Brucella Infection Research Articles

Brucella-Induced Downregulation of lncRNA Gm28309 Triggers Macrophages Inflammatory Response Through the miR-3068-5p/NF-κB Pathway.

ObjectivesThe underlying mechanism of the inflammatory response against Brucellosis caused by Brucella remains poorly understood. This study aimed to determine the role of long non-coding RNAs (lncRNAs) in regulating of inflammatory and anti-Brucella responses.Materials and methodsMicroarray analysis was performed to detect differentially expressed lncRNAs in THP-1 cells infected with an S2308 Brucella strain. The candidate lncRNAs were screened using bioinformatic analysis and siRNAs; bioinformatic prediction and luciferase reporter assay were also conducted, while inflammatory responses was assessed using RT‐qPCR, western blot, immunofluorescence, ELISA, HE, and immunohistochemistry.ResultsThe lncRNA Gm28309 was identified to be involved in regulating inflammation induced by Brucella. Gm28309, localized in the cytoplasm, was down-expressed in RAW264.7 cells infected with S2308. Overexpression of Gm28309 or inhibition of miR-3068-5p repressed p65 phosphorylation and reduced NLRP3 inflammasome and IL-1β and IL-18 secretion. Mechanistically, Gm28309 acted as a ceRNA of miR-3068-5p to activate NF-κB pathway by targeting κB-Ras2, an inhibitor of NF-κB signaling. Moreover, the number of intracellular Brucella was higher when Gm28309 was overexpressed or when miR-3068-5p or p65 was inhibited. However, these effects were reversed by the miR-3068-5p mimic.ConclusionsOur study demonstrates, for the first time, that LncRNAs are involved in regulating immune responses during Brucella infection, and Gm28309, an lncRNA, plays a crucial role in activating NF-κB/NLRP3 inflammasome signaling pathway.

Lack of Interleukin-6 Affects IFN-γ and TNF-α Production and Early In Vivo Control of Brucella abortus Infection.

Interleukin-6 (IL-6) is a pleiotropic cytokine promptly produced in response to infections, which contributes to host defense through the stimulation of acute phase immune responses. Brucella abortus is an intracellular bacterium that causes chronic disease in humans and domestic animals and triggers a robust immune response, characterized by the production of inflammatory cytokines. However, the mechanisms of IL-6-related immune responses in the context of Brucella infections are not completely understood. In this report, we describe an increased susceptibility of IL-6 knockout (KO) mice in the early phase of Brucella infection. Furthermore, we demonstrate that IL-6 is required for interferon (IFN)-γ and tumor necrosis factor (TNF)-α induction by infected splenocytes, indicating a protective role for IL-6 against B. abortus that parallels with Th1 type of immune response. Additionally, IL-6 KO mice exhibited reduced splenomegaly during the early phase of the infection. Corroborating this result, IL-6 KO mice displayed reduced numbers of macrophages, dendritic cells, and neutrophils in the spleen and reduced myeloperoxidase activity in the liver compared to wild-type infected mice. However, we demonstrate that IL-6 is not involved in B. abortus intracellular restriction in mouse macrophages. Taken together, our findings demonstrate that IL-6 contributes to host resistance during the early phase of B. abortus infection in vivo, and suggest that its protective role maybe partially mediated by proinflammatory immune responses and immune cell recruitment.

Small ubiquitin-related modifier 2 affects the intracellular survival of Brucella abortus 2308 by regulating activation of the NF-κB pathway.

Brucella is a genus of Gram-negative intracellular pathogens that cause animal and human diseases. Brucella survival and replication inside immune cells is critical for the establishment of chronic infections. Protein modifications by small ubiquitin-related modifier proteins and the NF-κB pathway are involved in many cellular activities, playing major roles in regulating protein function that is essential for pathogenic bacteria during infection. However, the relationship between them in the intracellular survival of Brucella is still largely unknown. We demonstrated that Brucella abortus 2308 infection can activate the expression of small ubiquitin-related modifier-2 proteins in a time-dependent manner. We found the production of Th1 cytokines (IFN-γ and TNF-α) and the transcription of NF-κB/p65 were promoted by overexpression and inhibited by interference of small ubiquitin-related modifier-2. In addition, we showed that small ubiquitin-related modifier-2 can inhibit intracellular survival of Brucella abortus 2308 by regulating activation of the NF-κB pathway. Taken together, this work shows that small ubiquitin-related modifier-2 modification of NF-κB2/p65 is essential for the survival of Brucella abortus 2308 inside macrophages. This work may help to unravel the pathogenic mechanisms of Brucella infections.

Administration of Exogenous Progesterone Protects Against Brucella abortus Infection-Induced Inflammation in Pregnant Mice.

Progesterone has been recognized as essential for the establishment and maintenance of pregnancy, and is typically known as an immunosuppressive agent. However, its effects on mediating Brucella infection-induced inflammation have not been evaluated. Here we demonstrated that Brucella abortus infection inhibits progesterone levels in the pregnant mouse by suppressing the production of progesterone by placenta. Progesterone treatment significantly reduced the secretion of inflammatory cytokines in serum, macrophages, and trophoblasts of B. abortus-infected mice, leading to decreased placentitis and enhancing the pup viability. Mechanistically, this decreased inflammatory response results from inhibition of NF-kB activation by progesterone. Moreover, progesterone treatment suppresses B. abortus growth within trophoblasts associated with an inability of bacteria to escape the late endosome compartment in vitro. Collectively, our data illustrate that progesterone treatment might be useful therapeutically in protection against placentitis or abortion caused by B. abortus infection.

Brucella abortus BspJ Is a Nucleomodulin That Inhibits Macrophage Apoptosis and Promotes Intracellular Survival of Brucella.

To date, a variety of Brucella effector proteins have been found to mediate host cell secretion, autophagy, inflammation, and other signal pathways, but nuclear effector proteins have not yet been reported. We identified the first Brucella nucleomodulin, BspJ, and we screened out the BspJ interaction host proteins NME/NM23 nucleoside diphosphate kinase 2 (NME2) and creatine kinase B (CKB) through yeast two-hybrid and co-immunoprecipitation assays. These proteins are related to the host cell energy synthesis, metabolism, and apoptosis pathways. Brucella nucleomodulin BspJ will decrease the expression level of NME2 and CKB. In addition, BspJ gene deletion strains promoted the apoptosis of macrophages and reduced the intracellular survival of Brucella in host cells. In short, we found nucleomodulin BspJ may directly or indirectly regulate host cell apoptosis through the interaction with NME2 and CKB by mediating energy metabolism pathways in response to the intracellular circulation of Brucella infection, but the mechanism needs further study.

Revisiting Brucellosis in Small Ruminants of Western Border Areas in Pakistan.

Brucellosis, globally known bacterial zoonosis, is endemic to Pakistan. B. abortus in bovines, B. melitensis in small ruminants and B. canis in dogs mainly cause this disease. A total of 1821 sera (1196 from sheep and 625 from goats) from animal herds near the Pakistan–Afghanistan border were collected. In parallel testing of sera for anti-Brucella antibodies (B. abortus and B. melitensis) was carried out by RBPT and indirect ELISA. The presence of Brucella DNA in sera was tested by real-time PCR. The overall percentage of seropositive samples was 0.99 (18/1821) by both tests. All positive samples originated from Baluchistan territory which translated into 1.76% (18/1021). None of the positive sera had signals for Brucella DNA and none of sera from goats carried detectable antibodies. Both tests showed an almost perfect agreement with Kappa statistics. The flock size was found to be associated with the presence of anti-Brucella antibodies. The samples of Khyber Pakhtunkhwa (KPK) tested negative in both serological tests and hence were not processed for real-time PCR. The present study shows the presence of anti-Brucella antibodies in sheep in the Baluchistan region of Pakistan. Diagnostic services need to be improved and test and slaughter policies might be implemented for eradication of Brucella infection in these areas. Awareness about the infection is needed at the farmer’s level. Isolation and molecular biology of the isolates could help with understanding the prevailing etiology in a better way.

Isolation of Brucella melitensis from seronegative camel: potential implications in brucellosis control

Brucellosis is a significant zoonotic infection in Iran impacting both humans and animal health status. A number of reasons such as few clinical signs complicate the diagnosis of this infection in Camelidae. Despite the ubiquitous use of serological tests for the first screening of brucellosis in camel, this approach showed several restrictions because of the intracellular properties of this organism as well as decline antibody titers in chronic stage. This study aimed at identifying the presence of Brucella spp. in blood and lymph node samples collected from slaughtered male camels of Sistan-Baluchistan province by serology, culture and polymerase chain reaction (PCR) assay. For this purpose, 2854 blood camel samples were sampled and analyzed for Brucella detection by serological screening tests. The molecular detection of IS711 gene and Bruce-ladder assay as well as culture were performed using the lymph nodes of all seropositive camel (n = 10) and 30 seronegative samples. Results showed that 0.35% (10/2854), 0.24% (7/2854) and 0.21% (6/2854) of blood samples were positive by RBPT, SAT and 2ME, respectively. However, 0% (0/10) and 70% (7/10) of lymph node samples collected from seropositive camels were positive for Brucella infection by culture and PCR, respectively. Furthermore, 6.6% (2/30) of seronegative lymph node specimens showed the presences of Brucella by PCR and culture assay. The results of the present study indicated the low seroprevalence of Brucella infection in male camels of the Sistan-Baluchistan province and highlighted the complementary role of PCR techniques for a better screening of Brucella infection among seronegative camels. Moreover, the potential shedding of Brucella within undiagnosed camel milk and secretions is a serious problem which may result in further spread and maintenance of Brucella infection among both human and livestock. Thus, for brucellosis detection and control, our results suggested that a first PCR screening supported by a bacteriological isolation on positive samples should be performed along with the serological test in endemic countries to identify the source and prevent the uncontrolled spread of the disease among camels.

Treatment of Brucellosis in Guinea Pigs via a Combination of Engineered Novel pH-Responsive Curcumin Niosome Hydrogel and Doxycycline-Loaded Chitosan-Sodium Alginate Nanoparticles: an In Vitro and In Vivo Study.

Brucellosis is a common zoonotic infection, particularly in the developing world. The recommended treatment regimens for brucellosis involve the use of two medications such as doxycycline and curcumin in order to avoid relapses and prolonged use of these drugs. Doxycycline has excellent activity in the acidic phagolysosomal environment, while curcumin modulates the immune system function and macrophage activity. Due to the intracellular existence of Brucellae and the different anti-immune mechanisms of Brucella, the treatment of Brucella infection faces many limitations. The design of nanosystems is a promising treatment approach for brucellosis. The objective of this study was to design and evaluate the efficacy of in situ pH-responsive curcumin-loaded niosome hydrogel and doxycycline-loaded chitosan-sodium alginate nanoparticles as chemotherapeutic agents against brucellosis. The prepared formulae showed a spherical nano shape with a slow drug release pattern and small particle size. The prepared formulae were evaluated in vivo using Guinea pigs experimentally infected with Brucella melitensis biovar3. The prepared formula combination gave a significant high reduction rate of Brucella spleen viable count compared with that of untreated controls at p < 0.05. The results showed that the treatment schemes were not fully successful in eliminating Brucella infection in Guinea pigs; however, they significantly (p < 0.05) reduced the viable Brucella count in a shorter time and sub-therapeutic doses. Collectively the novel prepared formulae could be a successful therapy for the effective treatment of brucellosis infection at the recommended therapeutic doses. Graphical abstract.

Brucella suppress STING expression via miR-24 to enhance infection.

Brucellosis, caused by a number of Brucella species, remains the most prevalent zoonotic disease worldwide. Brucella establish chronic infections within host macrophages despite triggering cytosolic innate immune sensors, including Stimulator of Interferon Genes (STING), which potentially limit infection. In this study, STING was required for control of chronic Brucella infection in vivo. However, early during infection, Brucella down-regulated STING mRNA and protein. Down-regulation occurred post-transcriptionally, required live bacteria, the Brucella type IV secretion system, and was independent of host IRE1-RNase activity. STING suppression occurred in MyD88-/- macrophages and was not induced by Toll-like receptor agonists or purified Brucella lipopolysaccharide (LPS). Rather, Brucella induced a STING-targeting microRNA, miR-24-2, in a type IV secretion system-dependent manner. Furthermore, STING downregulation was inhibited by miR-24 anti-miRs and in Mirn23a locus-deficient macrophages. Failure to suppress STING expression in Mirn23a-/- macrophages correlated with diminished Brucella replication, and was rescued by exogenous miR-24. Mirn23a-/- mice were also more resistant to splenic colonization one week post infection. Anti-miR-24 potently suppressed replication in wild type, but much less in STING-/- macrophages, suggesting most of the impact of miR-24 induction on replication occurred via STING suppression. In summary, Brucella sabotages cytosolic surveillance by miR-24-dependent suppression of STING expression; post-STING activation "damage control" via targeted STING destruction may enable establishment of chronic infection.

Prostaglandin I2 (PGI2) inhibits Brucella abortus internalization in macrophages via PGI2 receptor signaling, and its analogue affects immune response and disease outcome in mice

To date, the implications of prostaglandin I2 (PGI2), a prominent lipid mediator for modulation of immune responses, has not been clearly understood in Brucella infection. In this study, we found that cyclooxygenase-2 (COX-2) was significantly expressed in both infected bone marrow-derived macrophages (BMMs) and RAW 264.7 cells. Prostaglandin I2 synthase (PTGIS) expression was not significantly changed, and PGI2receptor (PTGIR) expression was downregulated in BMMs but upregulated in RAW 264.7 macrophages at late infection. Here, we presented that PGI2, a COX-derived metabolite, was produced by macrophages during Brucella infection and its production was regulated by COX-2 and IL-10. We suggested that PGI2 and selexipag, a potent PGI2 analogue, inhibited Brucella internalization through IP signaling which led to down-regulation of F-actin polymerization and p38α MAPK activity. Administration with selexipag suppressed immune responses and resulted in a notable reduction in bacterial burden in spleen of Brucella-challenged mice. Taken together, our study is the first to characterize PGI2 synthesis and its effect in evasion strategy of macrophages against Brucella infection.

Investigation of The Presence of Brucella canis in Dogs in Western Part of Turkey

Background: Brucellosis is a zoonotic infection that usually settles in the genital organs, causing chronic, infectious and necrotic inflammatory disorders characterised by abortion and infertility mastitis in females and orchitis, epididymitis and testicular atrophy in male animals. Brucella canis causes Brucella infections in dogs. Less concern has showed to B. canis in Turkey, although dogs usually live in close contact with their owners and there is an increasing incidence of breeding kennels and stray dogs with poor state of health. The scope of this study is to determine the regional prevalance of canine brucellosis caused by Brucella canis using a 2-mercaptaethanol rapid slide agglutination test and species-specific PCR method in the western part of Turkey. Methods: A total of 200 blood samples (80 from Aydýn Province, 60 from Ýzmir Province and 60 from Muðla Province) were collected between March 2019 and February 2020. Serological analysis was performed via mercaptoethanol microagglutination test. Brucella canis-specific PCR procedures were used to detect brucellosis at the molecular level. Result: Twelve (6%) of the serum samples were positive for 2-ME RSAT. B. canis positivity was detected in 10 (5%) out of 200 samples via PCR test. Twelve positive samples were found via 2-ME RSAT and 10 positive samples were found via molecular testing. B. canis positivity was 7.5% in Aydýn and 6.6% in Muðla, as revealed via molecular tests in pet dogs in contact with stray dogs. The presence of B. canis was not observed in the dogs examined from Ýzmir Province, which were not in contact with strays.

Brucella melitensis infection in dog: a critical issue in the control of brucellosis in ruminant farms

Canine brucellosis is a contagious disease associated with health implications for humans as well as for a wide range of wild and domesticated animals. In this study, 173 dog blood specimens were sampled from herding dogs in three different provinces including Tehran (n = 127), Qom (n = 40) and Alborz (n = 6) provinces. The presence of Brucella antibodies was determined using Rose Bengal plate test (RBPT), slow agglutination test (SAT) and 2-mercaptoethanol (2-ME), respectively. The seropositive samples were further screened using blood culture and PCR tests to identify and differentiate the implicated Brucella species. According to our results, 24.3% (42/173), 13.8% (24/173) and 6.3% (11/173) of blood samples were tested positive using RBPT, SAT and 2-ME, respectively. However, among 42 seropositive samples, only 38.1% (16/42) and 14.2% (6/42) were positive by PCR and culture, respectively. Brucella melitensis biovar 1 and biovar 2 was isolated from the bacterial cultures of 6 blood samples and confirmed by biotyping, AMOS PCR and Bruce-ladder PCR assays. These findings highlight the potential risk of Brucella transmission from dog to humans along with other livestock and reflect the critical role of infected dogs in the persistence of Brucella infections among ruminant farms. This study stresses the need for further epidemiological investigations on canine brucellosis among herding dogs and suggests the systematic screening of the disease among companion animals such as dogs in order to improve brucellosis surveillance and control programs.

Enhancing the Detection of Brucella-Specific CD4+ T Cell Responses in Cattle via in vitro Antigenic Expansion and Restimulation.

Bovine brucellosis, cause by infection with Brucella abortus, causes reproductive failure in cattle, has a major economic impact to producers, and as a zoonoses, it is a disease of public health concern. Characterization of the protective immune response against Brucella infection is important to our understanding of disease pathogenesis and for the development of diagnostic assays and vaccines. Most of the knowledge regarding protection against Brucella comes from studies in the murine model, but less is known about the immune responses in cattle. Assessment of antigen-specific T cell frequency and functional phenotype are critical to understand the immune status of the host, characterize mechanisms of protective immunity and immunopathology, and to predict immune protection. The frequency of circulating T cells specific for a particular pathogen is often very low, making analysis of such responses difficult. Our goal was to develop a flow-cytometry based approach to better track Brucella-specific T cell responses. Using peripheral blood mononuclear cells (PMBC) from Brucella abortus strain RB51-vaccinated cattle, we optimized an in vitro stimulation protocol based on a combination of antigen and pan-T cell stimulation. We then assessed RB51-specific T cell responses by concurrently measuring proliferation and cytokine production using flow-cytometry. This methodology enhances the detection of peripheral, Brucella-specific responses in cattle following RB51 vaccination. This protocol is versatile in that it can be modified to fit other in vitro stimulation systems and additional functional or phenotypic parameters can be added for flow cytometric detection and characterization of antigen-specific T cells.

Bir üniversite hastanesi personelinin Brusella hakkındaki bilgi, tutum ve davranışlarının değerlendirilmesi

Amaç: XXXXXX Üniversitesi (XXX) Hastanesinde çalışan sağlık profesyonelleri dışındaki personelin sosyodemografik özelliklerinin tanımlanması, Bruselloz ve Brusellozdan korunma hakkındaki bilgilerinin değerlendirilmesi, Brusella enfeksiyonuna yol açabilecek bazı riskli uygulamalarla olan ilişkilerinin belirlenmesi amaçlanmıştır. Gereç ve Yöntem: Araştırmadaki veriler 25 soruluk anket formu ile, yüz yüze görüşme tekniği kullanılarak toplanmıştır. Anketler, XXX Hastanesinde uygulanmıştır. Bulgular: Bruselloz ülkemizde sık görülen bir hastalıktır. Çalışmamıza katılan kişiler farklı yaş gruplarında ve hastanede çalışmasına rağmen Brusellozun sadece hayvanlarla temas sonucu bulaşabildiği (%4,65) (%0,58 - %8,72) oranında bilinmiştir. Yaş ve eğitim seviyesi artıkça Brusella hakkındaki bilgi, tutum ve davranışların çoğu zaman olumsuz yönde etkilendiği görülmüştür. Sonuç: Bruselloz hakkında hastane çalışanları dahil bilgilendirilmeli, hastalığın hayvanlar ve/veya çıkartılarıyla temas sonucu bulaşabileceği riski konusundaki bilinç artırılmalıdır.

Characterizing the transport and utilization of the neurotransmitter GABA in the bacterial pathogen Brucella abortus.

The neurotransmitter gamma-aminobutyric acid (GABA) is the most abundant inhibitory neurotransmitter in the human brain; however, it is becoming more evident that this non-proteinogenic amino acid plays multiple physiological roles in biology. In the present study, the transport and function of GABA is studied in the highly infectious intracellular bacterium Brucella abortus. The data show that 3H-GABA is imported by B. abortus under nutrient limiting conditions and that the small RNAs AbcR1 and AbcR2 negatively regulate this transport. A specific transport system, gts, is responsible for the transport of GABA as determined by measuring 3H-GABA transport in isogenic deletion strains of known AbcR1/2 regulatory targets; however, this locus is unnecessary for Brucella infection in BALB/c mice. Similar assays revealed that 3H-GABA transport is uninhibited by the 20 standard proteinogenic amino acids, representing preference for the transport of 3H-GABA. Metabolic studies did not show any potential metabolic utilization of GABA by B. abortus as a carbon or nitrogen source, and RNA sequencing analysis revealed limited transcriptional differences between B. abortus 2308 with or without exposure to GABA. While this study provides evidence for GABA transport by B. abortus, questions remain as to why and when this transport is utilized during Brucella pathogenesis.

Analysis of quantitative changes of γδT cells in the peripheral blood of patients with chronic brucellosis

Objective: To investigate the quantitative changes of γδT cells in peripheral blood before and after anti-Brucella treatment in patients with chronic brucellosis. Methods: A prospective design was used to 88 patients with chronic brucellosis who were admitted to the Second People's Hospital of Tianjin from September 2012 to April 2018. The patients took anti-brucella drugs, And the changes in the number of γδT cell, CD3(+), CD4(+), CD8(+)T lymphocytes and CD4/8 in peripheral blood before treatment, 6 weeks and 12 weeks after treatment were analyzed. Thirty volunteers were selected as the healthy control group from Tianjin Second People's Hospital employee health checkup in 2014. Results: After 6 weeks antibacterial therapy, the counts of CD3(+), CD4(+) and CD8(+)T lymphocytes were significantly lower than before treatment in patients with chronic brucellosis (P<0.05) . After 12 weeks antibacterial therapy, the counts of γδT cell, CD3(+), CD4(+) and CD8(+)T lymphocytes were significantly lower than before treatment (P<0.05) , but CD4/8 was higher than before treatment in patients with chronic brucellosis (P<0.05) . Compared with healthy control group, after 6 weeks antibacterial treatment, the γδT cell count was still significantly higher, but the CD4(+)T lymphocyte count was lower (P<0.05) . After 12 weeks treatment, the γδT cell count was still significantly higher than that of the healthy control group (P<0.01) . Conclusion: γδ T cells, CD4(+), CD8(+) and CD3(+)T lymphocytes may play a role in human body resistance to chronic Brucella infection.

The global epidemiology of Brucella infections in terrestrial wildlife: A meta-analysis.

Brucellosis is a widespread zoonotic disease with serious consequences on human and animal health. Brucella infections were reported in many terrestrial wild animals, from subtropical and temperate regions to arctic regions. In many areas, the epidemiology of brucellosis in wildlife is closely associated with the occurrence of the disease in livestock. Some wild species may contribute to the re-introduction of Brucella infections in livestock (spillback), even in officially brucellosis-free (OBF) regions. Through meta-regression analysis, this study draws a global picture of the prevalence of Brucella spp. in terrestrial wild animals, trying to determine most affected subgroups as well as preferential sampling and screening methods. For this purpose, a literature search was carried out among publications published from 1983 to 2019. Different subgroups were compared according to animal species, feeding, gender, age as well as the method used for sampling and for brucellosis diagnostic. To determine heterogeneity of studies, chi-squared test was used and a random-effects model (REM) estimated the pooled prevalence among subgroups. A total of 68 publications, comprising 229 data reports/studies, were selected. The most-reported Brucella species in wildlife was Brucella abortus, and the highest prevalence rate was found in American bison, Bison bison (39.9%) followed by Alpine ibex, Capra ibex (33%). Serology was the most widely applied diagnostic approach (66%), while PCR appeared to be highly sensitive (36.62% of positive results). The gender of animals showed no significant association with the prevalence of brucellosis (p>.05). Blood samples and visceral organs constituted the great majority of specimen used for the detection of Brucella spp., while lymph nodes showed a high prevalence of positive samples (94.6%). The present study provides insight into the global epidemiology and enzootic potential of brucellosis in wild terrestrial animals worldwide, aiming at helping the appropriate authorities to strengthen prevention, surveillance and control strategies.

Meta-analysis of brucellosis vaccinology in natural hosts

ABSTRACT: Brucellosis is a relevant zoonotic disease for which the most important tool for control is vaccination of susceptible animals. Assessment of vaccine efficacy in natural hosts is based on prevention of abortion and Brucella infection in organs of immunized animals. A meta-analysis of experimental vaccination of Brucella spp. natural hosts was performed, including 45 PubMed and/or Scopus-indexed publications, representing 116 individual experiments. Difference of risk was calculated as an indicator of protection, and a temporal analysis (1980-2016) demonstrated that experimental vaccines tested on natural hosts provided levels of protection that were stable over the past decades. The meta-regression model developed in this study included different vaccine categories (attenuated, inactivated, mutant, subunit, and vectored) considering the difference of risk as the dependent variable. The subcutaneous route of vaccination provided better protection when compared to the intramuscular and oral routes of vaccination. Surprisingly, inactivated vaccines provided better protection than live naturally attenuated vaccine strains (spontaneous mutations) that were considered the reference, whereas subunit vaccines provided lower levels of protection. This is the first meta-analysis of Brucella vaccinology in the natural hosts. These results are useful for the development of new vaccination protocols for controlling animal brucellosis.

Roles of novel IL-1 family (IL-36, IL-37, and IL-38) members in chronic brucellosis

The secretion of interleukin (IL)-1 family cytokines is one of the most potent and earliest pro-inflammatory responses triggered by brucellosis. However, the roles of the most recently discovered IL-1 family members, IL-36, IL-37, and IL-38, in the transition into the chronic form of brucellos is remain largely unknown. Therefore, in this study, the roles of IL-36, IL-37, and IL-38 in brucella infections and their effects on the transition from the acute to chronic form of the disease were investigated. Using peripheral blood samples from 40 patients with acute brucellosis, 40 patients with chronic brucellosis, and 40 healthy control subjects, we analysed the serum concentrations of secreted IL-36, IL-37, and IL-38 using ELISA. The findings were confirmed by using RT-qPCR to analyse the mRNA levels of the genes encoding IL-36, IL-37, and IL-38 in peripheral blood mononuclear cells (PBMCs) from 10 randomly selected patients from each of the three groups. Our results showed that serum IL-37 (p < 0.001) and IL-38 (p < 0.001) concentrations were lower in patients with brucellosis than in the healthy controls. In addition, serum IL-37 and IL-38 concentrations were higher in the chronic patient group than in the acute patient group. The mRNA expression levels of IL-37 and IL1F10, genes that encode IL-38, did not affect serum cytokine secretion levels. This result suggests that the high secretion levels of IL-37 and IL-38 may be related to the progression into the chronic form of brucellosis. Our findings will aid in clarifying the mechanism of the transition of brucellosis from the acute to the chronic form of the disease.

Recombinant Lactococcus Lactis Displaying Omp31 Antigen of Brucella melitensis Can Induce an Immunogenic Response in BALB/c Mice.

Since Brucella infection mostly occurs through the mucosal surfaces, immune response induced by vaccine that is delivered by a way of mucosal route can be drastically enhanced to control the brucellosis. Omp31is the major outer membrane protein of Brucella, and is considered as a protective antigen against Brucella infection. Accordingly, Lactococcus lactis has been used as an antigen-delivering vector to develop a vaccine-induced mucosal response for having a safer vaccination against brucellosis. A designed omp31 gene fused to the usp45 signal peptide and M6 cell wall anchor was sub cloned in the pNZ7021 expression vector, and a recombinant L. lactis displaying Omp31 was constructed. Omp31 protein expression was confirmed using Western blotting and immunofluorescence analysis. Animals were orally and intraperitoneally immunized with live or killed L. lactis expressing Omp31, respectively. The humoral and cellular immune responses were evaluated by measuring the specific cytokines and antibodies. sIgA, serum IgA, IgM, and total IgG antibodies significantly increased in the mice immunized with live recombinant L. lactis expressing Omp31 and also serum IgM, and total IgG antibodies significantly increased in mice immunized with killed recombinant L. lactis expressing Omp31. Among IgG subtypes, IgG2a response was significantly higher in both groups compared to IgG1. In mice groups immunized with recombinant L. lactis, the IFN-γ and IL-10 level elevated; however, there was no change in the level of IL-4. These results indicated that recombinants L. lactis induce both humoral and cellular immune responses in mice, and also vaccines based on L. lactis-derived live carriers are promising interventions against Brucella melitensis infections.