Brucella Abortus Research Articles (Page 1)

Determinants of bovine brucellosis across herds and individuals: A Bayesian meta-analysis.

ABSTRACTBrucella abortus S19 is a widely used live attenuated vaccine strain for bovine brucellosis control; however, its long‐term efficacy is challenged by genomic plasticity and adaptive mechanisms. This study presents a comprehensive comparative genomic and immunoinformatics analysis of a field strain (B. abortus S19, BAS19) isolated from an aborted cattle placenta 3 years post‐vaccination in Erzurum, Turkey. Whole‐genome sequencing was performed using Oxford Nanopore Technology, followed by genome assembly, functional annotation and comparative analyses against the reference strain (B. abortus S19, BAR19). Genomic variations, including 1153 single nucleotide polymorphisms (SNPs), 120 insertions and 2501 deletions, were identified. Annotation revealed 772 hypothetical proteins in BAS19 compared to 604 in BAR19, with distinct differences in virulence‐associated genes. Immunoinformatics analysis of 95 outer membrane proteins (OMPs) indicated significant antigenic variation, with 47 proteins exhibiting epitope loss and 11 displaying novel epitope gains. Beta‐barrel structure prediction demonstrated a reduction in structural stability, with nine OMPs losing beta‐barrel motifs, potentially influencing host‐pathogen interactions. These findings highlight key genomic adaptations in BAS19 that may influence its immunogenic properties and vaccine efficacy. The results contribute to a deeper understanding of B. abortus genomic diversity, providing insights for the rational design of improved vaccines and therapeutics tailored to regional epidemiological needs.

A retrospective study of risk factors associated to brucellosis seropositivity and bacterial isolation in bovine carcasses with cervical bursitis from the states of Mato Grosso, Pará and Tocantins - Brazil.

Brucellosis can be transmitted by blood transfusion. This study aimed to further explore the necessity of initiating brucellosis serological testing among blood donors in highly endemic areas by conducting a systematic review and meta-analysis of the detection rate of human brucellosis seropositivity to reduce the risk of transfusion-transmitted brucellosis and inform blood safety practices in endemic areas. We searched English databases (Medline, Embase, Web of Science and Cochran Library) and Chinese databases (China Knowledge Network, Wanfang Data Knowledge Service Platform, Wipro Chinese Biomedical Journal Database and China Biomedical Literature Service) for all articles on brucellosis serology in the blood donor population from January 1990 to July 2024, and analysed the results. The combined detection rate and its 95% confidence interval (CI) were estimated using R 4.0.3. Sensitivity analyses were performed to address heterogeneity. Egger’s test was used to evaluate publication bias. The meta-analysis included 76,860 subjects from 15 eligible studies. The pooled estimate of the seropositive detection rate for Brucella abortus disease among the included subjects was 0.91% (95% CI: 0.65–1.16%). A certain level of seropositive detection is sufficient to suggest that recipients can be transfused with blood products from donors already infected with brucellosis, with a high likelihood of transfusion-transmitted brucellosis infection. There is a potential risk of blood-borne transmission of brucellosis. In order to lower the risk of brucellosis transmission through blood transfusion, it is necessary to screen the population of blood donors in highly endemic areas using health counseling and serological testing for Brucella.Supplementary InformationThe online version contains supplementary material available at 10.1038/s41598-025-21873-y.

GntR transcription factors are emerging as critical regulators of bacterial metabolism, stress responses, and pathogenicity, however, their roles in the virulence mechanisms of Brucella abortus remain poorly understood. In this study, we generated a gntR8 (BAB_RS24500) deletion strain (Δ gntR8 ) in B. abortus 2308 and systematically investigated its role in virulence. The results demonstrate that deletion of gntR8 markedly impairs intracellular survival of B. abortus in RAW264.7 cells and significantly reduces virulence in a mouse infection model. Moreover, the Δ gntR8 strain exhibited increased sensitivity to oxidative stress, correlating with decreased expression of stress response genes. Integrative Dap-seq and RNA-seq analyses revealed that GntR8 directly binds to and positively regulates the clpP gene, a key component involved in oxidative stress defense. Deletion of clpP similarly resulted in diminished antioxidant capacity and intracellular survival, supporting a critical regulatory axis mediated by GntR8. Collectively, these findings provide novel insights into the molecular mechanisms by which GntR8 transcriptionally regulates oxidative stress responses and pathogenicity in B. abortus . The identification of GntR8 as a key virulence regulator highlights its potential as a therapeutic target, offering promising avenues for novel intervention strategies against brucellosis.

Brucellosis, a contagious zoonotic bacterial infection affecting livestock and wildlife, is primarily caused by Brucella abortus, globally. However, in South Africa, the true prevalence of bovine brucellosis remains unknown because of a lack of epidemiological data. Therefore, this study used diagnostic data to evaluate and determine the seropositivity of bovine brucellosis based on Rose Bengal test (RBT) screening and confirmation with complement fixation test (CFT) in Limpopo and Free State provinces between 2013 and 2022. The use and limitations of this data were also evaluated based on the bovine brucellosis scheme in South Africa. The study revealed the overall seropositivity of 4.2% (n = 8980/212 440) for bovine brucellosis based on RBT and CFT in series. In Limpopo province, the brucellosis seropositivity was slightly higher at 4.3% (n = 7488/173 011) compared to 3.8% (n = 1492/39 429) in Free State province. Analysis of brucellosis distribution over the study period indicated significant variation (p < 0.001) both between and within the provinces. Notably, the highest prevalence in Limpopo occurred during 2013–2017, whereas in Free State, peak prevalence was observed in 2013 and 2016. Challenges preventing an accurate reflection of the brucellosis seropositivity in these provinces for the period include a lack of data on vaccination history and herd status of the samples submitted, as well as the inability to match the CFT results from different laboratories, because some laboratories are only accredited to perform the RBT.ContributionInsights gained from retrospective studies such as this study can play crucial roles in shaping effective control and preventative measures against bovine brucellosis. Given the challenges in obtaining confirmatory test results, we suggest that brucellosis tests be conducted at a single central laboratory or that the government provides a central database where all laboratories can enter their data. Furthermore, information submitted to the laboratories must make herd and vaccine history compulsory for sample submission to ensure more accurate data.

Background: Brucellosis is a zoonotic disease caused by Brucella species, gram-negative intracellular bacteria that primarily infect food-producing animals such as cattle and buffaloes. The infection poses a serious public health and economic threat in developing countries due to its impact on livestock productivity and its potential for human transmission through unpasteurized milk. The Milk Ring Test (MRT) serves as a rapid, cost-effective, and indirect method for detecting anti-Brucella antibodies in milk samples. Objective: This study aimed to determine the frequency of brucellosis among milk samples of cows and buffaloes in Tehsil Bahrain, Swat, using serological and bacteriological methods. Methods: The study was conducted in the Department of Microbiology, Government College Madyan, Swat, from July to December 2024 after ethical approval from the institutional research committee. A total of 160 raw milk samples were collected—100 from cows and 60 from buffaloes—from both individual animals and bulk milk tanks. Samples were aseptically collected in sterile containers, refrigerated at 4°C, and analyzed using the MRT. For each test, 1 mL of milk was mixed with 0.03 mL of hematoxylin-stained antigen and incubated at 37°C for one to three hours. The formation of a blue ring indicated a positive result. Biochemical identification of Brucella species was performed according to standard protocols, and data were analyzed using SPSS version 16. Results: Out of 160 milk samples, 20 (12%) tested positive for Brucella antibodies. Among these, 14 (14%) were from cows and 6 (10%) from buffaloes. The predominant species isolated were Brucella melitensis (64.2% in cows; 66.6% in buffaloes) and Brucella abortus (35.7% in cows; 33.3% in buffaloes). Seasonal variation analysis revealed the highest seropositivity in December and the lowest in July, suggesting environmental influence on disease occurrence. Conclusion: Brucellosis remains a persistent zoonotic and economic concern in Tehsil Bahrain, Swat, with higher seroprevalence observed during the rainy season. MRT proved to be a reliable and practical diagnostic method for rapid surveillance of Brucella infection in dairy herds, underscoring the need for routine screening and preventive measures.

Introduction Donkeys are vital to livelihoods in Kenya, yet their exclusion from national disease surveillance leaves potential health risks underexplored. Brucellosis, a significant zoonosis, remains poorly characterized in donkeys despite frequent close contact with humans. This study aimed to determine the seroprevalence, molecular detection, and risk factors for Brucella spp. infection in donkeys, and to assess owner knowledge, attitudes, and practices (KAP) across seven Kenyan counties representing diverse production systems. Methods Between October 2024 and February 2025, a cross-sectional survey sampled 392 donkeys. Serum was tested using the Rose Bengal Plate Test (RBPT) and indirect ELISA (iELISA). Donkeys testing seropositive on either test (n = 42) had their corresponding whole blood samples subjected to DNA extraction for PCR analysis, targeting Brucella abortus and Brucella melitensis . Structured interviews with owners were conducted to assess knowledge, attitudes, and practices (KAP). Mixed-effects logistic regression in R was used to identify risk factors. Results Overall seroprevalence was 10.7% by RBPT, 2.0% by iELISA, and 0.0% by PCR. All iELISA-positive cases (n = 8) were from Turkana (4), Narok (3), and Nairobi (1). Young donkeys (&amp;lt;3 years) had significantly higher odds of being seropositive (aOR = 11.8; 95% CI: 1.70–81.99; p = 0.013). Owner knowledge was low—only 25.3% had heard of brucellosis and risky practices were common, with 91.1% assisting foaling without protective equipment and 19.4% consuming donkey products, often raw. Conclusion Donkeys in Kenya may contribute to Brucella transmission within mixed livestock systems and to humans. Inclusion of donkeys in brucellosis surveillance, targeted community education, and improved diagnostics are recommended. These findings provide the first field-based evidence of donkey brucellosis in Kenya and underscore the importance of integrating donkeys into One Health strategies to reduce zoonotic risk.

BackgroundBrucellosis poses a significant threat to human health and the livestock industry, particularly affecting small-scale farmers. Several studies have demonstrated that TLR2 can recognize the Brucella abortus (B. abortus) surface lipoproteins (i.e. Omp10, Omp16 and Omp19), thus activating the immune response. This process can be altered by single nucleotide polymorphisms (SNPs) in TLR gene. This study aims to investigate whether the presence of SNPs in TLR2 could influence the resistance against brucellosis in Italian Mediterranean river buffalo, through case-control study and computational analysis. The study involved 194 Italian Mediterranean buffaloes, from three herds located in Caserta (Campania, Italy), grouped into 98 positive and 96 negative to brucellosis. Both groups, aged 40-90 months, were raised under similar environmental and management conditions to ensure consistency in the sampling. ResultsThe integration of association study with in silico analysis demonstrated that the c.374T, located in exon 2 of the TLR2 gene, could be associated with resistance to brucellosis (OR = 0.61; p-value = 0.037).ConclusionsThis study highlights how TLRs genetic variations may influence protein activity and resistance to brucellosis. The genotyping analysis combined with in silico investigation could be considered an efficient approach for detecting possible candidate marker of resistance to buffalo brucellosis.Supplementary InformationThe online version contains supplementary material available at 10.1186/s12917-025-05067-2.

Brucellosis poses a significant threat to animal and human health globally. However, how Brucella subverts the immune response to establish persistent infections remains unclear. We utilized single-cell RNA sequencing (scRNA-seq) to decipher the immune landscape of mice infected by Brucella abortus. Flow cytometry, transgenic cell line and mouse, and antibody blockage were utilized to explore the relevant mechanisms. Brucella infection induced significant changes in the composition and signaling pathways of immune cells, and flow cytometry analysis further confirmed the scRNA-seq data. An in-depth analysis with macrophages, the main target cell for Brucella, demonstrated activation of type I IFN and type II IFN signaling, TNF production, diverse cell deaths, etc. Specifically, Vir-2308 Brucella infection induced IFN-β expression, primarily originating from macrophages. In vitro, a significantly lower level of intracellular Brucella survival was observed in ifnar1-/- macrophages. In vivo, ifnar1 genetic deficiency rendered the mice less susceptible to Brucella challenge with a lower bacterial load and higher levels of macrophages and neutrophils. Interestingly, Brucella infection induced a dramatic reduction of NK cells along with the upregulation of CD94:NKG2A, one typical immune checkpoint module of NK cells. Further blockage of the NKG2A receptor in mice significantly reduced the bacterial load in the tissues, concurrent with a higher ratio of mature dendritic cells and a lower proportion of B cells. scRNA-seq revealed that Brucella infection significantly alters the immune microenvironment in mice, providing insight into a better understanding of brucellosis pathogenesis and the immune evasion strategies of this sophisticated pathogen.

Brucellosis remains an underreported zoonotic disease in Ecuador. Its control program in cattle integrates diagnostic testing, vaccination, and eradication incentives, although participation is largely voluntary. Since 2025, vaccination has become compulsory nationwide. Human surveillance remains largely passive, and strain-level data are very limited. This study applied an integrated approach, combining serology (Rose Bengal and SAT-EDTA), microbiological culture, and molecular diagnostics, to assess the presence and diversity of Brucella spp. in cattle and pigs from six slaughterhouses in the northern Andean highlands. A total of 2054 cattle and 1050 pigs from Carchi, Imbabura, and Pichincha were sampled. Among cattle, 133 (6.5%; 95% CI: 5.5–7.6) were seropositive, and viable B. abortus strains were isolated from 17 (12.8%). Genus identification was confirmed by IS711-PCR, while species- and biovar-level differentiation was achieved with AMOS-PCR; additional assays targeting the ery gene and RB51 marker were used to distinguish field from vaccine strains. Biotyping and molecular analysis revealed a predominance of B. abortus biovar 4 (13/17 isolates) over biovar 1, all confirmed as field strains. In pigs, 10 animals (0.95%) tested seropositive, but no isolates were recovered, highlighting limitations of serology in swine. Most livestock, including the positives, originated locally, reinforcing the representativeness of our findings. The successful isolation and molecular characterization of B. abortus demonstrates the value of combining diagnostic strategies beyond serology. These results underscore the utility of active surveillance when supported by traceability systems; this approach may also contribute to guide interventions to reduce infection risk in livestock and humans.

Intracellular pathogens such as Neospora caninum, Brucella abortus, and Bovine Viral Diarrhea Virus (BVDV) are major contributors to bovine abortions, yet many cases remain without a definitive etiological diagnosis despite inflammatory evidence. This study aimed to characterize the immune response in bovine fetuses aborted due to these intracellular agents, comparing them with fetuses showing inflammatory lesions of probable infectious origin and with negative controls. We analyzed cytokine expression (IFN-γ, TNFα, IL-4, IL-8, IL-12) and haptoglobin levels in mid- and late-gestation fetuses. Mid-gestation fetuses infected with intracellular agents exhibited elevated IFN-γ and IL-8 expressions, suggesting a Th1-type immune response, while late-gestation fetuses showed decreased of these cytokines, indicating a shift toward a Th2-type response. Probable infectious abortions at late gestation also showed downregulation of IFN-γ. No significant differences were observed in TNF-α and IL-12 expressions. Additionally, haptoglobin levels were lower in mid-gestation infected fetuses compared to controls. These findings highlight gestational age-dependent immune modulation in response to intracellular infections and suggest that other unidentified pathogens may contribute to abortions with inflammatory lesions but no confirmed etiology. This study enhances our understanding of fetal immune responses in bovine abortions and may support improved diagnostic approaches for reproductive losses in cattle.

Brucella abortus exploits the endoplasmic reticulum as a site for replication, triggering the unfolded protein response (UPR). While various pathogens have developed strategies to manipulate mitochondrial dynamics, the mechanisms underlying bacterial infection and mitochondrial dynamics interactions remain poorly understood. Here, we demonstrate that B. abortus induces mitochondrial fragmentation via IRE1α. Our findings reveal that Brucella-induced mitochondrial fission is mediated by dynamin-related protein 1 (DRP1), a pivotal regulator of mitochondrial fission. Moreover, we have demonstrated that DRP1 is activated by the UPR. Brucella-induced fragmentation leads to mitochondrial energetic dysfunction, marked by impaired mitochondrial ATP production and compromised bioenergetic capacity. Furthermore, we reveal a novel role for DRP1 in regulating type I IFN production and signaling during B. abortus infection. Mechanistically, mitochondrial fission facilitates the release of mitochondrial DNA, a potent inducer of type I IFN responses. Despite its impact on mitochondrial function and IFN signaling, DRP1 does not influence the control of B. abortus infection. Our findings uncover a unique mechanism by which B. abortus-induced UPR triggers mitochondrial fragmentation affecting innate immune signaling and cellular metabolism.

Brucellosis is a zoonosis that occurs worldwide, and vaccination is the main strategy for controlling it. In China, the Brucella abortus A19-ΔVirB12 strain is utilized in main vaccines. However, a high-sensitivity nucleic acid detection method to effectively differentiate Brucella infections from immunization with the A19-ΔVirB12 strain is lacking. Therefore, in this study, a duplex droplet digital PCR (ddPCR) assay was established using primers and probes targeting the VirB8 gene and the deleted VirB12 gene in the A19-ΔVirB12 strain. The specificity of the method was tested using genomic DNA of Mycobacterium bovis, Escherichia coli (O:157), Salmonella spp., Streptococcus spp., and A19-ΔVirB12 Brucella. Only A19-ΔVirB12 amplified VirB8 gene. The detection limits of the method for VirB8 and VirB12 were 2.13 × 100 and 2.26 × 100 copies/μL, respectively. In the detection of DNA in epidemic-related samples, the positive rate of ddPCR was much higher than that in the samples analyzed using the commercial fluorescence quantitative reagent kits. Meanwhile, the ddPCR of the A19-ΔVirB12 Brucella vaccine strain was identified in the clinical samples. In summary, the ddPCR method with high sensitivity and specificity was established, which will support the future identification of A19-ΔVirB12 Brucella vaccine strains in immunized and wild-type Brucella.

Differentiating Infected from Vaccinated Animals: Validation and Application of NH-AGID Assay in Heifers Immunized with Brucella abortus Strain A19-∆VirB12

Brucella abortus causes brucellosis in humans and cows worldwide. The lack of effective treatment against zoonotic infection brucellosis in cows necessitates finding an urgent remedy. Therefore, the research aims to create a multi-epitope vaccination to combat infectious brucellosis. An in silico immunoinformatic approach was employed using bioinformatics tools and databases to design multimeric subunit vaccination, as opposed to generating the vaccine from the entire pathogen. Essential antigenic proteins, Biotin synthase (bioB) and Nitrous oxide reductase (nosZ), were identified as non-toxic, non-allergenic, and stable through toxicity, allergenicity, and physicochemical analyses. Secondary structures of immunogenic proteins were predicted, followed by the prediction and evaluation of their tertiary structures. Subsequently, shortlisted proteins underwent (T and B) cell epitope prediction. Highly conserved antigenic, immunogenic, nonal¬lergic, and nontoxic epitopes have been short-listed for vaccination advancement. Multi-epitope vaccine (comprising 481 amino acids) constructed with (shortlisted 33 epitopes, linkers, EAAAK, AAY, KK, adju¬vant, beta-defensin three). Moreover, structure prediction with model evaluation was performed to evaluate structural stability and quality. Additionally, the docking technique was employed to predict the binding potential of Toll-like receptor nine. Dynamics simulation predicted the structural flexibility of the docked complex to assess its reliability. The vaccine showed immunological effects, indicating promising results. However, experiments and laboratory research are necessary to prove the vaccine’s immunogenicity.

Brucellosis is caused by Gram-negative coccobacilli of the Brucella genus, with cattle mainly infected with Brucella abortus. The disease burden is a threat to socioeconomic development (agriculture/tourism) as well as to animal health, biodiversity and to human health due to the zoonotic nature of this pathogen. In South Africa (S.A), the prevalence of the disease in cattle and livestock in general is mostly unknown in communal farms. A cross-sectional study with a multistage sampling strategy was applied in communal areas from three district municipalities, i.e., Mopani, Capricorn and Sekhukhune of Limpopo province, South Africa. Sera (n = 1133) were collected and screened for antibodies against the Brucella species using the Rose Bengal Test (RBT) and confirmation of positive reactors with a Complement Fixation Test (CFT). The brucellosis seroprevalence was found to be 0.79% (95% CI: 0.38-1.45) by a CFT. Univariate analysis indicated that only the frequency of birth was significantly associated with CFT positivity (OR = 20; 95% Cl: 1.61-247.99; p = 0.039). The multivariable logistic regression model revealed that the frequency of birth, age, breed, gender, municipality and district were not statistically significant predictors at 0.05 level. However, some variables like cattle aged more than five years, had higher odds of CFT positivity compared to those younger than five years (OR = 5.66; 95% CI: 0.36-87.97), although the association was not statistically significant (p = 0.215). All positive reactors detected originated from the Mopani district municipality. Overall, the findings reveal a much lower seroprevalence of brucellosis in the communal farms of Limpopo province than previously assumed. We are of the opinion that the low seroprevalence is attributed to effective control strategies implemented by the Limpopo provincial veterinary services and hence provide important information to assist the regulatory bodies in the control and eradication of the disease.

Brucellosis, a zoonotic infection caused by the intracellular pathogen Brucella, leads to chronic multi-organ damage. Currently, rapid, accurate, and sensitive diagnostic technologies are crucial for the prevention and control of brucellosis. This study describes the development of a chemiluminescent immunoassay (Bru-CLIA) for sheep and bovine brucellosis antibody detection, utilizing Brucella abortus strain A19 lipopolysaccharide-coated magnetic particles (LPS-MPs) as the serum antigen and acridinium ester-labeled recombinant streptococcal protein G (AE-SPG) for signal generation. After optimizing the assay’s parameters, the Bru-CLIA demonstrated a sensitivity of approximately 1 IU/mL and 2 IU/mL for detecting sheep and bovine brucellosis, respectively. No cross-reactivity was observed with sera from animals immunized with Escherichia coli O157:H7, Mycobacterium tuberculosis, Vibrio cholerae, Legionella, Salmonella, Foot and Mouth Disease virus types O and A, Bovine viral diarrhea virus, Sheep contagious pleuropneumonia, Goat pox virus, or Peste des Petits Ruminants virus, indicating strong specificity. The testing of 81 sheep serum samples and 96 bovine serum samples revealed that Bru-CLIA showed 87.65% and 93.75% concordance with the ID-VET commercial kits for sheep and bovine brucellosis detection, respectively. These results demonstrate that Bru-CLIA offers high specificity, sensitivity, repeatability, and reliability, making it a viable rapid diagnostic tool for the epidemiological surveillance of brucellosis.

Brucellosis remains a critical zoonotic disease affecting livestock productivity and human health, especially in regions where intensive livestock husbandry is practiced. In the United Arab Emirates (UAE), camels contribute economically and culturally through meat, milk, and racing, yet data on brucellosis in camels and its zoonotic risk remain limited. This cross-sectional study aimed to determine the seroprevalence and molecular detection of Brucella species in camels and abattoir workers in the Emirate of Abu Dhabi, UAE. A total of 356 camels from 102 herds, 368 slaughter camels, and 86 abattoir workers were included. Competitive enzyme-linked immunosorbent assay (cELISA) was used for antibody detection, while species-specific quantitative PCR (qPCR) targeted Brucella abortus, Brucella melitensis, and Brucella ovis in seropositive samples. Herd-level seroprevalence was 10.8% (95% CI: 5.5%–18.5%) and significantly associated with herd size (p < 0.05). Animal seroprevalence was 5.9% (95% confidence level [CI]: 3.7%–8.9%) in field camels and 3.0% (95% CI: 1.51%–5.30%) in slaughtered camels. Seven abattoir workers (8.1%) were seropositive, with butchers at greater risk. By species, B. ovis, B. abortus and B. melitensis were detected in camels, while only B. ovis and B. abortus were in abattoir workers. These findings indicate ongoing zoonotic risks in abattoir settings and support integrated One Health surveillance and control strategies.

Post-vaccination sero-monitoring of bovine calves in Indian subcontinent: A review on progress towards brucellosis control.