Different resistance patterns of reference and field strains of Brucella abortus.

The aim of this study was to evaluate the growth of the B. abortus reference strains and field isolates on media containing different inhibitor agents. Reference strains were seeded on tryptose agar containing: i-erythritol (1.0 mg/mL), fuchsin (20 µg/mL and 80 µg/mL), thionin (2.5 µg/mL and 10 µg/mL), rifampicin (200 µg/mL) and safranin O (200 µg/mL). Field isolates were tested only on media containing i-erythritol, rifampicin and thionin. Furthermore, each suspension was also inoculated on tryptose agar incubated in air, to test its ability to grow without CO 2 . Sensitivity to fuchsin was similar among reference strains evaluated. Growth of S19, 544 and 2308 but not RB51 were inhibited on media containing rifampicin. Medium with safranin O showed no inhibition for RB51, 544 and 2308, but it partially inhibited the S19 growth as well as medium containing i-erythritol. Treatment/control growth ratio for 2308 on tryptose agar containing thionin (2.5 µg/mL) was approximatelly 1.0, whereas S19 and RB51 showed 0.85 and 0.89 ratios, respectively. Growth of 544, S19 and RB51 but not 2308 was completely inhibited on medium with thionin (10 µg/mL). All field strains grew on medium containing i-erythritol, but were completelly inhibited by rifampicin. With exception of A1 ( B. abortus biovar 3) all field isolates grew on medium with thionin, although some strains showed a treatment/control growth ratio of 0.75-0.80 (10 µg/mL). These results showed that tryptose agar with thionin, i-erythritol or rifampicin could be useful for differentiating vaccine, challenge and field strains of B. abortus.

Different resistance patterns of reference and field strains of Brucella abortus

The aim of this study was to evaluate the growth of the B. abortus reference strains and field isolates on media containing different inhibitor agents. Reference strains were seeded on tryptose agar containing: i-erythritol (1.0 mg/mL), fuchsin (20 μg/mL and 80 μg/mL), thionin (2.5 μg/mL and 10 μg/mL), rifampicin (200 μg/mL) and safranin O (200 μg/mL). Field isolates were tested only on media containing i-erythritol, rifampicin and thionin. Furthermore, each suspension was also inoculated on tryptose agar incubated in air, to test its ability to grow without CO2. Sensitivity to fuchsin was similar among reference strains evaluated. Growth of S19, 544 and 2308 but not RB51 were inhibited on media containing rifampicin. Medium with safranin O showed no inhibition for RB51, 544 and 2308, but it partially inhibited the S19 growth as well as medium containing i-erythritol. Treatment/control growth ratio for 2308 on tryptose agar containing thionin (2.5 μg/mL) was approximatelly 1.0, whereas S19 and RB51 showed 0.85 and 0.89 ratios, respectively. Growth of 544, S19 and RB51 but not 2308 was completely inhibited on medium with thionin (10 μg/mL). All field strains grew on medium containing i-erythritol, but were completelly inhibited by rifampicin. With exception of A1 (B. abortus biovar 3) all field isolates grew on medium with thionin, although some strains showed a treatment/control growth ratio of 0.75–0.80 (10 μg/mL). These results showed that tryptose agar with thionin, i-erythritol or rifampicin could be useful for differentiating vaccine, challenge and field strains of B. abortus.

Uso do ensaio imunoenzimático e imunoblotting para detecção de imunoglobulinas contra Campylobacter fetus em muco cérvico-vaginal de fêmeas bovinas / The use of enzyme-linked immunosorbent assay and immunoblotting for the detection of Campylobacter fetus immunoglobulins in the cervico-vaginal mucus of female cattle

Foi padronizado um ensaio imunoenzimático do tipo indireto para detecção de imunoglobulina A (ELISA IgA) anti- Campylobacter fetus subp. venerealis em muco cérvico- vaginal bovino utilizando um extrato protéico de Campylobacter fetus subsp. venerealis produzido pelo método de extração ácida pelo tampão de glicina (0,2M; pH2,2). A média dos valores de densidade ótica (DO450) foi de 0,143±0,09. As bandas protéicas dos antígenos de Campylobacter fetus subsp. venerealis e de Campylobacter fetus subsp. fetus melhor reconhecidas pela IgA do muco cérvico- vaginal migraram em 42,6 kDa mas a proteina evidenciada em 93 kDa foi reconhecida exclusivamente pelo Campylobacter fetus subsp. venerealis. Os anticorpos presentes na amostra de muco vaginal testada no “immunoblotting” que apresentou resultado positivo no ELISA IgA, reconheceu antígenos de C. jejuni subsp. jejuni e C. fetus subsp. fetus.

An indirect enzyme-linked immunosorbent assay was developed to detect antigenspecific secretory IgA antibodies to Campylobacter fetus subsp. venerealis in bovine vaginal mucus with a protein extract of the Campylobacter fetus subsp. venerealis by the acid glycine extraction method. Mean optical density measurement (λ=450 nm) was 0.143±0.9. The most immunoreactive protein bands of the Campylobacter fetus subsp. venerealis or Campylobacter fetus subsp. fetus recognized by IgA in immunoblotting, using bovine vaginal mucus samples, migrate at 42.6 kDa. The protein that migrates at 93 kDa was recognized exclusively for C. fetus subsp. venerealis. A positive vaginal mucus sample of a cow from negative herd recognized antigens of C. jejuni subsp. jejuni e C. fetus subsp. fetus.

Modulation of the bovine trophoblastic innate immune response by Brucella abortus.

Brucellosis is still a widespread zoonotic disease. Very little is known about the interaction between Brucella abortus and trophoblastic cells, which is essential for better understanding the pathogenesis of the Brucella-induced placentitis and abortion, a key event for transmission of the disease. The goal of this study was to evaluate the profile of gene expression by bovine trophoblastic cells during infection with B. abortus. Explants of chorioallantoic membranes were inoculated with B. abortus strain 2308. Microarray analysis was performed at 4 h after infection, and expression of cytokines and chemokines by trophoblastic cells was assessed by real-time reverse transcription-PCR at 6 and 12 h after inoculation. In addition, cytokine and chemokine expression in placentomes from experimentally infected cows was evaluated. Expression of proinflammatory genes by trophoblastic cells was suppressed at 4 h after inoculation, whereas a significant upregulation of CXC chemokines, namely, CXCL6 (GCP-2) and CXCL8 (interleukin 8), was observed at 12 but not at 6 h after inoculation. Placentomes of experimentally infected cows had a similar profile of chemokine expression, with upregulation of CXCL6 and CXCL8. Our data indicate that B. abortus modulates the innate immune response by trophoblastic cells, suppressing the expression of proinflammatory mediators during the early stages of infection that is followed by a delayed and mild expression of proinflammatory chemokines, which is similar to the profile of chemokine expression in the placentomes of experimentally infected cows. This trophoblastic response is likely to contribute to the pathogenesis of B. abortus-induced placentitis.