Erythritol Availability in Bovine, Murine and Human Models Highlights a Potential Role for the Host Aldose Reductase during Brucella Infection

Brucella melitensis Rev1Δwzm: Placental pathogenesis studies and safety in pregnant ewes

One of the main causes of human brucellosis is Brucella melitensis infecting small ruminants. To date, Rev1 is the only vaccine successfully used to control ovine and caprine brucellosis. However, it is pathogenic for pregnant animals, resulting in abortions and vaginal and milk shedding, as well as being infectious for humans. Therefore, there is an urgent need to develop an effective vaccine that is safer than Rev1. In efforts to further attenuate Rev1, we recently used wzm inactivation to generate a rough mutant (Rev1Δwzm) that retains a complete antigenic O-polysaccharide in the bacterial cytoplasm. The aim of the present study was to evaluate the placental pathogenicity of Rev1Δwzm in trophoblastic cells, throughout pregnancy in mice, and in ewes inoculated in different trimesters of pregnancy. This mutant was evaluated in comparison with the homologous 16MΔwzm derived from a virulent strain of B. melitensis and the naturally rough sheep pathogen B. ovis. Our results show that both wzm mutants triggered reduced cytotoxic, pro-apoptotic, and pro-inflammatory signaling in Bewo trophoblasts, as well as reduced relative expression of apoptosis genes. In mice, both wzm mutants produced infection but were rapidly cleared from the placenta, in which only Rev1Δwzm induced a low relative expression of pro-apoptotic and pro-inflammatory genes. In the 66 inoculated ewes, Rev1Δwzm was safe and immunogenic, displaying a transient serological interference in standard RBT but not CFT S-LPS tests; this serological response was minimized by conjunctival administration. In conclusion, these results support that B. melitensis Rev1Δwzm is a promising vaccine candidate for use in pregnant ewes and its efficacy against B. melitensis and B. ovis infections in sheep warrants further study.

"Phylogenomic insights into brucellaceae: The Pseudochrobactrum algeriensis case"

The genus Pseudochrobactrum encompasses free-living bacteria phylogenetically close to Ochrobactrum opportunistic pathogens and to Brucella, facultative intracellular parasites causing brucellosis, a worldwide-extended and grave zoonosis. Recently, Pseudochrobactrum strains were isolated from Brucella natural hosts on Brucella selective media, potentially causing diagnostic confusions. Strikingly, P. algeriensis was isolated from cattle lymph nodes, organs that are inimical to bacteria. Here, we analyse P. algeriensis potential virulence factors in comparison with Ochrobactrum and Brucella. Consistent with genomic analyses, Western-Blot analyses confirmed that P. algeriensis lacks the ability to synthesize the N-formylperosamine O-polysaccharide characteristic of the lipopolysaccharide (LPS) of smooth Brucella core species. However, unlike other Pseudochrobactrum but similar to some early diverging brucellae, P. algeriensis carries genes potentially synthetizing a rhamnose-based O-polysaccharide LPS. Lipid A analysis by MALDI-TOF demonstrated that P. algeriensis LPS bears a lipid A with a reduced pathogen-associated molecular pattern, a trait shared with Ochrobactrum and Brucella that is essential to generate a highly stable outer membrane and to delay immune activation. Also, although not able to multiply intracellularly in macrophages, the analysis of P. algeriensis cell lipid envelope revealed the presence of large amounts of cationic aminolipids, which may account for the extremely high resistance of P. algeriensis to bactericidal peptides and could favor colonization of mucosae and transient survival in Brucella hosts. However, two traits critical in Brucella pathogenicity are either significantly different (T4SS [VirB]) or absent (erythritol catabolic pathway) in P. algeriensis. This work shows that, while diverging in other characteristics, lipidic envelope features relevant in Brucella pathogenicity are conserved in Brucellaceae. The constant presence of these features strongly suggests that reinforcement of the envelope integrity as an adaptive advantage in soil was maintained in Brucella because of the similarity of some environmental challenges, such as the action of cationic peptide antibiotics and host defense peptides. This information adds knowledge about the evolution of Brucellaceae, and also underlines the taxonomical differences of the three genera compared.

A Review on the Methodology and Use of the Pregnant Mouse Model in the Study of Brucella Reproductive Pathogenesis and Its Abortifacient Effect

Brucellosis is one of the most common and widespread bacterial zoonoses and is caused by Gram-negative bacteria belonging to the genus Brucella. These organisms are able to infect and replicate within the placenta, resulting in abortion, one of the main clinical signs of brucellosis. Although the mouse model is widely used to study Brucella virulence and, more recently, to evaluate the protection of new vaccines, there is no clear consensus on the experimental conditions (e.g., mouse strains, doses, routes of inoculation, infection/pregnancy time) and the natural host reproducibility of the pregnant mouse model for reproductive brucellosis. This lack of consensus calls for a review that integrates the major findings regarding the effect of Brucella wild-type and vaccine strains infections on mouse pregnancy. We found sufficient evidence on the utility of the pregnant mouse model to study Brucella-induced placentitis and abortion and propose suitable experimental conditions (dose, time of infection) and pregnancy outcome readouts for B. abortus and B. melitensis studies. Finally, we discuss the utility and limitations of the pregnant mouse as a predictive model for the abortifacient effect of live Brucella vaccines.

Molecular examination for Coxiella burnetii and Brucella spp. infections in Iranian women experiencing spontaneous miscarriage

BACKGROUND

Spontaneous miscarriage, a leading health concern globally, often occurs due to various factors, including infections. Among these, Coxiella burnetii and Brucella spp. may have adverse effects on pregnancy outcomes. While previous research has established a link between infections and spontaneous miscarriage, our study aimed specifically to investigate the presence of these two pathogens in abortion samples from women who experienced spontaneous miscarriages in Iran. Our study can add to the existing knowledge by focusing on Iran, a region with a high prevalence of C. burnetii and Brucella spp. As a result, it could provide a better understanding and unique insights into the relationship of these pathogens with spontaneous miscarriages in endemic regions.

METHODS

From March 2021 to March 2022, a total of 728 abortion samples (including placenta and cotyledon) were collected from 409 women who had experienced spontaneous miscarriages in the provinces of Tehran, Fars, and West Azerbaijan in Iran. The specimens included 467 Formalin-Fixed Paraffin-Embedded (FFPE) and 261 fresh frozen samples. After DNA extraction from abortion samples, the quantitative real-time PCR (qPCR) assay targeted a specific fragment of the IS1111 and IS711 elements for molecular identification of C. burnetii and Brucella spp., respectively. Furthermore, the qPCR assay employing specific primers for different species was used to determine the species of Brucella.

RESULTS

Among the studied women, 1 out of 409 (0.24%) samples tested positive for Brucella spp., specifically Brucella melitensis. There were no positive specimens for C. burnetii.

CONCLUSIONS

Our study contributes to understanding the potential involvement of Brucella species in spontaneous infectious abortion within endemic regions. The identification of B. melitensis in this study highlights the need for further research in this area. However, while our results suggest a relatively low or zero identification of these pathogens in our sample population, this does not rule out the possibility of undetected infections. Therefore, it is critical to acknowledge the limitations of the molecular techniques used (qPCR), which may have potential limitations such as sensitivity and specificity. Moreover, because 64.15% of our samples were FFPE, the sensitivity of the qPCR test may be reduced. These raise concerns about the accuracy of the reported prevalence rates and the potential for false positives or negatives.

Immune Responses Potentially Involved in the Gestational Complications of Brucella Infection

Infection by Brucella species in pregnant animals and humans is associated with an increased risk of abortion, preterm birth, and transmission of the infection to the offspring. The pathogen has a marked tropism for the placenta and the pregnant uterus and has the ability to invade and replicate within cells of the maternal-fetal unit, including trophoblasts and decidual cells. Placentitis is a common finding in infected pregnant animals. Several proinflammatory factors have been found to be increased in both the placenta of Brucella-infected animals and in trophoblasts or decidual cells infected in vitro. As normal pregnancies require an anti-inflammatory placental environment during most of the gestational period, Brucella-induced placentitis is thought to be associated with the obstetric complications of brucellosis. A few studies suggest that the blockade of proinflammatory factors may prevent abortion in these cases.

Erythronate utilization activates VdtR regulating its metabolism to promote Brucella proliferation, inducing abortion in mice

Brucella is a facultative intracellular pathogen that preferentially colonizes reproductive organs and utilizes erythritol as a preferred carbon source for its survival and proliferation. In this study, we identified a virulence-related DeoR-family transcriptional regulator (VdtR) and an erythronate metabolic pathway responsible for four-carbon acid sugar metabolism of D-erythronate and L-threonate in Brucella. We found that VdtR plays an important role in Brucella intracellular survival and trafficking to the endoplasmic reticulum in RAW 264.7 macrophages and in virulence in a mouse model. More importantly, we found that VdtR negatively regulates the erythronate metabolic pathway to promote extracellular proliferation of Brucella, depending on utilization of D-erythronate, an oxidative product of erythritol in the host. In a pregnant mouse model, the erythronate metabolic pathway was shown to cooperate with erythritol metabolism and play a crucial role in Brucella proliferation in the placenta, inducing placentitis and finally resulting in abortion or stillbirth. Our results demonstrate that, in addition to erythritol, erythronate is a preferred carbon source for Brucella utilization to promote its extracellular proliferation. This discovery updates the information on the preferential colonization of reproductive organs by Brucella and provides a novel insight into the Brucella-associated induction of abortion in pregnant animals. IMPORTANCE Brucella is an intracellular parasitic bacterium causing zoonosis, which is distributed worldwide and mainly characterized by reproductive disorders. Erythritol is found in allantoic fluid, chorion, and placenta of aborted animals, preferentially utilized by Brucella to cause infertility and abortion. However, the erythritol metabolism-defected mutant was unable to function as a vaccine strain due to its residual virulence. Here, we found that erythronate, an oxidative product of erythritol in the host, was also preferentially utilized by Brucella relying on the function of a deoxyribonucleoside regulator-family transcriptional regulator VdtR. Erythronate utilization activates VdtR regulation of the erythronate metabolic pathway to promote Brucella extracellular proliferation, inducing placentitis/abortion in mice. Double mutations on Brucella erythritol and D-erythronate metabolisms significantly reduced bacterial virulence. This study revealed a novel mechanism of Brucella infection-induced abortion, thus providing a new clue for the study of safer Brucella attenuated vaccines.

Cell and Tissue Tropism of Brucella spp

Brucella spp. are facultatively intracellular bacteria that can infect, survive, and multiply in various host cell types in vivo and/or in vitro. The genus Brucella has markedly expanded in recent years with the identification of novel species and hosts, which has revealed additional information about the cell and tissue tropism of these pathogens. Classically, Brucella spp. are considered to have tropism for organs that contain large populations of phagocytes such as lymph nodes, spleen, and liver, as well as for organs of the genital system, including the uterus, epididymis, testis, and placenta. However, experimental infections of several different cultured cell types indicate that Brucella may actually have a broader cell tropism than previously thought. Indeed, recent studies indicate that certain Brucella species in particular hosts may display a pantropic distribution in vivo. This review discusses the available knowledge on cell and tissue tropism of Brucella spp. in natural infections of various host species, as well as in experimental animal models and cultured cells.

Inflammatory Mechanism of Brucella Infection in Placental Trophoblast Cells

Brucellosis is a severe zoonotic infectious disease caused by the infection of the Brucella, which is widespread and causes considerable economic losses in underdeveloped areas. Brucella is a facultative intracellular bacteria whose main target cells for infection are macrophages, placental trophoblast cells and dendritic cells. The main clinical signs of Brucella infection in livestock are reproductive disorders and abortion. At present, the pathogenesis of placentitis or abortion caused by Brucella in livestock is not fully understood, and further research on the effect of Brucella on placental development is still necessary. This review will mainly introduce the research progress of Brucella infection of placental trophoblast cells as well as the inflammatory response caused by it, explaining the molecular regulation mechanism of Brucella leading to reproductive system disorders and abortion, and also to provide the scientific basis for revealing the pathogenesis and infection mechanism of Brucella.

Phytostimulants in sustainable agriculture

The consistent use of synthetic fertilizers and chemicals in traditional agriculture has not only compromised the fragile agroecosystems but has also adversely affected human, aquatic, and terrestrial life. The use of phytostimulants is an alternative eco-friendly approach that eliminates ecosystem disruption while maintaining agricultural productivity. Phytostimulants include living entities and materials, such as microorganisms and nanomaterials, which when applied to plants or to the rhizosphere, stimulate plant growth and induce tolerance to plants against biotic and abiotic stresses. In this review, we focus on plant growth-promoting rhizobacteria (PGPR), beneficial fungi, such as arbuscular mycorrhizal fungi (AMF) and plant growth-promoting fungi (PGPF), actinomycetes, cyanobacteria, azolla, and lichens, and their potential benefits in the crop improvement, and mitigation of abiotic and biotic stresses either alone or in combination. PGPR, AMF, and PGPF are plant beneficial microbes that can release phytohormones, such as indole acetic acid (IAA), gibberellic acid (GA), and cytokinins, promoting plant growth and improving soil health, and in addition, they also produce many secondary metabolites, antibiotics, and antioxidant compounds and help to combat biotic and abiotic stresses. Their ability to act as phytostimulator and a supplement of inorganic fertilizers is considered promising in practicing sustainable agriculture and organic farming. Glomalin is a proteinaceous product, produced by AMF, involved in soil aggregation and elevation of soil water holding capacity under stressed and unstressed conditions. The negative effects of continuous cropping can be mitigated by AMF biofertilization. The synergistic effects of PGPR and PGPF may be more effective. The mechanisms of control exercised by PGPF either direct or indirect to suppress plant diseases viz. by competing for space and nutrients, mycoparasitism, antibiosis, mycovirus-mediated cross-protection, and induced systemic resistance (ISR) have been discussed. The emerging role of cyanobacterial metabolites and the implication of nanofertilizers have been highlighted in sustainable agriculture.

Comparative Review of Brucellosis in Small Domestic Ruminants

Brucella melitensis and Brucella ovis are the primary etiological agents of brucellosis in small domestic ruminants. B. melitensis was first isolated in 1887 by David Bruce in Malta Island from spleens of four soldiers, while B. ovis was originally isolated in Australia and New Zealand in early 1950's from ovine abortion and rams epididymitis. Today, both agents are distributed worldwide: B. melitensis remains endemic and associated with an extensive negative impact on the productivity of flocks in -some regions, and B. ovis is still present in most sheep-raising regions in the world. Despite being species of the same bacterial genus, B. melitensis and B. ovis have extensive differences in their cultural and biochemical characteristics (smooth vs. rough colonial phases, serum and CO2 dependence for in vitro growth, carbohydrate metabolism), host preference (female goat and sheep vs. rams), the outcome of infection (abortion vs. epididymitis), and their zoonotic potential. Some of these differences can be explained at the bacterial genomic level, but the role of the host genome in promoting or preventing interaction with pathogens is largely unknown. Diagnostic techniques and measures to prevent and control brucellosis in small ruminants vary, with B. melitensis having more available tools for detection and prevention than B. ovis. This review summarizes and analyzes current available information on: (1) the similarities and differences between these two etiological agents of brucellosis in small ruminants, (2) the outcomes after their interaction with different preferred hosts and current diagnostic methodologies, (3) the prevention and control measures, and (4) alerting animal producers about the disease and raise awareness in the research community for future innovative activities.

Kinetics of Placental Infection by Different Smooth Brucella Strains in Mice

Abortion and reproductive failures induced by Brucella are the main symptoms of animal brucellosis. Laboratory animal models are essential tools of research to study the Brucella pathogenesis before experimentation in natural hosts. To extend the existing knowledge, we studied B. melitensis 16M (virulent) and Rev1 (attenuated) as well as B. suis bv2 infections in pregnant mice. Here, we report new information about kinetics of infection (in spleens, blood, placentas, vaginal shedding, and foetuses), serum cytokine profiles, and histopathological features in placentas and the litter throughout mice pregnancy. Both B. melitensis strains showed a marked placental tropism and reduced viability of pups (mainly in 16M infections), which was preceded by an intense Th1-immune response during placental development. In contrast, B. suis bv2 displayed lower placental tropism, mild proinflammatory immune response, and scarce bacterial transmission to the litter, thus allowing foetal viability. Overall, our studies revealed three different smooth Brucella patterns of placental and foetal pathogenesis in mice, providing a useful animal model for experimental brucellosis.

Spatiotemporal distribution and temporal trends of brucellosis and tuberculosis in water buffalo (Bubalus bubalis) in Brazil

The buffalo herds in Brazil have been an alternative for increasing the economy in different biomes. For this reason, knowledge of the spatial distribution of diseases of mandatory notification in buffalo herds, such as brucellosis and tuberculosis, is essential to guarantee the quality of exported animal products, as well as assist in strategies of national control and eradication programs. In the present study, we aimed to evaluate the spatiotemporal distribution and temporal trends of brucellosis and tuberculosis in buffalo in Brazilian states between 2012-2019. During this period, 474 cases of brucellosis and 604 cases of tuberculosis were observed in buffalo in Brazil, with no significant differences between the total number of cases and incidence risk. The spatial distribution for the states was mostly heterogeneous, showing similarities of occurrences for both diseases in the south, north, and the states of Minas Gerais and Pernambuco. In the eight years evaluated, tuberculosis showed cyclical variation every 1-2 years; however, for brucellosis, there was a cyclical trend only between 2012-2015, with a significant decrease until 2018. Among Brazilian states, Pará had greater disease case numbers, with 34 % for brucellosis and 40.6 % for tuberculosis. Temporal trend analysis showed an increase for Pernambuco (annual percentage change [APC]: 21.0 [CI = 20.3; 21.8]), Paraná (APC: 27.1 [CI = 5.6; 53.0]), and Santa Catarina (APC: 10.4 [CI = 0.8; 21.0]) for brucellosis, and for tuberculosis, only for Santa Catarina state (APC: 24.1 [CI = 15.5; 33.3]). Spatiotemporally, there were four high-risk brucellosis clusters with a primary cluster, cluster A (relative risk [RRs] = 53.42, P < 0.001), involving the state of Amazonas between 2014-2015. For tuberculosis, there were three states of high risk, with a primary cluster, cluster E (RRs = 28.18, P < 0.001), involving the states of Pará, Roraima, Amazonas, Rondônia, and Acre in 2014. In conclusion, brucellosis and tuberculosis in buffalo in Brazil are heterogeneously distributed, with well-defined regions of high historical risk of infection. Among these regions, the states of Amazonas, Pará, Amapá, and Minas Gerais stand out due to the higher risk of infection for both brucellosis and tuberculosis, alerting Brazilian authorities to the need for disease control actions.

Phenotypic changes in group B streptococci grown in the presence of the polyols, erythritol, sorbitol and mannitol

BACKGROUND

Group B streptococci (GBS) are important neonatal bacterial pathogens that can cause severe invasive disease in the newborn. It is thought that in many cases of invasive neonatal GBS disease, the bacteria ascend the vagina into the uterus and infect the amniotic fluid surrounding the fetus. Important constituents of this environment include the polyols or sugar alcohols of which erythritol, sorbitol and mannitol are examples. The aim of our study was to investigate the effect of polyols on GBS grown in media containing these sugar alcohols.

RESULTS

GBS incubated in varying concentrations of polyols (erythritol, sorbitol or mannitol) did not display any significant enhancement or inhibition of bacterial growth. However, growth of GBS in the presence of erythritol significantly increased the surface expression of GBS-PGK (a plasminogen binding protein) 1.25 to 1.5-fold depending on the erythritol concentration and significantly enhanced the survival in human blood 3X to 18X depending on the concentration of polyol used. Interestingly, GBS grown in 1% erythritol significantly increased invasion by the bacteria of HeLa cells (epithelial cell line) (150% vs 100%) however, at higher concentrations (2% or 4% of polyol) the number of CFUs was significantly reduced (55-75% vs 100%) suggesting higher concentrations of polyols may inhibit invasion. Erythritol also increased GBS hemolytic activity as well as enhancing biofilm formation 1.4X to 3.3X depending on the concentration of polyol used.

CONCLUSIONS

GBS grown in the presence of polyols alters the bacteria's phenotype resulting in changes associated with GBS virulence. This effect was greatest for the polyol erythritol.

Uncovering the Hidden Credentials of Brucella Virulence

Bacteria in the genus Brucella are important human and veterinary pathogens. The abortion and infertility they cause in food animals produce economic hardships in areas where the disease has not been controlled, and human brucellosis is one of the world's most common zoonoses. Brucella strains have also been isolated from wildlife, but we know much less about the pathobiology and epidemiology of these infections than we do about brucellosis in domestic animals. The brucellae maintain predominantly an intracellular lifestyle in their mammalian hosts, and their ability to subvert the host immune response and survive and replicate in macrophages and placental trophoblasts underlies their success as pathogens. We are just beginning to understand how these bacteria evolved from a progenitor alphaproteobacterium with an environmental niche and diverged to become highly host-adapted and host-specific pathogens. Two important virulence determinants played critical roles in this evolution: (i) a type IV secretion system that secretes effector molecules into the host cell cytoplasm that direct the intracellular trafficking of the brucellae and modulate host immune responses and (ii) a lipopolysaccharide moiety which poorly stimulates host inflammatory responses. This review highlights what we presently know about how these and other virulence determinants contribute to Brucella pathogenesis. Gaining a better understanding of how the brucellae produce disease will provide us with information that can be used to design better strategies for preventing brucellosis in animals and for preventing and treating this disease in humans.

Seroprevalence and risk factors of brucellosis and the brucellosis model at the individual level of dairy cattle in the West Bandung District, Indonesia

Background and Aim

Brucellosis is a zoonotic bacterial infectious disease. West Bandung is a center for dairy farming in West Java Province District and endemic for brucellosis. The aim of the study was to determine the prevalence, the associated risk factors, and the brucellosis model at the individual level of dairy cattle in the West Bandung District.

Materials and Methods

The research was conducted through a cross-sectional study. The samples were collected from the serum blood of dairy cattle. Data obtained from the questionnaire were used to investigate risk factors. Multistage random sampling was applied as the sampling technique; therefore, a sample size of 540 cows was selected. The number of farms and cattle on each farm was calculated using a variant effect design of the farm as well as 108 farms was selected with five cattle samples per farm. The results in regard of the research sample acquisition in the West Bandung District included 588 dairy cows from 116 farms, exceeds the number of samples calculated (540 dairy cows and 108 farms). The rose Bengal test (RBT) and the complement fixation test (CFT) were performed for brucellosis testing. Data associated with brucellosis cases at the individual level of the dairy cattle were analyzed using descriptive statistics univariate, bivariate with Chi-square, and odds ratio (OR). Moreover, multivariate logistic regression was used for the analysis during modeling.

Results

The results showed that the prevalence of brucellosis at the individual level in the West Bandung District was 5.10%. Risk factors associated with brucellosis in cattle included the history of abortion (p=0.000; OR=9.9), the history of placental retention (p=0.000; OR=6.6), the history of endometritis (p=0.000; OR=5.5), the history of stillbirth (p=0.043; OR=3.0), the history of pregnancy abortion age at 7-8 months (p=0.000; OR=15.2), and the history of pregnancy abortion at the age of 4-6 months (p=0.007; OR=3.8). The model of brucellosis in dairy cows was the following: = -3.2843+3.41033 the history of pregnancy abortion at the age of 7-8 months +2.54503 the history of pregnancy abortion at the age of 4-6 months +1.86185 age of cattle >2 years - 1.0469 Calving interval 12 months. The model showed the factors that were associated with brucellosis at the individual level of dairy cattle included the history of pregnancy abortion at the age of 7-8 months (β=+3.41033; OR=30.3), the history of pregnancy abortion at the age of 4-6 months (β=+2.54503; OR=12.7); age of cattle >2 years (β=+1.86185; OR=1.2), and Calving interval ≤12 months (β=-1.04691; OR=0.34).

Conclusion

The results of this research showed that the prevalence of brucellosis at the individual level of dairy cattle in the West Bandung district was 5.10%. The risk factors could contribute to the increase of the brucellosis cases, that is, the history of pregnancy abortion at the age of 7-8, the history of pregnancy abortion at the age of 4-6 months, and the age of cattle >2 years. The risk factors can be decreased in the brucellosis cases, that is, calving intervals ≤12 months.

Seroprevalence and risk factors for bovine brucellosis in the Chittagong Metropolitan Area of Bangladesh

Brucellosis is a neglected endemic zoonosis in Bangladesh and has a significant impact on public health and animal welfare of dairy farming as well as dairy farm economics. A cross‐sectional study was conducted to evaluate the seroprevalence of and risk factors for brucellosis in dairy cattle in the Chittagong metropolitan area (CMA) of Chittagong, Bangladesh. We collected serum samples (n = 158) from six randomly selected dairy farms in the CMA between February and November, 2015. The Rose Bengal Plate Test (RBPT) and a competitive ELISA (cELISA) were used as the screening and confirmatory tests respectively. Farm level and animal level demographic and risk factor data were collected using a questionnaire. The risk factors were analysed using a multivariable logistic regression with random effects. The overall seroprevalences of antibodies against brucellosis in cattle were 21.5% (34/158) and 7.6% (12/158) based on parallel and serial interpretation of the two tests respectively. Our results revealed that 20.3% (32/158) samples were positive using the RBPT and 8.9% (14/158) were positive using the cELISA. The within‐herd seroprevalence ranged from 10% to 26.3% and 5 to 20.7% using the RBPT and cELISA tests respectively. The odds of seropositivity were significantly higher in lactating cows (OR: 2.59; 95% CI: 1.02–6.55), cows producing less than 2 litres of milk (OR: 29.6; 95% CI: 4.3–353.8), cow producing 2–12 litres of milk (OR: 4.8; 95% CI: 1.1–33.4) and cows with reproductive disorders (OR: 3.2; 95% CI: 1.2–10.1). About 7.6% (12/158) and 1.3% (2/158) of cattle were found to be infected with acute and chronic brucellosis respectively. Based on these results, we suggest that cows that have reproductive disorders and are producing little milk should be prioritized for brucellosis screening in CMA. The screening tests should be used to control brucellosis in cattle in order to protect animal welfare, human health and to minimize the economic losses.

Intratracheal Inoculation with Brucella melitensis in the Pregnant Guinea Pig Is an Improved Model for Reproductive Pathogenesis and Vaccine Studies

Reproductive failure is the hallmark of brucellosis in animals. An uncommon but important complication in pregnant women who become acutely infected with Brucella melitensis is spontaneous pregnancy loss or vertical transmission to the fetus. Unfortunately, the mechanism behind reproductive failure is still obscure, partially due to the lack of a proper study model. Recently, it was demonstrated that intratracheal (IT) inoculation of nonpregnant guinea pigs would replicate features of clinical disease in humans. To determine if IT inoculation would induce reproductive disease, guinea pigs were infected at mid-gestation and monitored daily for fever and abortions. Fever developed between day 14 to 18 postinoculation, and by 3 weeks postinoculation, 75% of pregnant guinea pigs experienced stillbirths or spontaneous abortions mimicking natural disease. Next, to investigate the guinea pig as a model for evaluating vaccine efficacy during pregnancy, nonpregnant guinea pigs were vaccinated with S19, 16MΔvjbR + Quil-A, or 100 μl PBS + Quil-A (as control). Guinea pigs were bred and vaccinated guinea pigs were challenged at mid-gestation with B. melitensis IT inoculation and monitored for fever and abortions. Vaccination with both vaccines prevented fever and protected against abortion. Together, this study indicates that pregnant guinea pigs are an appropriate animal model to study reproductive disease and offer an improved model to evaluate the ability of vaccine candidates to protect against a serious manifestation of disease.

Evaluation of human trophoblasts and ovine testis cell lines for the study of the intracellular pathogen Brucella ovis

Since pathogenic Brucella survive and replicate inside phagocytes, cellular models of infection constitute important tools in brucellosis research. We describe the behavior of B. ovis PA (which causes a type of ovine brucellosis mainly affecting the male reproductive tract) and representative attenuated mutants in two commercially available cell lines of non-professional phagocytes related to Brucella tissue preference: OA3.Ts ovine testis cells and JEG-3 human trophoblasts. In comparison with J774.A1 macrophages and HeLa cells, intracellular bacteria were enumerated at several post-infection time points and visualized by confocal microscopy. Replication of B. ovis in OA3.Ts and JEG-3 cells was equivalent to that observed in J774.A1 macrophages-despite the more efficient internalization in the latter-and better than in HeLa cells. Multiplication and/or survival in all phagocytes was dependent on virB2 and vjbR but independent of cgs, despite the attenuation in mice of the Δcgs mutant. However, Omp25c was required for B. ovis internalization only in HeLa cells, and removal of Omp31 increased bacterial internalization in human HeLa and JEG-3 cells. The results presented here demonstrate variability in the interaction of B. ovis with different host cells and provide advantageous models of non-professional phagocytes to study the intracellular behavior of B. ovis.

Infection by Brucella melitensis or Brucella papionis modifies essential physiological functions of human trophoblasts

Brucellosis is a zoonosis caused by bacteria of the Brucella genus. In ruminants, brucellosis causes abortion, followed by chronic infection and secretion of bacteria in milk. In humans, it usually presents as flu-like symptoms, with serious complications if untreated. Epidemiological studies have only recently established that brucellosis can also cause pregnancy complications in women, but the pathogenic mechanisms are unknown. Pioneering studies in ruminants showed that Brucella infect trophoblasts and then colonise the placenta where they grow to high density. A recent study showed that the main zoonotic Brucella species can infect human cytotrophoblasts (CTB) and extravillous trophoblasts (EVT). In this work, we show that Brucella papionis (associated with stillbirth in primates) also infects human trophoblasts. However, it replicates actively in CTB, whereas its replication is very restricted within EVT. We also observed alteration of several trophoblastic functions upon infection by B. papionis or Brucella melitensis (the most prevalent species in human brucellosis). Infection altered the production of hormones, the ability of CTB to form syncytiotrophoblasts, and the invasion capacity of EVT. We also found that infection can spread between different types of trophoblasts. These findings constitute a new step in understanding how Brucella infection causes adverse pregnancy outcomes.

The CO2-dependence of Brucella ovis and Brucella abortus biovars is caused by defective carbonic anhydrases

Brucella bacteria cause brucellosis, a major zoonosis whose control requires efficient diagnosis and vaccines. Identification of classical Brucella spp. has traditionally relied on phenotypic characterization, including surface antigens and 5–10% CO₂ necessity for growth (CO₂-dependence), a trait of Brucella ovis and most Brucella abortus biovars 1–4 strains. Although molecular tests are replacing phenotypic methods, CO₂-dependence remains of interest as it conditions isolation and propagation and reflects Brucella metabolism, an area of active research. Here, we investigated the connection of CO₂-dependence and carbonic anhydrases (CA), the enzymes catalyzing the hydration of CO₂ to the bicarbonate used by anaplerotic and biosynthetic carboxylases. Based on the previous demonstration that B. suis carries two functional CAs (CAI and CAII), we analyzed the CA sequences of CO₂-dependent and -independent brucellae and spontaneous mutants. The comparisons strongly suggested that CAII is not functional in CO₂-dependent B. abortus and B. ovis, and that a modified CAII sequence explains the CO₂-independent phenotype of spontaneous mutants. Then, by mutagenesis and heterologous plasmid complementation and chromosomal insertion we proved that CAI alone is enough to support CO₂-independent growth of B. suis in rich media but not of B. abortus in rich media or B. suis in minimal media. Finally, we also found that insertion of a heterologous active CAII into B. ovis reverted the CO₂-dependence but did not alter its virulence in the mouse model. These results allow a better understanding of central aspects of Brucella metabolism and, in the case of B. ovis, provide tools for large-scale production of diagnostic antigens and vaccines.

Mitochondrial fragmentation affects neither the sensitivity to TNFα-induced apoptosis of Brucella-infected cells nor the intracellular replication of the bacteria

Mitochondria are complex organelles that participate in many cellular functions, ranging from ATP production to immune responses against viruses and bacteria. This integration of a plethora of functions within a single organelle makes mitochondria a very attractive target to manipulate for intracellular pathogens. We characterised the crosstalk that exists between Brucella abortus, the causative agent of brucellosis, and the mitochondria of infected cells. Brucella replicates in a compartment derived from the endoplasmic reticulum (ER) and modulates ER functionality by activating the unfolded protein response. However, the impact of Brucella on the mitochondrial population of infected cells still requires a systematic study. We observed physical contacts between Brucella containing vacuoles and mitochondria. We also found that B. abortus replication is independent of mitochondrial oxidative phosphorylation and that mitochondrial reactive oxygen species do not participate to the control of B. abortus infection in vitro. We demonstrated that B. abortus and B. melitensis induce a drastic mitochondrial fragmentation at 48 hours post-infection in different cell types, including myeloid and non-myeloid cells. This fragmentation is DRP1-independent and might be caused by a deficit of mitochondrial fusion. However, mitochondrial fragmentation does not change neither Brucella replication efficiency, nor the susceptibility of infected cells to TNFα-induced apoptosis.

Enhancement of erythritol production by Trichosporonoides oedocephalis ATCC 16958 through regulating key enzyme activity and the NADPH/NADP ratio with metal ion supplementation

Erythritol, a well-known natural sweetener, is mainly produced by microbial fermentation. Various metal ions (Al³⁺, Cu²⁺, Mn²⁺, and Ni²⁺) were added to the culture medium of Trichosporonoides oedocephalis ATCC 16958 at 30 mg/L in shake flask cultures. Compared with controls, Cu²⁺ increased the erythritol content by 86% and decreased the glycerol by-product by 31%. After 48 hr of shake flask culture, sodium dodecyl sulfate polyacrylamide gel electrophoresis showed that expression levels of erythrose reductase (ER) in the presence of 30 mg/L CuSO₄ · 5H₂O were higher than those obtained after treatment with other examined metal ions. Furthermore, after 108 hr of batch culture in a 5-L bioreactor, supplementation with 30 mg/L of CuSO₄ · 5H₂O increased the specific erythritol content by 27%. Further studies demonstrated that ER activity under 30 mg/L CuSO₄ · 5H₂O supplementation in a fermentor was overtly increased compared with the control after 60 hr, while glycerol-3-phosphate dehydrogenase activity was clearly reduced in most of the fermentation process. Furthermore, the NADPH/NADP ratio was slightly lower in T. oedocephalis cells treated with Cu²⁺ compared with control cells. These results provide further insights into Cu²⁺ effects on erythritol biosynthesis in T. oedocephalis and should improve the industrial production of erythritol by biological processes.

3D correlative electron microscopy reveals continuity of Brucella-containing vacuoles with the endoplasmic reticulum

Entry of the facultative intracellular pathogen Brucella into host cells results in the formation of endosomal Brucella-containing vacuoles (eBCVs) that initially traffic along the endocytic pathway. eBCV acidification triggers the expression of a type IV secretion system that translocates bacterial effector proteins into host cells. This interferes with lysosomal fusion of eBCVs and supports their maturation to replicative Brucella-containing vacuoles (rBCVs). Bacteria replicate in rBCVs to large numbers, eventually occupying most of the cytoplasmic volume. As rBCV membranes tightly wrap each individual bacterium, they are constantly being expanded and remodeled during exponential bacterial growth. rBCVs are known to carry endoplasmic reticulum (ER) markers; however, the relationship of the vacuole to the genuine ER has remained elusive. Here, we have reconstructed the 3-dimensional ultrastructure of rBCVs and associated ER by correlative structured illumination microscopy (SIM) and focused ion beam/scanning electron microscopic tomography (FIB/SEM). Studying B. abortus-infected HeLa cells and trophoblasts derived from B. melitensis-infected mice, we demonstrate that rBCVs are complex and interconnected compartments that are continuous with neighboring ER cisternae, thus supporting a model that rBCVs are extensions of genuine ER.