Microarray analysis of gene expression profiles of total mRNA was studied in rams experimentally-infected with the virulent strain of Brucella ovis (B. ovis). The tissues studied included reproductive organs (epididymus, testicles, ampolae, vesicular glands, bulbourethral glands) and a pool of lymph nodes (inguinal and scrotal). The microarray analysis of each tissue was done at three time points: acute infection (60 days post infection [dpi]), chronic infection phase I (120 dpi), and chronic infection phase II (240 dpi). The gene expression profiles associated to B. ovis infection were determined using the Affymetrix Bovine Genome Array and expression levels of infected and uninfected rams (control group, 0 dpi) were compared. Of the 23,000 genes analyzed in the microarrays, 139 during acute phase of infection, 930 during the chronic phase I and 744 genes from the chronic phase II were identified as Differentially Expressed Genes (DEGs). Thirty known genes and fourteen unknown genes were expressed during the three phases of infection in all tissues. The biological functions of these genes included immune cell trafficking, immunological disease, infectious disease, inflammatory disease, inflammatory response and cellular movement, and significant differences were observed at the three phases of infection and in all infected tissues. For the first analysis, 8 genes in common during the three time points and to all infected tissues were chosen for the microarray validation. Acute phase of infection supported the relevance of the ataxia telangiectasia-mutated ATMIN (ATM interactor) gene. RCHY1 (ring finger and CHY zinc finger domain containing 1), ANKFY1 (ankyrin repeat and FYVE domain containing 1) and EFEMP1 (EGF-containing fibulin-like extracellular matrix protein 1) were also highlighted by the analysis during chronic phase I of infection. ZRAB2 (Zinc finger, RAN-binding domain containing 2) was validated at chronic phase II. This study represents the first analysis of microarray gene expression in different tissues of rams infected with of B. ovis at various times during infection and many of the genes identified require further study. These results expand the knowledge of the pathogenesis of this B. ovis strain infection in rams and suggest new genes and pathways for further investigation.

This work was supported by Fundação de Amparo a Pesquisa do Estado de São Paulo-FAPESP (2008/03962-0), and by Conselho Nacional de Desenvolvimento Científico e Tecnológico-CNPQ (559023/2010-3). J.M.A.P. Antunes was granted with a full tuition FAPESP scholarship (2008/03837-0) in Brazil, and a full tuition of Coordenação de Aperfeiçoamento de Pessoal de Nível Superior-CAPES scholarship (Programa Institucional de Doutorado Sanduíche no Exterior, Processo BEX 0987∕11-5) in Spain.

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