Overview and phylogeny of Mycobacterium tuberculosis complex organisms: implications for diagnostics and legislation of bovine tuberculosis

Enhanced analysis of the genomic diversity of Mycobacterium bovis in Great Britain to aid control of bovine tuberculosis

Bovine tuberculosis (bTB) is an endemic disease in Great Britain (GB) that affects mainly cattle but also other livestock and wild mammal species, leading to significant economic and social impact. Traditional genotyping of Mycobacterium bovis (M. bovis) isolates, which cause bTB, had been used routinely since the late 1990s as the main resource of genetic information in GB to describe their population and to understand their epidemiology. Since 2017, whole-genome sequencing (WGS) has been implemented on M. bovis isolates collected during routine surveillance. In this study, we analysed genome sequences from 3,052 M. bovis isolates from across GB to characterise their diversity and population structure in more detail. Our findings show that the M. bovis population in GB, based on WGS, is more diverse than previously indicated by traditional genotyping and can be divided into seven major clades, with one of them subdivided further into 29 clades that differ from each other by at least 70 single-nucleotide polymorphisms (SNPs). Based on the observed phylogenetic structure, we present a SNP-based classification system that replaces the genotype scheme that had been used until recently in GB. The predicted function and associated processes of the genes harbouring these SNPs are discussed with potential implications for phenotypic/functional differences between the identified clades. At the local scale, we show that WGS provides greater discriminatory power and that it can reveal the origin of infection and associated risk pathways even in areas of high bTB prevalence. The difficulty in determining transmission pathways due to the limited discrimination of isolates by traditional typing methods has compromised bTB control, as without such information it is harder to determine the relative efficacy of potential intervention measures. This study demonstrates that the higher resolution provided by WGS data can improve determination of infection sources and transmission pathways, provide important insights that will inform and shape bTB control policies in GB, as well as improve farm specific advice on interventions that are likely to be effective.

Exploring the Chemical Space of Mycobacterial Oxidative Phosphorylation Inhibitors Using Molecular Modeling

Mycobacteria are opportunistic intracellular pathogens that have plagued humans and other animals throughout history and still are today. They manipulate and hijack phagocytic cells of immune systems, enabling them to occupy this peculiar infection niche. Mycobacteria exploit a plethora of mechanisms to resist antimicrobials (e. g., waxy cell walls, efflux pumps, target modification, biofilms, etc.) thereby evolving into superbugs, such as extensively drug-resistant tuberculosis (XDR TB) bacilli and the emerging pathogenic Mycobacterium abscessus complex. This review summarizes the mechanisms of action of some of the surging antimycobacterial strategies. Exploiting the fact that mycobacteria are obligate aerobes and the differences between their oxidative phosphorylation pathways versus their human counterpart opens a promising avenue for drug discovery. The polymorphism of respiratory complexes across mycobacterial pathogens imposes challenges on the repositioning of antimycobacterial agents to battle the rise in nontuberculous mycobacterial infections. In silico strategies exploiting mycobacterial respiratory machinery data to design novel therapeutic agents are touched upon. The potential druggability of mycobacterial respiratory elements is reviewed. Future research addressing the health challenges associated with mycobacterial pathogens is discussed.

Natural outbreak of Mycobacterium caprae infection in imported laboratory cynomolgus macaques (Macaca fascicularis): diagnostic pitfalls and management of safety precautions

Tuberculosis (TB) is a major health threat for humans and for non-human primates used for toxicology or research purposes. Emerging mycobacterial species represent a major challenge for diagnosis and surveillance programs. Here, we report a natural outbreak of Mycobacterium caprae in imported cynomolgus macaques (Macaca fascicularis) that occurred at AnaPath Research S.A.U. (APR). The macaques underwent repeated negative intradermal tuberculin tests (IDT) before importation and at the European quarantine station. Exhaustive TB screening was started at APR after confirmation of one positive case at another facility. The animal in question belonged to the same colony received at APR. Diagnostic approaches included clinical examination, PCR, culture, spoligotyping, IDT testing, interferon-γ release assay (IGRA), and thoracoabdominal ultrasound (US). Three regulatory toxicity studies and stock animals were affected. The macaques lacked clinical signs, except for one showing a fistulizing nodule in the right inguinal area, which tested positive for the Mycobacterium tuberculosis complex by PCR. All animals were necropsied and 10 macaques (n=114) showed gross and histologic findings compatible with TB confirmed by PCR and culture. M. caprae was identified as the etiological agent by Direct Variable Repeat spacer oligonucleotide typing (DVR spoligotyping). The infection was traced to Asia via the SB1622 spoligotype involved, confirming that the animals were infected prior to their import into Europe. Tuberculin skin test (TST), IGRA, and US were only sensitive in detecting advanced cases of M. caprae infection. One staff member showed a positive TST reaction, which was handled in accordance with the Spanish government's health regulations. All the sanitary measures implemented were effective in eradicating the disease.

Macrophage polarization in lymph node granulomas from cattle and pigs naturally infected with Mycobacterium tuberculosis complex

Tuberculosis in animals is caused by members of the Mycobacterium tuberculosis complex (MTC), with the tuberculous granuloma being the main characteristic lesion. The macrophage is the main cell type involved in the development of the granuloma and presents a wide plasticity ranging from polarization to classically activated or pro-inflammatory macrophages (M1) or to alternatively activated or anti-inflammatory macrophages (M2). Thus, this study aimed to analyze macrophage polarization in granulomas from cattle and pig lymph nodes naturally infected with MTC. Tuberculous granulomas were microscopically categorized into four stages and a panel of myeloid cells (CD172a/calprotectin), M1 macrophage polarization (iNOS/CD68/CD107a), and M2 macrophage polarization (Arg1/CD163) markers were analyzed by immunohistochemistry. CD172a and calprotectin followed the same kinetics, having greater expression in late-stage granulomas in pigs. iNOS and CD68 had higher expression in cattle compared with pigs, and the expression was higher in early-stage granulomas. CD107a immunolabeling was only observed in porcine granulomas, with a higher expression in stage I granulomas. Arg1+ cells were significantly higher in pigs than in cattle, particularly in late-stage granulomas. Quantitative analysis of CD163+ cells showed similar kinetics in both species with a consistent frequency of immunolabeled cells throughout the different stages of the granuloma. Our results indicate that M1 macrophage polarization prevails in cattle during early-stage granulomas (stages I and II), whereas M2 phenotype is observed in later stages. Contrary, and mainly due to the expression of Arg1, M2 macrophage polarization is predominant in pigs in all granuloma stages.

Effect of IL-17A on the immune response to pulmonary tuberculosis induced by high- and low-virulence strains of Mycobacterium bovis

Tuberculosis (TB) is an infectious, chronic, and progressive disease occurring globally. Human TB is caused mainly by Mycobacterium tuberculosis (M. tuberculosis), while the main causative agent of bovine TB is Mycobacterium bovis (M. bovis). The latter is one of the most important cattle pathogens and is considered the main cause of zoonotic TB worldwide. The mechanisms responsible for tissue damage (necrosis) during post-primary TB remain elusive. Recently, IL-17A was reported to be important for protection against M. tuberculosis infection, but it is also related to the production of an intense inflammatory response associated with necrosis. We used two M. bovis isolates with different levels of virulence and high IL-17A production to study this important cytokine's contrasting functions in a BALB/c mouse model of pulmonary TB. In the first part of the study, the gene expression kinetics and cellular sources of IL-17A were determined by real time PCR and immunohistochemistry respectively. Non-infected lungs showed low production of IL-17A, particularly by the bronchial epithelium, while lungs infected with the low-virulence 534 strain showed high IL-17A expression on Day 3 post-infection, followed by a decrease in expression in the early stage of the infection and another increase during late infection, on Day 60, when very low bacillary burdens were found. In contrast, infection with the highly virulent strain 04-303 induced a peak of IL-17A expression on Day 14 of infection, 1 week before extensive pulmonary necrosis was seen, being lymphocytes and macrophages the most important sources. In the second part of the study, the contribution of IL-17A to immune protection and pulmonary necrosis was evaluated by suppressing IL-17A via the administration of specific blocking antibodies. Infection with M. bovis strain 534 and treatment with IL-17A neutralizing antibodies did not affect mouse survival but produced a significant increase in bacillary load and a non-significant decrease in inflammatory infiltrate and granuloma area. In contrast, mice infected with the highly virulent 04-303 strain and treated with IL-17A blocking antibodies showed a significant decrease in survival, an increase in bacillary loads on Day 24 post-infection, and significantly more and earlier necrosis. Our results suggest that high expression of IL-17A is more related to protection than necrosis in a mouse model of pulmonary TB induced by M. bovis strains.

Proteomic analysis of granulomas from cattle and pigs naturally infected with Mycobacterium tuberculosis complex by MALDI imaging

Matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) has recently gained prominence for its ability to provide molecular and spatial information in tissue sections. This technology has the potential to uncover novel insights into proteins and other molecules in biological and immunological pathways activated along diseases with a complex host-pathogen interaction, such as animal tuberculosis. Thus, the present study conducted a data analysis of protein signature in granulomas of cattle and pigs naturally infected with the Mycobacterium tuberculosis complex (MTC), identifying biological and immunological signaling pathways activated throughout the disease. Lymph nodes from four pigs and four cattle, positive for the MTC by bacteriological culture and/or real-time PCR, were processed for histopathological examination and MALDI-MSI. Protein identities were assigned using the MaTisse database, and protein-protein interaction networks were visualized using the STRING database. Gene Ontology (GO) analysis was carried out to determine biological and immunological signaling pathways in which these proteins could participate together with Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis. Distinct proteomic profiles between cattle and pig granulomas were displayed. Noteworthy, the GO analysis revealed also common pathways among both species, such as "Complement activation, alternative pathway" and "Tricarboxylic acid cycle", which highlight pathways that are conserved among different species infected by the MTC. In addition, species-specific terms were identified in the current study, such as "Natural killer cell degranulation" in cattle or those related to platelet and neutrophil recruitment and activation in pigs. Overall, this study provides insights into the immunopathogenesis of tuberculosis in cattle and pigs, opening new areas of research and highlighting the importance, among others, of the complement activation pathway and the regulation of natural killer cell- and neutrophil-mediated immunity in this disease.

Optimizing antigen selection for the development of tuberculosis vaccines

Tuberculosis (TB) remains a prevalent global infectious disease caused by genetically closely related tubercle bacilli in Mycobacterium tuberculosis complex (MTBC). For a century, the Bacillus Calmette-Guérin (BCG) vaccine has been the primary preventive measure against TB. While it effectively protects against extrapulmonary forms of pediatric TB, it lacks consistent efficacy in providing protection against pulmonary TB in adults. Consequently, the exploration and development of novel TB vaccines, capable of providing broad protection to populations, have consistently constituted a prominent area of interest in medical research. This article presents a concise overview of the novel TB vaccines currently undergoing clinical trials, discussing their classification, protective efficacy, immunogenicity, advantages, and limitations. In vaccine development, the careful selection of antigens that can induce strong and diverse specific immune responses is essential. Therefore, we have summarized the molecular characteristics, biological function, immunogenicity, and relevant studies associated with the chosen antigens for TB vaccines. These insights gained from vaccines and immunogenic proteins will inform the development of novel mycobacterial vaccines, particularly mRNA vaccines, for effective TB control.

The Establishment of a Novel γ-Interferon In Vitro Release Assay for the Differentiation of Mycobacterial Bovis-Infected and BCG-Vaccinated Cattle

BCG vaccination is increasingly reconsidered in the effective prevention of bovine tuberculosis (bTB). However, the primary challenge in BCG vaccination for cattle is the lack of a technique for differentiating between infected and vaccinated animals (DIVA). This study aimed to establish a novel DIVA diagnostic test based on an interferon-gamma in vitro release assay (IGRA). The plasmid encoding three differential antigens (Rv3872, CFP-10, and ESAT-6) absent in BCG genes but present in virulent M. bovis was previously constructed. Thus, a recombinant protein called RCE (Rv3872, CFP-10, and ESAT-6) was expressed, and an RCE-based DIVA IGRA (RCE-IGRA) was established. The RCE concentration was optimized at 4 μg/mL by evaluating 97 cattle (74 of which were bTB-positive, and 23 were negative) using a commercial IGRA bTB diagnostic kit. Further, 84 cattle were tested in parallel with the RCE-IGRA and commercial PPD-based IGRA (PPD-IGRA), and the results showed a high correlation with a kappa value of 0.83. The study included BCG-vaccinated calves (n = 6), bTB-positive cattle (n = 6), and bTB-negative non-vaccinated calves (n = 6). After 3 months post-vaccination, PPD-IGRA generated positive results in both vaccinated and infected calves. However, RCE-IGRA developed positive results in infected calves but negative results in vaccinated calves. In conclusion, this DIVA method has broad prospects in differentiating BCG vaccination from natural infection to prevent bTB.

Temporal dynamics of the early immune response following Mycobacterium bovis infection of cattle

Bovine tuberculosis is an infectious disease of global significance that remains endemic in many countries. Mycobacterium bovis infection in cattle is characterized by a cell-mediated immune response (CMI) that precedes humoral responses, however the timing and trajectories of CMI and antibody responses determined by newer generation assays remain undefined. Here we used defined-antigen interferon-gamma release assays (IGRA) and an eleven-antigen multiplex ELISA (Enferplex TB test) alongside traditional tuberculin-based IGRA and IDEXX M. bovis antibody tests to assess immune trajectories following experimental M. bovis infection of cattle. The results show CMI responses developed as early as two-weeks post-infection, with all infected cattle testing positive three weeks post-infection. Interestingly, 6 of 8 infected animals were serologically positive with the Enferplex TB assay as early as 4 weeks post-infection. As expected, application of the tuberculin skin test enhanced subsequent serological reactivity. Infrequent M. bovis faecal shedding was observed but was uncorrelated with observed immune trajectories. Together, the results show that early antibody responses to M. bovis infection are detectable in some individuals and highlight an urgent need to identify biomarkers that better predict infection outcomes, particularly for application in low-and-middle income countries where test-and-slaughter based control methods are largely unfeasible.

Combination with Annual Deworming Treatments Does Not Enhance the Effects of PCV2 Vaccination on the Development of TB in Wild Boar Populations

Vaccination against PCV2 has been proven to be an effective measure to reduce the severity of TB in wild boar. The combination of this measure with strategies focused on treating other key concomitant pathogens, such as nematodes, could be a useful strategy. This study assesses whether a combination of deworming treatments and PCV2 vaccination may reduce the prevalence and severity of TB in wild boar. The study was conducted on five game estates in mid-western Spain where four groups of wild boar were produced: control, vaccinated, dewormed and vaccinated-dewormed. Wild boars from all groups were hunted between 2017 and 2020, and all of them received a TB diagnosis based on pathological and microbiological tests. Generalised linear models were used to explore the effect of deworming and PCV2 vaccination on TB prevalence and severity. PCV2-vaccinated animals showed lower probabilities of suffering severe TB lesions. However, no differences regarding TB severity were found between dewormed and non-dewormed wild boar. PCV2 vaccination reduces TB severity in wild boar. However, annual deworming does not produce a long-term parasitological reduction that can influence the development of TB in wild boar, nor does it improve the effect of PCV2 vaccination on TB.

Large scale spatio-temporal modelling of risk factors associated with tuberculosis exposure at the wildlife-livestock interface

The management of animal tuberculosis (TB) is a priority for European Union animal health authorities. However, and despite all the efforts made to date, a significant part of Spain has as yet been unable to obtain the officially tuberculosis-free (OTF) status. Information regarding wildlife disease status is usually scarce, signifying that the role played by wildlife is usually ignored or poorly assessed in large-scale TB risk factor studies. The National Wildlife Health Surveillance Plan in Spain now provides information on infection rates in wildlife reservoirs at a national level, but there are limitations as regards the sample size, the spatio-temporal distribution of the samples, and the lack of homogeneity of the diagnostic techniques employed. The objective of the study described herein was, therefore, to employ a Bayesian approach with the intention of identifying the risk factors associated with four TB rates in cattle: prevalence, incidence, maintenance and persistence in Spain during the period 2014-2019. The modeling approach included highly informative spatio-temporal latent effects with which to control the limitations of the data. Variation partitioning procedures were carried out, and the pure effect of each factor was mapped in order to identify the most relevant factors associated with TB dynamics in cattle in each region. This made it possible to disclose that the movement of cattle, particularly from counties with herd incidence > 1%, was the main driver of the TB dynamics in cattle. The abundance of herds bred for bullfighting was retained in all four models, but had less weight than the movements. After accounting for farm-related factors, the TB prevalence in wild boar was retained in all the models and was significantly related to incidence, maintenance and persistence. With regard to the incidence, variation partitioning revealed that wildlife was the most explicative factor, thus suggesting that it plays a role in the introduction of the pathogen into uninfected herds, and consequently highlighting its importance in breakdowns. These results show, for the first time on a national scale, that wild ungulates play a relevant role in the spatio-temporal variability of TB in cattle, particularly as regards their disease status. Moreover, the spatial representation of the pure effect of each factor made it possible to identify which factors are driving the disease dynamics in each region, thus showing that it is a valuable tool with which to focus efforts towards achieving the OTF status.

Monitoring the immune response of macrophages in tuberculous granuloma through the expression of CD68, iNOS and HLA-DR in naturally infected beef cattle

Bovine tuberculosis still represents a universal threat that creates a wider range of public and animal health impacts. One of the most important steps in the pathogenesis of this disease and granuloma formation is the phagocytosis of tuberculous bacilli by macrophages. Mycobacteria replicate in macrophages, which are crucial to the pathophysiology of mycobacterial infections; however, scarce information is available about the dynamics of the granuloma-stage immunological response. Therefore, immunohistochemistry was used in this work to evaluate the expression of CD68, iNOS, and HLA-DR in different stages of TB granulomas from naturally infected cattle with tuberculosis. Two thousand, one hundred and fifty slaughtered beef cattle were examined during the period from September 2020 to March 2022. Sixty of them showed gross tuberculous pulmonary lesions and samples were collected from all of them for histopathological examination, Ziehl-Neelsen (ZN) staining, and bacteriological culturing. Selected samples that yielded a positive result for ZN and mycobacterial culturing were subjected to an immunohistochemical study of CD68, iNOS, and HLA-DR expression by macrophages according to granuloma stages. Immunohistochemical analysis revealed that the immunolabeling of CD68+, iNOS+, and HLA-DR+ macrophages significantly reduced as the stage of granuloma increased from stage I to stage IV (P < 0.003, P < 0.002, and P < 0.002, respectively). The distribution of immunolabeled macrophages was similar for the three markers, with immunolabeled macrophages distributed throughout early-stage granulomas (I, II), and surrounding the necrotic core in late-stage granulomas (III, IV). Our results suggest a polarization to the pro-inflammatory environment and increased expression of CD68+, iNOS+, and HLA-DR+ macrophages in the early stages of granulomas (I, II), which may play a protective role in the immune response of naturally infected beef cattle with tuberculosis.

Vaccination of White-Tailed Deer with Mycobacterium bovis Bacillus Calmette-Guérin (BCG): Effect of Mycobacterium avium ssp. paratuberculosis Infection

In many parts of the world, bovine tuberculosis eradication efforts are hampered by wildlife reservoirs of Mycobacterium bovis, which serve as a constant source of M. bovis for nearby cattle. The human tuberculosis vaccine, M. bovis 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 M. bovis 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 M. tuberculosis complex. M. avium subspecies paratuberculosis (Map) infection is not uncommon in ruminants such as deer. Using natural exposure to Map and experimental infection with M. bovis, we demonstrate that Map infection increased BCG vaccine efficacy as measured by lesion severity scores.

Biocomputational characterisation of MBO_200107 protein of Mycobacterium tuberculosis variant caprae: a molecular docking and simulation study

The principal objective of this study was to delineate the potentiality of the MBO_200107 protein from the Mycobacterium tuberculosis variant caprae in cancer research. It is a cytoplasmic protein, comprised of a 354-long amino acid chain, alkaline, had a molecular weight of 39089.37 Da, an isoelectric point of 9.62 and a grand average of hydropathicity of -0.345. One of the functional domains was predicted as Gammaglutamylcyclotransferase (GGCT). Among tertiary structures, the Modeller and Phyre2 model satisfied all the quality parameters, though they are truncated; contrarily, the I-TASSER model is full length and contains the sequence for the GGCT domain, though it did not meet all the quality parameters. It also has significant sequence similarities (47.5% by EMBOSS Water and 72.4% by EMBOSS Matcher) with a human GGCT, and the conserved sequences are confined to the GGCT domain of the MBO_200107. According to molecular docking analyses, the protein has a binding affinity of -4.8 kcal/mol by Autodock Vina and -56.465 kcal/mol by HPEPDOCK to the human glutathione (GSH), an essential metabolite for GGCT metabolism. The Molecular dynamic simulation of the docked complex showed the binding efficiency of the GSH to MBO_200107 with a minimal structural alteration. The in silico findings mentioned above revealed that the protein could be used as a supplementary tool in cancer research, such as designing vaccines or drugs where the role of GGCT has been implicated. Further, we recommend fully characterising the protein and conducting essential in vitro and in vivo experiments to determine its detailed usefulness.Communicated by Ramaswamy H. Sarma.

Development of lateral flow assays to detect host proteins in cattle for improved diagnosis of bovine tuberculosis

Bovine tuberculosis (bTB), caused by Mycobacterium bovis (M. bovis) infection in cattle, is an economically devastating chronic disease for livestock worldwide. Efficient disease control measures rely on early and accurate diagnosis using the tuberculin skin test (TST) and interferon-gamma release assays (IGRAs), followed by culling of positive animals. Compromised performance of TST and IGRA, due to BCG vaccination or co-infections with non-tuberculous mycobacteria (NTM), urges improved diagnostics. Lateral flow assays (LFAs) utilizing luminescent upconverting reporter particles (UCP) for quantitative measurement of host biomarkers present an accurate but less equipment- and labor-demanding diagnostic test platform. UCP-LFAs have proven applications for human infectious diseases. Here, we report the development of UCP-LFAs for the detection of six bovine proteins (IFN-γ, IL-2, IL-6, CCL4, CXCL9, and CXCL10), which have been described by ELISA as potential biomarkers to discriminate M. bovis infected from naïve and BCG-vaccinated cattle. We show that, in line with the ELISA data, the combined PPDb-induced levels of IFN-γ, IL-2, IL-6, CCL4, and CXCL9 determined by UCP-LFAs can discriminate M. bovis challenged animals from naïve (AUC range: 0.87-1.00) and BCG-vaccinated animals (AUC range: 0.97-1.00) in this cohort. These initial findings can be used to develop a robust and user-friendly multi-biomarker test (MBT) for bTB diagnosis.

Exploring the role of wastewater-based epidemiology in understanding tuberculosis burdens in Africa

Tuberculosis (TB) remains a persistent challenge to public health and presents a substantial menace, especially in developing nations of sub-Saharan Africa. It exerts a considerable strain on healthcare systems in these regions. Effective control requires reliable surveillance, which can be improved by incorporating environmental data alongside clinical data. Molecular advances have led to the development of alternative surveillance methods, such as wastewater-based epidemiology. This studyinvestigated the presence, concentration, and diversity of Mycobacterium tuberculosis complex, the cause of TB, in from six African countries: Ghana, Nigeria, Kenya, Uganda, Cameroon, and South Africa. Samples were collected from wastewater treatment plants. All samples were found to contain Mycobacterium species that have been linked to TB in both humans and animals, including Mycobacterium tuberculosis complex, Mycobacterium tuberculosis, Mycobacterium bovis, Mycobacterium africanum, and Mycobacterium caprae, at varying concentrations. The highest median concentration was found in Ghana, reaching up to 4.7 Log copies/ml for MTBC, 4.6 Log copies/ml for M. bovis, and 3.4 Log copies/ml for M. africanum. The presence of M. africanum outside of West Africa was found in South Africa, Kenya, and Uganda and could indicate the spread of the pathogen. The study underscores the usefulness of wastewater-based epidemiology for tracking TB and shows that even treated wastewater may contain these pathogens, posing potential public health risks.

Molecular Characterisation of Mycobacterium bovis Isolates from Cattle Slaughtered in Adamawa and Gombe States, North-Eastern Nigeria

Bovine tuberculosis is endemic in Nigeria with control measures as provided by the laws of the country being minimally enforced mostly at the abattoirs only. This study focused on bovine tuberculosis in Adamawa and Gombe States. Tuberculosis lesions were observed in 183 of 13,688 slaughtered cattle in the regions between June and December 2020. Analysis of tissue samples resulted in 17 Mycobacterium bovis isolates, predominantly from Gombe State. Spoligotyping identified four spoligotypes, including SB0944, SB1025, SB1104, and one novel pattern. MIRU-VNTR analysis further differentiated these spoligotypes into eight profiles. All isolates belonged to the Af1 clonal complex. The study emphasises the need for broader coverage and more isolates to comprehensively understand the molecular epidemiology of bovine tuberculosis in Nigeria. To enhance research and surveillance, a cost-effective approach is proposed, utilising a discriminatory VNTR panel comprising five or nine loci. The five-locus panel consists of ETR-C, QUB26, QUB11b, MIRU04, and QUB323. Alternatively, the nine-locus panel includes ETR-A, ETR-B, QUB11a, and MIRU26. Implementing this approach would provide valuable insights into the genetic diversity of M. bovis strains in Nigeria. These findings are crucial for developing effective control measures and minimising the impact of bovine tuberculosis on both animal and human health.

IgYs: on her majesty's secret service

There has been an increasing interest in using Immunoglobulin Y (IgY) antibodies as an alternative to "classical" antimicrobials. Unlike traditional antibiotics, they can be utilized on a continual basis without leading to the development of resistance. The veterinary IgY antibody market is growing because of the demand for minimal antibiotic use in animal production. IgY antibodies are not as strong as antibiotics for treating infections, but they work well as preventative agents and are natural, nontoxic, and easy to produce. They can be administered orally and are well tolerated, even by young animals. Unlike antibiotics, oral IgY supplements support the microbiome that plays a vital role in maintaining overall health, including immune system function. IgY formulations can be delivered as egg yolk powder and do not require extensive purification. Lipids in IgY supplements improve antibody stability in the digestive tract. Given this, using IgY antibodies as an alternative to antimicrobials has garnered interest. In this review, we will examine their antibacterial potential.

Seroepidemiology of tuberculosis in sheep in southern Spain

Tuberculosis (TB) is a multi-host infectious disease caused by members of the Mycobacterium tuberculosis complex (MTC). In Mediterranean ecosystems, where multiple animal hosts of TB are present, identifying the role of the different species involved in the epidemiology of TB is a key point to be able to implement proper control measures. Sheep are susceptible to MTC infection but have traditionally been considered a spillover host. However, the occurrence of outbreaks involving sheep in recent years evidences the need to better understand the role of this small ruminant species in the epidemiology of the disease. Here, we aimed to determine the seroprevalence and risk factors associated with MTC seropositivity in sheep in Andalusia (southern Spain), a region with one of the highest prevalence of MTC infection in both cattle and wild ungulates. A total of 2266 sheep from 83 flocks were tested for antibodies against MTC using an in-house indirect ELISA. Anti-MTC antibodies were detected in 16 (0.7%) of the 2266 sheep (adjusted true prevalence 0.29%, 95% posterior probability interval 0.01-1.05). Seropositivity was found in 14.5% (12/83; 95%CI: 6.9-22.0) of the sheep farms analyzed. A semi-extensive management system was identified as a risk factor associated with MTC seropositivity in sheep farms (OR = 3.7; p < 0.038; 95%CI: 1.1-12.4) in the study area. To the best of the authors' knowledge, this is the first active TB surveillance study carried out to assess MTC exposure in sheep. Our results indicate MTC circulation in sheep farms in southern Spain. However, the low individual seroprevalence obtained suggests that sheep may play a limited role in the epidemiology of TB in this region. Serosurveillance programs could be a valuable tool to detect MTC circulation in sheep in risk scenarios or target farms, in order to optimize control measures on TB animal in multi-host Mediterranean ecosystems.

The eradication of M. caprae tuberculosis in wild boar (Sus scrofa) in the Bieszczady Mountains, southern Poland – an administrative perspective

Introduction

Animal tuberculosis (TB) is a zoonotic disease caused by acid-fast bacteria belonging to the Mycobacterium tuberculosis complex (MTBC). Both animals and humans are susceptible to infection by the MTBC. Interspecies transmission is also possible, including to livestock and humans. In the years 1997–2013, many tuberculosis cases were recorded in European bison in the Bieszczady Mountains; more alarmingly, TB was also recorded in wild boar in the years 2013–2020.

Material and Methods

In the years 2013–2020, 104 wild boar from the Bieszczady Mountains were tested for TB through necropsy, mycobacterial culture, strain identification and spoligotyping.

Results

The microbiological examination confirmed TB in 46 wild boar; these infections were identified as M. caprae, spoligotype SB2391.

Conclusion

Free-living European bison are at risk of TB infection from wild boar carrying M. caprae. This situation also poses a risk to local cattle. There is a need for further activities aimed at monitoring the disease, preventing further transmission, and minimising the risk to public health.

Computational design of MmpL3 inhibitors for tuberculosis therapy

Tuberculosis is a chronic communicable disease caused by Mycobacterium tuberculosis (Mtb) and spreads from lungs to lymphatic system. The cell wall of mycobacterium plays a prominent role in maintaining the virulence and pathogenicity and also acts as prime target for drug discovery. Hence, this study has put into emphasis with target MmpLs (Mycobacterial membrane proteins Large) which are significant for the growth and survival of Mycobacterium tuberculosis. MmpLs belongs to the resistance, nodulation and division (RND) protein superfamily. MmpL3 is the only MmpL deemed essential for the replication and viability of mycobacterial cells. For the study, we have selected SQ109 derivatives as Mmpl3 inhibitor, which holds non-covalent property. Structure-based pharmacophore model of MmpL3 target protein with SQ109 as co-crystallized ligand (PDB: 6AJG) was generated to screen the ligand database. Compounds with decent fitness score and pharmacophoric features were compared with standard drug and taken for molecular docking studies. Further prime molecular mechanics-Poisson-Boltzmann surface area (MM-GBSA) and induced fit calculations identified potential molecules for further drug-likeness screening. Overall computational calculations identified ZINC000000016638 and ZINC000000003594 as potential in silico MmpL3 inhibitors. Molecular dynamics simulations integrated with MM-PBSA free energy calculations identified that MmpL3-ZINC000000016638 complex was more stable. Study can be further extended for synthesis and biological evaluation, derivatization of active compound to identify potential and safe lead compounds for effective tuberculosis therapy.

One Health risk challenges and preparedness regarding bovine tuberculosis at abattoirs in North-central Nigeria: Associated drivers and health belief

Background

Bovine tuberculosis (bTB) is a serious public health and neglected zoonotic disease responsible for 147,000 human cases and 12,500 deaths annually. This study assessed knowledge, risk perceptions, and preventive practices regarding bTB among occupationally exposed abattoir workers and drivers for transmission in slaughterhouses.

Methods

Using a pre-tested questionnaire, we surveyed a cross-section of workers in five main abattoirs in North-central Nigeria between 2018 and 2019. Data were analysed using descriptive statistics and univariable/multivariable logistic regression analyses at a 95% confidence level.

Results

All recruited respondents (n = 422: 77.7% meat processors and 22.3% meat and sanitary inspectors) participated and 10.4% had no formal education. About 44.0% and 27.0% of workers knew about bTB occurrence at the abattoirs and its transmission to humans, respectively. Less than one-third use personal protective equipment (PPE) during meat handling, only a few workers correctly practised routine handwashing, and 21.8% sterilized meat handling tools. A few participants (6.4%) had BCG vaccination against tuberculosis. Demographic characteristics (age, gender, occupation, and formal education) significantly influenced the perception and practices about bTB. A few workers perceived raw meat and milk, direct contact with infected carcasses, organs and contaminated fomites, contaminated environment through infected blood, dirty slaughtering floor, and aerosols of contaminated faeces as high-risk bTB transmission routes. Perceived drivers that influenced bTB transmission at abattoirs include unhygienic meat processing (OR = 5.4, 95%CI = 3.1–9.4, p < 0.001) and non-enforcement of abattoir standard operating systems (OR = 10.4, 95%CI = 6.0–18.5, p = 0.001).

Conclusion

The workers have low knowledge levels, perceptions, and practices toward bTB emergence. These demand the workers’ education on hygienic meat handling to mitigate the menace of the disease. Surveillance and preventive preparedness considering the identified drivers through the ’One Health’ approach are recommended.

Non-tuberculous mycobacteria, not Mycobacterium bovis, are a significant cause of TB-like lesions observed in slaughtered cattle in Ghana

Objectives

The aim was to isolate and identify the species of mycobacteria causing tuberculous-like (TB-like) lesions in cattle in Ghana.

Methods

Between 2019 and 2020, 68 bovine tissue samples with TB-like lesions, identified during post slaughter examination, were obtained from four major abattoirs close to border towns in Ghana. The samples were cultured on Lowenstein-Jensen medium. Isolated bacteria were characterized by Ziehl-Neelsen staining and observation for acid-fast bacilli (AFB) under a microscope. DNA was extracted from AFB-positive isolates, and mycobacterial speciation was performed by line probe assay using GenoType Mycobacterium CM and also with mycobacterial 16S rRNA gene amplification and sequencing.

Results

No Mycobacterium bovis was identified; however 53 bacterial isolates were obtained, of which 41 were non-tuberculous mycobacteria (NTM) strains and 12 were gram-positive bacteria. The predominant NTM species was M. fortuitum (43.9%, 18/41), with the rest being M. novocastrense, M. terrae, M. flavescens, M. holsaticum, M. cosmeticum, M. virginiense, M. intracellulare, M. mageritense, M. minnesotensis, M. duvalii, M. lehmannii, and M. koreense.

Conclusions

In cattle, NTM contribute significantly to lesions observed during slaughter examination and may be an important cause of zoonotic tuberculosis. A One Health surveillance of NTM in Ghana would provide insights into their clinical significance.

The Role of Histopathology as a Complementary Diagnostic Tool in the Monitoring of Bovine Tuberculosis

The diagnosis of bovine tuberculosis (bTB) is based on the single intradermal tuberculin test (SIT), interferon gamma, and compulsory slaughter of reactor animals. Culture and PCR from fresh tissue are regarded as gold standard techniques for post-mortem confirmation, with the former being time-consuming and presenting moderate to low sensitivity and the latter presenting promising results. Histopathology has the advantage to identify and categorize lesions in both reactor and non-reactor animals. Therefore, this study aims to highlight the role of histopathology in the systematic diagnosis of bTB to shorten the time to disclose positive animals. Blood (212) and lymph node (681) samples were collected for serological, bacteriological, and histopathological analyses from a total of 230 cattle subjected to the Spanish bTB eradication program. Seventy-one lymph nodes and 59 cattle yielded a positive result to bacteriology, with 59 lymph nodes and 48 cattle presenting a positive result in real-time PCR from fresh tissue. Roughly 19% (40/212) of sera samples gave a positive result to ELISA. Tuberculosis-like lesions (TBLs) were observed in 11.9% (81/681) of the lymph nodes and 30.9% (71/230) of cattle. Noteworthy, TBLs were evidenced in 18 out of 83 SIT⁻ and real-time PCR and bacteriology negative animals, with 11/18 disclosing a positive result to Ziehl-Neelsen technique and two of them to ddPCR from paraffin blocks targeting IS6110. Six out of these 11 ZN⁺ corresponded with mesenteric LN and were confirmed positive to paratuberculosis. Histopathology yielded a sensitivity of 91.3% (CI₉₅ 83.2–99.4%) and a specificity of 84.4% (CI₉₅ 78.6–89.3%) with good agreement (κ = 0.626) when compared with real-time PCR. Our results confirm that histopathology allows a rapid confirmation of real-time PCR and bacteriology, emphasizing its contribution to bTB control and monitoring.

Mycobacterium tuberculosis sensu stricto in African Apes, What Is Its True Health Impact?

Since the Symposium on Mycobacterial Infections of Zoo Animals held at the National Zoological Park, Smithsonian Institution in 1976, our understanding of tuberculosis (TB) in non-domestic animals has greatly expanded. Throughout the past decades, this knowledge has resulted in improved zoo-habitats and facilities design, stricter biosecurity measures, and advanced diagnostic methods, including molecular techniques, that have significantly decreased the number of clinical disease caused by Mycobacterium tuberculosis in apes under human care settings. In the other hand, exponential growth of human populations has led to human encroachment in wildlife habitat which has resulted in increased inter-species contact and recurrent conflict between humans and wild animals. Although it is widely accepted that non-human primates are susceptible to M. tb infection, opinions differ with regard to the susceptibility to develop disease amongst different taxa. Specifically, some authors suggest that African apes are less susceptible to clinical tuberculosis than other species of primates. The aim of this review article is to evaluate the current scientific literature to determine the actual health impact of disease caused by Mycobacterium tuberculosis and more specifically Mycobacterium tuberculosis sensu stricto in African apes. The literature review included literature databases: Web of Science, Pubmed, Scopus, Wiley, Springer and Science direct, without temporal limit and proceedings of annual conferences in the field of wildlife health. Our general inclusion criteria included information about serological, molecular, pathological (macroscopic and/or microscopic), and clinical evidence of TB in African apes; while our, our more stringent inclusion selection criteria required that in addition to a gross pathology, a molecular test confirmed Mycobacterium tuberculosis sensu stricto as the cause of disease or death. We identified eleven reports of tuberculosis in African apes; of those, only four reports met the more stringent selection criteria that confirmed M. tb sensu stricto in six individuals. All reports that confirmed M. tb sensu stricto originated from zoological collections. Our review suggests that there is little evidence of disease or mortality caused by M. tb in the different species of African apes both under human care and free ranging populations. Additional studies are needed in free-ranging, semi-captive populations (sanctuaries) and animals under human care (zoos and rescue centers) to definitely conclude that this mycobacteria has a limited health effect in African ape species.

The potential risk of international spread of Mycobacterium bovis associated with movement of alpacas

Introduction

The study highlights the transboundary nature of tuberculosis (TB) in alpacas and the failure of current ante-mortem testing protocols (the tuberculin skin and Enferplex Camelid TB tests) to identify TB-free alpaca herds and individuals for export. Our research and the available literature indicate that the alpaca (Vicugna pacos) is extremely susceptible to Mycobacterium bovis infection, and that testing periodicity fails to take into account that animals do not manifest disease symptoms for a long time. The skin test failed to identify Mycobacterium bovis infection in two alpacas prior to their movement from the UK to Poland. The animals were purchased by a breeding centre in Poland, and were then shown at an international animal exhibition. The last owner of the alpacas before their deaths from TB bought the infected animals unwittingly in order to run rehabilitation activities with disabled children on his farm.

Material and Methods

Thoracic lymph node, lung and liver tissue samples obtained at necropsy were examined histopathologically after Ziehl–Neelsen staining. Tissue samples were homogenised and mycobacteria present there were cultured on Stonebrink’s medium during a 6-week incubation. A commercial test using polymorphism of the chromosomal direct repeat region provided species identification and additional identification was by spacer oligonucleotide typing and mycobacteria interspersed repetitive unit–variable number tandem repeat analysis with a gel electrophoresis protocol.

Results

The microbiological examination confirmed multiorgan TB caused by the SB0666 spoligotype of Mycobacterium bovis.

Conclusion

Due to the suboptimal performance of current diagnostic tests for TB in alpacas, there is a risk that infected animals may be moved unwittingly. A risk of TB spread associated with the international movement of alpacas is implied by this study.

Evaluation of the discriminatory power of spoligotyping and 19-locus mycobacterial interspersed repetitive unit-variable number of tandem repeat analysis (MIRU-VNTR) of Mycobacterium bovis strains isolated from cattle in Algeria

Bovine tuberculosis (bTB) caused by Mycobacterium (M.) bovis and M. caprae is a transmissible disease of livestock, notifiable to the World Organization for Animal Health (OIE). BTB particularly affects cattle and small ruminants and can be transmitted to humans thereby posing a significant threat to veterinary and public health worldwide. M. bovis is the principal cause of bTB in Algeria. In order to better understand the route of spreading and elaborate an eradication program, isolation and characterization of mycobacteria from Algerian cattle was performed. Sixty strains belonging to the M. tuberculosis complex were analyzed by spoligotyping, thereof 42 by 19-locus-MIRU-VNTR-typing. Spoligotyping revealed 16 distinguishable patterns (Hunter-Gaston discriminatory index [HGDI] of 0.8294), with types SB0120 (n = 20) and SB0121 (n = 13) being the most frequent patterns, representing 55% of the strains. Analyses based on 19-locus-MIRU-VNTR yielded 32 different profiles, five clusters and one orphan pattern, showing higher discriminatory power (HGDI = 0.9779) than spoligotyping. Seven VNTR-loci [VNTR 577 (alias ETR C), 2163b (QU11b), 2165 (ETR A), 2461 (ETR B), 3007 (MIRU 27), 2163a (QUB11a) and 3232 (QUB 3232)] were the most discriminative loci (HGDI ˃ 0.50). In conclusion, 19-locus-MIRU-VNTR yielded more information than spoligotyping concerning molecular differentiation of strains and better supports the elucidation of transmission routes of M. bovis between Algerian cattle herds.

The Bovine Tuberculoid Granuloma

The bovine tuberculoid granuloma is the hallmark lesion of bovine tuberculosis (bTB) due to Mycobacterium bovis infection. The pathogenesis of bTB, and thereby the process of bovine tuberculoid granuloma development, involves the recruitment, activation, and maintenance of cells under the influence of antigen, cytokines and chemokines in affected lungs and regional lymph nodes. The granuloma is key to successful control of bTB by preventing pathogen dissemination through containment by cellular and fibrotic layers. Paradoxically, however, it may also provide a niche for bacterial replication. The morphologic and cellular characteristics of granulomas have been used to gauge disease severity in bTB pathogenesis and vaccine efficacy studies. As such, it is critical to understand the complex mechanisms behind granuloma initiation, development, and maintenance.

Ocular Tuberculosis: More than 'Of Mice and Men'

Tuberculosis (TB), caused by infection with members of the Mycobacterium tuberculosis-complex, is one of the oldest known infectious disease entities, resulting in the death of millions of humans each year. It also results in a substantial degree of morbidity and mortality in animal species. Extrapulmonary TB is well recognized in humans, and the eye is one site that can be affected. Studies seeking to understand ocular TB have often relied on animal models; however, these have their limitations and may not truly reflect what happens in humans. We wish to raise awareness among ophthalmologists and vision scientists of naturally occurring cases of ocular TB in animals, namely cattle and domestic cats, and the possibilities of gaining further understanding of this presentation of TB by adopting a collaborative approach. This will hopefully improve outcomes for both human and animal patients.

Recombinant AhpC antigen from Mycobacterium bovis boosts BCG-primed immunity in mice

Tuberculosis (TB) is still one of the most common infectious diseases around the world despite the widespread use of BCG (bacille Calmette-Guerin) strain of Mycobacterium bovis as a vaccine. This vaccine does not always protect people from TB, and, thus, new effective vaccines or vaccination strategies are being investigated. In this study, alkyl hydroperoxide reductase (AhpC) from M. bovis was evaluated as a new candidate vaccine antigen against TB in BALB/c mice model. The ahpC gene was amplified from M.bovis genome, cloned, and expressed in Escherichia coli. Vaccine antigen AhpC was formulated with Montanide ISA 61 VG, an oil-based emulsion adjuvant. Both IgG and IL-12 responses were observed in mice after administering the formulation both as a subunit vaccine alone and also as a booster vaccine for BCG immunization. However, a long-lasting response was observed when AhpC formulation was used as a booster (for BCG-primed immunization) as compared to being used as a subunit vaccine alone. In short, these findings suggested that AhpC has the potential to be used as a booster vaccine candidate for BCG-primed immunization.

The hard numbers of tuberculosis epidemiology in wildlife: A meta-regression and systematic review

Tuberculosis (TB) is a widespread disease that crosses the human and animal health boundaries, with infection being reported in wildlife, from temperate and subtropical to arctic regions. Often, TB in wild species is closely associated with disease occurrence in livestock but the TB burden in wildlife remains poorly quantified on a global level. Through meta-regression and systematic review, this study aimed to summarize global information on TB prevalence in commonly infected wildlife species and to draw a global picture of the scientific knowledge accumulated in wildlife TB. For these purposes, a literature search was conducted through the Web of Science and Google Scholar. The 223 articles retrieved, concerning a 39-year period, were submitted to bibliometric analysis and 54 publications regarding three wildlife hosts fulfilled the criteria for meta-regression. Using a random-effects model, the worldwide pooled TB prevalence in wild boar is higher than for any other species and estimated as 21.98%, peaking in Spain (31.68%), Italy (23.84%) and Hungary (18.12%). The pooled prevalence of TB in red deer is estimated at 13.71%, with Austria (31.58%), Portugal (27.75%), New Zealand (19.26%) and Spain (12.08%) positioning on the top, while for European badger it was computed 11.75%, peaking in the UK (16.43%) and Ireland (22.87%). Despite these hard numbers, a declining trend in wildlife TB prevalence is apparent over the last decades. The overall heterogeneity calculated by multivariable regression ranged from 28.61% (wild boar) to 60.92% (red deer), indicating that other unexplored moderators could explain disease burden. The systematic review shows that the most prolific countries contributing to knowledge related with wildlife TB are settled in Europe and Mycobacterium bovis is the most reported pathogen (89.5%). This study provides insight into the global epidemiology of wildlife TB, ascertaining research gaps that need to be explored and informing how should surveillance be refined.

The open pan-genome architecture and virulence landscape of Mycobacterium bovis

Animal tuberculosis (TB) is an emergent disease caused by Mycobacterium bovis, one of the animal-adapted ecotypes of the Mycobacterium tuberculosis complex (MTC). In this work, whole-genome comparative analyses of 70 M. bovis were performed to gain insights into the pan-genome architecture. The comparison across M. bovis predicted genome composition enabled clustering into the core- and accessory-genome components, with 2736 CDS for the former, while the accessory moiety included 3897 CDS, of which 2656 are restricted to one/two genomes only. These analyses predicted an open pan-genome architecture, with an average of 32 CDS added by each genome and show the diversification of discrete M. bovis subpopulations supported by both core- and accessory-genome components. The functional annotation of the pan-genome classified each CDS into one or several COG (Clusters of Orthologous Groups) categories, revealing ‘transcription’ (total average CDSs, n=258), ‘lipid metabolism and transport’ (n=242), ‘energy production and conversion’ (n=214) and ‘unknown function’ (n=876) as the most represented. The closer analysis of polymorphisms in virulence-related genes in a restrict group of M. bovis from a multi-host system enabled the identification of clade-monomorphic non-synonymous SNPs, illustrating clade-specific virulence landscapes and correlating with disease severity. This first comparative pan-genome study of a diverse collection of M. bovis encompassing all clonal complexes indicates a high percentage of accessory genes and denotes an open, dynamic non-conservative pan-genome structure, with high evolutionary potential, defying the canons of MTC biology. Furthermore, it shows that M. bovis can shape its virulence repertoire, either by acquisition and loss of genes or by SNP-based diversification, likely towards host immune evasion, adaptation and persistence.

Two target genes based multiple cross displacement amplification combined with a lateral flow biosensor for the detection of Mycobacterium tuberculosis complex

Background

Tuberculosis (TB) is a serious chronic infectious disease caused by Mycobacterium tuberculosis complex (MTBC). Hence, the development of a novel, simple, rapid and sensitive method to detect MTBC is of great significance for the prevention and treatment of TB.

Results

In this study, multiple cross displacement amplification (MCDA) combined with a nanoparticle-based lateral flow biosensor (LFB) was developed to simultaneously detect two target genes (IS6110 and mpb64) of MTBC (MCDA-LFB). One suite of specific MCDA primers designed for the IS6110 and mpb64 genes was validated using genomic DNA extracted from the reference strain H37Rv. The MCDA amplicons were analyzed using a real-time turbidimeter, colorimetric indicator (malachite green, MG) and LFBs. The optimal amplification temperature and time were confirmed, and the MCDA-LFB method established in the current report was evaluated by detecting various pathogens (i.e., reference strains, isolates and clinical sputum samples). The results showed that the two sets of MCDA primers targeting the IS6110 and mpb64 genes could effectively detect MTBC strains. The optimal reaction conditions for the MCDA assay were determined to be 67 °C for 35 min. The MCDA assay limit of detection (LoD) was 100 fg per reaction for pure genomic DNA. The specificity of the MCDA-LFB assay was 100%, and there were no cross-reactions for non-MTBC strains. For sputum samples and MTBC strain detection, the positive rate of MCDA-LFB for the detection of MTBC strains was consistent with seminested automatic real-time PCR (Xpert MTB/RIF) and higher than acid-fast staining (AFS) and culture assays when used for sputum samples. The MCDA-LFB assay was a rapid tool, and the whole procedure for MCDA-LFB, including DNA template preparation, MCDA reaction and amplification product analysis, was completed within 70 min.

Conclusion

The MCDA-LFB assay targeting the IS6110 and mpb64 genes is a simple, rapid, sensitive and reliable detection method, and it has potential significance for the prevention and treatment of TB.

Mycobacterium microti at the Environment and Wildlife Interface

An unexpected high presence of Mycobacterium&nbsp;microti in wild boar in Northern Italy (Garda Lake) has been reported since 2003, but the factors contributing to the maintenance of this pathogen are still unclear. In this study, we investigated the presence of M.&nbsp;microti in wild rodents and in water and soil samples collected at wild boar aggregation areas, such as watering holes, with the aim of clarifying their role in M.&nbsp;microti transmission. In total, 8 out of 120 captured animals tested positive for the Mycobacterium&nbsp;tuberculosis complex (MTBC) as assessed by real-time PCR, and six samples were confirmed to be M.&nbsp;microti. A strain with a genetic profile similar to those previously isolated in wild boars in the same area was isolated from one sample. Of the 20 water and 19 mud samples, 3 and 1, respectively, tested positive for the presence of MTBC, and spacer oligotype SB0118 (vole type) was detected in one sample. Our study suggests that wild rodents, in particular Apodemus&nbsp;sylvaticus, Microtus sp. and Apodemus&nbsp;flavicollis, play roles in the maintenance of M.&nbsp;microti infections in wild boar through ingestion or by contact with either infected excreta or a contaminated environment, such as at animal aggregation sites.

Attempt of thyX gene silencing and construction of a thyX deleted clone in a Mycobacterium bovis BCG

Mycobacterium tuberculosis, the causative agent of tuberculosis, possess flavin-dependent thymidylate synthase, ThyX. Since thyX is absent in humans and was shown to be essential for M. tuberculosis normal growth, ThyX is thought to be an attractive novel TB drug target. This study assessed thyX essentiality in Mycobacterium bovis BCG strains using CRISPR interference based gene silencing and found that thyX is not essential in an M. bovis BCG Tokyo derivative strain. A thyX deletion mutant strain was successfully constructed from that strain, which reinforces the non-essentiality of thyX under a certain genetic background.

Pathology of Bovine Tuberculosis in Three Breeds of Dairy Cattle and Spoligotyping of the Causative Mycobacteria in Ethiopia

Different breeds of cattle were observed to have a variable degree of susceptibility to bovine tuberculosis (bTB). The screening of bTB was conducted on 720 dairy cattle consisting of three breeds using the single intradermal cervical comparative tuberculin (SICCT) test. Besides this, 43 SICCT test-positive cattle were used to compare the severity of the pathology of bTB among the three breeds and to identify the causative mycobacteria using spoligotyping. The overall SICCT test positivity was 17.92% (129/720) by pooling all animals in the three farms. There was a significant difference in SICCT test positivity among the three breeds (χ2 = 71.06; p < 0.001); the highest (25.34%) was recorded in the crossbreed followed by the Boran breed (10.08%), while the least (3.14%) was recorded in the Jersey breed. On other hand, the highest median pathology score (10.0, interquartile range, IQR = 6.0-17.0) was recorded in Boran followed by cross (5.0, IQR = 3.5-7.5), while the least (3.0, IQR = 2.25-3.0) was recorded in Jersey. Thus, the difference in the median pathology scores was significant [Kruskal Wallisχ ( 2 ) 2 = 18.78, p < 0.001] among the three breeds. Furthermore, multivariate analysis using ordinal logistic regression by considering age, sex, breed, reproductive status, and location of the farms also showed a significant [χ ( 2 ) 2 = 11.97, p < 0.01] difference in pathology scores among the three breeds of cattle. Even at a single-herd level at Holeta, the difference in severity of pathology between the Boran and crossbreeds was significant (U = 33.5; p < 0.01). Culture positivity was 39% in 108 suspicious tissues. Fourteen Mycobacterium bovis (M. bovis) and two Mycobacterium tuberculosis (M. tuberculosis) were isolated from the lesions. All the 14 M. bovis isolates belonged to SB0912, while the two M. tuberculosis belonged to SIT54. In conclusion, although the frequency of the SICCT test positivity was high in the crossbreed, a more severe pathology was observed on the Boran (zebu) breed. In addition M. tuberculosis was isolated from TB lesions of dairy cattle, demonstrating the role of M. tuberculosis in causing TB in cattle.

Whole-Genome SNP Analysis Identifies Putative Mycobacterium bovis Transmission Clusters in Livestock and Wildlife in Catalonia, Spain

The high-resolution WGS analyses of MTBC strains have provided useful insight for determining sources of infection for animal tuberculosis. In Spain, tuberculosis in livestock is caused by Mycobacterium bovis and Mycobacterium caprae, where wildlife reservoirs play an important role. We analyzed a set of 125 M. bovis isolates obtained from livestock and wildlife from Catalonia to investigate strain diversity and identify possible sources and/or causes of infection. Whole-genome SNP profiles were used for phylogenetic reconstruction and pairwise SNP distance analysis. Additionally, SNPs were investigated to identify virulence and antimicrobial resistance factors to investigate clade-specific associations. Putative transmission clusters (≤12 SNPs) were identified, and associated epidemiological metadata were used to determine possible explanatory factors for transmission. M. bovis distribution was heterogeneous, with 7 major clades and 21 putative transmission clusters. In order of importance, the explanatory factors associated were proximity and neighborhood, residual infection, livestock-wildlife interaction, shared pasture, and movement. Genes related to lipid transport and metabolism showed the highest number of SNPs. All isolates were pyrazinamide resistant, and five were additionally resistant to isoniazid, but no clade-specific associations could be determined. Our findings highlight the importance of high-resolution molecular surveillance to monitor bovine tuberculosis dynamics in a low-prevalence setting.

Aptamer-Based Diagnostic Systems for the Rapid Screening of TB at the Point-of-Care

The transmission of Tuberculosis (TB) is very rapid and the burden it places on health care systems is felt globally. The effective management and prevention of this disease requires that it is detected early. Current TB diagnostic approaches, such as the culture, sputum smear, skin tuberculin, and molecular tests are time-consuming, and some are unaffordable for low-income countries. Rapid tests for disease biomarker detection are mostly based on immunological assays that use antibodies which are costly to produce, have low sensitivity and stability. Aptamers can replace antibodies in these diagnostic tests for the development of new rapid tests that are more cost effective; more stable at high temperatures and therefore have a better shelf life; do not have batch-to-batch variations, and thus more consistently bind to a specific target with similar or higher specificity and selectivity and are therefore more reliable. Advancements in TB research, in particular the application of proteomics to identify TB specific biomarkers, led to the identification of a number of biomarker proteins, that can be used to develop aptamer-based diagnostic assays able to screen individuals at the point-of-care (POC) more efficiently in resource-limited settings.

Enhanced Detection of Mycobacterium bovis-Specific T Cells in Experimentally-Infected Cattle

Bovine tuberculosis (bTB), caused by infection with Mycobacterium bovis, continues to be a major economic burden associated with production losses and a public health concern due to its zoonotic nature. As with other intracellular pathogens, cell-mediated immunity plays an important role in the control of infection. Characterization of such responses is important for understanding the immune status of the host, and to identify mechanisms of protective immunity or immunopathology. This type of information can be important in the development of vaccination strategies, diagnostic assays, and in predicting protection or disease progression. However, the frequency of circulating M. bovis-specific T cells are often low, making the analysis of such responses difficult. As previously demonstrated in a different cattle infection model, antigenic expansion allows us to increase the frequency of antigen-specific T cells. Moreover, the concurrent assessment of cytokine production and proliferation provides a deeper understanding of the functional nature of these cells. The work presented here, analyzes the T cell response following experimental M. bovis infection in cattle via in vitro antigenic expansion and re-stimulation to characterize antigen-specific CD4, CD8, and γδ T cells and their functional phenotype, shedding light on the variable functional ability of these cells. Data gathered from these studies can help us better understand the cellular response to M. bovis infection and develop improved vaccines and diagnostic tools.

The Association between Palmer Drought Severity Index Data and Tuberculosis-like Lesions Occurrence in Mediterranean Hunted Wild Boars

Simple Summary

Climate is one of the most influential factors in the dynamics of tuberculosis in the Mediterranean Iberic wildlife population. In this study, we aim to address how drought as a risk factor influences the occurrence of Tuberculosis-like lesions (TBL) in wild boar inspected in the field. With this focus, our study contributes to pointing out the importance of periods of drought in the increased TBL occurrence in wild boars inspected in the field in the subsequent season. The results of our study allow hunting managers to be advised, in advance, on whether they should adopt extra protective measures when they are aware of the presence of periods of drought. This climate trait can become an alert sign for increased TBL occurrence in the following season, allowing for the implementation of a feasible, timely, and effective measures to control TB in the wild boar population.

Abstract

In the Iberian Peninsula, the prevalence of tuberculosis differs for each region and for different wild disease hosts and the region affected by a Mediterranean climate will be the most affected. The Mediterranean Iberic regions have a favourable ecosystem for the development of Mycobacterium tuberculosis complex agents, where habitat, population dynamics, and climate (especially drought) are important factors affecting the high prevalence of tuberculosis in the wild boar population. Our objective was to study the association between the Palmer Drought Severity Index (PDSI) and the occurrence of tuberculosis-like lesions (TBL) in wild boar during nine hunting seasons (2008/09 to 2016/17) in Idanha-a-Nova County. To this end, statistical analysis revealed a significant association (p < 0.05) between the occurrence of TBL in wild boar in Idanha-a-Nova County and the analysed risk factor—previous season with periods of drought—which indicated that, when one season experiences some periods of drought, the probability of TBL occurrence in wild boars was 1.2 (OR = 1.2) times higher in the next hunting season than when there were no periods of drought. Therefore, our study contributes to the discovery of a positive effect of periods of drought on the transmission of tuberculosis in Iberian wildlife.

Systemic Bovine Tuberculosis in a Crested Porcupine (Hystrix cristata) in the Marche Region, Italy

Tuberculosis is a worldwide zoonosis involving a wide range of hosts among domestic and wild animals. We describe tuberculosis caused by Mycobacterium bovis in a wild crested porcupine (Hystrix cristata) found dead in the district of Macerata, Marche Region, Italy in 2019.

Histological and immunohistochemical features suggesting aetiological differences in lymph node and (muco)cutaneous feline tuberculosis lesions

OBJECTIVES

To identify and describe histological and immunohistochemical criteria that may differentiate between skin and lymph node lesions associated with Mycobacterium (M.) bovis and M. microti in a diagnostic pathology setting.

MATERIALS AND METHODS

Archived skin and lymph node biopsies of tuberculous lesions were stained with haematoxylin and eosin, Ziehl-Neelsen and Masson's Trichrome. Immunohistochemistry was performed to detect the expression of calprotectin, CD3 and Pax5. Samples were scored for histological parameters (i.e. granulomas with central necrosis versus small granulomas without central necrosis, percentage necrosis and/or multinucleated giant cells), number of acid-fast bacilli (bacterial index) and lesion percentage of fibrosis and positive immunohistochemical staining.

RESULTS

Twenty-two samples were examined (M. bovis n=11, M. microti n=11). When controlling for age, gender and tissue, feline M. bovis-associated lesions more often featured large multi-layered granulomas with central necrosis. Conversely, this presentation was infrequent in feline M. microti-associated lesions, where small granulomas without central necrosis predominated. The presence of an outer fibrous capsule was variable in both groups, as was the bacterial index. There were no differences in intralesional expression of immunohistochemical markers.

CLINICAL SIGNIFICANCE

Differences in the histological appearance of skin and lymph node lesions may help to infer feline infection with either M. bovis or M. microti at an earlier stage when investigating these cases, informing clinicians of the potential zoonotic risk. Importantly, cases of tuberculosis can present with numerous acid-fast bacilli. This implies that a high bacterial index does not infer infection with non-zoonotic non-tuberculous mycobacteria.

Host Genetic Diversity and Infectious Diseases. Focus on Wild Boar, Red Deer and Tuberculosis

Host genetic diversity tends to limit disease spread in nature and buffers populations against epidemics. Genetic diversity in wildlife is expected to receive increasing attention in contexts related to disease transmission and human health. Ungulates such as wild boar (Sus scrofa) and red deer (Cervus elaphus) are important zoonotic hosts that can be precursors to disease emergence and spread in humans. Tuberculosis is a zoonotic disease with relevant consequences and can present high prevalence in wild boar and red deer populations. Here, we review studies on the genetic diversity of ungulates and determine to what extent these studies consider its importance on the spread of disease. This assessment also focused on wild boar, red deer, and tuberculosis. We found a disconnection between studies treating genetic diversity and those dealing with infectious diseases. Contrarily, genetic diversity studies in ungulates are mainly concerned with conservation. Despite the existing disconnection between studies on genetic diversity and studies on disease emergence and spread, the knowledge gathered in each discipline can be applied to the other. The bidirectional applications are illustrated in wild boar and red deer populations from Spain, where TB is an important threat for wildlife, livestock, and humans.

Retrospective analysis of the control and prevention of tuberculosis among cattle in Ukraine in the period 1994–2020

Bovine tuberculosis (bTB) – is a chronic infectious disease, the causative agent of which affects many species of mammals. It is a zoonosis caused by various types of mycobacteria in the complex Mycobacterium tuberculosis family Mycobacteriaceae. The most important etiological agent of bTB in cattle is M. bovis, which has been isolated from tuberculosis infected cattle for centuries. Livestock and species of the Bovidae family are the most susceptible to this pathogen and are the main reservoir species for animals and humans. In Ukraine, the main methods of diagnosing tuberculosis in animal husbandry are lifetime (clinical examination, allergic intradermal test with tuberculin), and postmortem techniques (pathological changes, bacteriological investigation). The authors performed a retrospective analysis of the epizootic situation of tuberculosis among cattle in Ukraine for the period 1994–2020 and conducted a critical assessment of the work done to prevent and control this disease. In total, over the last 27 years, 219 088 head of cattle with tuberculosis and 933 affected locations have been identified in Ukraine. The results of this work showed that in our country the epizootic situation of bovine tuberculosis on farms of various forms of ownership is fully controlled. The most active fight against tuberculosis was carried out during 1995–2015. In 1994–1997, the largest number of affected locations was registered, from 90 to 144, respectively, and the largest number of animals with tuberculosis – 21 395–33 474. In 1994–1995, the largest number of sick animals per one affected point was registered (371.9 and 471.7 head, respectively). Currently, official statistics show that many farms, especially in Vinnytska, Cherkaska and Kyivska regions, continue to show positive allergic reactions to tuberculin (46 898 reactions for the last 12 years). Applying diagnostic methods of research in complex (bacteriological, bioassay, molecular), excludes affection of cattle by pathogenic mycobacteria. This study showed that for the last 5 years no farms with confirmed pathological diagnosis by bacteriological methods have been registered and no culture of the pathogen from animals has been detected. Besides the scurpulous work of the veterinary service, in our opinion, the catastrophic decline in the number of cattle in Ukraine also had a significant impact on improving the epizootic situation regarding tuberculosis.

Heterogeneity of Pulmonary Granulomas in Cattle Experimentally Infected With Mycobacterium bovis

Mycobacterium bovis is the cause of tuberculosis in most animals, most notably cattle. The stereotypical lesion of bovine tuberculosis is the granuloma; a distinct morphological lesion where host and pathogen interact and disease outcome (i.e., dissemination, confinement, or resolution) is determined. Accordingly, it is critical to understand host-pathogen interactions at the granuloma level. Host-pathogen interactions within individual granulomas at different stages of disease have not been examined in cattle. We examined bacterial burden and cytokine expression in individual pulmonary granulomas from steers at 30, 90, 180, and 270 days after experimental aerosol infection with M. bovis. Bacterial burdens within individual granulomas examined 30 days after infection were greater and more heterogenous (variable) than those examined 90 to 270 days after infection. Bacterial burdens did not correlate with expression of IFN-γ, TNF-α, TGF-β, granuloma stage, or lung lesion score, although there was a modest positive correlation with IL-10 expression. Granuloma stage did have modest positive and negative correlations with TNF-α and IL-10, respectively. Heterogeneity and mean expression of IFN-γ, IL-10 and TNF-α did not differ significantly over time, however, expression of TGF-β at 90 days was significantly greater than that seen at 30 days after infection.

The puzzle of the evolutionary natural history of tuberculosis

Several pieces of the puzzle of the natural history of tuberculosis are assembled in this review to illustrate the potential reservoirs and sources of the Mycobacterium tuberculosis complex (MTBC) mycobacteria, their transmission to animals and humans, and their fate in populations, in a co-evolutionary perspective. Millennia-old companions of mammalian and human populations, MTBC are detected in the soil, in which they infect and survive within vegetative amoebae and cysts, except for Mycobacterium canettii. Never detected in the sphere of plants, they are transmissible by transcutaneous, digestive and respiratory routes and cause an infection of the lymphatic system with secondary dissemination in most tissues, in which they determine a specific and non-pathognomonic granulomatous inflammatory reaction; in which MTBC survives in dormant form irrespective of MTBC species and mammalian species; indicating that the current epidemiology in mammalian populations is essentially governed by the probabilities of contact between mammalian species and MTBC species. Individual variabilities in clinical expression of tuberculosis are related to MTBC species, strain and inoculum; host genetic factors; acquired modulations of the inflammatory response; and probably human microbiota. This review of the literature suggests an evolutionary natural history of telluric environmental mycobacteria, satellites of unicellular eukaryotes, transmissible to mammals via the digestive and then respiratory tracts, in which they determine a fatal contagious infection that is primarily lymphatic and a quiescence-mimicking encysted form. This review opens perspectives for microbiological and translational medical research.

Cell-Mediated Immunological Biomarkers and Their Diagnostic Application in Livestock and Wildlife Infected With Mycobacterium bovis

Mycobacterium bovis has the largest host range of the Mycobacterium tuberculosis complex and infects domestic animal species, wildlife, and humans. The presence of global wildlife maintenance hosts complicates bovine tuberculosis (bTB) control efforts and further threatens livestock and wildlife-related industries. Thus, it is imperative that early and accurate detection of M. bovis in all affected animal species is achieved. Further, an improved understanding of the complex species-specific host immune responses to M. bovis could enable the development of diagnostic tests that not only identify infected animals but distinguish between infection and active disease. The primary bTB screening standard worldwide remains the tuberculin skin test (TST) that presents several test performance and logistical limitations. Hence additional tests are used, most commonly an interferon-gamma (IFN-γ) release assay (IGRA) that, similar to the TST, measures a cell-mediated immune (CMI) response to M. bovis. There are various cytokines and chemokines, in addition to IFN-γ, involved in the CMI component of host adaptive immunity. Due to the dominance of CMI-based responses to mycobacterial infection, cytokine and chemokine biomarkers have become a focus for diagnostic tests in livestock and wildlife. Therefore, this review describes the current understanding of host immune responses to M. bovis as it pertains to the development of diagnostic tools using CMI-based biomarkers in both gene expression and protein release assays, and their limitations. Although the study of CMI biomarkers has advanced fundamental understanding of the complex host-M. bovis interplay and bTB progression, resulting in development of several promising diagnostic assays, most of this research remains limited to cattle. Considering differences in host susceptibility, transmission and immune responses, and the wide variety of M. bovis-affected animal species, knowledge gaps continue to pose some of the biggest challenges to the improvement of M. bovis and bTB diagnosis.

Global trends of epidemiological research in livestock tuberculosis for the last four decades

Animal tuberculosis (TB) caused by Mycobacterium tuberculosis complex (MTC) bacteria remains as one of the most significant infectious diseases of livestock, despite decades of eradication programmes and research efforts, in an era where the livestock sector is among the most important and rapidly expanding commercial agricultural segments worldwide. This work provides a global overview of the spatial and temporal trends of reported scientific knowledge of TB in livestock, aiming to gain insights into research subtopics within the animal TB epidemiology domain and to highlight territorial inequalities regarding data reporting and research outputs over the years. To deliver such information, peer-reviewed reports of TB studies in livestock were retrieved from the Web of Science and Google Scholar, systematized and dissected. The validated data set contained 443 occurrence observations, covering the 1981-2020 period (39 years). We highlight a clear move towards transdisciplinary areas and the One Health approach, with a global temporal increase in publications combining livestock with wildlife and/or human components, which reflect the importance of non-prototypical hosts as key to understanding animal TB. It becomes evident that cattle is the main host across works from all continents; however, many regions remain poorly surveyed. TB research in livestock in low-/middle-income countries is markedly growing, reflecting changes in animal husbandry, but also mirroring the globalization era, with a marked increase in international collaboration and capacitation programmes for scientific and technological development. This review gives an overview of the most prolific continents, countries and research fields in animal TB epidemiology, clearly outlining knowledge gaps and key priority topics. The estimated growth trend of livestock production until 2050, particularly in Asia and Africa, in response to human population growth and animal-protein demand, will require further investment in early surveillance and adaptive research to accommodate the higher diversity of livestock species and MTC members and raising the possibility to fine-tune funding schemes.

Most likely causes of infection and risk factors for tuberculosis in Spanish cattle herds

INTRODUCTION

This study aims to assess the most likely causes of Bovine tuberculosis (bTB) breakdowns in Spanish cattle herds and to identify the main risk factors at farm-level.

METHODS

Causes of bTB breakdowns were assessed through a qualitative risk-assessment based on decision-trees by analysing surveillance data from 3819 bTB breakdowns detected during 2014-2016. Results were compared to veterinary officers' (VO) opinions. Risk factors were identified through a case-control study with data from 196 bTB cases and 160 controls collected during 2014-2018.

RESULTS

The decision tree analysis identified residual infections and interactions with wildlife as the most frequent causes of breakdowns (36% each), followed by purchasing infected cattle (14%). These results were not supported by VOs' opinions. According to the regression models, the risk of bTB increased by sharing pastures (odds ratios [OR] = 2.7; 95% confidence interval [CI] = 1.6-4.4) and by increasing inwards cattle movements. The presence of wildlife reservoirs represented a significant risk for extensively-managed farms if other cattle farms are situated within a one-kilometre radius (OR = 2.3; 95% CI = 1.1-5.1).

DISCUSSION

To prevent bTB breakdowns, efforts should be devoted to decrease the likelihood of residual infections and improve farm biosecurity. The adoption of biosecurity measures might be influenced by farmers' perceptions, which should be carefully evaluated to ensure the effectiveness of such strategies.