Rapid multiplex PCR assay for the simultaneous detection of the Brucella Genus, B. abortus, B. melitensis, and B. suis

Serological and molecular prevalence of Brucella spp. among livestock species in Rajasthan, India

A seroprevalence and molecular study was carried out in six districts of the state of Rajasthan, India to detect brucellosis in major livestock species. This study involves the testing of 3,245 livestock samples using the Rose Bengal Plate Test (RBPT), Indirect Enzyme-Linked Immunosorbent Assay (i-ELISA), and genus-specific polymerase chain reaction (PCR) markers for molecular diagnosis of the disease. In the tested samples, seroprevalence was 5.06% (CI: 1.96-8.15) using the RBPT test and 6.88% (CI: 1.98-11.78) using the i-ELISA test, while the cumulative seroprevalence (RBPT and i-ELISA) was 3.63% (CI: 0.44-6.83). The prevalence of the disease was 1.27% (CI: 0.56-3.11) when tested using molecular markers. The highest prevalence of brucellosis was detected in Cattle (7.00, 3.22%), followed by camels (5.50, 2.50%), buffalo (2.66, 0.00%), sheep (2.43, 0.41%), and goats (0.58, 0.23%) when serological (cumulative) and molecular diagnosis were considered preferred methods of detection. Cattle (3.22%) and camels (2.50%) also showed a high prevalence of disease when tested using molecular markers. The results of this study reveal that cattle, camel, and sheep brucellosis is prevalent in the study areas.

Design of a new multi-epitope vaccine against Brucella based on T and B cell epitopes using bioinformatics methods

Brucellosis is one of the most serious and widespread zoonotic diseases, which seriously threatens human health and the national economy. This study was based on the T/B dominant epitopes of Brucella outer membrane protein 22 (Omp22), outer membrane protein 19 (Omp19) and outer membrane protein 28 (Omp28), with bioinformatics methods to design a safe and effective multi-epitope vaccine. The amino acid sequences of the proteins were found in the National Center for Biotechnology Information (NCBI) database, and the signal peptides were predicted by the SignaIP-5.0 server. The surface accessibility and hydrophilic regions of proteins were analysed with the ProtScale software and the tertiary structure model of the proteins predicted by I-TASSER software and labelled with the UCSF Chimera software. The software COBEpro, SVMTriP and BepiPred were used to predict B cell epitopes of the proteins. SYFPEITHI, RANKpep and IEDB were employed to predict T cell epitopes of the proteins. The T/B dominant epitopes of three proteins were combined with HEYGAALEREAG and GGGS linkers, and carriers sequences linked to the N- and C-terminus of the vaccine construct with the help of EAAAK linkers. Finally, the tertiary structure and physical and chemical properties of the multi-epitope vaccine construct were analysed. The allergenicity, antigenicity and solubility of the multi-epitope vaccine construct were 7.37–11.30, 0.788 and 0.866, respectively. The Ramachandran diagram of the mock vaccine construct showed 96.0% residues within the favoured and allowed range. Collectively, our results showed that this multi-epitope vaccine construct has a high-quality structure and suitable characteristics, which may provide a theoretical basis for future laboratory experiments.

Brucella melitensis, a latent "travel bacterium," continual spread and expansion from Northern to Southern China and its relationship to worldwide lineages

Brucellosis caused by Brucella melitensis is considered to be one of the most important zoonotic diseases in China. In this study, Conventional bio-typing, MLVA (multiple locus variable-number tandem repeat analysis), and WGS (whole-genome sequencing)-SNP (single nucleotide polymorphism) were used to study the genetic similarity of B. melitensis in northern and southern China and analyze its relationship with worldwide lineages. Currently, the distribution of species/biovars of B. melitensis has obviously changed, and B. melitensis has become the dominant species in southern regions of China. Strains from the southern had a common geographic origin with strains from the northern. Many MLVA-16 events were shared in the genotypes of the southern and northern strains, suggest that genotypic movement occurred from north to south. Based on WGS-SNP analysis, strains from different provinces were closely related and may have descended from one common ancestor, suggests that the southern strains originated from northern China. These data indicate that B. melitensis is a latent “travel bacterium” that spread and expanded from North China to South China. Moreover, B. melitensis strains from China are also genetically related to strains from other Asian regions (Kazakhstan, Russia, Mongolia, and India). The movement of infected sheep and their products requires control.

Multiplex PCR Assay for the Simultaneous Detection of the Brucella Genus in Human Whole Blood and Serum

Background:

Brucellosis disease is a serious zoonosis worldwide and only 17 countries have been recognized as free of brucellosis. The World Health Organization has reported that the incidence of brucellosis is 500,000 cases in a year. Multiplex polymerase chain reaction (PCR) is an ideal method for the identification of brucellosis. The most common primers for the diagnosis of Brucella include B4/B5 and F4/R2. The advantages of multiplex PCR include targeting multiple sequences at the same time, and multiple results are produced in a single test run which saves time and the reagents simultaneously. The purpose of this investigation was to extend and optimize a multiplex PCR for the identification of genus Brucella from serum and whole blood samples.

Methods:

In this experimental and sectional study, blood samples of 25 suspected patients in the acute phase of brucellosis with serum titers higher than 1:80 were collected. Two pairs of specific primers of B4 and B5 the specific gene was amplified. PCR and Multiplex PCR were performed on blood and serum samples.

Results:

Among 25 blood samples, 15 cases (60%) and 9 cases (36%) and among 25 serum samples, 23 cases (92%) and 13 cases (52%) were positive for B4/B5 and F4/R2 in PCR, respectively. In multiplex PCR, among 25 blood samples, 5 cases (20%) showed both bands, 11 cases (44%) showed band 222bp, 4 cases (16%) showed band 905bp and 5 cases (20%) showed no bands. Among 25 serum samples, 6 cases (24%) showed both bands, 15 cases (60%) showed band 222bp, 3 cases (12%) showed band 905bp and 1 case (4%) showed no bands.

Conclusion:

The results of this study show that this multiplex PCR can be used for the diagnosis of brucellosis with high sensitivity in clinical laboratories routinely and it can serve as an alternative substitution for risky culture method and nonspecific serological methods.

Immunological pathways of macrophage response to Brucella ovis infection

As the molecular mechanisms of Brucella ovis pathogenicity are not completely clear, we have applied a transcriptome approach to identify the differentially expressed genes (DEGs) in RAW264.7 macrophage infected with B. ovis. The DEGs related to immune pathway were identified by Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) functional enrichment analysis. Quantitative real-time PCR (qRT-PCR) was performed to validate the transcriptome sequencing data. In total, we identified 337 up-regulated and 264 down-regulated DEGs in B. ovis-infected group versus mock group. Top 20 pathways were enriched by KEGG analysis and 20 GO by functional enrichment analysis in DEGs involved in the molecular function, cellular component, and biological process and so on, which revealed multiple immunological pathways in RAW264.7 macrophage cells in response to B. ovis infection, including inflammatory response, immune system process, immune response, cytokine activity, chemotaxis, chemokine-mediated signaling pathway, chemokine activity, and CCR chemokine receptor binding. qRT-PCR results showed Ccl2 (ENSMUST00000000193), Ccl2 (ENSMUST00000124479), Ccl3 (ENSMUST00000001008), Hmox1 (ENSMUST00000005548), Hmox1 (ENSMUST00000159631), Cxcl2 (ENSMUST00000075433), Cxcl2 (ENSMUST00000200681), Cxcl2 (ENSMUST00000200919), and Cxcl2 (ENSMUST00000202317). Our findings firstly elucidate the pathways involved in B. ovis-induced host immune response, which may lay the foundation for revealing the bacteria–host interaction and demonstrating the pathogenic mechanism of B. ovis.

Laboratory Diagnosis of Human Brucellosis

The clinical presentation of brucellosis in humans is variable and unspecific, and thus, laboratory corroboration of the diagnosis is essential for the patient's proper treatment. The diagnosis of brucellar infections can be made by culture, serological tests, and nucleic acid amplification assays. Modern automated blood culture systems enable detection of acute cases of brucellosis within the routine 5- to 7-day incubation protocol employed in clinical microbiology laboratories, although a longer incubation and performance of blind subcultures may be needed for protracted cases. Serological tests, though they lack specificity and provide results that may be difficult to interpret in individuals repeatedly exposed to Brucella organisms, nevertheless remain a diagnostic cornerstone in resource-poor countries. Nucleic acid amplification assays combine exquisite sensitivity, specificity, and safety and enable rapid diagnosis of the disease. However, long-term persistence of positive molecular test results in patients that have apparently fully recovered is common and has unclear clinical significance and therapeutic implications. Therefore, as long as there are no sufficiently validated commercial tests or studies that demonstrate an adequate interlaboratory reproducibility of the different homemade PCR assays, cultures and serological methods will remain the primary tools for the diagnosis and posttherapeutic follow-up of human brucellosis.

Human brucellosis: Experience from a tertiary care hospital in southern India

The aim of our study was to examine and compare the clinical presentations, complications, laboratory findings, treatment and outcome of patients with acute, subacute and chronic forms of brucellosis in a tertiary care setting. This hospital-based observational study was undertaken between April 2015 and March 2017. Patients diagnosed with brucellosis, either by blood culture and/or serology, were recruited. A total of 94 cases of brucellosis of acute, subacute and chronic forms were observed in 78.7%, 15.9% and 5.3%, respectively. Blood culture grew Brucella spp. in 70.2% cases. Serological tests showed positivity in 96.8% of the patients. Using multivariate logistic regression analysis, fever and upper back pain were significant predictors for both acute and chronic forms of the disease, respectively. There is a need to increase awareness and understand the local sero-epidemiological pattern of brucellosis as it is still little known.

Detection of Brucella spp. in milk from seronegative cows by real-time polymerase chain reaction in the region of Batna, Algeria

Aim:

The aim of this study was to detect Brucella spp. DNA in milk samples collected from seronegative cows using the real-time polymerase chain reaction (PCR) assay for diagnosis of brucellosis in seronegative dairy cows to prevent transmission of disease to humans and to reduce economic losses in animal production.

Materials and Methods:

In this study, 65 milk samples were investigated for the detection of Brucella spp. The detection of the IS711 gene in all samples was done by real-time PCR assay by comparative cycle threshold method.

Results:

The results show that of the 65 DNA samples tested, 2 (3.08%) were positive for Brucella infection. The mean cyclic threshold values of IS711 real-time PCR test were 37.97 and 40.48, indicating a positive reaction.

Conclusion:

The results of the present study indicated that the real-time PCR appears to offer several advantages over serological tests. For this reason, the real-time PCR should be validated on representative numbers of Brucella-infected and free samples before being implemented in routine diagnosis in human and animal brucellosis for controlling this disease.

Serum biochemical profile and molecular detection of pathogens in semen of infertile male dromedary camels (Camelus dromedarius)

Detection of pathogens in the semen of camels has not been completely elucidated. Therefore, the current study aimed to determine the association of some economically important pathogens with infertility in 94 male infertile camels through molecular detection and estimation of selected biochemical parameters in serum of these animals compared with a control non infected fertile animals (n=40). PCR analysis of semen samples of infertile camels indicated that, four potential pathogens namely Mycoplasma spp., Leptospira spp., Brucella melitensis, and Bovine viral diarrhea virus (BVDV) were detected in 50 semen samples of infertile camels whereas, 44 semen samples of infertile camels were free of pathogens and all tested semen samples were negative for bovine herpes virus 1, Salmonella spp. and Trypanosoma evansi. Single and mixed infection was detected in 88% and 12% of the infected semen samples, respectively. Mycoplasma spp., Leptospira spp., Brucella and Bovine viral diarrhea virus infection represented 66%, 27.2%, 4.5% and 2.3% of the single infected semen samples. Mycoplasma spp.+Leptospira spp. and Mycoplasma spp.+Brucella spp. were detected in 83.3% and 16.7% of mixed infected semen samples, respectively. Testosterone concentration decreased significantly in infertile infected camels compare to both control and infertile non infected animals that remained comparable. The current findings reported the molecular detection of mixed infection in camel semen for the first time. Mycoplasma spp. is the most widely recognized microorganism in the present study and together with Leptospira spp., Brucella spp. and Bovine viral diarrhea virus, might be associated with infertility in dromedary camels.

PUP MORTALITY AND EVIDENCE FOR PATHOGEN EXPOSURE IN GALAPAGOS SEA LIONS (ZALOPHUS WOLLEBAEKI) ON SAN CRISTOBAL ISLAND, GALAPAGOS, ECUADOR

The Galapagos sea lion ( Zalophus wollebaeki ), an endangered species, experiences high pup mortality (up to 100%) in years when El Niño events reduce food supply in the Galapagos Islands. Mortality of pups in non-El Niño years is estimated to be 5% in undisturbed colonies. From 2009 to 2012 we observed high pup mortality (up to 67%) in colonies close to the Galapagos capital, Puerto Baquerizo Moreno, where contact with humans, domestic animals, and rats is frequent. Gross postmortem findings from 54 pups included hemorrhagic lesions in liver and congestion in lungs; histopathology suggested a possible association with infectious diseases. Evidence of Leptospira infection was found in five out of seven samples collected in 2010. Canine distemper viral (CDV) RNA was detected in tissues from six sea lions (in 2011-12), four of which were confirmed by nucleotide sequencing. The absence of CDV antibodies in 109 juvenile animals tested in 2014 at urban and remote colonies could indicate that the CDV infection observed in 2011 was likely confined to a few animals. Our results indicated that Galapagos sea lions have been exposed at least to two pathogens, Leptospira and CDV; however, the impact of these infections on the sea lions is unclear.

Evaluation of Different Primers for Detection of Brucella by Using PCR Method

INTRODUCTION

Brucellosis is a worldwide zoonosis and a significant cause of loss of health in humans and animals. Traditionally, classic diagnosis is carried out by isolation of Brucella, which is time-consuming, technically challenging and potentially dangerous. The aim of this study was to expand a molecular test that would be used for the develop detection of Brucella in a single reaction with high sensitivity and specificity, by targeting IS711element.

METHODS

This study was carried out from 2015 to 2016 at the Ayatolla Rohani hospital in Babol, Iran. The present study was designed to develop PCR assay, based on IS711 gene for rapid diagnosis of Brucella spp. and immediate detection of Brucella, with high sensitivity and specificity. Four pairs of oligo-nucleotide primers with sizes of 547, 403, 291 and 127bp respectively, were planned to exclusively amplify the targeted genes of Brucella species.

RESULTS

Our results show that, five PCR primers set up, would be helpful in amplifying the DNAs from the genus Brucella with high specificity and sensitivity so it can be 12 fg, for Brucella species to provide a valuable tool for diagnosis.

CONCLUSION

This method can be more useful than serological and biochemical tests and in addition, this reduces the number of required tests more rapidly and economically.

Polymerase chain reaction-based assays for the diagnosis of human brucellosis

Polymerase chain reaction (PCR) is an in vitro technique for the nucleic acid amplification, which is commonly used to diagnose infectious diseases. The use of PCR for pathogens detection, genotyping and quantification has some advantages, such as high sensitivity, high specificity, reproducibility and technical ease. Brucellosis is a common zoonosis caused by Brucella spp., which still remains as a major health problem in many developing countries around the world. The direct culture and immunohistochemistry can be used for detecting infection with Brucella spp. However, PCR has the potential to address limitations of these methods. PCR are now one of the most useful assays for the diagnosis in human brucellosis. The aim of this review was to summarize the main PCR techniques and their applications for diagnosis and follow-up of patients with brucellosis. Moreover, advantages or limitation of the different PCR methods as well as the evaluation of PCR results for treatment and follow-up of human brucellosis were also discussed.

A duplex PCR for rapid and simultaneous detection of Brucella spp. in human blood samples

OBJECTIVE

To design a duplex PCR for rapid and simultaneous detection of Brucella species. in human blood samples.

METHODS

Fifty-two peripheral bloods samples were collected from suspicious patients with brucellosis. Following DNA extraction, PCR assay were performed, using three primers that could simultaneously identify and differentiate three major species of pathogenic Brucella in humans and animals.

RESULTS

Of the 52 peripheral bloods samples tested, 25 sample (48%) showed positive reactions in PCR. Twelve samples were positive for Brucella abortus 39 (B. abortus 39) (23%), 13 for Brucella melitensis 39 (B. melitensis 39) (25%) and 0 for Brucella ovis 39 (B. ovis 39) (0%).

CONCLUSIONS

This work demonstrates that in case where specific primers were utilized, duplex PCR has proved to be a simple, fast, and relatively inexpensive method for simultaneous detection of important species of Brucella in clinical samples.

Brucellosis in low-income and middle-income countries

PURPOSE OF REVIEW

Human brucellosis is a neglected, underrecognized infection of widespread geographic distribution. It causes acute febrile illness and a potentially debilitating chronic infection in humans, and livestock infection has substantial socioeconomic impact. This review describes new information regarding the epidemiology of brucellosis in the developing world and advances in diagnosis and treatment.

RECENT FINDINGS

The highest recorded incidence of human brucellosis occurs in the Middle East and Central Asia. Fever etiology studies demonstrate brucellosis as a cause of undifferentiated febrile illness in the developing world. Brucellosis is a rare cause of fever among returning travelers, but is more common among travelers returning from the Middle East and North Africa. Sensitive and specific rapid diagnostic tests appropriate for resource-limited settings have been validated. Randomized controlled trials demonstrate that optimal treatment for human brucellosis consists of doxycycline and an aminoglycoside. Decreasing the burden of human brucellosis requires control of animal brucellosis, but evidence to inform the design of control programs in the developing world is needed.

SUMMARY

Brucellosis causes substantial morbidity in human and animal populations. While improvements in diagnostic options for resource-limited settings and stronger evidence for optimal therapy should enhance identification and treatment of human brucellosis, prevention of human disease through control in animals remains paramount.

Brucellosis in dairy cattle and goats in northern Ecuador

The purpose of this study was to conduct a convenience study for brucellosis prevalence in dairy-producing animals in northern Ecuador. In total, 2,561 cows and 301 goats were tested. Cattle sera were tested using the Rose Bengal card antigen test (RBCT), yielding an overall apparent prevalence of 5.5% (95% confidence interval [95% CI] = 4.7-6.5%) and true prevalence of 7.2% (95% CI = 6.0-8.5%). Prevalence varied by herd size and was highest in larger commercial herds. Polymerase chain reaction was used to test goat milk and lymph nodes, resulting in 9% and 8% positivity, respectively. The RBCTs from goat sera yielded an adjusted true prevalence of 17.8% (95% CI = 6.2-44.2%). Our findings are similar to other overall prevalence estimates for dairy herds but show higher prevalence in commercial herds compared with small groups (less than five animals). We also identify urban milking goats living in metropolitan Quito as a potential source of zoonosis.

Simultaneous detection and differentiates of Brucella abortus and Brucella melitensis by combinatorial PCR

OBJECTIVE

To evaluate simultaneous detection and differentiates of Brucella abortus (B. abortus) and Brucella melitensis (B. melitensis) through the combinatorial PCR method.

METHODS

This study was designed using three primers that could simultaneously identify and differentiate two major species of pathogenic Brucella in humans and animals. Identification and differentiation of each species using the size of the PCR product were determined. To determine the specificity of the method, bacteria close to the genus Brucella were used. Finally, to confirm PCR products, In addition to the products sequence, RFLP was performed on PCR products using restriction enzymes.

RESULTS

The method of optimized combinatorial PCR in this study could simultaneously detect and differentiate B. abortus and B. melitensis with high specificity and sensitivity in clinical samples. Differentiation of species is based on the resulting bands; therefore, the band 494 bp for B. abortus and 733 bp for B. melitensis were obtained. RFLP and sequencing results confirmed PCR results.

CONCLUSIONS

The results of this study shows that without routine diagnostic methods such as culture and serology tests, using the molecular method of combinatorial PCR, important species of Brucella can be simultaneously identified and differentiated in clinical samples.