Laboratory Animal Models for Brucellosis Research

Brucellosis is a chronic infectious disease caused by Brucella spp., a Gram-negative facultative intracellular pathogen that affects humans and animals, leading to significant impact on public health and animal industry. Human brucellosis is considered the most prevalent bacterial zoonosis in the world and is characterized by fever, weight loss, depression, hepato/splenomegaly, osteoarticular, and genital infections. Relevant aspects of Brucella pathogenesis have been intensively investigated in culture cells and animal models. The mouse is the animal model more commonly used to study chronic infection caused by Brucella. This model is most frequently used to investigate specific pathogenic factors of Brucella spp., to characterize the host immune response, and to evaluate therapeutics and vaccines. Other animal species have been used as models for brucellosis including rats, guinea pigs, and monkeys. This paper discusses the murine and other laboratory animal models for human and animal brucellosis

Laboratory animal models for brucellosis research.

Brucellosis is a chronic infectious disease caused by Brucella spp., a gram-negative facultative intracellular pathogen that affects humans and animals, leading to significant impact on public health and animal industry. Human brucellosis is considered the most prevalent bacterial zoonosis in the world and is characterized by fever, weight loss, depression, hepato/splenomegaly, osteoarticular, and genital infections. Relevant aspects of Brucella pathogenesis have been intensively investigated in culture cells and animal models. The mouse is the animal model more commonly used to study chronic infection caused by Brucella. This model is most frequently used to investigate specific pathogenic factors of Brucella spp., to characterize the host immune response, and to evaluate therapeutics and vaccines. Other animal species have been used as models for brucellosis including rats, guinea pigs, and monkeys. This paper discusses the murine and other laboratory animal models for human and animal brucellosis

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

Lack of endogenous IL-10 enhances production of proinflammatory cytokines and leads to Brucella abortus clearance in mice.

IL-10 is a cytokine that regulates the balance between pathogen clearance and immunopathology. Brucella abortus is an intracellular bacterium that causes chronic disease in humans and domestic animals. Here we evaluated the contribution of IL-10 in host immune response and pathology during B. abortus infection. To assess the role of IL-10 in vivo, IL-10 knockout (KO) or 129 Sv/Ev (wild-type) mice were infected with B. abortus and the number of viable bacteria from the spleen was determined at 1, 2, 3, 6 and 14-weeks postinfection. IL-10 KO mice showed reduced bacterial loads in the spleen when compared to wild-type mice during all time points studied. Additionally, at 14-weeks postinfection IL-10 KO mice had totally cleared the infection. This clearance was preceded by an enhanced IFN-γ, TNF-α and IL-17 responses in both the serum and the spleen of IL-10 KO mice. Additionally, dendritic cells from infected IL-10 KO mice produced elevated levels of IL-12 and TNF-α compared to wild-type animals. Histopathology analysis was performed and both KO and wild-type mice developed multifocal granulomas and necrosis in the liver. However, at six-weeks postinfection reduced numbers of granulomas was detected in IL-10 KO mice compared to wild-type animals. This reduced liver pathology at later stage of infection was accompanied by increased numbers of CD4+CD25+foxp3+ T cells and expression of TGF-β in IL-10 KO splenocytes. Taken together, our findings demonstrate that IL-10 modulates the proinflammatory immune response to B. abortus infection and the lack of IL-10 increases resistance to Brucella infection

Iron acquisition pathways and colonization of the inflamed intestine by Salmonella enterica serovar Typhimurium.

Salmonella enterica serotype Typhimurium is able to expand in the lumen of the inflamed intestine through mechanisms that have not been fully resolved. Here we utilized streptomycin-pretreated mice and dextran sodium sulfate (DSS)-treated mice to investigate how pathways for S. Typhimurium iron acquisition contribute to pathogen expansion in the inflamed intestine. Competitive infection with an iron uptake-proficient S. Typhimurium strain and mutant strains lacking tonB feoB, feoB, tonB or iroN in streptomycin pretreated mice demonstrated that ferric iron uptake requiring IroN and TonB conferred a fitness advantage during growth in the inflamed intestine. However, the fitness advantage conferred by ferrous iron uptake mechanisms was independent of inflammation and was only apparent in models where the normal microbiota composition had been disrupted by antibiotic treatment

Development and evaluation of a species-specific PCR assay for the detection of Brucella ovis infection in rams

Brucella ovis infection is a major cause of epididymitis and infertility in rams, resulting in reproductive failure and significant economic losses worldwide. The goal of this study was to develop a PCR test targeting specific B. ovis genomic sequences. Specific primer pairs were designed targeting 12 of those ORFs. Samples of blood, serum, semen, urine, and preputial wash were collected from experimentally infected rams (n = 9) every other week up to 180 days post infection (dpi), when tissue samples were obtained. Blood, serum, semen, urine, and preputial wash samples were obtained, in weekly intervals for 1 month, from eight rams belonging to a B. ovis-free flock. Semen samples were also obtained from rams belonging to naturally infected flocks (n = 40). The limit of detection of this PCR protocol was 100, 10, and 1 CFU/mL for semen, urine and prepucial wash samples, respectively. Sensitivity and specificity values obtained with this PCR method were similar to that of bacteriology when evaluating biological samples. Agreement between PCR and bacteriology results was greater than 90%. These results clearly indicate that this speciesspecific PCR method is highly efficient for the diagnosis of B. ovis infection in semen, urine, preputial wash and tissue samples from infected rams.Estación Experimental Agropecuaria BarilocheFil: Xavier, Mariana N. Universidade Federal de Minas. Escola de Veterinária. Departamento de Clínica e Cirurgia Veterinária; BrasilFil: Silva, Teane M.A. Universidade Federal de Minas. Escola de Veterinária. Departamento de Clínica e Cirurgia Veterinária; BrasilFil: Costa, Erica A. Universidade Federal de Minas. Escola de Veterinária. Departamento de Clínica e Cirurgia Veterinária; BrasilFil: Paixao, Tatiane A. Universidade Federal de Minas. Escola de Veterinária. Departamento de Clínica e Cirurgia Veterinária; BrasilFil: Moustacas, Valeria S. Universidade Federal de Minas. Escola de Veterinária. Departamento de Clínica e Cirurgia Veterinária; BrasilFil: Carvalho Junior, Custodio A. Universidade Federal de Minas. Escola de Veterinária. Departamento de Clínica e Cirurgia Veterinária; BrasilFil: Sant’Anna, Felipe M. Universidade Federal de Minas. Escola de Veterinária. Departamento de Clínica e Cirurgia Veterinária; BrasilFil: Robles, Carlos Alejandro. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Bariloche. Grupo de Sanidad Animal; ArgentinaFil: Gouveia, Aurora M.G. Universidade Federal de Minas Gerais. Escola de Veterinária. Departamento de Medicina Veterinaria Preventiva; BrasilFil: Lage, Andrey P. Universidade Federal de Minas Gerais. Escola de Veterinária. Departamento de Medicina Veterinaria Preventiva; BrasilFil: Tsolis, Renee M. University of California. Department of Medical Microbiology and Immunology; Estados UnidosFil: Santos, Renato L. Universidade Federal de Minas. Escola de Veterinária. Departamento de Clínica e Cirurgia Veterinária; Brasi

Iron acquisition pathways and colonization of the inflamed intestine by Salmonella enterica serovar Typhimurium.

Salmonella enterica serotype Typhimurium is able to expand in the lumen of the inflamed intestine through mechanisms that have not been fully resolved. Here we utilized streptomycin-pretreated mice and dextran sodium sulfate (DSS)-treated mice to investigate how pathways for S. Typhimurium iron acquisition contribute to pathogen expansion in the inflamed intestine. Competitive infection with an iron uptake-proficient S. Typhimurium strain and mutant strains lacking tonB feoB, feoB, tonB or iroN in streptomycin pretreated mice demonstrated that ferric iron uptake requiring IroN and TonB conferred a fitness advantage during growth in the inflamed intestine. However, the fitness advantage conferred by ferrous iron uptake mechanisms was independent of inflammation and was only apparent in models where the normal microbiota composition had been disrupted by antibiotic treatment

Morphometric analysis, histopathology and immunohistochemistry of hepatic tissue of <i>B. abortus</i> infected IL-10 KO mice.

<p>(A) Columns indicate volumetric proportions of tissue components. The number of portal space, central lobular vein, granuloma, necrosis and parenchyma were evaluated and transformed in percentage at 1, 2 or 6 weeks postinfection. Statistically significant differences relative to non-infected group (NI) are represented by an asterisk (p<i><</i>0.05). Differences relative to granuloma number from IL-10 KO mice compared to wild-type mice at six-week postinfection are indicated by #. Similar results were obtained in two-independent experiments. (B-F) Representative of hematoxylin- and-eosin-stained sections of hepatic tissue from wild-type mice uninfected (B) or infected at one- (C), two- (D), three- (E) or six-weeks (F). (H-L) Representative of hematoxylin- and eosin-stained sections of hepatic tissue from IL-10 KO mice uninfected (H) or infected at one- (I), two- (J), three- (K) or six-weeks (L). Immunohistochemistry sections of hepatic tissue from wild-type (G) and IL-10 KO (M) mice containing the <i>B. abortus</i> inside the granuloma. The arrows indicate the <i>B. abortus</i> within the granuloma. Scale bars: 20 µm.</p