Andrological, pathologic, morphometric, and ultrasonographic findings in rams experimentally infected with Brucella ovis

A subunit vaccine based on Brucella rBP26 induces Th1 immune responses and M1 macrophage activation

Brucellosis is a global zoonotic infection caused by Brucella bacteria, which poses a significant burden on society. While transmission prevention is currently the most effective method, the absence of a licenced vaccine for humans necessitates the urgent development of a safe and effective vaccine. Recombinant protein-based subunit vaccines are considered promising options, and in this study, the Brucella BP26 protein is expressed using prokaryotic expression systems. The immune responses are evaluated using the well-established adjuvant CpG-ODN. The results demonstrate that rBP26 supplemented with a CpG adjuvant induces M1 macrophage polarization and stimulates cellular immune responses mediated by Th1 cells and CD8 + T cells. Additionally, it generates high levels of rBP26-specific antibodies in immunized mice. Furthermore, rBP26 immunization activates, proliferates, and produces cytokines in T lymphocytes while also maintaining immune memory for an extended period of time. These findings shed light on the potential biological function of rBP26, which is crucial for understanding brucellosis pathogenesis. Moreover, rBP26 holds promise as an effective subunit vaccine candidate for use in endemic areas.

Antigenic and molecular evidence of Brucella sp.-associated epididymo-orchitis in frugivorous (Artibeus lituratus) and nectarivorous (Glossophaga soricina) bats in Brazil

This study included 47 free-ranging bats from the State of Minas Gerais, Brazil. Six bats (12.8%) had genital inflammatory lesions, and two of them (one Artibeus lituratus and one Glossophaga soricina, a frugivorous and a nectarivorous, respectively) were diagnosed with Brucella sp. infection through PCR, and antigens in intralesional macrophages were detected using immunohistochemistry.

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.

Pathogenesis of Brucella ovis in pregnant mice and protection induced by the candidate vaccine strain B. Ovis ΔabcBA

Ovine brucellosis caused by Brucella ovis is a major cause of reproductive failure in sheep. This study aimed to evaluate transplacental infection and pathogenicity of B.ovis wild type strain ATCC 25,840 (WT B.ovis) and the candidate vaccine strain B.ovis ΔabcBA in pregnant mice. A total of 40 BALB/c mice were equally divided into 4 groups: (i) non immunized and uninfected control mice (3/10 mice became pregnant); (ii) non immunized and challenged with WT B.ovis (5/10 pregnant); (iii) inoculated only with B.ovis ΔabcBA (6/10 pregnant); (iv) immunized with B.ovis ΔabcBA and challenged with WT B.ovis (5/10 pregnant). Female mice bred, and five days after visualization of the vaginal plug, they were inoculated intraperitoneally (ip) with 100 µL of sterile PBS, 100 µL of 1 × 10⁶ CFU of B.ovis ΔabcBA, or 100 µL of 1 × 10⁶ CFU of B.ovis WT, according to each group. At the 17th day of gestation, samples of spleen, liver, uterus, placenta, fetus and mammary gland were obtained for bacteriology, histopathology and immunohistochemistry. Non immunized mice challenged with B.ovis WT developed necrotizing placentitis as well as microgranulomas in the liver and spleen. These findings support the notion that B.ovis infection in pregnant mice induces lesions that are similar to those caused by B.abortus in the same animal model. B.ovis ΔabcBA was not recovered from any of the sampled organs, and it did not cause any gross or microscopic lesions, indicating that it is a safe and attenuated strain in this experimental model. In addition, B.ovis ΔabcBA was induced protective immunity as demonstrated by decreased numbers of B.ovis WT in the liver, uterus and fetuses of immunized mice after the challenge with B.ovis WT.

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.

Management of Reproductive Diseases in Male Small Ruminants

Reproductive tract diseases can be a significant cause of subfertility or infertility in male small ruminants. Affected males can usually be identified early by performing routine serologic screening and yearly breeding soundness examinations. Early diagnosis will either maximize treatment success or expedite culling decisions. Once clinical signs of diseases develop, prognosis for breeding ability declines. Veterinary practitioners should used ancillary diagnostic techniques, such as ultrasound examination and laboratory testing to acquire a diagnosis and determine prognosis of reproductive lesions. Some diseases (eg, brucellosis) should be ruled out immediately to cull affected animals and minimize transmission within the herd.

Pathogenic potential of Brucella ovis field isolates with different genotypic profile and protection provided by the vaccine strain B. ovis ΔabcBA against B. ovis field isolates in mice

ABSTRACT: Brucella ovis causes economic and reproductive losses in sheep herds. The goal of this study was to characterize infection with B. ovis field isolates in a murine model, and to evaluate protection induced by the candidate vaccine strain B. ovis ΔabcBA in mice challenged with these field isolates. B. ovis field strains were able to colonize and cause lesions in the liver and spleen of infected mice. After an initial screening, two strains were selected for further characterization (B. ovis 94 AV and B. ovis 266 L). Both strains had in vitro growth kinetics that was similar to that of the reference strain B. ovis ATCC 25840. Vaccination with B. ovis ΔabcBA encapsulated with 1% alginate was protective against the challenge with field strains, with the following protection indexes: 0.751, 1.736, and 2.746, for mice challenged with B. ovis ATCC25840, B. ovis 94 AV, and B. ovis 266 L, respectively. In conclusion, these results demonstrated that B. ovis field strains were capable of infecting and inducing lesions in experimentally infected mice. The attenuated vaccine strain B. ovis ΔabcBA induced protection in mice challenged with different B. ovis field isolates, resulting in higher protection indexes against more pathogenic strains.

Modelling the immunopathophysiology of Brucella melitensis and its lipopolysaccharide in mice infected via oral route of exposure

Brucella melitensis is one of the leading zoonotic pathogens with significant economic implications in animal industry worldwide. Lipopolysaccharide, however, remains by far the major virulence with substantial role in diseases pathogenesis. Nonetheless, the effect of B. melitensis and its lipopolysaccharide on immunopathophysiological aspects largely remains an enigma. This study examines the effect of B.melitensis and its lipopolysaccharide on immunopathophysiological parameters following experimental infection using mouse model. Eighty four (n = 84) mice, BALB/c, both sexes with equal gender distribution and 6-8 weeks-old were randomly assigned into three groups. Group 1-2 (n = 72) were orally inoculated with 0.4 mL containing 10⁹ CFU/mL of B. melitensis and its LPS, respectively. Group 3 (n = 12) was challenged orally with phosphate buffered saline and served as a control group. Animals were observed for clinical signs, haematological and histopathological analysis for a period of 24 days post-infection. We hereby report that B.melitensis infected group demonstrated significant clinical signs and histopathological changes than LPS infected group. However, both infected groups showed elevated levels of interleukins (IL-1β and IL-6) and antibody levels (IgM and IgG) with varying degrees of predominance in LPS infected group than B. melitensis infected group. For hormone analysis, low levels of progesterone, estradiol and testosterone were observed in both B. melitensis and LPS groups throughout the study period. Moreover, in B. melitensis infected group, the organism was re-isolated from the organs and tissues of gastrointestinal, respiratory and reproductive systems thereby confirming the infection and transmission dynamics. This report is the first detailed investigation comparing the infection progression and host responses in relation to the immunopathophysiological aspects in a mouse model after oral inoculation with B. melitensis and its lipopolysaccharide.

Brucella ovis EM OVINOS: SOROPOSITIVIDADE E FATORES DE RISCO

Resumo Realizou-se um levantamento sorológico de Brucella ovis em ovinos do Estado de Sergipe, com o objetivo de determinar a positividade e a distribuição da infecção em propriedades rurais e analisar os possíveis fatores associados à infecção. Foram analisadas 54 propriedades criadoras de ovinos, das quais foram colhidas 932 amostras de soro sanguíneo de animais com idade superior a seis meses, nas três regiões do Estado. Todos os soros foram examinados por Imunodifusão em Gel de Agar (IDGA). De acordo com o teste realizado, 46,30% (25/54) das propriedades apresentaram evidência sorológica de infecção por B. ovis, com uma positividade de 4,40% (41/932) dos animais. Como fatores associados à infecção por B. ovis, observaram-se a presença de tratador de ovinos (OR=2,31) e propriedades com área superior a 50 ha (OR=1,98) e como fator de proteção, a utilização de cabanha (OR=0,37). Assim, verificou-se a presença de anticorpos contra Brucella ovis nos ovinos do Estado e salienta-se a importância de estudos complementares para determinação de medidas sanitárias específicas para prevenir os rebanhos desta enfermidade.

Immuno-pathophysiological responses of mouse model to experimental infection with Brucella melitensis and its lipopolysaccharides via intraperitoneal route

Brucella melitensis is one of the major zoonotic pathogens with significant economic implications worldwide. The pathogenicity is complex and not always well understood. Lipopolysaccharide (LPS) remains the major virulent factor of B. melitensis and responsible for the mechanism by which the pathogen causes its deleterious effects. In this study, 84 mice of 6-8 weeks old of both sexes were divided equally into 3 groups; namely Brucella melitensis infected group, lipopolysaccharide (LPS) infected group and control group. The former two groups contained 36 mice each with equal gender distribution. The control group consisted of 12 mice only. Animals in B. melitensis infected group, a single inoculum of 0.4 ml containing 10⁹ of B. melitensis were intraperitoneally challenged while animals in LPS group, a single dose of 0.4 ml containing LPS extracted from the B. melitensis were intraperitoneally inoculated. Animals in control group received intraperitoneally, a single dose of 0.4 ml phosphate buffered saline (PBS) of pH7. Animals that were infected intraperitoneally with B. melitensis demonstrated significant clinical presentation; gross and histo-pathological evidence than LPS infected group. However, both infected groups showed elevated levels of interleukins (IL-1β and IL6), antibody levels (IgM an IgG) as early as 3 days post-infection with predominance in LPS infected group. In contrast, low levels of sex related hormonal changes in which LPS infected group showed the least concentration were also detected throughout the experimental period. In conclusion, B. melitensis can be transmitted via gastrointestinal, respiratory and reproductive tract. Moreover, LPS stimulated significantly the innate and acquired immune system without significant systemic dysfunction, suggesting potentiality of the protective properties of this component as alternative vaccine for brucellosis infection.

Serologic and molecular evidence of Brucella ovis infection in ovine and caprine flocks in the State of Minas Gerais, Brazil

BACKGROUND

Brucella ovis infection is one of the leading causes of sub fertility and infertility in ovine, been characterized mainly by epididymitis, orchitis and testicular atrophy in rams. This study aimed to determine the frequency of B. ovis positivity in rams and goats flocks in the State of Minas Gerais, Brazil, by agarose gel immunodiffusion (AGID), ELISA, Rose Bengal, PCR and bacteriological isolation as diagnostic tools.

FINDINGS

Serum and urine samples were collected from properties with sheep or goat flocks, or from properties with mixed flock. Out of 50 sheep flocks, 6% (3/50) were seropositive by AGID while 4% (2/50) were positive by urine PCR for B. ovis. Out of five goat farms, 20% (1/5) were seropositive for B. ovis by AGID. Mixed flock farms had 11.1% (2/18) of positivity by AGID. By ELISA, 19.5% (8/41) of sheep properties and 61.1% (11/18) of the properties with mixed flocks were positive for B. ovis. No samples were positive in the test of Rose Bengal, ruling out exposure to smooth LPS Brucella species (particularly Brucella melitensis) and indicating that the positive in the ELISA was associated with Brucella spp. LPS rough (presumably B. ovis). No urine sample from sheep or goat was positive by bacteriological isolation.

CONCLUSIONS

Our results demonstrate serologic or molecular evidence of B. ovis infection in several rams and billy goats from meso-regions of the State of Minas Gerais, Brazil. Also, this study report the indirect ELISA as an important tool for the diagnosis of B. ovis infection, as indirect ELISA in this study demonstrated to be the most sensitive diagnostic method adopted.

Brucella spp. Virulence Factors and Immunity

Brucellosis, caused by bacteria of the genus Brucella, is an important zoonotic infection that causes reproductive disease in domestic animals and chronic debilitating disease in humans. An intriguing aspect of Brucella infection is the ability of these bacteria to evade the host immune response, leading to pathogen persistence. Conversely, in the reproductive tract of infected animals, this stealthy pathogen is able to cause an acute severe inflammatory response. In this review, we discuss the different mechanisms used by Brucella to cause disease, with emphasis on its virulence factors and the dichotomy between chronic persistence and reproductive disease.

The abcEDCBA-Encoded ABC Transporter and the virB Operon-Encoded Type IV Secretion System of Brucella ovis Are Critical for Intracellular Trafficking and Survival in Ovine Monocyte-Derived Macrophages

Brucella ovis infection is associated with epididymitis, orchitis and infertility in rams. Most of the information available on B. ovis and host cell interaction has been generated using murine macrophages or epithelial cell lines, but the interaction between B. ovis and primary ovine macrophages has not been studied. The aim of this study was to evaluate the role of the B. ovis abcEDCBA-encoded ABC transporter and the virB operon-encoded Type IV Secretion System (T4SS) during intracellular survival of B. ovis in ovine peripheral blood monocyte-derived macrophages. ΔabcBA and ΔvirB2 mutant strains were unable to survive in the intracellular environment when compared to the WT B. ovis at 48 hours post infection (hpi). In addition, these mutant strains cannot exclude the lysosomal marker LAMP1 from its vacuolar membrane, and their vacuoles do not acquire the endoplasmic reticulum marker calreticulin, which takes place in the WT B. ovis containing vacuole. Higher levels of nitric oxide production were observed in macrophages infected with WT B. ovis at 48 hpi when compared to macrophages infected with the ΔabcBA or ΔvirB2 mutant strains. Conversely, higher levels of reactive oxygen species were detected in macrophages infected with the ΔabcBA or ΔvirB2 mutant strains at 48 hpi when compared to macrophages infected with the WT strain. Our results demonstrate that B. ovis is able to persist and multiply in ovine macrophages, while ΔabcBA and ΔvirB2 mutations prevent intracellular multiplication, favor phagolysosome fusion, and impair maturation of the B. ovis vacuole towards an endoplasmic reticulum-derived compartment.

Encapsulated Brucella ovis Lacking a Putative ATP-Binding Cassette Transporter (ΔabcBA) Protects against Wild Type Brucella ovis in Rams

This study aimed to evaluate protection induced by the vaccine candidate B. ovis ΔabcBA against experimental challenge with wild type B. ovis in rams. Rams were subcutaneously immunized with B. ovis ΔabcBA encapsulated with sterile alginate or with the non encapsulated vaccine strain. Serum, urine, and semen samples were collected during two months after immunization. The rams were then challenged with wild type B. ovis (ATCC25840), and the results were compared to non immunized and experimentally challenged rams. Immunization, particularly with encapsulated B. ovis ΔabcBA, prevented infection, secretion of wild type B. ovis in the semen and urine, shedding of neutrophils in the semen, and the development of clinical changes, gross and microscopic lesions induced by the wild type B. ovis reference strain. Collectively, our data indicates that the B. ovis ΔabcBA strain is an exceptionally good vaccine strain for preventing brucellosis caused by B. ovis infection in rams.

Microbial diseases of the genital system of rams or bucks

Objective of the present paper is to review microbial diseases of the genital system of male small ruminants. The paper reviews the infections and the diseases by taking an organ approach within the genital system, whilst relevant health management actions are also discussed. Diseases of the genital organs of male small ruminants include orchitis, of bacterial or viral aetiology, epididymitis, primarily caused by Brucella ovis, by other bacteria as well (e.g., Actinobacillus seminis, Haemophilus somni), infections of the accessory glands, orf, other infections of the penis or prepuce and infections of the scrotum. The health management of rams/bucks include the appropriate diagnostic investigations, the relevant therapeutic approaches and, finally, the preventive measures.

Contagious epididymitis due to Brucella ovis: relationship between sexual function, serology and bacterial shedding in semen

BACKGROUND

Contagious Epididymitis (CE) due to Brucella ovis (B. ovis) is a contagious disease that impairs rams' fertility due to epididymis, testicle and accessory sexual gland alterations. An increased incidence of CE has been observed in South Eastern France ("PACA" region) since the Rev.1 vaccination against B. melitensis has been stopped in 2008. The objective of this study was to evaluate the relationship between the infection by B. ovis and the sexual function of rams. Two-hundred eighteen sexually-mature rams, from 11 seropositive flocks, were submitted to a clinical examination of the genital tract, a semen collection by electro-ejaculation for spermogram and culture, and a serological examination for anti-B. ovis antibodies by complement fixation test (CFT) and indirect ELISA (I-ELISA). The relationships between clinical, seminal, bacteriological and serological parameters were studied using the Fisher exact test and a logistic regression model (binomial logit).

RESULTS

B. ovis shedding in semen was significantly associated with seropositivity (CFT and I-ELISA; p < 0.001 and 0.01 respectively), genital tract alterations (p < 0.05) and poor semen quality (p < 0.001). Seropositive rams presented significantly more genital tract alterations (p < 0.001) and a poor seminal score (p < 0.001) than seronegative rams.

CONCLUSIONS

Since semen culture is not routinely feasible in field conditions, a control plan of CE should be based, where Rev.1 vaccination is not possible, on both systematic clinical and serological examination of rams, followed by the culling of seropositive and/or genital tract alterations carrier rams.

Protection Provided by an Encapsulated Live Attenuated ΔabcBA Strain of Brucella ovis against Experimental Challenge in a Murine Model

This study aimed to evaluate the Brucella ovis ΔabcBA strain as a vaccine candidate in the murine model. BALB/c mice were subcutaneously or intraperitoneally immunized with a single dose or three doses of the B. ovis ΔabcBA strain and then were challenged with wild-type B. ovis. Single or multiple immunizations provided only mild protection, with significantly smaller numbers of wild-type B. ovis CFU in the livers of immunized mice but not in the spleens. Encapsulation of B. ovis ΔabcBA significantly improved protection against experimental challenges in both BALB/c and C57BL/6 mice. Furthermore, immunization with encapsulated B. ovis ΔabcBA markedly prevented lesions in the spleens and livers of experimentally challenged mice. These results demonstrated that the encapsulated B. ovis ΔabcBA strain confers protection to mice; therefore, this strain has potential as a vaccine candidate for rams.

Indirect ELISA for diagnosis of Brucella ovis infection in rams

Brucella ovis is a major cause of epididymitis in sexually mature rams, resulting in subfertility, infertility, and economic losses for the sheep industry worldwide. The aim of this study was to develop an indirect ELISA (iELISA) using recombinant proteins, namely rBoP59 and rBP26, as antigens for serological diagnosis of B. ovisinfection. The BoP59 and BP26 recombinant proteins were expressed in E. coli and purified by affinity chromatography. Antigenicity was tested by Western blot and iELISA. Standardization of iELISA was performed with 500ng and 1µg BoP59 and rBP26 per well, testing serum from uninfected and experimentally infected rams. rBP26 was effective in distinguishing positive from negative rams. The rBP26 iELISA developed in this study is the first to use a completely purified rBP26 as antigen resulting in high sensitivity (100%) and specificity (90.2%), and an overall accuracy equal to 1.0.

Genetic diversity of Brucella ovis isolates from Rio Grande do Sul, Brazil, by MLVA16

Background

Ovine epididymitis is predominantly associated with Brucella ovis infection. Molecular characterization of Brucella spp. achieved by multi-locus variable number of tandem repeats (VNTR) analyses (MLVA) have proved to be a powerful tool for epidemiological trace-back studies. Thus, the aim of this study was to evaluate the genetic diversity of Brucella ovis isolates from Rio Grande do Sul State, Brazil, by MLVA16.

Findings

MLVA16 genotyping identified thirteen distinct genotypes and a Hunter-Gaston diversity index of 0.989 among the fourteen B. ovis genotyped strains. All B. ovis MLVA16 genotypes observed in the present study represented non-previously described profiles. Analyses of the eight conserved loci included in panel 1 (MLVA8) showed three different genotypes, two new and one already described for B. ovis isolates. Among ten B. ovis isolates from same herd only two strains had identical pattern, whereas the four isolates with no epidemiologic information exhibited a single MLVA16 pattern each. Analysis of minimal spanning tree, constructed using the fourteen B. ovis strains typed in this study together with all nineteen B. ovis MLVA16 genotypes available in the MLVAbank 2014, revealed the existence of two clearly distinct major clonal complexes.

Conclusions

In conclusion, the results of the present study showed a high genetic diversity among B. ovis field isolates from Rio Grande do Sul State, Brazil, by MLVA16.

Clinical and pathological changes in rams experimentally infected with Actinobacillus seminis and Histophilus somni

Infectious epididymitis is considered a major cause of economic losses for the sheep industry worldwide. This study aimed to investigate clinical and pathological changes associated with experimental infections with A. seminis and H. somni in rams. Twenty rams of age 18 to 24 months were infected by intraepididymal inoculation of A. seminis (n = 10) and H. somni (n = 10). Rams were weekly examined and biological samples were collected during six weeks. All rams inoculated with A. seminis and 80% inoculated with H. somni became infected. The recovery of bacteria was possible in semen and urine samples and tissues in both experimental groups. Clinically, there were a decrease in testicular consistency and an increase in measures of the left epididymis tails in both experimental groups. The main gross changes were observed in the reproductive tract. Microscopically, the main lesions were inflammatory changes in the genitourinary tract and testicular degeneration. A. seminis and H. somni were able to colonize several organs of the genitourinary tract in rams, being indistinguishable by clinical exam, necropsy or histopathology. For differential diagnosis, it is important to use diagnostic techniques for direct confirmation of the etiologic agent.

Brucella ovis lacking a species-specific putative ATP-binding cassette transporter is attenuated but immunogenic in rams

Ovine brucellosis caused by Brucella ovis is considered one of the most important reproductive diseases of rams worldwide. This study aimed to characterize the kinetics of infection of a ΔabcAB B. ovis mutant strain in rams. Twelve 1-year-old crossbred rams were used. Six rams were challenged with 2 mL of a suspension containing 1.2×10(9) CFU/mL of B. ovis strain ATCC25840 (wild type) by intraprepucial inoculation and additional 50 μL in each conjunctival sac of a suspension containing 1.2×10(10) CFU/mL of the same strain. The other six rams were challenged with an equivalent number of CFU of the mutant strain ΔabcAB B. ovis through the same routes. Serum samples for serology and semen and urine samples for bacteriologic culture and PCR were collected weekly during 24 weeks. At 24 weeks post infection, tissue samples were collected for bacteriologic culture and PCR. All rams inoculated with wild type or the ΔabcAB strain seroconverted at the fourth week post infection, remaining positive up to the 16th week post infection. PCR and bacteriology demonstrated that only rams inoculated with the wild type strain shed the organism in semen and urine. Lymphocytes from rams inoculated with wild type or ΔabcAB B. ovis had significantly higher proliferation in response to B. ovis antigens when compared with unstimulated controls. Tissue bacteriology and PCR detected B. ovis in all rams challenged with the wild type strain, whereas only one ΔabcAB-infected ram had a positive iliac lymph node sample by PCR.

Species-specific multiplex PCR for the diagnosis of Brucella ovis, Actinobacillus seminis, and Histophilus somni infection in rams

Background

Infectious ovine epididymitis results in substantial economic losses worldwide due to reproductive failure and culling of breeders. The most common causative agents of these infections are Brucella ovis, Actinobacillus seminis, and Histophilus somni. The aim of this study was to develop a multiplex PCR assay for simultaneous detection of Brucella ovis, Actinobacillus seminis, and Histophilus somni with species-specific primers applied to biological samples for molecular diagnosis of these infections.

Results

The multiplex assay was capable of detecting B. ovis, A. seminis, and H. somni DNA simultaneously from genomic bacterial DNA samples and pool of semen samples from experimentally infected rams. The method was highly specific since it did not amplify DNA from other bacterial species that can potentially cause epididymitis in rams as well as species phylogenetically related to B. ovis. All negative control samples were negative in PCR multiplex assay. Urine can be used as an alternative to semen samples.

Conclusions

The species-specific multiplex PCR assay developed in this study can be successfully used for the detection of three of the most common bacterial causes of ovine epididymitis.

MyD88 and TLR9 are required for early control of Brucella ovis infection in mice

Brucella ovis is an important cause of epididymitis in rams, which results in impaired fertility and economic losses. This study demonstrated the role of TLR during the acute phase of infection in the mouse model. C57BL/6 wild type and TLR2(-/-), TLR4(-/-), TLR9(-/-), and MyD88(-/-) mice were infected with B. ovis and bacteriology, histopathology, and pro-inflammatory gene expression were evaluated at 7days post-infection. MyD88(-/-) mice had higher bacterial loads in the spleen when compared to wild type mice. This enhanced susceptibility was associated with decreased inflammatory response in the liver. TLR9(-/-) mice also had higher bacterial loads when compared to wild type mice, but, surprisingly, they developed stronger inflammatory response. TLR2(-/-) and TLR4(-/-) mice were as susceptible as wild type mice to B. ovis infection. Therefore, MyD88 and TLR9 are required for controlling B. ovis multiplication during the early stages of infection.