Brucellosis vaccines for livestock

Infectious eye disease in the 21st century-an overview

Infectious diseases affecting the eye often cause unilateral or asymmetric visual loss in children and people of working age. This group of conditions includes viral, bacterial, fungal and parasitic diseases, both common and rare presentations which, in aggregate, may account for a significant portion of the global visual burden. Diagnosis is frequently challenging even in specialist centres, and many disease presentations are highly regional. In an age of globalisation, an understanding of the various modes of transmission and the geographic distribution of infections can be instructive to clinicians. The impact of eye infections on global disability is currently not sufficiently captured in global prevalence studies on visual impairment and blindness, which focus on bilateral disease in the over-50s. Moreover, in many cases it is hard to differentiate between infectious and immune-mediated diseases. Since infectious eye diseases can be preventable and frequently affect younger people, we argue that in future prevalence studies they should be considered as a separate category, including estimates of disability-adjusted life years (DALY) as a measure of overall disease burden. Numbers of ocular infections are uniquely affected by outbreaks as well as endemic transmission, and their control frequently relies on collaborative partnerships that go well beyond the remit of ophthalmology, encompassing domains as various as vaccination, antibiotic development, individual healthcare, vector control, mass drug administration, food supplementation, environmental and food hygiene, epidemiological mapping, and many more. Moreover, the anticipated impacts of global warming, conflict, food poverty, urbanisation and environmental degradation are likely to magnify their importance. While remote telemedicine can be a useful aide in the diagnosis of these conditions in resource-poor areas, enhanced global reporting networks and artificial intelligence systems may ultimately be required for disease surveillance and monitoring.

Development of a Plant-Expressed Subunit Vaccine against Brucellosis

Brucellosis is an important bacterial disease of livestock and the most common zoonotic disease. The current vaccines are effective but unsafe, as they result in animal abortions and are pathogenic to humans. Virus-like particles are being investigated as molecular scaffolds for foreign antigen presentation to the immune system. Here, we sought to develop a new-generation vaccine by presenting selected Brucella melitensis T cell epitopes on the surface of Orbivirus core-like particles (CLPs) and transiently expressing these chimeric particles in Nicotiana benthamiana plants. We successfully demonstrated the assembly of five chimeric CLPs in N. benthamiana plants, with each CLP presenting a different T cell epitope. The safety and protective efficacy of three of the highest-yielding CLPs was investigated in a mouse model of brucellosis. All three plant-expressed chimeric CLPs were safe when inoculated into BALB/c mice at specific antigen doses. However, only one chimeric CLP induced protection against the virulent Brucella strain challenge equivalent to the protection induced by the commercial Rev1 vaccine. Here, we have successfully shown the assembly, safety and protective efficacy of plant-expressed chimeric CLPs presenting B. melitensis T cell epitopes. This is the first step in the development of a safe and efficacious subunit vaccine against brucellosis.

Seroprevalence and related risk factors of Brucella spp. in livestock and humans in Garbatula subcounty, Isiolo county, Kenya

BACKGROUND

Brucellosis is a neglected zoonotic disease that affects both animals and humans, causing debilitating illness in humans and socio-economic losses in livestock-keeping households globally. The disease is endemic in many developing countries, including Kenya, but measures to prevent and control the disease are often inadequate among high-risk populations. This study aimed to investigate the human and livestock seroprevalence of brucellosis and associated risk factors of Brucella spp. in a pastoralist region of northern Kenya.

METHODS

A cross-sectional survey was conducted using a two-stage cluster sampling method to select households, livestock, and humans for sampling. Blood samples were collected from 683 humans and 2157 animals, and Brucella immunoglobulin G (IgG) antibodies were detected using enzyme-linked immunosorbent assays. A structured questionnaire was used to collect data on potential risk factors associated with human and animal exposures. Risk factors associated with Brucella spp. exposures in humans and livestock were identified using Multivariate logistic regression.

RESULTS

The results indicated an overall livestock Brucella spp. seroprevalence of 10.4% (95% Confidence Interval (CI): 9.2-11.7). Camels had the highest exposure rates at 19.6% (95% CI: 12.4-27.3), followed by goats at 13.2% (95% CI: 9.3-17.1), cattle at 13.1% (95% CI: 11.1-15.3) and sheep at 5.4% (95% CI: 4.0-6.9). The herd-level seroprevalence was 51.7% (95% CI: 47.9-55.7). Adult animals (Adjusted Odds Ratio (aOR) = 2.3, CI: 1.3-4.0), female animals (aOR = 1.7, CI: 1.1-2.6), and large herd sizes (aOR = 2.3, CI: 1.3-4.0) were significantly associated with anti-brucella antibody detection while sheep had significantly lower odds of Brucella spp. exposure compared to cattle (aOR = 1.3, CI: 0.8-2.1) and camels (aOR = 2.4, CI: 1.2-4.8). Human individual and household seroprevalences were 54.0% (95% CI: 50.2-58.0) and 86.4% (95% CI: 84.0-89.0), respectively. Significant risk factors associated with human seropositivity included being male (aOR = 2.1, CI:1.3-3.2), residing in Sericho ward (aOR = 1.6, CI:1.1-2.5) and having no formal education (aOR = 3.0, CI:1.5-5.9). There was a strong correlation between human seropositivity and herd exposure (aOR = 1.6, CI:1.2-2.3).

CONCLUSIONS

The study provides evidence of high human and livestock exposures to Brucella spp. and identifies important risk factors associated with disease spread. These findings emphasize the need for targeted prevention and control measures to curb the spread of brucellosis and implement a One Health surveillance to ensure early detection of the disease in Isiolo County, Northern Kenya.

A TLR4 agonist liposome formulation effectively stimulates innate immunity and enhances protection from bacterial infection

Stimulation of innate immunity can protect against infectious insult and could be used in combination with other therapies. Since antibiotic resistance is an increasing concern, strategies to reduce the dose or eliminate the need for these drugs are warranted. Lipo-CRX is a formulation in which the TLR4 agonist CRX-527 is incorporated into lipid membranes in liposomes. Lipo-CRX is less inflammatory than either CRX-527 or LPS, but retains unique capacity to enhance host defense responses. We compared lipo-CRX to other agonists in vitro using mammalian cells and in vivo in mice, and assessed indicators of innate immune responses and protection from bacterial infection. Lipo-CRX is similar to E. coli LPS in its capacity to activate bovine γδ T cells and to recruit neutrophils into mouse lungs, but with less reactivity in the LAL assay. However, lipo-CRX uniquely induced the production of systemic innate immune cytokines. In the mouse model of brucellosis, delivery of lipo-CRX to the lungs reduced the dissemination of B. abortus. While lipo-CRX or the antibiotic ampicillin alone did not alter B. abortus burdens in the lung, the combination had a synergistic beneficial effect. Our data suggest that stimulating the innate immune system with lipo-CRX, either alone or when combined with antibiotics, can enhance bacterial clearance in the mouse model of brucellosis.

Shedding rate of Brucella spp. in the milk of seropositive and seronegative dairy cattle

Brucellosis in cattle herds has caused severe economic losses in many regions worldwide. A cross-sectional study was performed to investigate the presence of Brucella spp. in industrial dairy cattle farms in Iran. For this purpose, 935 blood and 935 milk samples were randomly collected from industrial dairy cattle farms in Iran's Alborz and Tehran provinces. Blood and milk samples were collected on the same day from each cow. Serological, bacteriological, and molecular characterization of Brucella isolates were performed using standard methods. Our results revealed the seroprevalence of brucellosis in dairy cattle farms in the Alborz and Tehran provinces, reaching 19.8%, 6.7%, 5.1%, 14.1%, and 13.1% using the Rose Bengal plate test (RBPT), serum agglutination test (SAT), 2-mercaptoethanol test (2-ME), indirect enzyme-linked immunosorbent assay (i-ELISA) and milk ring test (MRT), respectively. Furthermore, the results of bacterial culture and PCR analyses showed the presence of Brucella abortus among dairy cattle in the Alborz province and Brucella melitensis and B. abortus among dairy cattle in the Tehran province. Moreover, statistical analysis with Cohen's Kappa has highlighted the near-perfect agreement between RBPT and i-ELISA (k = 0.86). In contrast, substantial agreement was shown between RBPT and SAT performance (k = 0.70) and moderate agreement between RBPT and 2-ME (k = 0.67). The findings of this investigation showed shedding of Brucella in the milk of seropositive cows, which is a serious problem involving the maintenance and further spread of Brucella infection on the farm. Therefore, for brucellosis detection or eradication in dairy cattle farms, bacteriological and serological tests of milk samples should be performed along with blood analysis to inhibit the uncontrolled spread of the disease in animals and humans.

Activation of mucosal immunity as a novel therapeutic strategy for combating brucellosis

Brucellosis is a disease of livestock that is commonly asymptomatic until an abortion occurs. Disease in humans results from contact of infected livestock or consumption of contaminated milk or meat. Brucella zoonosis is primarily caused by one of three species that infect livestock, Bacillus abortus in cattle, B. melitensis in goats and sheep, and B. suis in pigs. To aid in disease prophylaxis, livestock vaccines are available, but are only 70% effective; hence, improved vaccines are needed to mitigate disease, particularly in countries where disease remains pervasive. The absence of knowing which proteins confer complete protection limits development of subunit vaccines. Instead, efforts are focused on developing new and improved live, attenuated Brucella vaccines, since these mimic attributes of wild-type Brucella, and stimulate host immune, particularly T helper 1-type responses, required for protection. In considering their development, the new mutants must address Brucella's defense mechanisms normally active to circumvent host immune detection. Vaccination approaches should also consider mode and route of delivery since disease transmission among livestock and humans is believed to occur via the naso-oropharyngeal tissues. By arming the host's mucosal immune defenses with resident memory T cells (TRMs) and by expanding the sources of IFN-γ, brucellae dissemination from the site of infection to systemic tissues can be prevented. In this review, points of discussion focus on understanding the various immune mechanisms involved in disease progression and which immune players are important in fighting disease.

Live mucosal vaccination stimulates potent protection via varied CD4+ and CD8+ T cell subsets against wild-type Brucella melitensis 16M challenge

Re-emerging zoonotic pathogen Brucella spp. continues to impact developing countries and persists in expanding populations of wildlife species in the US, constantly threatening infection of our domestic herds. The development of improved animal and human vaccines remains a priority. In this study, immunity to a novel live attenuated B. melitensis strain, termed znBM-mC, was characterized. An oral prime, intranasal (IN) boost strategy conferred exquisite protection against pulmonary challenge, with wild-type (wt) B. melitensis providing nearly complete protection in the lungs and spleens from brucellae colonization. Vaccination with znBM-mC showed an IFN-γ⁺ CD8⁺ T-cell bias in the lungs as opposed to Rev 1-vaccinated mice showing IFN-γ⁺ CD4⁺ T-cell inclination. Lung CD4⁺ and CD8⁺ effector memory T cells (TEMs) increased over 200-fold; and lung CD4⁺ and CD8⁺ resident memory T cells (TRMs) increased more than 250- and 150-fold, respectively. These T cells served as the primary producers of IFN-γ in the lungs, which was essential for vaccine clearance and the predominant cytokine generated pre-and post-challenge with wt B. melitensis 16M; znBM-mC growth could not be arrested in IFN-γ^−/− mice. Increases in lung TNF-α and IL-17 were also induced, with IL-17 being mostly derived from CD4⁺ T cells. Vaccination of CD4^−/−, CD8^−/−, and B6 mice with znBM-mC conferred full protection in the lungs and spleens post-pulmonary challenge with virulent B. melitensis; vaccination of IL-17^−/− mice resulted in the protection of the lungs, but not the spleen. These data demonstrate the efficacy of mucosal vaccine administration for the generation of protective memory T cells against wt B. melitensis.

Evaluation of the Fluorescence Polarization Assay for the Diagnosis of Brucellosis in Goat Milk

The milk ring test is a detection assay for antibodies against Brucella in bovine milk. It has good sensitivity but tends to give false positive results. In this study, we standardized the application of the fluorescence polarization assay (FPA) for the detection of antibodies against B.melitensis in goat milk. We obtained negative serum and milk samples from healthy goat flocks in the northern zone of Nuevo León. Positive milk and negative, weak, and strong controls were obtained by mixing volumes of positive control serum with negative control milk. Milk samples were treated with citric acid, after which an FPA was performed. Results were then compared with the Rose Bengal test and the FPA in serum. Milk treatment allowed the quantification of antibodies in samples. Significant differences were found between the 2%, 4%, and 6% groups, compared with the control group (F3, 67 = 17.45, p < 0.0001) but not between the 2% and 4% groups (p = 0.0718). The cut-off value was 74.1 mP, with a sensitivity (Se) of 95% and a specificity (Sp) of 100%. Se and Sp values in field milk samples were 84% and 74.55%, respectively. Despite the FPA test on milk samples showed lower Se and Sp than the FPA test on serum samples, its cutoff may be adjusted. It may be recommended as a screening test in goat milk and become useful for the control and eradication of the disease.

Generation and Selection of Specific Aptamers Targeting Brucella Species through an Enhanced Cell-SELEX Methodology

Brucellae are Gram-negative, aerobic, non-motile coccobacilli causing brucellosis in man and animals. The disease is one of the most significant yet neglected global zoonoses. Especially in developing countries, brucellosis is causing public health problems and economic losses to private animal owners and national revenues. Composed of oligonucleotides, aptamers are chemical analogues of antibodies that are promising components for developing aptamer-based rapid, sensitive, and specific tests to identify the Brucella group of bacteria. For this purpose, aptamers were generated and selected by an enhanced protocol of cell systematic evolution of ligands by exponential enrichment (cell-SELEX). This enhanced cell-SELEX procedure involved the combination of both conventional and toggle cell-SELEX to boost the specificity and binding affinity to whole Brucella cells. This procedure, combined with high-throughput sequencing of the resulting aptamer pools, comprehensive bioinformatics analysis, and wet lab validation assays, led to the selection of a highly sensitive and specific aptamer for those Brucella species known to circulate in Egypt. The isolated candidate aptamer showed dissociation constant (K_D) values of 43.5 ± 11, 61.5 ± 8, and 56 ± 10.8 nM for B. melitensis, B. abortus, and B. suis, respectively. This is the first development of a Brucella-specific aptamer using an enhanced combination of conventional and toggle cell-SELEX to the authors’ best knowledge.

Cobalt (II) Chloride Regulates the Invasion and Survival of Brucella abortus 544 in RAW 264.7 Cells and B6 Mice

The effects of Cobalt (II) chloride (CoCl2) in the context of Brucella abortus (B. abortus) infection have not been evaluated so far. Firstly, we found that CoCl2 treatment inhibited the phagocytosis of B. abortus into RAW 264.7 cells. The inhibition of bacterial invasion was regulated by F-actin formation and associated with a reduction in the phosphorylation of ERK1/2 and HIF-1α expression. Secondly, the activation of trafficking regulators LAMP1, LAMP2, and lysosomal enzyme GLA at the transcriptional level activated immune responses, weakening the B. abortus growth at 4 h post-infection (pi). The silencing of HIF-1α increased bacterial survival at 24 h pi. At the same time, CoCl2 treatment showed a significant increase in the transcripts of lysosomal enzyme HEXB and cytokine TNF-α and an attenuation of the bacterial survival. Moreover, the enhancement at the protein level of HIF-1α was induced in the CoCl2 treatment at both 4 and 24 h pi. Finally, our results demonstrated that CoCl2 administration induced the production of serum cytokines IFN-γ and IL-6, which is accompanied by dampened Brucella proliferation in the spleen and liver of treated mice, and reduced the splenomegaly and hepatomegaly. Altogether, CoCl2 treatment contributed to host resistance against B. abortus infection with immunomodulatory effects.

Proteomic and Antibody Profiles Reveal Antigenic Composition and Signatures of Bacterial Ghost Vaccine of Brucella abortus A19

Brucellosis is an important zoonotic disease that causes great economic losses. Vaccine immunisation is the main strategy for the prevention and control of brucellosis. Although live attenuated vaccines play important roles in the prevention of this disease, they also have several limitations, such as residual virulence and difficulty in the differentiation of immunisation and infection. We developed and evaluated a new bacterial ghost vaccine of Brucella abortus A19 by a new double inactivation method. The results showed that the bacterial ghost vaccine of Brucella represents a more safe and efficient vaccine for brucellosis. We further characterised the antigenic components and signatures of the vaccine candidate A19BG. Here, we utilised a mass spectrometry-based label-free relative quantitative proteomics approach to investigate the global proteomics changes in A19BGs compared to its parental A19. The proteomic analysis identified 2014 proteins, 1116 of which were differentially expressed compared with those in A19. The common immunological proteins of OMPs (Bcsp31, Omp25, Omp10, Omp19, Omp28, and Omp2a), HSPs (DnaK, GroS, and GroL), and SodC were enriched in the proteome of A19BG. By protein micro array-based antibody profiling, significant differences were observed between A19BG and A19 immune response, and a number of signature immunogenic proteins were identified. Two of these proteins, the BMEII0032 and BMEI0892 proteins were significantly different (P < 0.01) in distinguishing between A19 and A19BG immune sera and were identified as differential diagnostic antigens for the A19BG vaccine candidate. In conclusion, using comparative proteomics and antibody profiling, protein components and signature antigens were identified for the ghost vaccine candidate A19BG, which are valuable for further developing the vaccine and its monitoring assays.

Brucellosis control methods with an emphasis on vaccination: a systematic review

INTRODUCTION

Brucellosis is considered as one of the main zoonotic infections and a major public health concern worldwide. The aim of the present study was to evaluate various strategies for controlling brucellosis with an especial emphasis on efficacy of vaccination.

AREAS COVERED

International databanks (Web of Science, PubMed, Embase) were searched for potentially relevant studies published from January 1, 2011 to March 25, 2021 using the following keywords: "Brucella", "Brucella abortus", "Brucella melitensis", "Brucella canis", "Brucella suis", "brucellosis", "Bang disease", "undulant fever", "Malta fever", "vaccination", "vaccine", and "immunization". The literature search was restricted to original articles published in English.

EXPERT OPINION

Various methods are employed to prevent and control brucellosis, such as removing sick animals by slaughtering, separating sick animals from the herd, and vaccination. Preventing, controlling, and eradicating brucellosis requires a lot of financial support, perseverance, and time. In order to conduct a detailed study, it is recommended that more studies be conducted in developing countries and different parts of the world.

Protection against virulent Brucella spp. by gamma-irradiated B. ovis in BALB/c mice model

Purpose

Brucella spp. is a zoonosis that causes undulant fever in humans and abortion in livestock worldwide. Lately, it was conveyed that vaccines developed by irradiation have induced a strong cellular and humoral immune response which have made these types of vaccines highly effective.

Materials and Methods

In this study, we aimed to use the gamma-irradiated B. ovis as a vaccine and to study the humoral immune response and cytokines production in order to evaluate it for protecting mice against B. abortus 544, B. melitensis 16M, and B. ovis.

Results

The humoral immune response in immunized mice with gamma-irradiated B. ovis showed a lasting for 8 weeks after immunization. Moreover, immunoglobulin G (IgG), IgG1, IgG2a, and IgG2b isotypes antibodies against B. ovis were observed after 4 and 8 weeks of the last immunization. It was noticed that the production of tumor necrosis factor-α, interferon-γ, and interleukin (IL)-10 continued after 4 and 8 weeks by splenocytes from immunized BALB/c mice, while no production of IL-4 or IL-5 was observed.

Conclusion

Our results indicate that the protection of BALB/c mice against B. melitensis 16M, B. abortus 544, and B. ovis was induced and the developed vaccine at our laboratory could stimulate similar protection to those induced by the traditional vaccine.

Epitope-Based Vaccine of a Brucella abortus Putative Small RNA Target Induces Protection and Less Tissue Damage in Mice

Brucella spp. are Gram-negative, facultative intracellular bacteria that cause brucellosis in humans and animals. Currently available live attenuated vaccines against brucellosis still have drawbacks. Therefore, subunit vaccines, produced using epitope-based antigens, have the advantage of being safe, cost-effective and efficacious. Here, we identified B. abortus small RNAs expressed during early infection with bone marrow-derived macrophages (BMDMs) and an apolipoprotein N-acyltransferase (Int) was identified as the putative target of the greatest expressed small RNA. Decreased expression of Int was observed during BMDM infection and the protein sequence was evaluated to rationally select a putative immunogenic epitope by immunoinformatic, which was explored as a vaccinal candidate. C57BL/6 mice were immunized and challenged with B. abortus, showing lower recovery in the number of viable bacteria in the liver, spleen, and axillary lymph node and greater production of IgG and fractions when compared to non-vaccinated mice. The vaccinated and infected mice showed the increased expression of TNF-α, IFN-γ, and IL-6 following expression of the anti-inflammatory genes IL-10 and TGF-β in the liver, justifying the reduction in the number and size of the observed granulomas. BMDMs stimulated with splenocyte supernatants from vaccinated and infected mice increase the CD86+ marker, as well as expressing greater amounts of iNOS and the consequent increase in NO production, suggesting an increase in the phagocytic and microbicidal capacity of these cells to eliminate the bacteria.

Bayesian Estimation of the Prevalence and Test Characteristics (Sensitivity and Specificity) of Two Serological Tests (RB and SAT-EDTA) for the Diagnosis of Bovine Brucellosis in Small and Medium Cattle Holders in Ecuador

In Ecuador, a national program for bovine brucellosis control has been in implementation since 2008. Given the costs, small- and medium-sized livestock holders are not completely committed to it. The objective of this study was to determine true prevalence (TP) of bovine brucellosis in small- and medium-sized herd populations, as well as the diagnostic sensitivity and specificity of the Rose Bengal (RB) test and the sero-agglutination test (SAT)-EDTA using a Bayesian approach. Between 2011 and 2016, 2733 cattle herds were visited, and 22,592 animal blood samples were taken in nineteen provinces on mainland Ecuador. Bayes-p and deviance information criterion (DIC) statistics were used to select models. Additionally, risk-factor analysis was used for herds according to their brucellosis test status. True prevalence (TP) in herds was estimated by pool testing. National seroprevalence of farms was 7.9% (95% CI: 6.79–9.03), and TP was 12.2% (95% CI: 7.8–17.9). Apparent prevalence (AP) in animals was 2.2% (95% CI: 1.82–2.67), and TP was 1.6% (95% CrI: 1.0–2.4). Similarly, the sensitivity of the RB was estimated at 64.6% (95% CrI: 42.6–85.3) and specificity at 98.9% (95% CrI: 98.6–99.0); for the SAT-EDTA test, sensitivity was 62.3% (95% CrI: 40.0–84.8) and 98.9% (95% CrI: 98.6–99.1) for specificity. Results of the two tests were highly correlated in infected and uninfected animals. Likewise, high spatial variation was observed, with the Coastal Region being the zone with the highest TP at 2.5%. (95% CrI: 1.3–3.8%) in individual animals and 28.2% (95% CI: 15.7–39.8) in herds. Risk factors include herd size, type of production (milk, beef, and mixed), abortions recorded, and vaccination. The results of this study serve to guide authorities to make decisions based on parallel testing at the beginning of a bovine brucellosis program for small livestock holders to increase sensitivity level of the screening tests in Ecuador.

Development of Brucella melitensis Rev.1 ΔOmp19 mutants with DIVA feature and comparison of their efficacy against three commercial vaccines in a mouse model

Brucella is an intracellular zoonotic pathogen that can affect many hosts. Brucella melitensis Rev.1 is a live attenuated, is one of the most effective vaccine strain against brucellosis. It can be used safely in sheep, goats, and even cattle. Although many studies are available on this topic, there is no effective vaccine strain for sheep and goats that distinguishes the antibody titer produced between the field infections and vaccinations. Outer membrane protein 19 (Omp 19) is both virulent and a protective antigen found on the cell-wall of the Brucella strain. In this study, used the suicide plasmid pJQ200KS, which contained homologous region without Omp19 Open Reading Frame (ORF) that was transferred to B. melitensis Rev.1 and further transformed into spheroplasts along with penicillin, ampicillin, and glycine by electroporation. To obtain a mutant vector from Escherichia coli, we used the heat shock transformation method along with the blue-white colony screening using X-gal media, whereas for the gene transfer in Brucella, we used electroporation. A scanning electron microscope (S.E.M) was used to observe the spheroplast transformation while the mutant vector and deletion mutants were confirmed through PCR and sequence analysis. In the mouse model efficacy trials, three commercial vaccines were found to comply with the OIE standards. Although the deletion mutants 19 and 44/10 had similar efficiency as the commercial vaccines in terms of stimulation power, the ELISA test with Omp19 protein showed the same results as the negative control. The Rev.1 Omp19 deletion mutants obtained in this study contained sufficient residual virulence, and their protective immunity was similar to the commercial vaccines. The study showed that a vaccine prepared using a B. melitensis Rev.1 ΔOmp19 can act as a marker vaccine or differentiate infected from vaccinated animals (DIVA) through the ELISA test that detects the Omp19 protein.

Study on immunogenicity and antigenicity of a novel brucella multiepitope recombined protein

Currently, brucellosis is a reemerged zoonotic infectious disease with an increased incidence in recent years. A simple, rapid and sensitive method for diagnosing brucellosis can help to reduce medical burden and economic loss. Previously, a multiple epitope recombinant protein was constructed based on linear B-cell epitope prediction tools. In this study, the recombinant protein was used as an antigen to study the immune response produced by immunized mice, and goat serum was used to verify its diagnostic accuracy. The production of antibodies was successfully induced in the vaccinated mice. Flow cytometric analysis revealed that the percentage of CD4⁺, CD8⁺ and the CD4+/CD8+ ratios were increased by T cell subsets in mouse splenocytes, indicating that the recombinant protein induced a strong immune response had strong immunoreactivity. Using indirect ELISA, the recombinant protein correctly diagnosed positive and negative brucellosis samples. Compared with the whole bacterial antigen, the recombinant protein had a weaker sensitivity but a stronger specificity. Animal experiments showed that the recombinant protein had good antigenicity, and indirect ELISA indicates that it can be used as an antigen to diagnose brucellosis. Therefore, the recombinant protein is a potential candidate antigen for brucellosis vaccine development and serological diagnosis.

The State of the Art in Biodefense Related Bacterial Pathogen Detection Using Bacteriophages: How It Started and How It's Going

Accurate pathogen detection and diagnosis is paramount in clinical success of treating patients. There are two general paradigms in pathogen detection: molecular and immuno-based, and phage-based detection is a third emerging paradigm due to its sensitivity and selectivity. Molecular detection methods look for genetic material specific for a given pathogen in a sample usually by polymerase chain reaction (PCR). Immuno-methods look at the pathogen components (antigens) by antibodies raised against that pathogen specific antigens. There are different variations and products based on these two paradigms with advantages and disadvantages. The third paradigm at least for bacterial pathogen detection entails bacteriophages specific for a given bacterium. Sensitivity and specificity are the two key parameters in any pathogen detection system. By their very nature, bacteriophages afford the best sensitivity for bacterial detection. Bacteria and bacteriophages form the predator-prey pair in the evolutionary arms race and has coevolved over time to acquire the exquisite specificity of the pair, in some instances at the strain level. This specificity has been exploited for diagnostic purposes of various pathogens of concern in clinical and other settings. Many recent reviews focus on phage-based detection and sensor technologies. In this review, we focus on a very special group of pathogens that are of concern in biodefense because of their potential misuse in bioterrorism and their extremely virulent nature and as such fall under the Centers for Disease and Prevention (CDC) Category A pathogen list. We describe the currently available phage methods that are based on the usual modalities of detection from culture, to molecular and immuno- and fluorescent methods. We further highlight the gaps and the needs for more modern technologies and sensors drawing from technologies existing for detection and surveillance of other pathogens of clinical relevance.

An estimate of the incidence and quantitative risk assessment of human brucellosis in mainland China

Two epidemiological models were applied to simulate whether animals with latent infections were contagious and calculate the outcomes of people that contracting brucellosis by all possible transmission routes under control measures implemented by the Chinese government. The health and economic burden of brucellosis overall presented an increasing trend from 2004 to 2017. Scenarios from epidemiological models showed that a larger scale of vaccine coverage would contribute to fewer infections in livestock and humans. S2 vaccine, the disinfection of the environment and the protection of the susceptible animals and humans could effectively reverse the trend of increasing brucellosis and reduce the incidence rates of brucellosis in humans to curb the epidemic of brucellosis in China.

Xyloglucan based mucosal nanovaccine for immunological protection against brucellosis developed by supercritical fluid technology

Vaccines delivered via the mucosal route have logistic benefits over parenteral or intramuscular vaccines as they offer patient compliance. This study presents the first intranasal, controlled release, subunit nanovaccine comprising mucoadhesive tamarind seed polymer (xyloglucan) based nanoparticles produced using an efficient, environmentally compatible, and industrially scalable technique: rapid expansion of supercritical solution. The nanovaccine formulation aimed against brucellosis comprised xyloglucan nanoparticles loaded separately with antigenic acellular lipopolysaccharides from B. abortus (S19) and the immunoadjuvant quillaja saponin. The nanovaccine elicited prolonged humoral and cell-mediated immunity in female Balb/c mice. Nasal vaccination with the nanovaccine resulted in higher levels of mucosal IgA and IgG than with an aqueous solution of soluble lipopolysaccharides and quillaja saponin. Systemic immunity triggered by the nanovaccine was evidenced by higher IgG levels in sera post priming and boosting. The nanovaccine induced a mixed Th1/Th2 type of immunity with higher IgG2a levels and thus a polarized Th1 response. The results suggest that the nanovaccine administered by homologous nasal route can prime the immune system via the mucosal and systemic pathways and is a good candidate for vaccine delivery.

A safe non-toxic Brucella abortus ghosts induce immune responses and confer protection in BALB/c mice

Brucellosis, which is caused by Brucella spp., is an important zoonotic infectious disease that can cause great hazard to public health and safety. However, the current vaccines have several drawbacks, including residual virulence for animals and humans. Bacterial ghost is the empty envelopes of bacteria, which emerge as a proper vaccine candidate. With the purpose of generating B. abortus ghosts and investigating the immunogenicity of bacterial ghosts as vaccine candidate, we used homologous recombination and bacterial ghost technologies to construct 2308ΔgntR ghost strain. Mice were injected with 2308ΔgntR ghost and the safety and immunogenicity of ghost were further evaluated. The mice inoculated with ghost showed no splenomegaly. The 2308ΔgntR ghost induced high protective immunity in BALB/c mice against challenge with S2308, and elicited an anti-Brucella-specific immunoglobulin G (IgG) response and induced the secretion of interferon gamma (IFN-γ) and interleukin-4 (IL-4). Additionally, 2308ΔgntR ghost demonstrated strong spleen CD4⁺ and CD8⁺ T cell responses. These results suggest that 2308ΔgntR ghost is a potential vaccine candidate and may represent a promising new approach for vaccination against Brucella infection.

A novel recombinant multiepitope protein candidate for the diagnosis of brucellosis: A pilot study

Brucellosis is a zoonotic disease transmitted to humans from infected animals. As a systemic disease, it can harm any organ or system of the host body. Human brucellosis presents with various clinical symptoms, which makes diagnosis challenging. Serological diagnosis of brucellosis is based on ELISA or agglutination tests, which use colorimetry to detect antibodies generated against lipopolysaccharide (LPS) or extracts from whole-cell bacteria. To construct a protein that can specifically recognize Brucella, we analyzed hydrophilicity, accessibility, flexibility, antigenicity, and β-turns using a protein network server. Then, we chose the most abundant immunodominant epitopes of the outer membrane proteins omp31, BP26, omp2b and omp16. Based on the sequences of these major epitopes, fifteen major immunodominant epitopes were selected to construct a synthetic Brucella recombinant multiepitope outer membrane protein (rOmp) gene. This recombinant gene was expressed in E. coli, and the produced protein was purified by Ni-NTA affinity purification. The purified protein was tested in an indirect ELISA assay, demonstrating a high level of sensitivity and specificity. This technique is creating a unique antigen that, coupled with overexpression and low-cost purification, offers a promising diagnosis of both human and animal brucellosis, with the potential to avoid the disadvantages of whole brucellosis-antigen-based assays.

Synthetic carbohydrate-based vaccines: challenges and opportunities

Glycoconjugate vaccines based on bacterial capsular polysaccharides (CPS) have been extremely successful in preventing bacterial infections. The glycan antigens for the preparation of CPS based glycoconjugate vaccines are mainly obtained from bacterial fermentation, the quality and length of glycans are always inconsistent. Such kind of situation make the CMC of glycoconjugate vaccines are difficult to well control. Thanks to the advantage of synthetic methods for carbohydrates syntheses. The well controlled glycan antigens are more easily to obtain, and them are conjugated to carrier protein to from the so-call homogeneous fully synthetic glycoconjugate vaccines. Several fully glycoconjugate vaccines are in different phases of clinical trial for bacteria or cancers. The review will introduce the recent development of fully synthetic glycoconjugate vaccine.

Research Progress on Brucellosis

Brucellosis is a debilitating febrile illness caused by an intracellular Brucella. The disease is distributed in humans and animals widely, especially in developing countries. Ten species are included in the genus Brucella nowadays; four species of them are pathogenic to humans, which make brucellosis a zoonosis with more than 500,000 new cases reported annually. For human brucellosis, the most pathogenic species is B. melitensis followed by B. suis, while B. abortus is the mildest type of brucellosis. The infection mechanism of Brucella is complicated and mostly relies on its virulence factors. The therapy of the disease contains vaccination and antibiotic. However, there are some defects in currently available vaccines such as the lower protective level and safety. Thus, safe and efficient vaccines for brucellosis are still awaited. The dual therapy of antibacterial is effective in the treatment of brucellosis if a rapid and exact detection method is found.

Brucellosis in India: results of a collaborative workshop to define One Health priorities

Brucellosis is an important zoonosis worldwide. In livestock, it frequently causes chronic disease with reproductive failures that contribute to production losses, and in humans, it causes an often-chronic febrile illness that is frequently underdiagnosed in many low- and middle-income countries, including India. India has one of the largest ruminant populations in the world, and brucellosis is endemic in the country in both humans and animals. In November 2017, the International Livestock Research Institute invited experts from government, national research institutes, universities, and different international organizations to a one-day meeting to set priorities towards a "One Health" control strategy for brucellosis in India. Using a risk prioritization exercise followed by discussions, the meeting agreed on the following priorities: collaboration (transboundary and transdisciplinary); collection of more epidemiological evidence in humans, cattle, and in small ruminants (which have been neglected in past research); Economic impact studies, including cost effectiveness of control programmes; livestock vaccination, including national facilities for securing vaccines for the cattle population; management of infected animals (with the ban on bovine slaughter, alternatives such as sanctuaries must be explored); laboratory capacities and diagnostics (quality must be assured and better rapid tests developed); and increased awareness, making farmers, health workers, and the general public more aware of risks of brucellosis and zoonoses in general. Overall, the meeting participants agreed that brucellosis control will be challenging in India, but with collaboration to address the priority areas listed here, it could be possible.

Identification of Cross-Protective Potential Antigens against Pathogenic Brucella spp. through Combining Pan-Genome Analysis with Reverse Vaccinology

Brucellosis is a zoonotic infectious disease caused by bacteria of the genus Brucella. Brucella melitensis, Brucella abortus, and Brucella suis are the most pathogenic species of this genus causing the majority of human and domestic animal brucellosis. There is a need to develop a safe and potent subunit vaccine to overcome the serious drawbacks of the live attenuated Brucella vaccines. The aim of this work was to discover antigen candidates conserved among the three pathogenic species. In this study, we employed a reverse vaccinology strategy to compute the core proteome of 90 completed genomes: 55 B. melitensis, 17 B. abortus, and 18 B. suis. The core proteome was analyzed by a metasubcellular localization prediction pipeline to identify surface-associated proteins. The identified proteins were thoroughly analyzed using various in silico tools to obtain the most potential protective antigens. The number of core proteins obtained from analyzing the 90 proteomes was 1939 proteins. The surface-associated proteins were 177. The number of potential antigens was 87; those with adhesion score ≥ 0.5 were considered antigen with "high potential," while those with a score of 0.4-0.5 were considered antigens with "intermediate potential." According to a cumulative score derived from protein antigenicity, density of MHC-I and MHC-II epitopes, MHC allele coverage, and B-cell epitope density scores, a final list of 34 potential antigens was obtained. Remarkably, most of the 34 proteins are associated with bacterial adhesion, invasion, evasion, and adaptation to the hostile intracellular environment of macrophages which is adjusted to deprive Brucella of required nutrients. Our results provide a manageable list of potential protective antigens for developing a potent vaccine against brucellosis. Moreover, our elaborated analysis can provide further insights into novel Brucella virulence factors. Our next step is to test some of these antigens using an appropriate antigen delivery system.

Development of new generation of vaccines for Brucella abortus

Brucella abortus is a Gram-negative facultative and intracellular bacteria, it causes bovine brucellosis, a zoonotic disease that is responsible for considerable economic loss to owners of domesticated animals and can cause problems in otherwise healthy humans. There are a few available live attenuated vaccines for animal immunization against brucellosis; however, these have significant side effects and offer insufficient protective efficacy. Thus, the need for more research into the Molecular pathobiology and immunological properties of B. abortus that would lead to the development of better and safer vaccines. In this paper we have reviewed the main aspects of the pathology and the responsive immunological mechanisms, we have also covered current and new prospective vaccines against B. abortus.

Herd-level risk factors associated with Brucella sero-positivity in cattle, and perception and behaviours on the disease control among agro-pastoralists in Tanzania

Brucellosis is endemic in Tanzania, particularly in agro-pastoral areas. This study investigated the herd-level sero-prevalence and risk factors for Brucella sero-positivity in cattle, and perception and behaviours associated with brucellosis control among agro-pastoralists in Morogoro Region, Tanzania. A cross-sectional study involving herd milk diagnosis by indirect enzyme-linked immunosorbent assay and questionnaire survey was conducted in 124 farms. Questions included potential risk factors, knowledge of brucellosis, willingness-to-pay for cattle vaccination, and item count technique (ICT) for selling behaviour of cows that experienced abortion. Risk factor analysis for Brucella sero-positivity in cattle and analysis of factors associated with willingness-to-pay were conducted using classical tests and generalised linear models. Most farmers had little knowledge about brucellosis (disease name: 13.7%, symptoms: 3.2%, transmission from cattle to human: 2.4%, and Brucella vaccine: 2.4%). The proportion of Brucella sero-positive herd was 44.4% (55/124, 95%CI: 35.5-53.5). No risk factors for Brucella sero-positivity were identified; however, using a veterinary service was identified as a preventive factor (OR = 0.39, 95%CI: 0.18-0.84, p =  0.02). For scenarios of vaccinating all cattle and only calves, 59.7% and 89.5% of farmers were willing to pay for vaccination, respectively. Being a Maasai tribe member was a hesitating factor for vaccinating all cattle (OR = 0.39, 95%CI: 0.19-0.83, p =  0.01) and using a veterinary service was an encouraging factor for vaccinating calves (OR = 4.0, 95%CI: 1.2-13.0, p =  0.02). The ICT found that 45.1% of farmers sold cows that experienced abortion. This estimate was not statistically different from that obtained by direct questioning (34.1%, SE = 7.5%, binomial p value = 0.27, factor score = 1.32), suggesting that farmers did not hesitate to sell such cows. The Maasai conducted more risky behaviours for human infection such as drinking raw milk (p = 0.06) or blood (p <  0.01) and helping delivery with bare hands (p = 0.03) than other tribes. Community-based brucellosis control programmes with calf vaccination may be feasible in the study areas. A One Health approach including the promotion of health education and expansion of veterinary services is crucial for disease control.

Evaluation of DNA vaccine encoding BCSP31 surface protein of Brucella abortus for protective immunity

Brucellosis is a highly contagious and zoonotic disease and has a considerable impact on animal health and economy of a country, principally in Pakistan, where rural income largely depends upon livestock farming and dairy products. The disease burden is more in underdeveloped/developing countries due to the low economy and limited access to the diagnostic facilities. In Pakistan, the prevalence of Brucella abortus is very high, so it is the need of the hour to control this disease through more advanced methods. This study was designed with the aim to construct the DNA based vaccine of gene encoding antigenic surface protein (BCSP₃₁). For this purpose, the BCSP₃₁ gene was amplified, purified and ligated in pTZ57 R/T (cloning vector). Dubbed BCSP₃₁-pTZ57 R/T vector was transformed into competent cells (DH5α). After plasmid extraction, the plasmid and pET-28a vector was restricted with EcoRI and BamHI. Again, ligation was done and dubbed pET-28a-BCSP₃₁ transformed into E. coli (BL21). After expression, the protein was purified and used for evaluation of immunogenic response. The protective and immunogenic efficacy of the vaccine was evaluated in rabbits (n = 20). The rabbits were divided into four equal groups. Groups A-C were given purified protein diluted in normal saline @ 750, 1500 and 3000 μg/0.2 mL, respectively through intraconjunctival route. Group D was given 0.2 mL normal saline through intraconjunctival route. Specific immunoglobulin G (IgG) responses were measured through indirect ELISA on a weekly basis. The titer of IgG against the antigen was significantly (p < 0.05) higher in vaccinated groups A-C as compared to group D (control group) in a dose dependent manner. Moreover, log units of protection produced by DNA based vaccine in the rabbits (3.02) also indicated the protective efficacy of the DNA vaccine against B. abortus challenge. The response of this vaccine in rabbit suggested its potential effectiveness against Brucella abortus in large animals.

Risk factors of brucellosis (re-)incidence in sheep and goat flocks in an endemic area of Portugal

This study aimed to determinate the main risk factors of brucellosis recurrence or highest animal incidence in flocks, under pastoralism, in an endemic area of Northeast Portugal. An epidemiological survey was performed on 25 recurrent (n = 18) or highest seropositive (n = 7) sheep and mixed goat flocks and 19 historical (≥ 10 years) brucellosis-free flock, between 2014 and 2017, within the same epidemiological area presenting an average annual incidence around 6%. According to the multivariable logistic model (P < 0.001), the lack of neighboring brucellosis-free flocks (odds ratio OR = 7.79; CI % 1.49-65.06), the occurrence of more than 50% of lambing or kidding in common paths and pastures (OR = 24.17; CI % 3.0-606.54), and the animal replacement with Rev.1 non-vaccinated young animals (OR = 18.47; CI % 2.54-408.21) were the causes that influence the recurrence and highest animal incidence in flocks. In extensive production systems, the confinement of the peri-parturient and the small ruminant replacement with Rev.1 vaccinated young females seems to play a major role on brucellosis control and eradication.

Protective role of Brucella abortus specific murine antibodies in inhibiting systemic proliferation of virulent strain 544 in mice and guinea pig

Aim:

The major objective of the investigation was to evaluate the hitherto uncharacterized potential of Brucella-specific antibodies to win the battle against virulent Brucellaabortus infection.

Materials and Methods:

Brucella-specific immune serum was raised in mice. The antibody titer of serum was determined by standard tube agglutination test and indirect enzyme-linked immunosorbent assays (iELISA). Groups of mice and guinea pigs were passively immunized with serum containing specific agglutinin titers. 24 h after immunization, all animals along with unimmunized controls were challenged with B. abortus S544. Total B. abortus S544 counts in the spleen of each animal collected on the 7^th day of challenge was determined to evaluate the protective index (PI) of anti-Brucella serum by statistical analysis.

Result:

A dose-dependent protective response to immune mice serum was observed in both experimental models though the values of PI of mice were higher than those obtained for guinea pigs. The PI values in mice passively immunized with 50 IU or 25 IU antibodies were 1.38 and 0.69, respectively. In guinea pigs, however, animals passively immunized with 50 IU or 25 IU antibodies showed PI values equivalent to 0.79 and 0.41, respectively.

Conclusion:

The observations support our hypothesis that the presence of antibodies inhibits the initial multiplication and eventual colonization of systemic organs by B. abortus. Therefore, a predominant antibody-mediated response induced by a vaccine is expected to protect the animal against the most severe clinical outcome of infection.

Changing Epidemiology of Human Brucellosis, China, 1955-2014

Brucellosis, a zoonotic disease, was made statutorily notifiable in China in 1955. We analyzed the incidence and spatial–temporal distribution of human brucellosis during 1955–2014 in China using notifiable surveillance data: aggregated data for 1955–2003 and individual case data for 2004–2014. A total of 513,034 brucellosis cases were recorded, of which 99.3% were reported in northern China during 1955–2014, and 69.1% (258, 462/374, 141) occurred during February–July in 1990–2014. Incidence remained high during 1955–1978 (interquartile range 0.42–1.0 cases/100,000 residents), then decreased dramatically in 1979–1994. However, brucellosis has reemerged since 1995 (interquartile range 0.11–0.23 in 1995–2003 and 1.48–2.89 in 2004–2014); the historical high occurred in 2014, and the affected area expanded from northern pastureland provinces to the adjacent grassland and agricultural areas, then to southern coastal and southwestern areas. Control strategies in China should be adjusted to account for these changes by adopting a One Health approach.

The Influence of Vaccine on Febrile Seizure

BACKGROUND

The protective value of vaccines to the public has made vaccines among the major public health prophylactic measures through the entire history. However, there has been some controversy about their safety; particularly concerns have been rising about febrile seizures (FS). Vaccination was found to be the second most common cause of FS.

METHODS

We research and collect relative online content for reviewing the effects of vaccine in FS.

RESULTS

there is no causal relationship between FS and vaccination. This relationship is complex by other factors, such as age, genetic inheritance, type of vaccine, combination of different types of vaccines and the timing of vaccination.

CONCLUSION

In order to reduce FS after vaccination, it is important to understand the mechanism of epilepsy and relationship between specific vaccines and FS. Parents should be informed that some vaccines could be associated with an increased risk of FS, particularly, in children with personal and family history of FS. Children with genetic epilepsy syndrome are prone to seizures and certain vaccinations should be avoided in these children. It is highly recommended to choose vaccines with lower risk of developing FS and to administer these vaccines during the low risk window of immunizations schedule.

Alternative strategies for vaccination to brucellosis

Brucellosis remains burdensome for livestock and humans worldwide. Better vaccines for protection are needed to reduce disease incidence. Immunity to brucellosis and barriers to protection are discussed. The benefits and limitations of conventional and experimental brucellosis vaccines are outlined, and novel vaccination strategies needed to ultimately protect against brucellosis are introduced.

Brucellosis: Improved Diagnostics and Vaccine Insights from Synthetic Glycans

Brucellosis is a serious zoonotic bacterial disease that is ranked by the World Health Organization among the top seven “neglected zoonoses” that threaten human health and cause poverty. It is a costly, highly contagious disease that affects ruminants, cattle, sheep, goats, and other productive animals such as pigs. Symptoms include abortions, infertility, decreased milk production, weight loss, and lameness. Brucellosis is also the most common bacterial disease that is transmitted from animals to humans, with approximately 500 000 new human cases each year. Detection and slaughter of infected animals is required to eradicate the disease, as vaccination alone is currently insufficient. However, as the most protective vaccines compromise serodiagnosis, this creates policy dilemmas, and these often result in the failure of eradication and control programs. Detection of antibodies to the Brucella bacterial cell wall O-polysaccharide (OPS) component of smooth lipopolysaccharide is used in diagnosis of this disease, and the same molecule contributes important protective efficacy to currently deployed veterinary whole-cell vaccines. This has set up a long-standing paradox that while Brucella OPS confers protective efficacy to vaccines, its presence results in similar antibody profiles in infected and vaccinated animals. Consequently, differentiation of infected from vaccinated animals (DIVA) is not possible, and this limits efforts to combat the disease. Recent clarification of the chemical structure of Brucella OPS as a block copolymer of two oligosaccharide sequences has provided an opportunity to utilize unique oligosaccharides only available via chemical synthesis in serodiagnostic tests for the disease. These oligosaccharides show excellent sensitivity and specificity compared with the native polymer used in current commercial tests and have the added advantage of assisting discrimination between brucellosis and infections caused by several bacteria with OPS that share some structural features with those of Brucella. During synthesis and immunochemical evaluation of these synthetic antigens, it became apparent that an opportunity existed to create a polysaccharide–protein conjugate vaccine that would not create antibodies that give false positive results in diagnostic tests for infection. This objective was reduced to practice, and immunization of mice showed that antibodies to the Brucella A antigen could be developed without reacting in a diagnostic test based on the M antigen. A conjugate vaccine of this type could readily be developed for use in humans and animals. However, as chemical methods advance and modern methods of bacterial engineering mature, it is expected that the principles elucidated by these studies could be applied to the development of an inexpensive and cost-effective vaccine to combat endemic brucellosis in animals.

The Brucella melitensis M5-90ΔmanB live vaccine candidate is safer than M5-90 and confers protection against wild-type challenge in BALB/c mice

Brucellosis is a globally distributed zoonotic disease that causes animal and human diseases. Although effective, the current Brucella vaccines (strain M5-90 or others) have several drawbacks. The first is their residual virulence for animals and humans and the second is their inability to differentiate natural infection from that caused by vaccination. In the present study, Brucella melitensis M5-90 manB mutant (M5-90ΔmanB) was generated to overcome these drawbacks. M5-90ΔmanB showed significantly reduced survival in macrophages and mice, and induced strong protective immunity in BALB/c mice. It elicited anti-Brucella-specific IgG1 and IgG2a subtype responses and induced the secretion of gamma interferon (IFN-γ) and interleukin-4(IL-4). Results of immune assays showed, M5-90ΔmanB immunization induced the secretion of IFN-γ in goats, and serum samples from goats inoculated with M5-90ΔmanB were negative by Bengal Plate Test (RBPT) and Standard Tube Agglutination Test (STAT). Further, the ManB antigen also allows serological assays differentiate infections caused by wild strains from infections by vaccination. These results show that M5-90ΔmanB is a suitable attenuated vaccine candidate against virulent Brucella melitensis 16 M (16 M) infection.

A comprehensive proteogenomic study of the human Brucella vaccine strain 104 M

BACKGROUND

Brucella spp. are Gram-negative, facultative intracellular pathogens that cause brucellosis in both humans and animals. The B. abortus vaccine strain 104 M is the only vaccine available in China for the prevention of brucellosis in humans. Although the B. abortus 104 M genome has been fully sequenced, the current genome annotations are not yet complete. In addition, the main mechanisms underpinning its residual toxicity and vaccine-induced immune protection have yet to be elucidated. Mapping the proteome of B. abortus 104 M will help to improve genome annotation quality, thereby facilitating a greater understanding of its biology.

RESULTS

In this study, we utilized a proteogenomic approach that combined subcellular fractionation and peptide fractionation to perform a whole-proteome analysis and genome reannotation of B. abortus 104 M using high-resolution mass spectrometry. In total, 1,729 proteins (56.3% of 3,072) including 218 hypothetical proteins were identified using the culture conditions that were employed this study. The annotations of the B. abortus 104 M genome were also refined following identification and validation by reverse transcription-PCR. In addition, 14 pivotal virulence factors and 17 known protective antigens known to be involved in residual toxicity and immune protection were confirmed at the protein level following induction by the 104 M vaccine. Moreover, a further insight into the cell biology of multichromosomal bacteria was obtained following the elucidation of differences in protein expression levels between the small and large chromosomes.

CONCLUSIONS

The work presented in this report used a proteogenomic approach to perform whole-proteome analysis and genome reannotation in B. abortus 104 M; this work helped to improve genome annotation quality. Our analysis of virulence factors, protective antigens and other protein effectors provided the basis for further research to elucidate the mechanisms of residual toxicity and immune protection induced by the 104 M vaccine. Finally, the potential link between replication dynamics, gene function, and protein expression levels in this multichromosomal bacterium was detailed.

Novel Solutions for Vaccines and Diagnostics To Combat Brucellosis

Brucellosis is diagnosed by detection of antibodies in the blood of animals and humans that are specific for two carbohydrate antigens, termed A and M, which are present concurrently in a single cell wall O-polysaccharide. Animal brucellosis vaccines contain these antigenic determinants, and consequently infected and vaccinated animals cannot be differentiated as both groups produce A and M specific antibodies. We hypothesized that chemical synthesis of a pure A vaccine would offer unique identification of infected animals by a synthetic M diagnostic antigen that would not react with antibodies generated by this vaccine. Two forms of the A antigen, a hexasaccharide and a heptasaccharide conjugated to tetanus toxoid via reducing and nonreducing terminal sugars, were synthesized and used as lead vaccine candidates. Mouse antibody profiles to these immunogens showed that to avoid reaction with diagnostic M antigen it was essential to maximize the induction of anti-A antibodies that bind internal oligosaccharide sequences and minimize production of antibodies directed toward the terminal nonreducing monosaccharide. This objective was achieved by conjugation of Brucella O-polysaccharide to tetanus toxoid via its periodate oxidized terminal nonreducing monosaccharide, thereby destroying terminal epitopes and focusing the antibody response on internal A epitopes. This establishes the method to resolve the decades-long challenge of how to create effective brucellosis vaccines without compromising diagnosis of infected animals.

Vaccination with a ΔnorD ΔznuA Brucella abortus mutant confers potent protection against virulent challenge

There remains a need for an improved livestock vaccine for brucellosis since conventional vaccines are only ∼70% efficacious, making some vaccinated animals susceptible to Brucella infections. To address this void, a vaccine capable of evoking protective immunity, while still being sufficiently attenuated to produce minimal disease, is sought. In this pursuit, the ΔnorD ΔznuA B. abortus-lacZ (termed as znBAZ) was developed to be devoid of functional norD and znuA B. abortus genes, and to contain the lacZ as a marker gene. The results show that znBAZ is highly attenuated in mouse and human macrophages, and completely cleared from mouse spleens within eight weeks post-vaccination. Producing less splenic inflammation, znBAZ is significantly more protective than the conventional RB51 vaccine by more than four orders of magnitude. Vaccination with znBAZ elicits elevated numbers of IFN-γ⁺, TNF-α⁺, and polyfunctional IFN-γ⁺ TNF-α⁺ CD4⁺ and CD8⁺ T cells in contrast to RB51-vaccinated mice, which show reduced numbers of proinflammatory cytokine-producing T cells. These results demonstrate that znBAZ is a highly efficacious vaccine candidate capable of eliciting diverse T cell subsets that confer protection against parenteral challenge with virulent, wild-type B. abortus.