Brucella Abortus Research Articles

Characteristics and outcomes of pediatric brucellosis cases collected from a tertiary academic hospital in Saudi Arabia

Brucellosis is a zoonotic disease caused by Brucella spp., affecting different body systems and leading to multiple complications. Although brucellosis is prevalent in several regions, including Saudi Arabia, limited research has focused on childhood brucellosis. This study aimed to characterize the features and outcomes of brucellosis in pediatric patients. We conducted a retrospective descriptive study involving children (<18 years) with confirmed brucellosis (diagnosed through culture, serology, or both) who received antibiotic therapy. Subjects were stratified into two groups based on age: younger (≤8 years) and older (>8 years). We assessed treatment outcomes, including clinical cure, mortality, and hospital length of stay. A total of 20 patients were included, with 52.3% in the younger group and 47.7% in the older group. The majority were male (65%), with a mean age of 8.9 years, and 45% required hospitalization. Out of all the patients, only 6 (30%) reported consuming dairy products. Serologically, the baseline median antibody titers for Brucella melitensis and Brucella abortus were 1:1280 and 1:640, respectively. In the younger group, half reported arthralgia and presented with fever. While white blood cell elevation was not significant, C-reactive protein, erythrocyte sedimentation rate, and liver enzymes were elevated at baseline. The administered regimen varied, but about half of the patients received at least three antibiotics. All patients experienced clinical cures, and there were no deaths. This study highlights the characteristics of pediatric brucellosis in a country where the disease is endemic and provides evidence of positive prognosis associated with appropriate antibiotic therapy.

Prevalence and Associated Risk Factors of Brucella abortus and Brucella melitensis in Humans and Cattle Populations: A Comprehensive Study

A zoonotic disease unique to South Asia, brucellosis causes major public health and financial problems, notably in Pakistan. This research aimed to ascertain the molecular frequency of Brucella abortus and Brucella melitensis in humans and cattle and to pinpoint related risk factors in the Southern Khyber Pakhtunkhwa, Pakistan, districts. A total of 800 blood samples, 600 from cattle and 200 from humans, were gathered and examined using traditional PCR targeting the IS711 locus. In humans, the molecular frequency of Brucella melitensis and Brucella abortus was 16.5%; in cattle, it was 9.1%. Risk factor analysis in cattle revealed that seasonality, geographic location, sex, and insemination method significantly impacted brucellosis prevalence· Higher risk was observed in female cattle, those naturally inseminated, and during the summer months, particularly in regions such as Bannu· In humans, univariate logistic regression identified potential risk factors, including age (25–50 years), rural residency, lower socioeconomic status, female gender, direct contact with animals, and consumption of raw animal products. However, none of these factors reached statistical significance. The findings underscore the importance of continuous surveillance and targeted preventive measures to control brucellosis transmission between cattle and humans. Understanding the molecular prevalence and risk factors can guide public health strategies and improve livestock management practices to mitigate this zoonotic disease.

Seroprevalence of brucellosis among cows and sheep in Assiut province: A pilot study

Brucellosis is a common neglected zoonotic disease with a global geographic distribution that endangers human health and animal production. However, there is a scarcity of studies focusing on brucellosis in neglected regions such as Assiut governorate in Egypt. Therefore, the objective of this study was to investigate the prevalence of antibodies reactive to Brucella sp. in sheep and cows, as well as the associated risk factors, in Assiut governorate. A total of 184 sheep and 166 cows were included in the study, and their serum samples were subjected to screening using the Rose-Bengal plate test, followed by confirmation through the serum tube agglutination test. The overall seroprevalence of Brucella antibodies in sheep of 8.2% (15/184), while in cows, the seroprevalence was 1.2% (2/166). Among sheep, the seropositivity for Brucella abortus was 4.3% (8/184), whereas for Brucella melitensis, it was 6% (11/184). In cows, one cow displayed seropositivity for Brucella abortus, while the other exhibited mixed infection with both Brucella abortus and Brucella melitensis. Moreover, animals originating from villages bordering Sohag governorate demonstrated a higher risk of contracting brucellosis while other risk factors did not impact the occurrence of brucellosis. In conclusion, this study provides compelling evidence of the endemic nature of brucellosis in the investigated areas, with a particularly high prevalence observed in sheep. Both cows and sheep are susceptible to infection by either Brucella abortus or Brucella melitensis. To gain a comprehensive understanding of the epidemiological factors associated with infection, it is imperative to conduct large-scale surveys that incorporate molecular isolation of various Brucella species to facilitate the development of appropriate prevention strategies.

Development of a colloidal gold immunochromatographic test strip for detecting the smooth Brucella

SummaryBrucellosis, caused by Gram-negative Brucella, spreads in human and animal populations through contact with infected animals and products. Developing a rapid and sensitive detection technology for pathogen is crucial to reduce the risk of this disease transmitting between animal populations and to humans. We produced a monoclonal antibody LPS-6B5, which shows high affinity to LPS and limited cross-reactivity with other bacteria. Based on LPS-6B5, a colloidal gold immunochromatographic assay (GICA) was developed which demonstrates high sensitivity and specificity in detecting cultured B. melitensis, B. abortus and B. suis. The Gold Immunochromatographic Assay (GICA) strips exhibited the most sensitive detection limits, with a value of 7.8125 × 105 CFU/mL for Brucella melitensis, surpassing the sensitivity levels observed for Brucella abortus and Brucella suis. It is also suitable for clinical and field samples, providing a cost-effective and user-friendly alternative to traditional methods.

Upregulation of TREM2 expression in M2 macrophages promotes Brucella abortus chronic infection.

Brucella abortus (B.abortus) is a zoonotic bacterial pathogen that causes chronic host infections. The eradication of brucellosis using antibiotic therapy is often incomplete or slow. In a mouse model, the predominance of alternatively activated macrophages (also known as M2) plays an essential role in sustaining chronic infection. The underlying functional mechanism by which M2 sustains chronic infection remains unclear. Here, we show that B. abortus can enter M2 via triggering receptor expressed on myeloid cells 2 (TREM2) and promotes the upregulation of TREM2 expression of M2 in a type IV secretion system (T4SS)-dependent manner. Increased TREM2 enhances B. abortus growth within M2 by suppressing intracellular ROS production, preventing M2 pyroptosis via suppression of mitochondrial ROS (mROS), and promoting M2 proliferation by increasing β-catenin expression. In line with these results, downregulation of TREM2 expression suppressed B. abortus intracellular growth and M2 proliferation and induced M2 pyroptosis. In our mouse model, upregulation of TREM2 expression sustained the accumulation of M2 and B. abortus chronic infection, whereas downregulation of TREM2 expression restricted M2 proliferation and chronic infection. Collectively, our results suggest that targeting TREM2 may be a potential adjunct to antibiotic therapy for the prevention of chronic Brucella infection.

UNDERSTANDING DAIRY SMALLHOLDERS’ INTENTION TO PARTICIPATE IN THE CONTROL AND ERADICATION OF BOVINE BRUCELLOSIS

<p><strong>Background:</strong> Brucellosis (<em>Brucella abortus</em>) is a disease that affects cattle and has a significant economic impact on the livelihood of farmers in developing countries. <strong>Objective:</strong> The research aimed to understand the dairy smallholders’ intention to participate in the national campaign to control and eradicate bovine brucellosis in Aculco, State of Mexico. <strong>Methodology:</strong> The study was conducted with 196 farmers who were already engaged in the campaign. The reasoned action approach (RAA) was used as a theoretical framework, and Spearman rank-order correlations were used to analyze the data. <strong>Results:</strong> The results showed that farmers firmly intended to participate in the campaign in the next 12 months. The intention was associated with farmers’ years of experience as milk producers and perception of the importance and usefulness of the campaign in addition to farm characteristics. Farmers’ intention was also related to positive beliefs (drivers), such as participation in the campaign, preventing the disease in the herd, enabling access to government support and subsidies, and avoiding spreading the disease to people. Other social referents such as veterinarians, farmers, and farmers’ sons also played an important role in farmers’ intentions. A couple of significant constraints were identified: the lack of financial resources, communication between farmers and personnel in charge of the campaign. <strong>Implications: </strong>The study provided insights to improve extension activities towards small-scale dairy farmers to participate in the national campaign of control and eradication of bovine brucellosis.<strong> </strong><strong>Conclusion:</strong> the three components of the RAA (attitude, perceived norms, and perceived behavioral control) were strong predictors of farmers’ intention to participate in the brucellosis eradication campaign. They enabled the factors influencing farmers’ intentions to be explored more deeply.</p>

Label-free electrochemical immunosensor for rapid and highly sensitive detection of Brucella abortus in serum

Accurate and efficient detection of Brucella is crucial to control the disease and mitigate its impact on animal health and human safety. In this study, a simple and rapid label-free electrochemical immunosensor for the detection of Brucella abortus was fabricated based on the principle of current decrease after specific capture of the bacteria. A certain proportion of multi-walled carbon nanotubes (MWCNTs), dopamine hydrochloride (DA), and gold nanoparticles (AuNPs) were modified on the surface of a gold disc electrode. Then, Brucella abortus antibody and bovine serum albumin (BSA) were immobilized in sequence to complete the assembly of the sensor. The electrodes from various assembly steps were characterized by a cyclic voltammetry (CV) curve. The immunosensor exhibited high sensitivity with a wide linear range between 10 CFU/mL and 108 CFU/mL. Additionally, the sensor displayed good repeatability, stability, and interference resistance. The recovery rates for low, medium, and high concentrations of bacteria were all within the range of 90 % to 100 %, indicating a high level of accuracy. The method established in this study can provide reference and assistance for early diagnosis of Brucella abortus in clinical practice.

Molecular investigation of Coxiella burnetii, Brucella spp., Ehrlichia spp., and Borrelia spp. among patients suspected of having Crimean-Congo Hemorrhagic Fever in Iran

ObjectivesCrimean-Congo Hemorrhagic Fever (CCHF) is a tick-borne zoonotic viral disease that could be a public health concern. The overlapping of clinical symptoms of some acute bacterial febrile diseases with CCHF is of importance for clinical diagnosis. This study aimed to molecularly examination of Brucella, Coxiella burnetii, Borrelia, and Ehrlichia infections among individuals suspected of CCHF in Iran. MethodsIn this study, 260 serum samples of suspected cases of CCHF with definitively negative laboratory test results for CCHF virus infection, were examined for Brucella spp., Coxiella burnetii, Borrelia spp., and Ehrlichia spp. by Real-time PCR. ResultsAccording to the results, 3.46% and 3.07% of the patients were positive for brucellosis and Q fever, respectively. Notably, no cases of borreliosis or ehrlichiosis were detected. Among the positive cases for brucellosis (N= 9), three cases were identified as Brucella abortus infection. Individuals under the age of 43 displayed a significantly higher positivity rate for Q fever (p < 0.01). Furthermore, patients presenting with chills had a 5.81-fold increased likelihood of being infected with Q fever (95% CI: 1.39–24.26) compared to those without chills. Notably, no other variables demonstrated a statistically significant association with Q fever infection. Discussion and ConclusionsThe results of this study showed that bacterial infections such as Q fever and brucellosis should be considered as differential diagnoses of CCHF. It is recommended that other bacterial infections that can cause early clinical symptoms similar to CCHF should also be taken into consideration in future studies and serological and molecular investigations of these infections should be tested on a wide scale.

RESTORATION OF VIRULENCE OF B.MELITENSIS 16 M STRAINS AND BRUCELLA ABORTUS 544

When testing anti-brucellosis vaccines, an important role is played by studying the infecting dose of control strains. To restore the virulent properties of the control strains Brucella melitensis 16 M and Brucella abortus 544, it is necessary to carry out multiple successive passages in different doses (starting from 1,000,000 colony-forming units, CFU/cm3 to 5 CFU/cm3), through the body of sensitive laboratory animals. In this case, for experimental work, we took 54 heads of guinea pigs (males) weighing 350-380 g, from which we created 9 groups of 6 heads each. The article reflects the progress and results of research into determining the minimum fixing infectious dose of the control reference strains Brucella melitensis 16 M and Brucella abortus 544.Based on the results of the studies, the minimum infectious dose (5 CFU) of Brucella after the ninth passage, which causes the generalized form of brucellosis, was determined. Spent virulent fixing doses (5 CFU/cm3) strains of Brucella melitensis 16 M and Brucella abortus 544 can be used for control infection when setting up various experiments to determine and evaluate the immunogenicity of anti-brucellosis vaccines and chemoprophylaxis.

Hypertonic Saline Induces Host Protective Immune Responses against Brucella abortus Infection in Mice.

Hypertonic saline (HTS) resuscitation can enhance immune responses against various pathogens, however, the effect of HTS on brucellosis is yet to be defined. In this study, we found that HTS inhibited Brucella infection in mice by augmenting Th1 immunity. HTS treatment enhanced the serum cytokines production and the expression of nitric oxide synthase (NOS2) and nuclear factor kappa B (NF-ĸB) p50 and p65, crucial anti-Brucella effectors in splenocytes. In addition, HTS treatment also inhibited the phosphorylation of MAPK signaling, accompanied by the down-regulation of the autophagy marker LC3B-II. Due to directing an appropriate immune response, HTS treatment substantially decreased bacterial burden in spleen and liver tissues. In summary, corroborating previous studies showing the antimicrobial effects of HTS, our findings indicate that HTS treatment triggers a protective immune response against Brucella infection. Additionally, these results provide promising evidence of the immunomodulatory role of HTS in controlling bacterial infections.

Investigated of Epidemiological and Incidence of Human Brucellosis in Southwest of Iran, a Retrospective Study from 2014 to 2021

Background: Brucellosis is the most common zoonotic disease worldwide, primarily caused by Brucella abortus, and can lead to potential infertility in both men and women. Objectives: The purpose of this study was to investigate the epidemiology of brucellosis over a seven-year period (2014 - 2021) in Andika city. Methods: This cross-sectional study utilized data from the medical records of brucellosis patients at the Health Vice-Chancellor of Jundishapur University of Medical Sciences, Ahvaz, during 2014 - 2021. The study variables included age, gender, history of contact with infected animals, place of residence, occupation, consumption of dairy products (milk, cheese, and yogurt), and education. The collected data were analyzed using SPSS software version 22. Results: A total of 162 patients were reported from 2014 to 2021. The highest number of brucellosis cases occurred in 2015. In this study, 42% of the patients were men and 58% were women. Of the total patients, 62.3% were from rural areas, while 37.7% were from other areas. Among occupational groups, homemakers had the highest frequency of brucellosis cases at 30.2%. The age group with the highest incidence was 21 - 30 years, at 21%. Conclusions: The results of this study indicate that the majority of patients were from rural areas and were female. The incidence of brucellosis in Andika city appears to be decreasing. Since human brucellosis incidence closely correlates with the incidence in animals, controlling the disease in animals can help reduce human cases.

Study of the Prevalence of Bovine Brucellosis (Brucella abortus) in General Proaño Parish: Evaluation using Rose Bengal Test and Confirmation through Competitive ELISA

Bovine brucellosis is an infectious pathology that compromises animal well-being and causes significant economic losses for livestock farmers. This disease leads to abortions and is caused by the bacterium Brucella abortus. In this research, the prevalence of bovine brucellosis (Brucella abortus) was estimated in General Proaño Parish using the Rose Bengal test and confirmation through competitive ELISA. Methodologically, The research was carried out between February and August 2023 on 100 animals from 25 locations in the Proaño parish, in the Morona canton, Ecuador. Blood serum was obtained from five breeds of cattle: Charolais, Holstein, Brown Swiss, Mestiza and Jersey. The collected samples were transported to the laboratory for their respective analysis. Five milliliters of venous blood were collected from the coccygeal vein, from which 1 mL of blood serum was obtained. The serum was used for disease diagnosis through the Rose Bengal test, and those that tested seropositive were reconfirmed using the competitive ELISA immunoassay method. The clinical analyses determined that there is a 0% prevalence of the pathology; based on these results, we can state that the null prevalence of Brucella may be due to environmental and geographical factors that influence its presence and transmission. Furthermore, the precision and sensitivity of the diagnostic methods used are crucial; however, the ELISA and Rose Bengal methods may have been insensitive and did not detect mild infections. Finally, Brucella infection may not be present during sampling due to temporal fluctuations in its prevalence. In conclusion, there is no scientific evidence of bovine brucellosis as the primary cause of abortions and gestational losses in the study area.

The effect of Brucella abortus on glial activation and cell death in adult male rat's hippocampus

A zoonotic disease called brucellosis can cause flu-like symptoms and heart inflammation. The bacteria responsible for this disease can also enter the brain, causing a condition called neurobrucellosis that can result in long-term neurological problems. In this study, researchers aimed to determine the changes in the hippocampal cells of rats infected with Brucella. For the study, 24 adult male albino rats were inoculated with 1 × 106 CFU Brucella abortus 544. The rats were then deeply anesthetized, and their hippocampus samples were taken for stereological, histological, and molecular studies. The results showed that the infected rats had increased microgliosis and astrogliosis. Furthermore, a high level of caspase-3 in their hippocampal tissue indicated their susceptibility to apoptosis. Additionally, there was a decrease in expression of Ki67, which further supported this. Sholl's analysis confirmed a significant failure in glial morphology. The study demonstrated that the pathogen has the ability to destroy the hippocampus and potentially affect its normal physiology. However, more research is needed to clarify various aspects of neurobrucellosis.

RNA-seq reveals the important role of transcriptional regulator DeoR1 in regulating Brucella abortus various pathways

Brucella spp. is an intracellular bacterium that uses its transcriptional regulator DeoR1 to promote intracellular transport and survival, but the molecular mechanism remains unknown. To analyze the role of DeoR1 in the virulence of B. abortus and the genes regulated by DeoR1, we created a A19ΔdeoR1 mutant of B. abortus A19 (A19). Virulence assay was performed using a murine macrophage cell line (RAW264.7) and mice. We observed that A19ΔdeoR1 mutant is attenuated in RAW264.7 cells and mice. We performed RNA-seq whole transcriptome analysis of A19ΔdeoR1 and A19 from infected RAW264.7 cells. A total of 135 differentially expressed genes were identified, including 100 up-regulated and 35 down-regulated genes. These differentially expressed genes were involved in amino acid synthesis and metabolism, energy production and conversion, stress proteins, chaperonin, hypothetical proteins and protein of unknown function, cell wall/membrane/envelope, intracellular transporting and secretion, and transcriptional regulator. Interestingly, genes involved in the intracellular trafficking and secretion were significantly down-regulated in A19ΔdeoR1. Furthermore, selected RNA-seq results were experimentally confirmed by qRT-PCR. Overall, these results deciphered differential phenomena associated with virulence in A19ΔdeoR1 and A19 from infected RAW264.7 cells, which provided important information for understanding the detailed role of DeoR1 in Brucella pathogenesis. SignificanceTranscriptional regulators are predominant bacterial signal transduction factors. The pathogenicity of Brucella is due to its ability to regulate the expression of virulence related genes. Transcriptional regulators are designed to regulate gene expression and enact an appropriate adaptive physiological response. Here, a total of 135 differentially expressed genes were identified in transcriptional regulator deoR1 mutant.

In Silico Evaluation of Lawsonia intracellularis Genes Orthologous to Genes Associated with Pathogenesis in Other Intracellular Bacteria.

Proliferative enteropathy is an enteric disease caused by the bacterium Lawsonia intracellularis, which affects several species of domestic and wild animals. The mechanisms underlying the mechanisms employed by L. intracellularis to cause host cell proliferation are poorly understood, mostly because this bacterium is extremely difficult to isolate and propagate in vitro. Comparative genomics methods for searching for genes orthologous to genes known to be associated with pathogenesis allow identification of genes potentially involved in pathogenesis by the pathogen of interest. The goal of this study was to carry out in silico research on L. intracellularis genes orthologous to genes required for intracellular invasion and survival present in other pathogenic bacteria, particularly Brucella abortus, B. melitensis, B. suis, Listeria monocytogenes, Mycobacterium tuberculosis, Mycobacterium avium subspecies paratuberculosis, Salmonella enterica, Yersinia pestis, Y. enterocolitica, and Y. pseudotuberculosis. A total of 127 genes associated with invasion and intracellular survival from five known intracellular bacteria were mapped against the predicted proteomes of all L. intracellularis strains publicly available on GenBank, using the OrthoFinder program. A total of 45 L. intracellularis genes were orthologous to genes associated with pathogenesis of other intracellular bacteria. Genes putatively associated with signal the transduction of chemotaxis and cell motility were identified. Genes related to DNA binding and repair were also identified, with some of them supporting a possible association of bacteria with macrophages or inducing pro-inflammatory responses. The homology-based identification of these genes suggests their potential involvement in the virulence and pathogenicity of L. intracellularis, opening avenues for future research and insights into the molecular mechanisms of Lawsonia-elicited proliferative enteropathy.

Identification of Brucella spp. in Aborted Fetuses by Guineapig inoculation

Abstract Background: Brucellosis is a zoonotic disease which is endemic in Bangladesh. The prevalence of bovine brucellosis in subsistence management system in Bangladesh is low. However, the prevalence of bovine brucellosis at Central Cattle Breeding and Dairy Farm (CCBDF) is reported to be very high and Brucella abortus DNA has also been detected from cows’ milk of this farm. The principal manifestation of bovine brucellosis is abortion in pregnant cows, which is common at CCBDF. The role of brucellosis in abortion at CCBDF has not been ascertained. Hence, this study was undertaken to confirm Brucella spp. as the etiology of abortion in cows at CCBDF. Materials and Methods: Aborted fetal membranes and vaginal swabs from 3 cows, in which late abortion occurred, were collected aseptically from the CCBDF. The samples were initially stained with modified Zeihl-Neelsen staining method. The stain-positive samples were ground individually using a pestle and mortar, and a homogenized mixture was prepared by adding normal saline. Two milliliters of the homogenate from each sample were inoculated subcutaneously into a guinea pig. The sera of guinea pigs were collected after 3rd week of inoculation to perform rose Bengal test (RBT) and rapid antibody test (RAT). Result: Samples from two cows showed positive staining result in which numerous pink-colored coccobacilli were seen. All the sera collected were tested positive for both RBT and RAT. It is evident from this study that three of two abortions at CCBDF were due to brucellosis. Conclusion: Guineapig inoculation technique could be used as a good alternative of culture for confirming the diagnosis of brucellosis from contaminated clinical samples like placenta.

Whole Genome Sequence Analysis of Brucella spp. from Human, Livestock, and Wildlife in South Africa

Brucellosis is an economically important zoonotic disease affecting humans, livestock, and wildlife health globally and especially in Africa. Brucella abortus and B. melitensis have been isolated from human, livestock (cattle and goat), and wildlife (sable) in South Africa (SA) but with little knowledge of the population genomic structure of this pathogen in SA. As whole genome sequencing can assist to differentiate and trace the origin of outbreaks of Brucella spp. strains, the whole genomes of retrospective isolates (n = 19) from previous studies were sequenced. Sequences were analysed using average nucleotide identity (ANI), pangenomics, and whole genome single nucleotide polymorphism (wgSNP) to trace the geographical origin of cases of brucellosis circulating in human, cattle, goats, and sable from different provinces in SA. Pangenomics analysis of B. melitensis (n = 69) and B. abortus (n = 56) was conducted with 19 strains that included B. abortus from cattle (n = 3) and B. melitensis from a human (n = 1), cattle (n = 1), goat (n = 1), Rev1 vaccine strain (n = 1), and sable (n = 12). Pangenomics analysis of B. melitensis genomes, highlighted shared genes, that include 10 hypothetical proteins and genes that encodes for acetyl-coenzyme A synthetase (acs), and acylamidase (aam) amongst the sable genomes. The wgSNP analysis confirmed the B. melitensis isolated from human was more closely related to the goat from the Western Cape Province from the same outbreak than the B. melitensis cattle sample from different cases in the Gauteng Province. The B. melitensis sable strains could be distinguished from the African lineage, constituting their own African sub-clade. The sequenced B. abortus strains clustered in the C2 lineage that is closely related to the isolates from Mozambique and Zimbabwe. This study identified genetically diverse Brucella spp. among various hosts in SA. This study expands the limited known knowledge regarding the presence of B. melitensis in livestock and humans in SA, further building a foundation for future research on the distribution of the Brucella spp. worldwide and its evolutionary background.

Beyond its preferential niche: Brucella abortus RNA down-modulates the IFN-γ-induced MHC-I expression in epithelial and endothelial cells.

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.

Development and Bayesian validation of a competitive inhibition ELISA for detection of antibodies against Brucella abortus in cattle

Bovine brucellosis is a zoonotic disease caused by Brucella abortus, responsible for abortions in cows. It is endemic in low- and middle-income countries, where the brucellosis control and eradication programs are based on compulsory vaccination, detection of infected cattle through serologic assays, and culling of infected animals at slaughterhouses. The development of high sensitivity and specificity, and low-cost serologic assays guarantee their implementation in countries where the disease is endemic. The aim of the present study was to develop and validate a competitive inhibition enzyme-linked immune assay (ciELISA) to detect anti-B. abortus antibodies in sera from cattle. The developed ciELISA was validated using 2833 serum samples from dairy and beef cattle. From these, 1515 sera were from uninfected cows that belonged to free of brucellosis herds and 1318 were from infected cows that belonged positive to brucellosis herds. Sera were analyzed with the developed ciELISA, the buffer plate antigen (BPA) test, and the complement fixation test (CFT). The brucellosis status of the herds was officially established according to the country legislation and consistent for at least 5 years and was defined for each cow using the CFT as gold standard. The cutoff for the ciELISA was calculated using a ROC curve and its sensitivity and specificity were analyzed using the Bayesian Latent Class Model (BLCM) approach. The agreement among tests was calculated using the kappa (κ) value. In addition, 15 calves were vaccinated with 3 × 1010 viable cells of B. abortus Strain 19 vaccine, and the dynamics of antibodies were measured by CFT, buffered plate antigen (BPA) test, and the developed ciELISA. The obtained cutoff for ciELISA was ≥ 47 percentage of inhibition (% I), at the BLCM approach the sensitivity was 99.01 % (95 % CI: 97.55–100) and the specificity 98.74 % (95 % CI: 97.68–99.8). The κ between the ciELISA and BPA was κ = 0.88 and between the ciELISA and CFT κ = 0.95. Antibodies against B. abortus were detected in all the vaccinated calves 7 days after vaccination (AV) by the three assays, at day 135 AV all the calves were negative to CFT (15/15), 93.3 % (14/15) to ciELISA and 73.3 % (11/15) to BPA, and at day 190 AV all the calves were negative to the three assays. The developed ciELISA showed a very good performance, could detect the majority of vaccinated animals as negative after 135 days and could be used for the detection of anti-B. abortus antibodies in serum samples for the brucellosis control and eradication program.

Molecular epidemiology of Brucella abortus isolated from the environment in Ningxia Hui autonomous region, China

Brucellosis is among the key zoonotic infectious diseases in China, and The Ningxia Hui Autonomous Region represents a major endemic area, and it is one of the main causes of poverty in the region due to illness. In Ningxia, there is substantial research on Brucella melitensis, studies on the molecular epidemiology of Brucella abortus are notably scarce. Consequently, this study aims to undertake pathogenic isolation and molecular epidemiological research on Brucella abortus isolated from the environment in Ningxia, providing insights and evidence to advance the prevention and control measures for brucellosis in the region. Building on traditional pathogenic detection methods, this research employs whole-genome sequencing(WGS) techniques and bioinformatics software to conduct a phylogenetic comparison of Ningxia strains and strains of Brucella abortus from various geographical origins. The results indicate that four Brucella abortus strains are classified as biovar 3 and MLST type ST2. It is shown that the local strains were closer phylogenetic relationships with strains from Asian and European countries. The presence of Brucella abortus in certain environmental sectors of Ningxia indicates a risk of transmission from the environment to animals and subsequently to humans. In conclusion, the Brucella abortus exists in some farming environments in Ningxia, and exists for a long time. Therefore, it is necessary to strengthen the monitoring of the disinfection effect of the farming environment to provide a basis for the forward movement of the gate of brucellosis prevention and control.