Research paper Differential expression of inflammatory and immune response genes in rams experimentally infected with a rough virulent strain of Brucella ovis Ruth C. Galindo a , Pilar M. Mun ˜oz b , Marı ´a J. de Miguel b , Clara M. Marin b , Jose ´ M. Blasco b , Christian Gortazar a , Katherine M. Kocan c , Jose ´ de la Fuente a,c, * a Instituto de Investigacio ´n en Recursos Cinege ´ticos IREC (CSIC-UCLM-JCCM), Ronda de Toledo s/n, 13005 Ciudad Real, Spain b Unidad de Sanidad Animal, Centro de Investigacio ´n y Tecnologı´a Agroalimentaria (CITA), Gobierno de Arago ´n, Apdo. Correos 727, 50080 Zaragoza, Spain c Department of Veterinary Pathobiology, Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK 74078, USA 1. Introduction Brucella ovis is one of at least eight Brucella spp. classified on the basis on their host tropism, antigenic structure and microbiological and molecular character- istics (Rajashekara et al., 2006; Foster et al., 2007). Infection of sheep with B. ovis results in ovine brucellosis, a disease characterized by infertility in rams, abortion in ewes and increased perinatal mortality in lambs (Burgess, 1982; Blasco, 1990). Brucellosis is a zoonotic chronic disease which is endemic in many areas of the world and is characterized by abortion and infertility in several mammal species including humans (Cutler et al., 2005; Rajashekara et al., 2006). Brucella spp. replicate and persist within macrophages but these bacteria also have the ability to infect other cells Veterinary Immunology and Immunopathology 127 (2009) 295–303 ARTICLE INFO Article history: Received 1 July 2008 Received in revised form 2 October 2008 Accepted 20 October 2008 Keywords: Brucella ovis Brucellosis Microarray Sheep Genomics Immunity ABSTRACT Infection of sheep with Brucella ovis results in ovine brucellosis, a disease characterized by infertility in rams, abortion in ewes and increased perinatal mortality in lambs. During the course of the infection both the ovine immune response and host cell gene expression are modified. The objective of this research was to conduct a preliminary characterization of differential gene expression in rams experimentally infected with B. ovis by microarray hybridization and real-time RT-PCR. Of the 600 ruminant inflammatory and immune response genes that were analyzed in the microarray, 20 and 14 genes displayed an expression fold change >1.75 with a P-value <0.05 at 15 and 60 days post-challenge (dpc), respectively. Of these genes, 16 were upregulated and 4 were downregulated in infected rams at 15 dpc. At 60 dpc, 11 and 3 genes were up- and down-regulated in infected rams, respectively. Only four genes, desmoglein, epithelial sodium channel, alpha subunit (ENaC-alpha), interleukin 18 binding protein (IL18BP) and macrophage migration inhibition factor (MIF) were found upregulated in infected rams at both 15 and 60 dpc. The analysis of differentially expressed genes demonstrated activation of inflammatory and innate immune pathways in infected animals. B. ovis infection also resulted in upregulation of genes involved in phagocytosis and downregulation of protective host defense mechanisms, both of which may contribute to the chronicity of B. ovis infection. The gene expression profiles differed between rams with severe and moderate B. ovis infection. This is the first analysis of differential gene expression in rough brucellae and particularly in B. ovis-infected rams. The characterization of the genes and their expression profiles in response to B. ovis infection further contributes to our understanding of the molecular mechanisms of infection and the pathogenesis of brucellosis. ß 2008 Elsevier B.V. All rights reserved. * Corresponding autor at: Department of Veterinary Pathobiology, Center for Veterinary Health Sciences, 250 McElroy Hall, Oklahoma State University, Stillwater, OK 74078, USA. Tel.: +1 405 7440372. E-mail addresses: jose_delafuente@yahoo.com, jose.de_la_fuente@okstate.edu (J. de la Fuente). Contents lists available at ScienceDirect Veterinary Immunology and Immunopathology journal homepage: www.elsevier.com/locate/vetimm 0165-2427/$ – see front matter ß 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.vetimm.2008.10.326