ABSTRACT
Brucellosis represents a major public health concern worldwide. Human transmission is mainly due to the consumption of unpasteurized milk and dairy products of infected animals. The gold standard for the diagnosis of Brucella spp in ruminants is the bacterial isolation, but it is time-consuming. Polymerase Chain Reaction (PCR) is a quicker and more sensitive technique than bacterial culture. Droplet digital PCR (ddPCR) is a novel molecular assay showing high sensitivity in samples with low amount of DNA and lower susceptibility to amplification inhibitors. Present study aimed to develop a ddPCR protocol for the detection of Brucella abortus in buffalo tissue samples. The protocol was validated using proficiency test samples for Brucella spp by real time qPCR. Furthermore, 599 tissue samples were examined. Among reference materials, qPCR and ddPCR demonstrated same performance and were able to detect up to 225 CFU/mL. Among field samples, ddPCR showed higher sensitivity (100%), specificity and accuracy of 93.4% and 94.15%, respectively. ddPCR could be considered a promising technique to detect B. abortus in veterinary specimens, frequently characterized by low amount of bacteria, high diversity in matrices and species and poor storage conditions.
Subject(s)
Brucella abortus , Brucellosis , Buffaloes , DNA, Bacterial , Real-Time Polymerase Chain Reaction , Sensitivity and Specificity , Animals , Brucella abortus/isolation & purification , Brucella abortus/genetics , Buffaloes/microbiology , Brucellosis/veterinary , Brucellosis/diagnosis , Brucellosis/microbiology , DNA, Bacterial/analysis , Real-Time Polymerase Chain Reaction/veterinary , Real-Time Polymerase Chain Reaction/methods , Polymerase Chain Reaction/veterinary , Polymerase Chain Reaction/methodsABSTRACT
Brucella spp. are facultative intracellular pathogens that cause zoonosis- brucellosis worldwide. There has been a trend of the re-emergence of brucellosis worldwide in recent years. The epidemic situation of brucellosis is serious in Xinjiang. To analyze the epidemic situation of Brucella spp. in Xinjiang among humans and animals, this study identified 144 Brucella isolates from Xinjiang using classical identification and 16 S rRNA sequencing. MLVA, drug resistance testing, and wgSNP detection were also performed. At the same time, analysis was conducted based on the published data of Brucella isolates worldwide. The results showed that the dominant species was B. melitensis biovar 3, which belonged to GT42 (MLVA-8 typing) and the East Mediterranean lineage. The correlation among isolates was high both in humans or animals. The isolates in Xinjiang exhibited higher polymorphism compared to other locations in China, with polymorphism increasing each year since 2010. No amikacin/kanamycin-resistant strains were detected, but six rifampicin-intermediate isolates were identified without rpoB gene variation. The NJ tree of the wgSNP results indicated that there were three main complexes of the B. melitensis epidemic in Xinjiang. Based on the results of this study, the prevention and control of brucellosis in Xinjiang should focus on B. melitensis, particularly strains belonging to B. melitensis bv.3 GT42 (MLVA-8 typing) and East Mediterranean lineage. Additionally, the rifampicin- and trimethoprim-sulfamethoxazole- resistance of isolates in Xinjiang should be closely monitored to avoid compromising the therapeutic efficacy and causing greater losses. These results provide essential data for the prevention and control of brucellosis in Xinjiang and China. Although the isolates from Xinjiang have significant characteristics among Chinese isolates and can reflect the epidemiological situation of brucellosis in China to some extent, this study cannot represent the characteristics of isolates from other regions.
Subject(s)
Anti-Bacterial Agents , Brucella melitensis , Brucellosis , Genotype , Brucellosis/epidemiology , Brucellosis/microbiology , Brucella melitensis/genetics , Brucella melitensis/drug effects , Brucella melitensis/isolation & purification , China/epidemiology , Humans , Animals , Anti-Bacterial Agents/pharmacology , Drug Resistance, Bacterial/genetics , Microbial Sensitivity Tests , RNA, Ribosomal, 16S/genetics , Phylogeny , Polymorphism, Genetic , EpidemicsABSTRACT
Metagenomic next-generation sequencing (mNGS) in diagnosis of human brucellosis is comparatively unexplored. This report details five human brucellosis cases diagnosed using mNGS based on Illumina sequencing platform, comprising three females and two males, four with epidemiological exposure. In cases 1 and 2, plasma mNGS results showed one positive and one negative for Brucella melitensis, and subsequent blood cultures were both positive. Cases 3, 4 and 5 involved spinal brucellosis, some with paravertebral abscesses. mNGS from infectious tissue samples successfully detected Brucella, with read counts ranging between 30 and 1314, yet cultures were negative in cases 4 and 5. Following antibiotic and surgical treatments, all patients showed clinical improvement. This report shows mNGS testing enhances the detection sensitivity of brucellosis diagnosis.
What is this summary about? Brucella is a type of bacteria that can infect humans and animals. It causes a disease called brucellosis. Symptoms of brucellosis include fever and fatigue, among others. Meta-genomic next-generation sequencing (mNGS) is a tool for sequencing the DNA of bacteria. In this report, we use mNGS to diagnose human brucellosis in five cases.What were the results? Brucella was found in the blood of two infected people, but mNGS found Brucella in only one. Of three people with Brucella infection of the spine, mNGS found Brucella in the infected tissue but Brucella was only cultured in one case. Following antibiotic and surgical treatments, all five patients showed improvement of their symptoms.What do the results of the study mean? mNGS is a relatively rapid and effective diagnostic method that can improve the detection of Brucella in brucellosis.
Subject(s)
Brucella melitensis , Brucellosis , High-Throughput Nucleotide Sequencing , Brucellosis/diagnosis , Brucellosis/microbiology , Humans , Male , Female , Middle Aged , Brucella melitensis/genetics , Brucella melitensis/isolation & purification , Adult , Metagenomics/methods , Anti-Bacterial Agents/therapeutic use , Anti-Bacterial Agents/pharmacologyABSTRACT
Brucella suis biovar 1 has the broadest animal host spectrum. Affects domestic animals and wildlife species. The aim of our study was to investigate the pathogenesis of B. suis biovar 1 infection in the armadillo (Chaetophractus villosus) under experimental conditions. One gravid female and three adult males were inoculated with a suspension containing 1×106 CFU/mL (colony-forming units) of B. suis biovar 1 by oral route. In addition, the gravid female and one male received the same suspension by the conjunctival route. A young male and two females not inoculated were kept in contact with the animals inoculated. The animals that tested seropositive were euthanized. All inoculated armadillos showed positive antibody titres 2 weeks post-inoculation. Of the three uninoculated animals, one female was seropositive for Brucella infection. Brucella was isolated from the spleen, liver, mesenteric lymph nodes, uterus, testes, and urine. Characteristic histologic lesions were found in the epididymis. These results suggest that armadillos can act as a reservoir for the spread of B. suis infection, and the persistence of Brucella in armadillo tissues constitutes a risk for humans, because of the cultural practice of armadillo meat consumption in rural communities.
Subject(s)
Armadillos , Brucella suis , Brucellosis , Animals , Armadillos/microbiology , Brucellosis/veterinary , Brucellosis/microbiology , Male , Female , Brucella suis/isolation & purificationABSTRACT
Brucella abortus (Ba) is a pathogen that survives inside macrophages. Despite being its preferential niche, Ba infects other cells, as shown by the multiple signs and symptoms humans present. This pathogen can evade our immune system. Ba displays a mechanism of down-modulating MHC-I on monocytes/macrophages in the presence of IFN-γ (when Th1 response is triggered) without altering the total expression of MHC-I. The retained MHC-I proteins are located within the Golgi Apparatus (GA). The RNA of Ba is one of the PAMPs that trigger this phenomenon. However, we acknowledged whether this event could be triggered in other cells relevant during Ba infection. Here, we demonstrate that Ba RNA reduced the surface expression of MHC-I induced by IFN-γ in the human bronchial epithelium (Calu-6), the human alveolar epithelium (A-549) and the endothelial microvasculature (HMEC) cell lines. In Calu-6 and HMEC cells, Ba RNA induces the retention of MHC-I in the GA. This phenomenon was not observed in A-549 cells. We then evaluated the effect of Ba RNA on the secretion of IL-8, IL-6 and MCP-1, key cytokines in Ba infection. Contrary to our expectations, HMEC, Calu-6 and A-549 cells treated with Ba RNA had higher IL-8 and IL-6 levels compared to untreated cells. In addition, we showed that Ba RNA down-modulates the MHC-I surface expression induced by IFN-γ on human monocytes/macrophages via the pathway of the Epidermal Growth Factor Receptor (EGFR). So, cells were stimulated with an EGFR ligand-blocking antibody (Cetuximab) and Ba RNA. Neutralization of the EGFR to some extent reversed the down-modulation of MHC-I mediated by Ba RNA in HMEC and A-549 cells. In conclusion, this is the first study exploring a central immune evasion strategy, such as the downregulation of MHC-I surface expression, beyond monocytes and could shed light on how it persists effectively within the host, enduring unseen and escaping CD8+ T cell surveillance.
Subject(s)
Brucella abortus , Endothelial Cells , Epithelial Cells , Histocompatibility Antigens Class I , Interferon-gamma , Humans , Interferon-gamma/metabolism , Interferon-gamma/pharmacology , Endothelial Cells/metabolism , Endothelial Cells/microbiology , Endothelial Cells/drug effects , Endothelial Cells/immunology , Epithelial Cells/metabolism , Epithelial Cells/microbiology , Epithelial Cells/immunology , Histocompatibility Antigens Class I/metabolism , Histocompatibility Antigens Class I/genetics , RNA, Bacterial/genetics , Cell Line , Down-Regulation/drug effects , ErbB Receptors/metabolism , Brucellosis/immunology , Brucellosis/metabolism , Brucellosis/microbiology , Brucellosis/genetics , Golgi Apparatus/metabolism , Macrophages/metabolism , Macrophages/immunology , Macrophages/microbiology , Monocytes/metabolism , Monocytes/immunology , Monocytes/drug effectsABSTRACT
Brucella canis is a zoonotic pathogen and the main causative agent of canine brucellosis. In the Netherlands, B. canis had previously only been detected in individual cases of imported dogs. However, an outbreak of B. canis occurred for the first time in a cohort of autochthonous dogs in a breeding kennel in 2019. The outbreak began with a positive serological test result of an imported intact male dog showing clinical symptoms of brucellosis. Consequently, urine and blood samples were collected and tested positive for B. canis by culture, matrix-assisted laser desorption/ionization - time of flight mass spectrometry (MALDI-TOF MS) and whole-genome-sequencing (WGS). Screening of the contact dogs in the kennel where the index case was kept, revealed that antibodies against B. canis could be detected in 23 out of 69 dogs (34â¯%) by serum agglutination test (SAT). Of the 23 seropositive dogs, B. canis could be cultured from the urine and/or heparin samples of 19 dogs (83â¯%). This outbreak represents the first documented case of transmission of B. canis to autochthonous contact dogs in the Netherlands. WGS revealed all B. canis isolates belonged to the same cluster, which means the transmission of B. canis in the breeding kennel was most likely caused by the introduction of one infected dog. Comparing this cluster with data from other B. canis isolates, it also appears that characteristic clusters of B. canis are present in several endemic countries. These clusters seem to remain stable over time and may help in locating the origin of new isolates found. This outbreak showed that the international movement of dogs from endemic countries poses a threat to the canine population, while serological screening and WGS proved to be valuable tools for respectively screening and the epidemiological investigation.
Subject(s)
Brucella canis , Brucellosis , Disease Outbreaks , Dog Diseases , Dogs , Animals , Brucella canis/isolation & purification , Brucella canis/genetics , Dog Diseases/microbiology , Dog Diseases/transmission , Dog Diseases/epidemiology , Brucellosis/veterinary , Brucellosis/transmission , Brucellosis/epidemiology , Brucellosis/microbiology , Male , Disease Outbreaks/veterinary , Netherlands/epidemiology , Whole Genome Sequencing , Antibodies, Bacterial/bloodABSTRACT
Brucella melitensis is a major livestock bacterial pathogen and zoonosis, causing disease and infection-related abortions in small ruminants and humans. A considerable burden to animal-based economies today, the presence of Brucella in Neolithic pastoral communities has been hypothesised but we lack direct genomic evidence thus far. We report a 3.45X B. melitensis genome preserved in an ~8000 year old sheep specimen from Mentese Höyük, Northwest Türkiye, demonstrating that the pathogen had evolved and was circulating in Neolithic livestock. The genome is basal with respect to all known B. melitensis and allows the calibration of the B. melitensis speciation time from the primarily cattle-infecting B. abortus to approximately 9800 years Before Present (BP), coinciding with a period of consolidation and dispersal of livestock economies. We use the basal genome to timestamp evolutionary events in B. melitensis, including pseudogenization events linked to erythritol response, the supposed determinant of the pathogen's placental tropism in goats and sheep. Our data suggest that the development of herd management and multi-species livestock economies in the 11th-9th millennium BP drove speciation and host adaptation of this zoonotic pathogen.
Subject(s)
Brucella melitensis , Brucellosis , Genome, Bacterial , Zoonoses , Brucella melitensis/genetics , Brucella melitensis/isolation & purification , Animals , Sheep/microbiology , Genome, Bacterial/genetics , Brucellosis/microbiology , Brucellosis/veterinary , Brucellosis/history , Humans , Zoonoses/microbiology , Phylogeny , Cattle , Bacterial Zoonoses/microbiology , Goats/microbiology , Evolution, Molecular , Livestock/microbiology , History, Ancient , Sheep Diseases/microbiology , FemaleABSTRACT
In recent years, immunization with the S2 live-attenuated vaccine has been recognized as the most economical and effective strategy for preventing brucellosis in Inner Mongolia, China. However, there are still challenges related to vaccine toxicity and the inability to distinguish between vaccine immunization and natural infection. Therefore, in this study, we developed a digital droplet polymerase chain reaction (ddPCR) assay based on single-nucleotide polymorphism (SNP) loci to identify wild Brucella strains and S2 vaccine strains. The assay demonstrated excellent linearity (R2> 0.99) with a lower detection limit of 10 copies/µL for both wild and vaccine strains. Additionally, the ddPCR assay outperformed the real-time fluorescent quantitative PCR (qPCR) assay in screening 50 clinical samples. We have established an effective and highly sensitive ddPCR assay for Brucella, providing an efficient method for detecting and differentiating wild strains of Brucella from the S2 vaccine strain.
Subject(s)
Brucella Vaccine , Brucella , Brucellosis , Polymerase Chain Reaction , Polymorphism, Single Nucleotide , Brucella/genetics , Brucella/classification , Brucella/isolation & purification , Humans , Brucella Vaccine/genetics , Brucella Vaccine/immunology , Brucellosis/diagnosis , Brucellosis/prevention & control , Brucellosis/microbiology , Polymerase Chain Reaction/methods , Sensitivity and Specificity , China , Vaccines, Attenuated/genetics , Real-Time Polymerase Chain Reaction/methods , DNA, Bacterial/geneticsABSTRACT
Introduction: Brucellosis in marine mammals (cetacean and pinnipeds) has emerged in a very significant way during the last two decades. Currently Brucella ceti and Brucella pinnipedialis are the two recognized species in marine mammals, but available information is still limited. Several genotypes have been identified, and studies on the relationship between sequence type (ST) and organ pathogenicity or tropism have indicated differences in pathogenesis between B. ceti sequences in cetaceans. The zoonotic potential of this disease is based on the identification of the main sources of introduction and spread of Brucella spp. in the marine environment as well as on the factors of exposure of marine mammals and humans to the bacteria. Bibliographic review: This article is a bibliographical review on marine mammal brucellosis, including the features, sources and transmission modes of each Brucella species, as well as their potential pathogenicity in animals and humans. Conclusion: Different genotypes of marine Brucella spp have been isolated from marine mammal species but without any evidence of pathology induced by these bacteria. Associated lesions are variable and include subcutaneous abscesses, meningo-encephalomyelitis, pneumonia, myocarditis, osteoarthritis, orchitis, endometritis, placentitis and abortion. The isolation of marine B. spp from marine mammal respiratory parasites associated to lung injury has raised the intriguing possibility that they may serve as a vector for the transmission of this bacterium.The severity of marine B. spp remains unknown due to the lack of an estimate of the prevalence of this disease in marine mammals. The number of suspected human cases is still very limited. However, by analogy with other germs of the genus Brucella responsible for abortion in ruminants and for a febrile and painful state in human beings, prevention measures are essential. The significant increase in the number of strandings coupled with a high seroprevalence in certain species of marine mammals must be considered for people in direct or indirect contact with these animals. Ongoing epidemiological monitoring combined with extensive post-mortem examinations (necropsy, bacteriology and sequencing) of all species of stranded marine mammals would deepen knowledge on the zoonotic potential of marine Brucella species.
Subject(s)
Brucella , Brucellosis , Caniformia , Cetacea , Animals , Brucellosis/transmission , Brucellosis/veterinary , Brucellosis/microbiology , Brucellosis/epidemiology , Humans , Brucella/pathogenicity , Brucella/isolation & purification , Brucella/genetics , Cetacea/microbiology , Caniformia/microbiology , Zoonoses/microbiology , Zoonoses/transmissionABSTRACT
Brucellosis, caused by various Brucella species, poses a significant threat to global public health and livestock industries. This study aims to fill the knowledge gap concerning the presence of Brucella spp. in rodents on livestock farms in Iran. Both bacteriological and molecular surveys were conducted to assess the prevalence of Brucella spp. in these rodent populations. A total of 16 rodents were captured in four seropositive dairy cattle farms (n = 7) and two seropositive sheep farms (n = 9) and were then examined for the presence of the Brucella-infection. Five cow milk samples and 53 bovine lymph node samples from these farms were also tested for Brucella spp. Lymph node samples from dairy cattle farms contained 32 B. abortus biovar 3 isolates and one B. melitensis Rev1 vaccine isolate. The bacterial culture of rodents identified 12.5% of them (Mus musculus and Rattus norvegicus) harboring Brucella strains in dairy cattle farms. The rodents had B. abortus biovar 3 and B. melitensis biovar 1, suggesting a reservoir for these bacteria. A two-step molecular assay, utilizing the Omp28 sequences in tissue samples of rodents, demonstrated that 68.75% (n = 11) of the tested rodents yielded positive results. Bruce-ladder PCR and wboA typing on isolated bacteria revealed a close relationship to field strain of Brucella species. The study reveals that rodents on seropositive livestock farms in Iran harbor Brucella spp., indicating a potential reservoir for these bacteria. This highlights the importance of monitoring rodent populations through the molecular and bacterial methods to manage and control brucellosis in livestock.
Subject(s)
Brucella , Brucellosis , Animals , Cattle , Iran/epidemiology , Rats , Brucella/isolation & purification , Brucella/classification , Sheep , Brucellosis/veterinary , Brucellosis/epidemiology , Brucellosis/microbiology , Mice , Sheep Diseases/microbiology , Sheep Diseases/epidemiology , Prevalence , Brucellosis, Bovine/epidemiology , Brucellosis, Bovine/microbiology , Milk/microbiology , Brucella abortus/isolation & purification , Brucella abortus/classification , Disease Reservoirs/veterinary , Disease Reservoirs/microbiology , FemaleABSTRACT
Any system or organ involvement can be seen in brucellosis, which is still a significant public health problem in developing countries. The rate of respiratory system involvement is lower than that of other systems and which is also difficult to document. Brucellosis-associated pleurisy is a rare complication even in endemic regions. In this case report, a 78-year-old male patient who was assessed for pleural effusion etiology is presented. Brucella spp. were isolated on the 14th day of the pleural fluid incubation in the blood culture set and the patienthas been treated successfully for brucellosis. Based on our experience we think that it is important to use blood culture media for sterile body fluids, particularly for microorganisms that are difficult to isolate such as Brucella spp.
Subject(s)
Brucella , Brucellosis , Pleurisy , Humans , Male , Brucellosis/diagnosis , Brucellosis/drug therapy , Brucellosis/microbiology , Aged , Pleurisy/microbiology , Brucella/isolation & purification , Pleural Effusion/microbiology , Anti-Bacterial Agents/therapeutic use , Treatment OutcomeABSTRACT
Brucellosis is a critical zoonotic disease impacting humans and animals globally, causing symptoms like fever and arthritis in humans and reproductive issues in animals. The disease stems from the Brucella genus, adept at evading the immune system and proliferating within host cells. This study explores how Brucella abortus manipulates host cellular mechanisms to sustain infection, focusing on the interaction with murine macrophages over 24 h. Initial host defenses involve innate immune responses, while Brucella's survival strategies include evading lysosomal degradation and modulating host cell functions through various pathways. The research identified significant transcriptional changes in macrophages post-infection, highlighting pathways such as cytokine storm, pyroptosis signaling, Toll-like receptor pathways, and LXRs/RXRs signaling. The findings shed light on Brucella's complex mechanisms to undermine host defenses and underscore the need for further investigation into therapeutic targets to combat brucellosis.
Subject(s)
Brucella abortus , Brucellosis , Gene Expression Profiling , Macrophages , Brucella abortus/genetics , Macrophages/microbiology , Macrophages/immunology , Animals , Mice , Brucellosis/microbiology , Brucellosis/immunology , Host-Pathogen Interactions , Immunity, Innate , Transcriptome , Signal TransductionABSTRACT
We describe a case of brucellosis in a man in his 20s, who presented to the emergency department with a 1-month history of fevers, dry cough and knee pain. Blood cultures were positive after 55 hours and Ochrobactrum daejeonense was identified on matrix-assisted laser desorption/ionisation time of flight (MALDI-TOF) mass spectrometry. Ochrobactrum spp are Gram-negative organisms that are phylogenetically related to Brucella spp but commercially available MALDI-TOF libraries cannot distinguish between the two genera. Further positive blood cultures for O. daejeonense combined with characteristic growth patterns for Brucella spp led to targeted questioning of the patient regarding potential exposure risks, which revealed a history of consumption of unpasteurised camel milk in the Middle East 3 months earlier. Treatment of brucellosis was initiated and subsequent whole genome sequencing identified the blood culture isolate as Brucella melitensis confirming the diagnosis of brucellosis. This case highlights the challenges in the diagnosis of brucellosis in low-incidence settings.
Subject(s)
Brucella melitensis , Brucellosis , Ochrobactrum , Humans , Brucella melitensis/isolation & purification , Brucella melitensis/genetics , Male , Brucellosis/diagnosis , Brucellosis/drug therapy , Brucellosis/microbiology , Ochrobactrum/genetics , Ochrobactrum/isolation & purification , Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization , Anti-Bacterial Agents/therapeutic use , Young Adult , Gram-Negative Bacterial Infections/diagnosis , Gram-Negative Bacterial Infections/microbiology , Diagnostic ErrorsABSTRACT
One zoonotic infectious animal disease is brucellosis. The bacteria that cause brucellosis belong to the genus Brucella. Numerous animal and human species are affected by brucellosis, with an estimated 500,000 human cases recorded annually worldwide. The occurrence of new areas of infection and the resurgence of infection in already infected areas indicate how dynamically brucellosis is distributed throughout different geographic regions. Bacteria originate from the blood and are found in the reticuloendothelial system, the liver, the spleen, and numerous other locations, including the joints, kidneys, heart, and genital tract. Diagnosis of this disease can be done by bacterial isolation, molecular tests, modified acid-fast stain, rose bengal test (RBT), milk ring test, complement fixation test, enzyme-linked immunosorbent assay, and serum agglutination test. The primary sign of a Brucella abortus infection is infertility, which can result in abortion and the birth of a frail fetus that may go on to infect other animals. In humans, the main symptoms are acute febrile illness, with or without localization signs, and chronic infection. Female cattle have a greater risk of contracting Brucella disease. Human populations at high risk of contracting brucellosis include those who care for cattle, veterinarians, slaughterhouse employees, and butchers. Antibiotic treatment of brucellosis is often unsuccessful due to the intracellular survival of Brucella and its adaptability in macrophages. A "one health" strategy is necessary to control illnesses like brucellosis.
Subject(s)
Brucellosis , Zoonoses , Brucellosis/veterinary , Brucellosis/epidemiology , Brucellosis/microbiology , Brucellosis/diagnosis , Animals , Zoonoses/microbiology , Humans , Brucella/isolation & purification , Cattle , Global HealthABSTRACT
Brucella is an intracellular parasitic bacterium lacking typical virulence factors, and its pathogenicity primarily relies on replication within host cells. In this study, we observed a significant increase in spleen weight in mice immunized with a Brucella strain deleted of the gene for alanine racemase (Alr), the enzyme responsible for alanine racemization (Δalr). However, the bacterial load in the spleen markedly decreased in the mutant strain. Concurrently, the ratio of white pulp to red pulp in the spleen was increased, serum IgG levels were elevated, but no significant damage to other organs was observed. In addition, the inflammatory response was potentiated and the NF-κB-NLRP3 signaling pathway was activated in macrophages (RAW264.7 Cells and Bone Marrow-Derived Cells) infect ed with the Δalr mutant. Further investigation revealed that the Δalr mutant released substantial amounts of protein in a simulated intracellular environment which resulted in heightened inflammation and activation of the TLR4-NF-κB-NLRP3 pathway in macrophages. The consequent cytoplasmic exocytosis reduced intracellular Brucella survival. In summary, cytoplasmic exocytosis products resulting from infection with a Brucella strain deleted of the alr gene effectively activated the TLR4-NFκB-NLRP3 pathway, triggered a robust inflammatory response, and reduced bacterial survival within host cells. Moreover, the Δalr strain exhibits lower toxicity and stronger immunogenicity in mice.
Subject(s)
Brucella suis , Brucellosis , Macrophages , NF-kappa B , NLR Family, Pyrin Domain-Containing 3 Protein , Toll-Like Receptor 4 , Animals , Mice , NLR Family, Pyrin Domain-Containing 3 Protein/genetics , NLR Family, Pyrin Domain-Containing 3 Protein/metabolism , NLR Family, Pyrin Domain-Containing 3 Protein/immunology , Toll-Like Receptor 4/genetics , Toll-Like Receptor 4/metabolism , NF-kappa B/metabolism , Brucellosis/immunology , Brucellosis/microbiology , Brucellosis/genetics , RAW 264.7 Cells , Brucella suis/immunology , Brucella suis/genetics , Brucella suis/pathogenicity , Virulence/genetics , Macrophages/immunology , Gene Deletion , Signal Transduction/immunology , Female , Mice, Inbred BALB C , Bacterial Proteins/genetics , Bacterial Proteins/immunology , Spleen/immunology , Inflammation/immunologyABSTRACT
The modulation of actin polymerization is a common theme among microbial pathogens. Even though microorganisms show a wide repertoire of strategies to subvert the activity of actin, most of them converge in the ones that activate nucleating factors, such as the Arp2/3 complex. Brucella spp. are intracellular pathogens capable of establishing chronic infections in their hosts. The ability to subvert the host cell response is dependent on the capacity of the bacterium to attach, invade, avoid degradation in the phagocytic compartment, replicate in an endoplasmic reticulum-derived compartment and egress. Even though a significant number of mechanisms deployed by Brucella in these different phases have been identified and characterized, none of them have been described to target actin as a cellular component. In this manuscript, we describe the identification of a novel virulence factor (NpeA) that promotes niche formation. NpeA harbors a short linear motif (SLiM) present within an amphipathic alpha helix that has been described to bind the GTPase-binding domain (GBD) of N-WASP and stabilizes the autoinhibited state. Our results show that NpeA is secreted in a Type IV secretion system-dependent manner and that deletion of the gene diminishes the intracellular replication capacity of the bacterium. In vitro and ex vivo experiments demonstrate that NpeA binds N-WASP and that the short linear motif is required for the biological activity of the protein.IMPORTANCEThe modulation of actin-binding effectors that regulate the activity of this fundamental cellular protein is a common theme among bacterial pathogens. The neural Wiskott-Aldrich syndrome protein (N-WASP) is a protein that several pathogens target to hijack actin dynamics. The highly adapted intracellular bacterium Brucella has evolved a wide repertoire of virulence factors that modulate many activities of the host cell to establish successful intracellular replication niches, but, to date, no effector proteins have been implicated in the modulation of actin dynamics. We present here the identification of a virulence factor that harbors a short linear motif (SLiM) present within an amphipathic alpha helix that has been described to bind the GTPase-binding domain (GBD) of N-WASP stabilizing its autoinhibited state. We demonstrate that this protein is a Type IV secretion effector that targets N-WASP-promoting intracellular survival and niche formation.
Subject(s)
Bacterial Proteins , Virulence Factors , Wiskott-Aldrich Syndrome Protein, Neuronal , Virulence Factors/metabolism , Virulence Factors/genetics , Wiskott-Aldrich Syndrome Protein, Neuronal/metabolism , Wiskott-Aldrich Syndrome Protein, Neuronal/genetics , Bacterial Proteins/metabolism , Bacterial Proteins/genetics , Humans , Type IV Secretion Systems/metabolism , Type IV Secretion Systems/genetics , Animals , Mice , Protein Binding , Brucella/metabolism , Brucella/genetics , Brucella/pathogenicity , Amino Acid Motifs , Actins/metabolism , Brucellosis/microbiology , Macrophages/microbiology , Host-Pathogen InteractionsABSTRACT
Brucellosis is a zoonotic disease caused by a Gram-negative coccus a facultative intracellular pathogen. Neurobrucellosis has an incidence rate of 3-7% among all patients with brucellosis, while spinal cord involvement is rare and carries a significant mortality risk. This report describes a case of brucellosis myelitis in a 55-year-old male patient who presented with recurrent paralysis, incontinence, and damage to the visual and auditory nerves. The diagnosis of neurobrucellosis involves a serum tube agglutination test, cerebrospinal fluid analysis, a physical examination of the nervous system, and a comprehensive review of the patient's medical history. The presence of brucellosis was confirmed in cerebrospinal fluid using MetaCAP™ sequencing. Treatment with a combination of rifampicin, doxycycline, ceftriaxone sodium, amikacin, compound brain peptide ganglioside, and dexamethasone resulted in significant improvement of the patient's clinical symptoms and a decrease in the brucellosis sequence count in cerebrospinal fluid. For the first time, MetaCAP™ sequencing has been used to treat pathogenic microbial nucleic acids, which could be a valuable tool for early diagnosis and treatment of neurobrucellosis.
Subject(s)
Anti-Bacterial Agents , Brucellosis , Myelitis , Humans , Male , Brucellosis/complications , Brucellosis/drug therapy , Brucellosis/diagnosis , Brucellosis/microbiology , Middle Aged , Myelitis/microbiology , Myelitis/diagnosis , Myelitis/drug therapy , Anti-Bacterial Agents/therapeutic use , Treatment Outcome , Magnetic Resonance ImagingABSTRACT
Bacterial zoonoses are diseases caused by bacterial pathogens that can be naturally transmitted between humans and vertebrate animals. They are important causes of non-malarial fevers in Kenya, yet their epidemiology remains unclear. We investigated brucellosis, Q-fever and leptospirosis in the venous blood of 216 malaria-negative febrile patients recruited in two health centres (98 from Ijara and 118 from Sangailu health centres) in Garissa County in north-eastern Kenya. We determined exposure to the three zoonoses using serological (Rose Bengal test for Brucella spp., ELISA for C. burnetti and microscopic agglutination test for Leptospira spp.) and real-time PCR testing and identified risk factors for exposure. We also used non-targeted metagenomic sequencing on nine selected patients to assess the presence of other possible bacterial causes of non-malarial fevers. Considerable PCR positivity was found for Brucella (19.4%, 95% confidence intervals [CI] 14.2-25.5) and Leptospira spp. (1.7%, 95% CI 0.4-4.9), and high endpoint titres were observed against leptospiral serovar Grippotyphosa from the serological testing. Patients aged 5-17 years old had 4.02 (95% CI 1.18-13.70, p-value = 0.03) and 2.42 (95% CI 1.09-5.34, p-value = 0.03) times higher odds of infection with Brucella spp. and Coxiella burnetii than those of ages 35-80. Additionally, patients who sourced water from dams/springs, and other sources (protected wells, boreholes, bottled water, and water pans) had 2.39 (95% CI 1.22-4.68, p-value = 0.01) and 2.24 (1.15-4.35, p-value = 0.02) times higher odds of exposure to C. burnetii than those who used unprotected wells. Streptococcus and Moraxella spp. were determined using metagenomic sequencing. Brucellosis, leptospirosis, Streptococcus and Moraxella infections are potentially important causes of non-malarial fevers in Garissa. This knowledge can guide routine diagnosis, thus helping lower the disease burden and ensure better health outcomes, especially in younger populations.
Subject(s)
Fever , Leptospira , Leptospirosis , Humans , Kenya/epidemiology , Adolescent , Male , Child , Female , Adult , Child, Preschool , Middle Aged , Leptospirosis/diagnosis , Leptospirosis/epidemiology , Leptospirosis/blood , Leptospirosis/microbiology , Fever/microbiology , Fever/diagnosis , Fever/epidemiology , Animals , Young Adult , Leptospira/genetics , Leptospira/isolation & purification , Leptospira/immunology , Bacterial Zoonoses/diagnosis , Bacterial Zoonoses/epidemiology , Bacterial Zoonoses/microbiology , Brucellosis/diagnosis , Brucellosis/epidemiology , Brucellosis/blood , Brucellosis/microbiology , Brucella/isolation & purification , Brucella/immunology , Brucella/genetics , Outpatients , Q Fever/diagnosis , Q Fever/epidemiology , Q Fever/microbiology , Q Fever/blood , Aged , Serologic Tests , Zoonoses/microbiology , Zoonoses/diagnosis , Zoonoses/epidemiologyABSTRACT
Brucellosis is a notifiable disease induced by a facultative intracellular Brucella pathogen. In this study, eight Brucella abortus and eighteen Brucella melitensis strains from Egypt were annotated and compared with RB51 and REV1 vaccines respectively. RAST toolkit in the BV-BRC server was used for annotation, revealing genome length of 3,250,377 bp and 3,285,803 bp, 3289 and 3323 CDS, 48 and 49 tRNA genes, the same number of rRNA (3) genes, 583 and 586 hypothetical proteins, 2697 and 2726 functional proteins for B. abortus and B. melitensis respectively. B. abortus strains exhibit a similar number of candidate genes, while B. melitensis strains showed some differences, especially in the SRR19520422 Faiyum strain. Also, B. melitensis clarified differences in antimicrobial resistance genes (KatG, FabL, MtrA, MtrB, OxyR, and VanO-type) in SRR19520319 Faiyum and (Erm C and Tet K) in SRR19520422 Faiyum strain. Additionally, the whole genome phylogeny analysis proved that all B. abortus strains were related to vaccinated animals and all B. melitensis strains of Menoufia clustered together and closely related to Gharbia, Dameitta, and Kafr Elshiek. The Bowtie2 tool identified 338 (eight B. abortus) and 4271 (eighteen B. melitensis) single nucleotide polymorphisms (SNPs) along the genomes. These variants had been annotated according to type and impact. Moreover, thirty candidate genes were predicted and submitted at GenBank (24 in B. abortus) and (6 in B. melitensis). This study contributes significant insights into genetic variation, virulence factors, and vaccine-related associations of Brucella pathogens, enhancing our knowledge of brucellosis epidemiology and evolution in Egypt.
Subject(s)
Brucella abortus , Brucella melitensis , Genome, Bacterial , Genomics , Phylogeny , Brucella melitensis/genetics , Brucella abortus/genetics , Egypt , Genomics/methods , Animals , Brucellosis/microbiology , Brucella Vaccine/genetics , Bacterial VaccinesABSTRACT
BACKGROUND: It is challenging to diagnose brucellosis in nonendemic regions because it is a nonspecific febrile disease. The accurate identification of Brucella spp. in clinical microbiology laboratories (CMLs) continues to pose difficulties. Most reports of misidentification are for B. melitensis, and we report a rare case of misidentified B. abortus. CASE PRESENTATION: A 67-year-old man visited an outpatient clinic complaining of fatigue, fever, and weight loss. The patient had a history of slaughtering cows with brucellosis one year prior, and his Brucella antibody tests were negative twice. After blood culture, the administration of doxycycline and rifampin was initiated. The patient was hospitalized due to a positive blood culture. Gram-negative coccobacilli were detected in aerobic blood culture bottles, but the CML's lack of experience with Brucella prevented appropriate further testing. Inaccurate identification results were obtained for a GN ID card of VITEK 2 (bioMérieux, USA) and matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) using a MALDI Biotyper (Bruker, Germany). The strain showed 100.0% identity with Brucella spp. according to 16S rRNA sequencing. MALDI-TOF MS peaks were reanalyzed using the CDC MicrobeNet database to determine Brucella spp. (score value: 2.023). The patient was discharged after nine days of hospitalization and improved after maintaining only doxycycline for six weeks. The isolate was also identified as Brucella abortus by genomic evidence. CONCLUSION: Automated identification instruments and MALDI-TOF MS are widely used to identify bacteria in CMLs, but there are limitations in accurately identifying Brucella spp. It is important for CMLs to be aware of the possibility of brucellosis through communication with clinicians. Performing an analysis with an additional well-curated MALDI-TOF MS database such as Bruker security-relevant (SR) database or CDC MicrobeNet database is helpful for quickly identifying the genus Brucella.