Open AccessIdentification and Isolation of Brucella suis Virulence Genes Involved in Resistance to the Human Innate Immune System
Author(s) -
JeanPierre Liautard,
Safia OuahraniBettache,
Véronique Jubier-Maurin,
Virginie Lafont,
Stephan Köhler,
JeanPierre Liautard
Publication year - 2007
Publication title -
infection and immunity
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.508
H-Index - 220
eISSN - 1070-6313
pISSN - 0019-9567
DOI - 10.1128/iai.00690-07
Subject(s) - biology , innate immune system , virulence , microbiology and biotechnology , brucella , immune system , immunity , intracellular parasite , brucella suis , virology , gene , immunology , genetics , brucella melitensis , brucellosis
Brucella strains are facultative intracellular pathogens that induce chronic diseases in humans and animals. This observation implies that Brucella subverts innate and specific immune responses of the host to develop its full virulence. Deciphering the genes involved in the subversion of the immune system is of primary importance for understanding the virulence of the bacteria, for understanding the pathogenic consequences of infection, and for designing an efficient vaccine. We have developed an in vitro system involving human macrophages infected by Brucella suis and activated syngeneic gamma9delta2 T lymphocytes. Under these conditions, multiplication of B. suis inside macrophages is only slightly reduced. To identify the genes responsible for this reduced sensitivity, we screened a library of 2,000 clones of transposon-mutated B. suis. For rapid and quantitative analysis of the multiplication of the bacteria, we describe a simple method based on Alamar blue reduction, which is compatible with screening a large library. By comparing multiplication inside macrophages alone and multiplication inside macrophages with activated gamma9delta2 T cells, we identified four genes of B. suis that were necessary to resist to the action of the gamma9delta2 T cells. The putative functions of these genes are discussed in order to propose possible explanations for understanding their exact role in the subversion of innate immunity.