Transcriptome Landscape of Intracellular Brucella ovis Surviving in RAW264.7 Macrophage Immune System

Abstract

Brucella ovis infection results in genital damage and epididymitis in rams, placental inflammation and rare abortion in ewes, and neonatal mortality in lambs. However, the mechanism underlying B. ovis infection remains unclear. In the present study, we used prokaryotic transcriptome sequencing to identify the differentially expressed genes (DEGs) between wild-type B. ovis and intracellular B. ovis in RAW264.7 macrophages. Gene ontology (GO) term enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis were performed, and quantitative reverse transcriptase PCR (qRT-PCR) was used to validate the top 10 upregulated and downregulated DEGs. The results showed that 212 genes were differentially expressed, including 68 upregulated and 144 downregulated genes, which were mainly enriched in 30 GO terms linked to biological process, cellular component, and molecular function. KEGG analysis showed that the DEGs were enriched in the hypoxia-inducible factor 1 (HIF-1) signaling pathway, mitogen-activated protein kinase (MAPK) signaling pathway, beta-alanine metabolism, and quorum sensing pathway. BME_RS01160, BME_RS04270, BME_RS08185, BME_RS12880, BME_RS25875, predicted_RNA865, and predicted_RNA953 were confirmed with the transcriptome sequencing data. Hence, our findings not only reveal the intracellular parasitism of B. ovis in the macrophage immune system, but also help to understand the mechanism of chronic B. ovis infection.

Pal Affects the Proliferation in Macrophages and Virulence of Brucella, and as Mucosal Adjuvants, Provides an Effective Protection to Mice Against Salmonella Enteritidis

“…Second, by secreting a variety of cytokines, macrophages play a role in promoting inflammatory response and immune activation and regulation [ 10 ]. In Burkholderia cenocepacia , Klebsiella pneumoniae ( K. pneumoniae ) and Escherichia coli ( E. coli ) , Pal can activate macrophages and induce them to secrete a variety of cytokines, and play a key role in the virulence of these bacteria [ 11 – 13 ].…”

The Three Flagellar Loci of Brucella ovis PA Are Dispensable for Virulence in Cellular Models and Mice

“…We have detected that B. ovis PA is able to transcribe flagellar genes located in the three main loci and that, as described for B. melitensis 16M ( 11 ), the transcription level is higher in the exponential growth phase, at least for fliF ( Figures 1B,C ). To our knowledge, no other studies have evaluated expression of flagellar genes in B. ovis , either in culture medium or inside phagocytes, and the sole study that analyzed the intracellular transcriptome of B. ovis did not report upregulation or downregulation of flagellar genes ( 46 ). However, expression of B. ovis flagellar genes in an intracellular environment, as it has been reported for B. melitensis 16M ( 11 ), cannot be discarded.…”