Structural and functional characterization of FabG4 from Mycolicibacterium smegmatis.

The rise in antimicrobial resistance is a global health crisis and necessitates the development of novel strategies to treat infections. For example, in 2022 tuberculosis (TB) was the second leading infectious killer after COVID-19, with multi-drug-resistant strains of TB having an ∼40% fatality rate. Targeting essential biosynthetic pathways in pathogens has proven to be successful for the development of novel antimicrobial treatments. Fatty-acid synthesis (FAS) in bacteria proceeds via the type II pathway, which is substantially different from the type I pathway utilized in animals. This makes bacterial fatty-acid biosynthesis (Fab) enzymes appealing as drug targets. FabG is an essential FASII enzyme, and some bacteria, such as Mycobacterium tuberculosis, the causative agent of TB, harbor multiple homologs. FabG4 is a conserved, high-molecular-weight FabG (HMwFabG) that was first identified in M. tuberculosis and is distinct from the canonical low-molecular-weight FabG. Here, structural and functional analyses of Mycolicibacterium smegmatis FabG4, the third HMwFabG studied to date, are reported. Crystal structures of NAD+ and apo MsFabG4, along with kinetic analyses, show that MsFabG4 preferentially binds and uses NADH when reducing CoA substrates. As M. smegmatis is often used as a model organism for M. tuberculosis, these studies may aid the development of drugs to treat TB and add to the growing body of research that distinguish HMwFabGs from the archetypal low-molecular-weight FabG.

Successful rescue TNF-α blocking for Mycobacterium genavense - Related immune reconstitution inflammatory syndrome: A case report.

Immune reconstitution inflammatory syndrome (IRIS) has been reported in immunocompromised patients with disseminated Mycobacterium genavense. Management relies on high-dose corticosteroids. We describe two cases of late-onset corticosteroid-refractory IRIS related to disseminated infection in a HIV-positive patient and a renal transplant patient who had a favorable outcome with a monoclonal TNF-α blocker.

Chest wall tumor following intravesical BCG instillation for non-muscle invasive bladder cancer.

Mycobacterium bovis bacille Calmette-Guérin (BCG) is the most effective intravesical immunotherapy for non-muscle invasive bladder cancer (NMIBC), administered after its transurethral resection. Although its instillation is generally well tolerated, BCG-related infectious complications may occur in up to 5% of patients. Clinical manifestations may arise in conjunction with initial BCG instillation or develop months or years after the last BCG instillation. The range of presentations and potential severity pose an imminent challenge for clinicians. We present a case of an isolated subcutaneous chest wall abscess in an immunocompetent 52-year-old patient nearly two years after intravesical BCG instillation for NMIBC, an absolute rarity. As the enlarging chest wall tumor may be misinterpreted as malignancy, its expedient diagnosis and prompt treatment are of critical importance.

Case Report on Mycobacterium tuberculosis Presenting As Lemierre's Syndrome: A Reemerging Catastrophe.

Lemierre's syndrome is characterized by internal jugular vein thrombophlebitis and bacteremia, primarily from anaerobic organisms. The condition usually arises after a recent oropharyngeal infection. Young, healthy people with prolonged pharyngitis that progresses into septicemia, pneumonia, or lateral neck stiffness should be suspected of having Lemierre's syndrome. Identifying internal jugular vein thrombophlebitis and developing anaerobic bacterial growth on blood culture are frequently used to confirm the diagnosis. Treatment consists of long-term antibiotic treatment, sometimes in conjunction with anticoagulant medication. In this case report, we describe the unique case of a 29-year-old male with Mycobacterium tuberculosis with pulmonary tuberculosis, tubercular meningitis, tuberculosis-related acute ischemic stroke with septic thrombophlebitis. The patient presented with sudden onset altered sensorium for 4 hours. Magnetic resonance imaging of the brain was done, which suggested obstructive hydrocephalus with periventricular ooze. The patient was started on antibacillary treatment, antibiotics, anticoagulants, and systemic steroids. The patient was vitally stable when he was discharged. Therefore, it is crucial to consider the likelihood of such atypical tuberculosis presentations while providing a prompt and relevant diagnosis and recommending the right course of therapy.

A robust computational quest: Discovering potential hits to improve the treatment of pyrazinamide-resistant Mycobacterium tuberculosis.

The rise of pyrazinamide (PZA)-resistant strains of Mycobacterium tuberculosis (MTB) poses a major challenge to conventional tuberculosis (TB) treatments. PZA, a cornerstone of TB therapy, must be activated by the mycobacterial enzyme pyrazinamidase (PZase) to convert its active form, pyrazinoic acid, which targets the ribosomal protein S1. Resistance, often associated with mutations in the RpsA protein, complicates treatment and highlights a critical gap in the understanding of structural dynamics and mechanisms of resistance, particularly in the context of the G97D mutation. This study utilizes a novel integration of computational techniques, including multiscale biomolecular and molecular dynamics simulations, physicochemical and medicinal chemistry predictions, quantum computations and virtual screening from the ZINC and Chembridge databases, to elucidate the resistance mechanism and identify lead compounds that have the potential to improve treatment outcomes for PZA-resistant MTB, namely ZINC15913786, ZINC20735155, Chem10269711, Chem10279789 and Chem10295790. These computational methods offer a cost-effective, rapid alternative to traditional drug trials by bypassing the need for organic subjects while providing highly accurate insight into the binding sites and efficacy of new drug candidates. The need for rapid and appropriate drug development emphasizes the need for robust computational analysis to justify further validation through in vitro and in vivo experiments.

Post-tuberculosis Destroyed Lung Syndrome in an Indian Male: A Case Report.

The term "destroyed lung" signifies the complete degradation of lung tissues, typically due to chronic or recurring lung infections, with tuberculosis often identified as a primary culprit. This condition, when occurs after tuberculosis and is known as post-tubercular destroyed lung syndrome, poses considerable difficulties, especially in areas where tuberculosis is prevalent. This paper outlines a case study involving a 50-year-old Indian man afflicted with destroyed lung syndrome. Despite having undergone tuberculosis treatment three years earlier, the patient exhibited symptoms such as a dry cough, coughing up blood, and difficulty breathing. A comprehensive clinical evaluation and radiological assessments confirmed the diagnosis of destroyed lung syndrome, leading to the commencement of appropriate treatment.

Rehabilitation management of patients with spinal tuberculosis (Review).

Spinal tuberculosis (ST) is a serious condition and a global health concern, accounting for a significant portion of musculoskeletal tuberculosis cases. It can lead to sever spinal and neurological complications. The management of ST involves a multidisciplinary approach, including medical treatment, surgery and rehabilitation. Rehabilitation is crucial through the course of the disease's and is tailored for each stage according to the patients' complaints, and clinical and functional complications. In the case of neurological issues due to spinal compression, rehabilitation aims at overcoming bed confinement complications, involving mobilization techniques, strengthening exercises and related vesico-sphincter disorders (urodynamics, catheterizing). The role of rehabilitation for the management of pain in patients with ST is based on bracing (restricting movements and relieving the pressure on harmed structures), and analgesic physical means (electrical stimulation and massage techniques). Several rehabilitation options may be used to address musculoskeletal complications. Range of motion exercises, muscle strengthening, and posture and balance correction using sensory perception and proprioception techniques, are commonly involved. Cardiorespiratory reconditioning is required to improve respiratory function, walking ability and cardiovascular endurance. Ultimately, rehabilitation allows for the minimization of disability and the prevention of the loss of autonomy, particularly in elderly patients. The advantage of the rehabilitation approach is its multi-optional characteristics including physical therapy, occupational therapy, ergonomic advices and assistive equipment. Despite its crucial role, rehabilitation remains understudied in the management of ST. Thus, the present mini-review aimed to address the rehabilitation options for the clinical features and complications of ST, according to the course of the disease.

[Prokaryotic Expression and Bioinformatic Analysis of Rv3432c From Mycobacterium tuberculosis]. / ç»“æ ¸åˆ†æžæ†èŒRv3432cè›‹ç™½çš„åŽŸæ ¸è¡¨è¾¾ä¸Žç”Ÿç‰©ä¿¡æ¯å­¦åˆ†æž.

Objective: To express the protein enconded by the Rv3432c gene of Mycobacterium tuberculosis (M.tb) in vitro by prokaryotic expression, to analyze the structure of the Rv3432c protein by using bioinformatics software, and to explore for new drug targets against M.tb. Methods: The Rv3432c gene was amplified by PCR using the genomic DNA of the inactivated M.tb strain H37Rv as the template and a recombinant plasmid was constructed with the expression vector pET-28a. The expression products were analyzed by SDS-PAGE and purified using affinity chromatography. The biological properties of Rv3432c were analyzed with Protparam, the Pfam online tool, SOMPA, Protscale, TMHMM Signalp 6.0, NetPhos3.1, SUMOsp 2.0, and SWISS-MODEL. Results: pET-28a-Rv3432c recombinant plasmid sequencing results were fully consistent with those of the target gene. SDS-PAGE analysis showed that the fusion protein existed in the form of a soluble protein with a relative molecular mass of about 55×103, which matched the expected size. ProtParam analysis showed that the Rv3432c protein was hydrophilic (showing a GRAVY value of －0.079). Rv3432c was a protein with no transmembrane structural domains or signal peptide. The secondary structure of Rv3432c mainly consisted of random coils (39.78%) and α-helix (39.57%) and was relatively loosely structured. Conclusion: We successfully constructed a prokaryotic expression plasmid of the Rv3432c protein and analyzed its structure using bioinformatics, laying the foundation for further research on the role of Rv3432c in the pathogenesis and progression of tuberculosis as well as the identification of new drug targets against M.tb.

The First Case Report of Inactive Nontuberculous Mycobacterial Pulmonary Disease (NTM-PD) in a Pneumoconiosis Patient Caused by Mycobacterium europaeum in China.

We reported a 51-year-old male electric welder with stage I pneumoconiosis, who had no significant cough, sputum, fever, chest pain, or other discomfort. However, regular physical examination at our hospital revealed bilateral pulmonary nodules with cavity formation. Blood routine, liver or kidney function, and infection-related biomarkers, including interleukin-6 (IL-6), high-sensitivity C-reactive protein (hs-CRP), and procalcitonin (PCT), were normal. Sputum and alveolar lavage fluid (BALF) acid-fast bacilli (AFB) smears, BALF Mycobacterium tuberculosis (TB) PCR, and T-SPOT.TB were negative. The nucleic acid sequence of Mycobacterium europaeum was detected by BALF metagenomic next-generation sequencing (mNGS), which was confirmed by the subsequent positive culture for NTM. Considering stable conditions, no significant discomfort, and no significant changes in the lung lesion, the patient was diagnosed with inactive nontuberculous mycobacterial pulmonary disease (NTM-PD).

Coinfection with Leprosy and Tuberculosis: A Case Series in Malagasy Patients.

Background: Leprosy and tuberculosis are two of the oldest and most common mycobacterial infections, caused by Mycobacterium leprae and Mycobacteium lepramatosis for leprosy and Mycobacterium tuberculosis for tuberculosis. Dual infections have been known since ancient times; however, cases remain rarely reported in the literature, even in countries where both diseases are endemic, such as Madagascar. Purpose: We report a case series of simultaneous occurrence of leprosy and tuberculosis. Patients and Methods: In this retrospective study, we reviewed the medical records of patients with leprosy registered at the Department of Dermatology, University Hospital Befelatanana, Antananarivo, Madagascar, between January 2012 and June 2021. Patients with leprosy and diagnosed as coinfected by tuberculosis were included in the study. Results: Of the 120 leprosy cases observed during the study period, coinfection with leprosy and tuberculosis was found in five patients. The mean age was 43.4 (SD 13.2) ranging, 21-59 years. Male gender was predominant (4/5). Four patients presented with lepromatous leprosy, and one with borderline lepromatous leprosy. Three patients experienced leprosy reaction. Four cases of pulmonary tuberculosis and one case of multifocal tuberculosis were observed. The diagnosis of leprosy preceded tuberculosis in four cases, and a coinfection diagnosis was made simultaneously in one case. The average time to develop tuberculosis was 38.8 (SD 10.2) months. HIV infection, malnutrition, alcohol consumption, and long-term corticosteroid therapy were the immunosuppressive factors reported in our patients. Three patients received concomitant multidrug therapy for leprosy and tuberculosis. Conclusion: Dermatologists should be aware of the importance of screening patients affected by leprosy for latent or active tuberculosis to prevent morbidity and mortality due to coinfection and to reduce the risk of acquired resistance to rifampicin, which is the greatest risk of this association.

Bacillus Calmette-Guérin (BCG) Revaccination and Protection Against Tuberculosis: A Systematic Review.

Bacillus Calmette-Guérin (BCG) vaccination remains a cornerstone in global efforts to combat tuberculosis (TB), a persistent public health threat worldwide. The purpose of this systematic review is to find out how well BCG revaccination protects against TB. This systematic review synthesized recent studies investigating the efficacy of BCG vaccination in preventing TB infection and disease. A total of 15 relevant publications were identified through a comprehensive search across multiple databases, including Cochrane Library, PubMed, Medline, and Scopus. The inclusion criteria encompassed studies involving humans, written in English, and categorized as case-control, cohort, meta-analysis, or full-text. Studies were selected based on their relevance to BCG revaccination and protection against TB, and a standardized data extraction form was used to gather pertinent information from each study. Quality assessment was conducted using established tools to evaluate the rigor, study design, and risk of bias in each included study. The findings revealed significant insights into BCG's effectiveness across different populations and age groups. Several studies demonstrated a substantial reduction in latent TB infection (LTBI) and incidence rates of TB following BCG vaccination. However, the protective efficacy of BCG revaccination varied across studies and populations, with some indicating modest protection against TB disease development, particularly in high-risk populations like healthcare workers. Furthermore, investigations into the immunological mechanisms underlying BCG's protective efficacy provided valuable insights into cytokine/chemokine profiles and immunomodulatory properties.

Amikacin Liposome Inhalation Suspension in the Real-World Management of Refractory Mycobacterium avium Complex Pulmonary Disease.

The increasing prevalence of Mycobacterium avium complex (MAC) pulmonary disease poses a significant therapeutic challenge, particularly due to the limited efficacy and systemic toxicity associated with conventional guideline-based therapy. Amikacin liposome inhalation suspension (ALIS) has been developed, yet its real-world application remains underreported. This retrospective analysis, conducted from March 2021 to February 2024, examined ALIS's clinical use in patients aged 20 years or older with refractory MAC pulmonary disease at our institution. The primary objective of this study is to describe the patient characteristics and clinical trajectories associated with the initiation of ALIS therapy in real-world settings for individuals diagnosed with MAC pulmonary disease. Of 11 patients initiated on ALIS, one was excluded due to financial constraints impacting continuation. The analysis proceeded with the remaining 10 subjects. The mean age of participants was 70.2 years, with a predominance of female patients (n = 7, 70%) and a higher incidence of M. avium infections (n = 6, 60%). Forty percent of the cohort (n = 4) had a history of ethambutol-induced optic neuritis leading to the cessation of the drug. The average interval from the initiation of guideline-based therapy to the start of ALIS was 8.5 ± 6.9 years (mean ± standard deviation). The majority (80%) presented with positive Gaffky scores at ALIS initiation, and a significant proportion exhibited resistance to clarithromycin and ethambutol. Comorbid conditions, including diabetes and previous cancer, were noted. The study also observed elevated anti-MAC antibody levels. Treatment duration varied, with fatigue leading to discontinuation in two cases. Treatment-emergent adverse events were documented in individual patients, each presenting with grade 1 severity: hemoptysis (n = 1, 10%), elevated creatinine levels (n = 1, 10%), and dysphonia (n = 2, 20%) were observed, respectively. Correlation analysis revealed a significant inverse relationship between body mass index (BMI) and ALIS discontinuation due to fatigue, and a positive correlation between Gaffky scores and C-reactive protein (CRP) levels. These results underscore the potential benefits and limitations of ALIS, suggesting that timely intervention and comprehensive healthcare support are crucial for optimal outcomes in the treatment of advanced MAC pulmonary disease.

Epididymal alveolar echinococcosis and tuberculosis co-infection: A case report.

Alveolar echinococcosis (AE) is a common and significant public health problem caused by the larvae of the Echinococcus multilocularis. The occurrence of epididymal AE is rare and often overlooked in combination with mycobacterium tuberculosis infection. We report a case of a 34-year-old man who presented with right-sided scrotal enlargement with pain. Physical examination revealed an enlarged right scrotum with rupture. CT examination showed a blurred border and non-enhancing lesion on the right epididymis. Postoperative pathology and molecular biology identified an epididymal E. multilocularis infection. We report this rare case to emphasise the difficulty of preoperative diagnosis and the importance of complete surgical excision of the lesion.

The great imitator: Tuberculosis with lymphadenopathy and splenomegaly.

Tuberculosis (TB) is a leading infectious killer worldwide. Over two-thirds of new TB diagnoses in the United States occur among first-generation immigrants, especially within a year of migration. Hodgkin lymphoma (HL) accounts for a minority of lymphoma cases but presents similarly to disseminated or extrapulmonary TB. Clinical overlap between TB and HL increases patient risk of misdiagnosis. Concomitant presentation of both diseases is not uncommon but infrequently reported. We present a case of isoniazid-resistant TB with progressively worsening lymphadenopathy and splenomegaly despite appropriate TB treatment. The patient was diagnosed with HL following PET/CT and axillary lymph node biopsy.

Unmasking the Hidden Burden: A Delayed Diagnosis of Leprosy Patients With Grade 2 Disability and Its Effects on the Healthcare System in Bangladesh.

Introduction Leprosy remains a significant cause of preventable disability worldwide. Early diagnosis and treatment of leprosy are critical not only to stop its spread but also to prevent physical and social complications and reduce the disease burden. Objectives The study aims to evaluate the factors that lead to a delayed leprosy diagnosis. Methods This study was conducted in the outpatient departments of Leprosy Control Institute and Hospital, Dhaka, Bangladesh, and at Medical College for Women and Hospital, Dhaka, Bangladesh, from March 2023 to June 2023. A total number of 252 male (148) and female (104) patients were selected with any sign of leprosy, including disability, age ranging from 15 to 74 years. Data was collected in a pre-designed structured questionnaire by the researchers. To assess the risk of independent exposures of Grade 2 leprosy disabilities, we used a logistic regression model. A chi-square test showed the association between significant effects and leprosy disabilities. A p-value of 0.05 was considered as significant. For statistical analysis, STATA version 15 (StataCorp LLC, College Station, Texas, USA) was used. Results The study participants exhibited a higher percentage of disability, with a rate of 25.8% for Grade 2 disabilities. In addition to this, males represented a more considerable proportion, 58.7%, than females among leprosy and disability patients across all levels of disability. In our study, lack of money and painless symptoms showed a significant association (p<0.001) with Grade 2 disability. Conclusion The study reveals that Grade 2 disabilities are more common in males and are particularly prevalent in lower socioeconomic groups.

Perioperative Considerations for the Surgical Treatment of Crohn's Disease with Discussion on Surgical Antibiotics Practices and Impact on the Gut Microbiome.

Crohn's disease, a chronic inflammatory process of the gastrointestinal tract defined by flares and periods of remission, is increasing in incidence. Despite advances in multimodal medical therapy, disease progression often necessitates multiple operations with high morbidity. The inability to treat Crohn's disease successfully is likely in part because the etiopathogenesis is not completely understood; however, recent research suggests the gut microbiome plays a critical role. How traditional perioperative management, including bowel preparation and preoperative antibiotics, further changes the microbiome and affects outcomes is not well described, especially in Crohn's patients, who are unique given their immunosuppression and baseline dysbiosis. This paper aims to outline current knowledge regarding perioperative management of Crohn's disease, the evolving role of gut dysbiosis, and how the microbiome can guide perioperative considerations with special attention to perioperative antibiotics as well as treatment of Mycobacterium avium subspecies paratuberculosis. In conclusion, dysbiosis is common in Crohn's patients and may be exacerbated by malnutrition, steroids, narcotic use, diarrhea, and perioperative antibiotics. Dysbiosis is also a major risk factor for anastomotic leak, and special consideration should be given to limiting factors that further perturb the gut microbiota in the perioperative period.

Clinical Strains of Mycobacterium tuberculosis Representing Different Genotype Families Exhibit Distinct Propensities to Adopt the Differentially Culturable State.

Growing evidence points to the presence of differentially culturable tubercle bacteria (DCTB) in clinical specimens from individuals with active tuberculosis (TB) disease. These bacteria are unable to grow on solid media but can resuscitate in liquid media. Given the epidemiological success of certain clinical genotype families of Mycobacterium tuberculosis, we hypothesize that different strains may have distinct mechanisms of adaptation and tolerance. We used an in vitro carbon starvation model to determine the propensity of strains from lineages 2 and 4 that included the Beijing and LAM families respectively, to generate DCTB. Beijing strains were associated with a greater propensity to produce DCTB compared to LAM strains. Furthermore, LAM strains required culture filtrate (CF) for resuscitation whilst starved Beijing strains were not dependent on CF. Moreover, Beijing strains showed improved resuscitation with cognate CF, suggesting the presence of unique growth stimulatory molecules in this family. Analysis of starved Beijing and LAM strains showed longer cells, which with resuscitation were restored to a shorter length. Cell wall staining with fluorescent D-amino acids identified strain-specific incorporation patterns, indicating that cell surface remodeling during resuscitation was distinct between clinical strains. Collectively, our data demonstrate that M. tuberculosis clinical strains from different genotype lineages have differential propensities to generate DCTB, which may have implications for TB treatment success.

Mycobacteriosis in a Pet Ferret (Mustela putorius furo) Caused by Mycobacterium xenopi: A Case Report on Neglected Risk of Zoonotic Transmission.

Ferrets are highly susceptible to a wide range of mycobacteria, mainly M. bovis, M. avium, and M. triplex. Therefore, ferrets pose a risk of transmission of mycobacteriosis, especially zoonotically relevant tuberculosis. The aim of this study was to describe the findings of M. xenopi mycobacteriosis in a pet ferret and emphasize its zoonotic potential. A pet ferret had a history of weight loss, apathy, hyporexia, and hair loss. Abdominal ultrasound revealed splenomegaly with two solid masses and cystic lesions of the liver. Fine-needle aspiration cytology revealed numerous acid-fast bacilli in epithelioid cells, thus leading to the suspicion of mycobacterial infection. Because of its poor general condition, the ferret was euthanized. Necropsy examination revealed generalized granulomatous lymphadenitis, pneumonia, myocarditis, splenitis, and hepatitis. Histologically, in all organs, there were multifocal to coalescing areas of inflammatory infiltration composed of epithelioid macrophages, a low number of lymphocytes, and plasma cells, without necrosis nor multinucleated giant cells. Ziehl-Neelsen staining detected the presence of numerous (multibacillary) acid-fast bacteria, which were PCR-typed as M. xenopi. This is the first study showing the antimicrobial susceptibility testing of M. xenopi in veterinary medicine, describing the resistance to doxycycline. Overall, our results could facilitate further diagnosis and provide guidelines for the treatment protocols for such infections.

Trends in Non-Tuberculous Mycobacterial Lung Disease and Treatment Outcomes in a Low-Tuberculosis Prevalence Setting: A Retrospective Analysis.

BACKGROUND: Information on the management of non-tuberculous mycobacterial (NTM) lung infection and disease is scarce. The aim of this study was to investigate the trends in NTM lung infections, and the factors associated with the initiation of treatment and treatment outcomes. METHODS: A retrospective analysis was carried out on patient medical records from Haukeland University Hospital, Bergen, Norway, from 2000 to 2021. RESULTS: Among 154 patients with NTM lung infection, the majority (70%) were older than 65 years, and 49% had an underlying pulmonary comorbidity. The most frequently observed mycobacterial species was M. avium complex (MAC), followed by M. malmoense and M. abscessus. In total, 72 (47%) patients received antibiotic treatment. Patients with high symptom scores, aged below 65, and with MAC infection had more than three times the odds of receiving antibiotic treatment. A favourable response and culture conversion was observed in 53 of 72 (74%) patients. However, 17 (32%) of them had a relapse. Out of 82 patients who did not receive treatment, 45 (55%) had spontaneous culture conversion, and 8 (18%) of them had a relapse. No factor was identified to be significantly associated with a favourable treatment response. CONCLUSION: A favourable response to treatment was seen in 74% of patients with a high relapse rate.

Cathepsin S Is More Abundant in Serum of Mycobacterium avium subsp. paratuberculosis-Infected Dairy Cows.

Mycobacterium avium subsp. paratuberculosis (MAP) is the causative agent of bovine paratuberculosis, a chronic granulomatous enteritis leading to economic losses and posing a risk to human health due to its zoonotic potential. The pathogen cannot reliably be detected by standard methods, and immunological procedures during the infection are not well understood. Therefore, the aim of our study was to explore host-pathogen interactions in MAP-infected dairy cows and to improve diagnostic tests. Serum proteomics analysis using quantitative label-free LC-MS/MS revealed 60 differentially abundant proteins in MAP-infected dairy cows compared to healthy controls from the same infected herd and 90 differentially abundant proteins in comparison to another control group from an uninfected herd. Pathway enrichment analysis provided new insights into the immune response to MAP and susceptibility to the infection. Furthermore, we found a higher abundance of Cathepsin S (CTSS) in the serum of MAP-infected dairy cows, which is involved in multiple enriched pathways associated with the immune system. Confirmed with Western blotting, we identified CTSS as a potential biomarker for bovine paratuberculosis. This study enabled a better understanding of procedures in the host-pathogen response to MAP and improved detection of paratuberculosis-diseased cattle.