Both Hemolytic Anemia and Malaria Parasite-Specific Factors Increase Susceptibility to Nontyphoidal Salmonella enterica Serovar Typhimurium Infection in Mice▿

Severe pediatric malaria is an important risk factor for developing disseminated infections with nontyphoidal Salmonella serotypes (NTS). While recent animal studies on this subject are lacking, early work suggests that an increased risk for developing systemic NTS infection during malaria is caused by hemolytic anemia, which leads to reduced macrophage microbicidal activity. Here we established a model for oral Salmonella enterica serotype Typhimurium challenge in mice infected with Plasmodium yoelii nigeriensis. Initial characterization of this model showed that 5 days after coinoculation, P. yoelii nigeriensis infection increased the recovery of S. Typhimurium from liver and spleen by approximately 1,000-fold. The increased bacterial burden could be only partially recapitulated by antibody-mediated hemolysis, which increased the recovery of S. Typhimurium from liver and spleen by 10-fold. These data suggested that both hemolysis and P. yoelii nigeriensis-specific factors contributed to the increased susceptibility to S. Typhimurium. The mechanism by which hemolysis impaired resistance to S. Typhimurium was further investigated. In vitro, S. Typhimurium was recovered 24 h after infection of hemophagocytic macrophages in 2-fold-higher numbers than after infection of mock-treated macrophages, making it unlikely that reduced macrophage microbicidal activity was solely responsible for hemolysis-induced immunosuppression during malaria. Infection with P. yoelii nigeriensis, but not antibody-mediated hemolysis, reduced serum levels of interleukin-12p70 (IL-12p70) in response to S. Typhimurium challenge. Collectively, studies establishing a mouse model for this coinfection suggest that multiple distinct malaria-induced immune defects contribute to increased susceptibility to S. Typhimurium

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