title: Lon Mutant of Brucella abortus Induces Tumor Necrosis Factor-Alpha in Murine J774.A1 Macrophage.
abstract: OBJECTIVE
  The objective of this study was to isolate a Brucella lon mutant and to analyze the cytokine response of B. lon mutant during macrophage infection.
  
  
  METHODS
  A wild-type Brucella abortus strain was mutagenized by Tn5 transposition. From the mouse macrophage J774.A1 cells, total RNA was isolated at 0 hours, 6 hours, 12 hours, and 24 hours after infection with Brucella. Using mouse cytokine microarrays, we measured transcriptional levels of the cytokine response, and validated our results with a reverse transcriptase-polymerase chain reaction (RT-PCR) assay to confirm the induction of cytokine messenger RNA (mRNA).
  
  
  RESULTS
  In host J774.A1 macrophages, mRNA levels of T helper 1 (Th1)-type cytokines, including tumor necrosis factor-alpha (TNF-α), interferon-gamma (IFN-γ), interleukin-2 (IL-2), and IL-3, were significantly higher in the lon mutant compared to wild-type Brucella and the negative control. TNF-α levels in cell culture media were induced as high as 2 μg/mL after infection with the lon mutant, a greater than sixfold change.
  
  
  CONCLUSIONS
  In order to understand the role of the lon protein in virulence, we identified and characterized a novel B. lon mutant. We compared the immune response it generates to the wild-type Brucella response in a mouse macrophage cell line. We demonstrated that the B. lon mutants induce TNF-α expression from the host J774.A1 macrophage.
authors: Division of Zoonoses, Korea National Institute of Health, Osong, Korea.
authors: Sungdo
authors: S
authors: Park
authors: Division of Zoonoses, Korea National Institute of Health, Osong, Korea.
authors: Young-Sill
authors: YS
authors: Choi
authors: Division of Zoonoses, Korea National Institute of Health, Osong, Korea.
authors: Sang-Hee
authors: SH
authors: Park
authors: Division of Zoonoses, Korea National Institute of Health, Osong, Korea.
authors: Young-Rok
authors: YR
authors: Kim
authors: Division of Zoonoses, Korea National Institute of Health, Osong, Korea.
authors: Hyuk
authors: H
authors: Chu
authors: Division of Zoonoses, Korea National Institute of Health, Osong, Korea.
authors: Kyu-Jam
authors: KJ
authors: Hwang
authors: Division of Zoonoses, Korea National Institute of Health, Osong, Korea.
authors: Mi-Yeoun
authors: MY
authors: Park
keywords: Brucella abortus; immune response; lon mutant