway was evaluated in infected bone marrow-derived macrophages (BMDMs) by measuring apoptotic cell death, loss of mitochondrial membrane potential and translocation of pore-forming proteins. Immunocytochemistry, western blotting and real-time PCR were also performed to assess the related protein expression levels after infection. Furthermore, these findings were validated by complementation of tbcm in BCG.
RESULTS
Deletion of the tbcm gene in BCG leads to reduced pathogenesis in a mouse model, compared to wild type BCG, by promoting apoptotic cell death and bacterial clearance. Based on these findings, we found that intrinsic apoptosis and mitochondrial impairment were promoted in B∆tbcm-infected BMDMs. B∆tbcm down-regulates the expression of Bcl-2, which leads to mitochondrial outer membrane permeabilization (MOMP), culminating in cytochrome c release from mitochondria. Consistent with this, transcriptome profiling also indicated that B∆tbcm infection is more closely related to altered mitochondrial-related gene expression than wild-type BCG infection, suggesting an inhibitory role of TBCM in mitochondrial dysfunction. Moreover, genetic complementation of B∆tbcm (C∆tbcm) restored its capacity to inhibit mitochondria-mediated apoptotic cell death.
CONCLUSIONS
Our findings demonstrate the contribution of TBCM to bacterial survival, inhibiting intrinsic apoptotic cell death of macrophages as a virulence factor of M. tuberculosis complex (MTBC) strains, which could be a potential target for the development of TB therapy.
Topics: Animals; Mice; Apoptosis; Chorismate Mutase; Macrophages; Mitochondria; Mycobacterium bovis; Mycobacterium tuberculosis; Tuberculosis
PubMed: 38110948
DOI: 10.1186/s12929-023-00988-2 -
Microorganisms Oct 2023In many parts of the world, bovine tuberculosis eradication efforts are hampered by wildlife reservoirs of , which serve as a constant source of for nearby cattle. The...
In many parts of the world, bovine tuberculosis eradication efforts are hampered by wildlife reservoirs of , which serve as a constant source of for nearby cattle. The human tuberculosis vaccine, BCG has been investigated for use in several wildlife species, including deer. In the US, white-tailed deer in Michigan have been the source of infection for over 82 cattle herds since was discovered in free-ranging deer in 1995. The efficacy of BCG may be influenced by many factors, including prior exposure or infection with non-tuberculous mycobacteria, that is, species other than members of the complex. subspecies () infection is not uncommon in ruminants such as deer. Using natural exposure to and experimental infection with we demonstrate that infection increased BCG vaccine efficacy as measured by lesion severity scores.
PubMed: 37894146
DOI: 10.3390/microorganisms11102488 -
Scientific Reports Jul 2023Tuberculosis, caused by Mycobacterium tuberculosis complex (MTBC) organisms, affects a range of humans and animals globally. Mycobacterial pathogenesis involves...
Tuberculosis, caused by Mycobacterium tuberculosis complex (MTBC) organisms, affects a range of humans and animals globally. Mycobacterial pathogenesis involves manipulation of the host immune system, partially through antigen presentation. Epitope sequences across the MTBC are evolutionarily hyperconserved, suggesting their recognition is advantageous for the bacterium. Mycobacterium tuberculosis var. bovis (MBO) strain Ravenel is an isolate known to provoke a robust immune response in cattle, but typically fails to produce lesions and persist. Unlike attenuated MBO BCG strains that lack the critical RD1 genomic region, Ravenel is classic-type MBO structurally, suggesting genetic variation is responsible for defective pathogenesis. This work explores variation in epitope sequences in MBO Ravenel by whole genome sequencing, and contrasts such variation against a fully virulent clinical isolate, MBO strain 10-7428. Validated MTBC epitopes (n = 4818) from the Immune Epitope Database were compared to their sequences in MBO Ravenel and MBO 10-7428. Ravenel yielded 3 modified T cell epitopes, in genes rpfB, argC, and rpoA. These modifications were predicted to have little effect on protein stability. In contrast, T cells epitopes in 10-7428 were all WT. Considering T cell epitope hyperconservation across MTBC variants, these altered MBO Ravenel epitopes support their potential contribution to overall strain attenuation. The affected genes may provide clues on basic pathogenesis, and if so, be feasible targets for reverse vaccinology.
Topics: Humans; Animals; Cattle; Mycobacterium bovis; Epitopes, T-Lymphocyte; Mycobacterium tuberculosis; Tuberculosis
PubMed: 37524777
DOI: 10.1038/s41598-023-39578-5 -
Access Microbiology 2024Tuberculosis (TB) remains a high-burden infectious disease worldwide. complex (MTBC) is the aetiological agent of TB.
BACKGROUND
Tuberculosis (TB) remains a high-burden infectious disease worldwide. complex (MTBC) is the aetiological agent of TB.
RESEARCH GAP
The TB burden is significantly linked to the development of drug-resistant strains. Thus, there is an urgent need for close surveillance of MTBC circulating in a given region, such as Western Kenya, for treatment of TB.
AIM
To determine the proportion of MTBC species, strains and genetic diversities in circulation in HIV/AIDS-prevalent regions, and Western Kenya in particular. The clinical MTBC isolates were collected from Moi Teaching and Referral Hospital (MTRH) at Eldoret-Kenya during 2013-14. All clinical MTBC isolates were confirmed by the gold standard method (Löwenstein-Jensen medium culture) before inclusion in the investigation.
METHODOLOGY
Twelve-loci mycobacterium interspersed repetitive unit - variable-number tandem repeats (MIRU-VNTR) genotyping was performed to determine the circulating species/strains of MTBC using the www.miru-vntrplus.org web platform. Allelic diversity was calculated using the Hunter-Gaston diversity index (HGDI).
RESULTS
The species , , , , , and were identified in the MTBC population. These strains were found in the Beijing, Latin American Mediterranean, Uganda 1/2, East African Indian, Ilama, West African 1/2, Harlem, URAL, Ghana, Seal, Cameroon and Vole etc. regions of Western Kenya. Notably, some isolates had unknown (new/unassigned) species. The strains were grouped into nine clusters with a clustering rate of 31.18 % and a high allelic diversity index of 0.53 was observed.
CONCLUSION
The present findings suggest that there is an urgent need for more awareness among healthcare professionals and stakeholders concerning the existence of foreign MTBC species/strains in Kenya. Furthermore, 12-loci MIRU-VNTR may not be suitable for the surveillance of MTBC strains in circulation in Kenya. Thus, high-resolution techniques such as whole-genome sequencing need to be adopted to resolve the genetic diversity and establish evolutionary trends for future and archived samples. This knowledge will be crucial in restraining TB, providing insights into new drug development, and developing prevention, control and treatment strategies for TB.
PubMed: 38482360
DOI: 10.1099/acmi.0.000729.v3 -
Journal of Cancer Prevention Mar 2024Bacillus Calmette-Guérin (BCG) is an attenuated strain of . Although it was developed as a prophylactic vaccine against tuberculosis (TB), researchers have also... (Review)
Review
Bacillus Calmette-Guérin (BCG) is an attenuated strain of . Although it was developed as a prophylactic vaccine against tuberculosis (TB), researchers have also evaluated it for preventing cancer development or progression. These studies were inspired by the available data regarding the protective effects of microbial infection against cancers and an inverse relationship between TB and cancer mortality. Initial studies demonstrated the efficacy of BCG in preventing leukemia, melanoma and a few other cancers. However, mixed results were observed in later studies. Importantly, these studies have led to the successful use of BCG in the tertiary prevention of non-muscle invasive bladder cancer, wherein BCG therapy has been found to be more effective than chemotherapy. Moreover, in a recently published 60-year follow-up study, childhood BCG vaccination has been found to significantly prevent lung cancer development. In the present manuscript, we reviewed the studies evaluating the efficacy of BCG in cancer prevention and discussed its putative mechanisms. Also, we sought to explain the mixed results of BCG efficacy in preventing different cancers.
PubMed: 38567111
DOI: 10.15430/JCP.23.036 -
Irish Veterinary Journal Aug 2023Bovine tuberculosis (TB), caused by Mycobacterium bovis, has a unique and complex ecology in New Zealand. Unlike elsewhere in the world, the disease is maintained in...
Bovine tuberculosis (TB), caused by Mycobacterium bovis, has a unique and complex ecology in New Zealand. Unlike elsewhere in the world, the disease is maintained in Australian brushtail possums (Trichosurus vulpecula) and so they are considered a vector for disease transmission in New Zealand. Possums were initially introduced to the country in the 1800's to establish a fur industry but later becoming a recognized pest to native New Zealand flora and fauna. The TB programme in New Zealand (TBFree NZ Ltd) is managed by a not-for-profit limited company partnership between primary industries and government (OSPRI - Operational Solutions for Primary Industries) that uses the basic tenets of disease management, movement control and vector control to eliminate TB in farmed cattle and deer. Evidence of resounding success in the TB control programme resulted in the 2016 decision to pursue full biological eradication of disease from the country by 2055, with the interim objectives of TB freedom in livestock herds by 2026 and TB freedom in possums by 2040. The programme has progressed from an all-time high of 1698 infected herds in 1995 to the lowest recorded point prevalence of 18 infected herds in May 2022. Enhancements that have contributed to the success of the programme include testing with gamma-interferon release assay (Bovigam™) of animals in infected herds that are negative to the skin test (parallel interpretation), culturing pooled lymph nodes from animals without visible lesions, increased testing of herds post-clearance and introduction of post-movement testing of high-risk animals.
PubMed: 37649127
DOI: 10.1186/s13620-023-00248-7 -
Veterinary Journal (London, England :... Apr 2024Cases of canine tuberculosis, a zoonotic infection of significant public health significance, are typically only sporadically reported in the literature. For this... (Review)
Review
Cases of canine tuberculosis, a zoonotic infection of significant public health significance, are typically only sporadically reported in the literature. For this observational study, case details were collated both retrospectively and prospectively for dogs infected with Mycobacterium tuberculosis-complex (MTBC) organisms. A total of 18 previously unreported cases as well as 565 historically reported confirmed cases were reviewed. A variety of diagnostic techniques were used to make a confirmed diagnosis of tuberculosis (culture, interferon-gamma release assay [IGRA], and PCR). The reference standard for diagnosis is culture; however, this was negative or not attempted in some dogs. Where fully speciated, all cases were caused by infection with one of three MTBC organisms: M. tuberculosis, Mycobacterium bovis, or Mycobacterium microti. This study includes the first documented canine infections with M. microti in the UK. All cases were assigned to one of four clinical groups based on the presenting signs: 44.1% were primarily pulmonary, 14.5% were primarily abdominal, and the remainder were disseminated or miscellaneous. The development of adjunctive tests remains necessary to support early treatment decisions pending reporting of culture for MTBC organisms, which can take weeks to months. Definitive treatment, where attempted, was successful in most cases. Of the 13 dogs treated by the authors with triple combination antimicrobial therapy, a good clinical outcome was seen in 12 (92%) of them.
Topics: Animals; Dogs; Retrospective Studies; Tuberculosis; Mycobacterium bovis; Mycobacterium tuberculosis; Zoonoses; Dog Diseases; Observational Studies as Topic; Observational Studies, Veterinary as Topic
PubMed: 38412886
DOI: 10.1016/j.tvjl.2024.106089 -
Frontiers in Immunology 2023bacilli Calmette-Guerin (BCG) is a licensed vaccine against tuberculosis. It requires attenuated live bacteria to be effective, possibly because actively secreted...
bacilli Calmette-Guerin (BCG) is a licensed vaccine against tuberculosis. It requires attenuated live bacteria to be effective, possibly because actively secreted proteins play a critical role in inducing anti-tuberculosis immunity. BCG also functions as an effective adjuvant. Moreover, the effects of BCG components as adjuvants are not important as those of attenuated live BCG, which is used in cancer immunotherapy. However, the BCG secreted proteins have not been paid attention in anticancer immunity. To understand mycobacterial secreted proteins' function, we investigate immune responses to BCG culture filtrate proteins (CFP). Here, CFP strongly induce both antigen-specific CD4+ T cells and specific CD8+ T cells, which may be functional cytotoxic T lymphocytes (CTLs). In this study, we clearly demonstrate that CFP acts as an adjuvant for CTL induction against specific co-administered proteins and propose CFP as a new protein adjuvant. The CTL response shows potent anticancer effects in mice. These findings could provide insight into the contribution of mycobacterial secreted proteins in both anticancer and antimycobacterial immunity.
Topics: Animals; Mice; Mycobacterium bovis; T-Lymphocytes, Cytotoxic; BCG Vaccine; Adjuvants, Immunologic; CD8-Positive T-Lymphocytes; Tuberculosis
PubMed: 37928526
DOI: 10.3389/fimmu.2023.1271228 -
Environmental Pollution (Barking, Essex... Jan 2024There are strong suggestions for a link between pulmonary tuberculosis (TB) and air quality. Diesel exhaust is one of the main contributors to pollution and it is...
There are strong suggestions for a link between pulmonary tuberculosis (TB) and air quality. Diesel exhaust is one of the main contributors to pollution and it is reported to be able to modify susceptibility to lung infections. In this study we exposed THP-1 human macrophages and Mycobacterium bovis BCG to diesel exhaust particles (DEPs). High cytotoxicity and activation of apoptosis was found in THP-1 cells at 3 and 6 days, but no effect was found on the growth of M. bovis BCG. Infection of THP-1 cells exposed to a non-cytotoxic DEP concentration showed a limited capacity to engulf latex beads. However, M. bovis BCG infection of macrophages did not result in an increase in the bacterial burden, but it did result in an increase in the bacteria recovered from the extracellular media, suggesting a poor contention of M. bovis BCG. We also observed that DEP exposure limited the production of cytokines. Using the Galleria mellonella model of infection, we observed that larvae exposed to low levels of DEPs were less able to survive after infection with M. bovis BCG and had a higher internal bacterial load after 4 days of infection. Unraveling the links between air pollution and impairment of human antimycobacterial immunity is vital, because pollution is rapidly increasing in areas where TB incidence is extremely high.
Topics: Animals; Humans; Mycobacterium bovis; Vehicle Emissions; Macrophages; Cytokines; Larva
PubMed: 37741543
DOI: 10.1016/j.envpol.2023.122597