Infection of Human Monocyte-Derived Macrophages With Coxiella burnetii - Bacterial Pathogenesis: Methods and Protocols - page 178

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Infection of Human Monocyte-Derived Macrophages
With Coxiella burnetii
Jeffrey G. Shannon and Robert A. Heinzen
Summary
Coxiella burnetii , the agent of Q fever, is an obligate intracellular bacterium that
has a tropism for cells of the mononuclear phagocyte system. Following internalization,
C. burnetii remains in a phagosome that ultimately matures into a vacuole with lysosomal
characteristics that supports pathogen replication. Most in vitro investigations of Coxiella -
macrophage interactions have employed continuous cell lines. Although these studies
have been informative, genetic alterations of immortalized cells may result in atten-
uated biological responses to infection relative to primary cells. Consequently, primary
macrophages are preferred as in vitro model systems. Here, we describe procedures for
propagation and isolation of C. burnetii from cell culture and the use of these preparations
to infect primary macrophages derived from human peripheral blood monocytes. Both
virulent phase I and avirulent phase II C. burnetii productively infect human monocyte-
derived macrophages (MDMs) and replicate with approximately the same kinetics, thereby
providing a more physiologically relevant in vitro model system to study the infectious
process of this pathogen.
Key Words: Coxiella ; macrophage; purification; quantitative PCR; Q fever;
phagolysosome; cell culture.
1. Introduction
Coxiella burnetii is a bacterial obligate intracellular pathogen and the etiologic
agent of humanacute andchronicQfever. Theorganismhas an impressivelybroad
host range that includes arthropods (primarily ticks), fish, birds, and a variety
of mammals (1) . C. burnetii has a worldwide distribution with the exception of
Antarctic regions and New Zealand (2,3) . In both wild and domestic animals,