Brucellosis 2003 proceedings - PHIDIAS

Keynote Lectures
in poly-ε-caprolactone microparticles (HS-PEC) by the solvent evaporation method,
as a vaccine delivery system for brucellosis. The resulting microparticles displayed
sub-5 µm sizes. SDS-PAGE and immunoblotting of the extracted antigenic complex
confirmed that the apparent molecular weight and antigenicity remained unaltered
after the encapsulation procedure. The in vitro release profile of HS from HS-PEC
microparticles appeared to be pulsatil. These microparticles were injected
subcutaneously in BALB/c mice in order to observe the protection conferred against
experimental infection with the virulent strains B. melitensis H38, B. abortus 2308 or
B. ovis PA. The results showed that administration of HS-PEC microparticles gave
high amounts of IFN-γ and IL-2 but low quantities of IL-4, and protected mice against
any of the challenge strains used. Such protection was similar to that provided by the
reference living attenuated B. melitensis Rev 1 vaccine. In a recent experiment, a
single dose of HS-PEC (equivalent to 0.8 mg of HS) was able to protect rams
challenged with B. ovis, the statistical level of significancy was not different to Rev1.
Additional research must be performed with higher doses to establish the protective
value of this innocuous rough subcellular vaccine.
PHYLOGENY AND EVOLUTION OF ALPHA-PROTEOBACTERIAL GENOMES.
Siv G. E. Andersson, Bastien Bosseau, Carolin Frank, Olof Karlberg, Boris Legault. Dept. of Molecular
Evolution, Evolutionary Biology Center, Uppsala University, Norbyvagen 18C, 752 36 Uppsala,
Sweden.
Members of the alpha-proteobacteria include pathogens of domestic animals
like Brucella, while others are pathogens of humans causing diseases such as
typhus, trench fever and cat scratch disease. Yet other species have evolved
elaborate interactions with plants. The recent sequencing of a dozen alphaproteobacterial
genomes, including our own completed genomes of Rickettsia
prowazekii, Bartonella quintana, the agent of trench fever and Bartonella henselae,
the agent of cat-scratch disease, enables a global genomic comparison of human,
animal and plant-associated bacteria. Here, we present the phylogenetic
relationships of the alpha-proteobacteria for which complete genome sequence data
is available and discuss genomic features that are shared between human, animal
and plant pathogens. We identify differences in gene numbers, genomic contents
and architectures that correlate with major lifestyle changes. We show that extreme
genome size expansions of a few thousand genes have accompanied the evolution
of the plant-associated bacteria. In contrast, eliminations of a few thousand genes
are characteristic of shifts to intracellular animal environments and vector-mediated
transmission pathways. We conclude that lifestyle characteristics and exposure or
lack of phage attacks have influenced the genomic evolution of bacteria that have
developed close interactions with plants and animals.
Brucellosis 2003 International Research Conference
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