RESUMO
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.
Assuntos
Brucella ovis/fisiologia , Brucelose/veterinária , Doenças das Cabras/genética , Doenças das Cabras/microbiologia , Cabras/microbiologia , Doenças dos Ovinos/genética , Doenças dos Ovinos/microbiologia , Ovinos/microbiologia , Animais , Brasil , Brucelose/sangue , Brucelose/genética , Brucelose/microbiologia , Ensaio de Imunoadsorção Enzimática , Doenças das Cabras/sangue , Imunodifusão , Reação em Cadeia da Polimerase , Doenças dos Ovinos/sangueRESUMO
Brucella ovis is a major cause of reproductive failure in rams and it is one of the few well-described Brucella species that is not zoonotic. Previous work showed that a B. ovis mutant lacking a species-specific ABC transporter (ΔabcBA) was attenuated in mice and was unable to survive in macrophages. The aim of this study was to evaluate the role of this ABC transporter during intracellular survival of B. ovis. In HeLa cells, B. ovis WT was able to survive and replicate at later time point (48 hpi), whereas an ΔabcBA mutant was attenuated at 24 hpi. The reduced survival of the ΔabcBA mutant was associated with a decreased ability to exclude the lysosomal marker LAMP1 from its vacuolar membrane, suggesting a failure to establish a replicative niche. The ΔabcBA mutant showed a reduced abundance of the Type IV secretion system (T4SS) proteins VirB8 and VirB11 in both rich and acid media, when compared to WT B. ovis. However, mRNA levels of virB1, virB8, hutC, and vjbR were similar in both strains. These results support the notion that the ABC transporter encoded by abcEDCBA or its transported substrate acts at a post-transcriptional level to promote the optimal expression of the B. ovis T4SS within infected host cells.