Summary Brucella species are facultative, intracellular, Gram-negative bacteria with marked tropism for the pregnant reproductive tract of domestic animals. All Brucella species establish persistent infection in the reticuloendothelial system of their natural hosts. The mechanisms of placenta localisation, trophoblast tropism and abortion are poorly understood. A complete picture of the molecular determinants and mechanisms of the cell internalisation process began to emerge only recently. Cyclic β-1,2-glucan is a molecule secreted into the periplasm of Brucella and is required for intracellular Brucella to avoid fusion of the phagosome with lysosomes. The type IV secretion system translocates Brucella effector proteins into host cells and is critical for both survival and replication of Brucella in infected host cells. Some aspects of the pathogenesis and pathobiology of brucellosis in productive domestic animals are discussed in this section.

https://web.oie.int/boutique/extrait/11poester105115.pdf

Pathogenesis and pathobiology of brucellosis in livestock

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.

Brucella spp. Virulence Factors and Immunity

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).

/pdf/contagious-epididymitis-due-to-brucella-ovis-relationship-ombga37k8p.pdf

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

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.

/pdf/species-specific-multiplex-pcr-for-the-diagnosis-of-brucella-58r4uimx55.pdf

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

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.

/pdf/the-abcedcba-encoded-abc-transporter-and-the-virb-operon-1yo366sz3u.pdf

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.

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

A infeccao por Brucella ovis e considerada uma das principais causas de epididimite e infertilidade em carneiros, resultando em falhas reprodutivas e perdas economicas significativas em rebanhos ovinos ao redor do mundo. O estudo teve o objetivo de avaliar tres testes sorologicos disponiveis para o diagnostico da brucelose ovina por B. ovis, utilizando 181 soros ovinos. Amostras de soro provenientes de carneiros experimentalmente infectados foram coletadas ao longo de 192 dias pos-infeccao (n=117) e durante o periodo pre-infeccao (n=9). Adicionalmente, amostras de soro foram obtidas de ovinos provenientes de um rebanho livre para B. ovis (n=55). As tecnicas de imunodifusao em gel de agar (IDGA), utilizando dois antigenos disponiveis comercialmente, e de fixacao de complemento foram comparadas (FC). Foram obtidos resultados de sensibilidade especificidade semelhantes para ambos os metodos de IDGA e ainda, a tecnica de IDGA foi mais eficiente do que a da FC para o diagnostico sorologico da infeccao por B. ovis.

/pdf/a-comparison-of-two-agar-gel-immunodiffusion-methods-and-a-1n7p5wmwse.pdf

A comparison of two agar gel immunodiffusion methods and a complement fixation test for serologic diagnosis of Brucella ovis infection in experimentally infected rams

Infectious agents that can cause infertility in rams.

Dermatosparaxis is a genetic disease that affects collagen maturation. This disease is characterized by marked impairment of the resistance of collagen fibers that leads to skin fragility, and it may affect several species. This is the first report of dermatosparaxis in sheep in Brazil. Clinically, two White Dorper lambs had multiple skin lacerations in the neck, dorsum and limbs. Transmission microscopy demonstrated irregular collagen fibers arranged in hieroglyphic shape and scanning electron microscopy demonstrated thin collagen fibrils that were not arranged in bundles as observed in the normal dermis. These findings are consistent with the diagnosis of dermatosparaxis.

/pdf/dermatosparaxis-in-two-white-doper-lambs-in-brazil-case-2ypfyz12bc.pdf

C. A. Carvalho Júnior

Papers

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

A comparison of two agar gel immunodiffusion methods and a complement fixation test for serologic diagnosis of Brucella ovis infection in experimentally infected rams

Infectious agents that can cause infertility in rams.

Dermatosparaxis in two White Doper lambs in Brazil: case report