Brucellosis 2003 proceedings - PHIDIAS

Keynote Lectures
BRUCELLOSIS IN WILDLIFE.
Darla R. Ewalt. US Department of Agriculture, Animal and Plant Health Inspection Service, Veterinary
Services, National Veterinary Services Laboratories, Ames, Iowa 50010, USA.
The study of brucellosis in wildlife has become more important as the
prevalence of the disease decreases in domestic animals. Numerous serological
studies and bacteriological studies to detect Brucella antibodies and infection in a
variety of species have been reported.
A major project involving the American bison located in the Greater
Yellowstone National Park Area has provided valuable information concerning the
pathogenesis and epidemiology of brucellosis in this population. Another problem
area in the western United States is the elk that are fed at the National Elk Refuge in
Wyoming. These animals are vaccinated with B. abortus strain 19 and the
prevalence in the herd is monitored serologically from hunter killed animals.
Researchers in Alaska, Canada, and Siberia have been studying brucellosis in
caribou and reindeer. These two animal species are infected with B. suis biovar 4
and pose a human health problem to the people raising and hunting them.
Feral swine remain a major source of infection. In the United States, the feral
swine are located in 26 states and exceed 2 million animals. Several instances of the
spread of B. suis from feral swine to domestic swine, cattle, and dogs have been
documented. Numerous bacteriological and serological studies have been conducted
to evaluate brucellosis in feral swine.
Since 1994, the prevalence of brucellosis in marine mammals has been
studied. Several serological and bacteriological studies have been conducted.
Current research is focused on studying the characteristics of the Brucella organism,
identifying marine mammal species that are infected with Brucella, and determining
the serological prevalence of the disease. Brucella has been isolated from a wide
variety of animals including seals, whales, dolphins and sea otters.
Brucella LPS A KEY IMMUNOMODULATOR OF IMMUNE RESPONSES IN MICE.
Jean-Pierre Gorvel. Centre d'Immunologie ISERM-CNRS de Marseille-Luminy, Marseille (France)
The properties of lipopolysaccharides (LPS) from intracellular Proteobacteria
such as Brucella, Chlamydia, Legionella, Rickettsia, and even from plant
endosymbionts such as Rhizobium reveal distinctive features that depart from
enterobacterial LPSs. Remarkably, low endotoxicity, deficient induction of host cell
activation and resistance to macrophage degradation of these LPSs are seen as a
virulence mechanism, which is particularly useful for an intracellular parasitic life
style. We have previously demonstrated that the low endotoxic B. abortus LPS
captured by macrophages was recycled back to the plasma membrane where it was
found associated with macrodomains. Here we show that LPS macrodomains
behave as lipid mega rafts, segregating several raft components, LPS-binding
proteins and the bulk of MHC class II molecules. These LPS macrodomains remain
for several months in macrophages, are resistant to the disruptive effects of β-
cyclodextrin on lipid rafts and hamper the presentation of peptides to specific T cells.
In addition, the LPS from Brucella abortus triggers CD4 + CD25 + T lymphocytes with a
phenotype compatible with activated/memory T cells recognizing MHC-II-LPS
macrodomains on the surface of antigen presenting cells (APCs). LPS-specific T cell
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Brucellosis 2003 International Research Conference