Abstract:
Caenorhabditis elegans exhibits avoidance behavior
when presented with diverse bacterial pathogens.
We hypothesized that exposure to pathogens might
not only cause worms to move away but also simulta-
neously activate pathways that promote resistance to
the pathogen. We show that brief exposure to virulent
or avirulent strains of the bacterial pathogen entero-
pathogenic E. coli (EPEC) ‘‘immunizes’’ C. elegans
to survive a subsequent exposure that would other-
wise prove lethal, a phenomenon we refer to as
‘‘conditioning.’’ Conditioning requires dopaminergic
neurons; the p38 MAP kinase pathway, which regu-
lates innate immunity; and the insulin/IGFR pathway,
which regulates lifespan. Our findings suggest that
the molecular pathways that control innate immunity
and lifespan may be regulated or ‘‘conditioned’’ by
exposure to pathogens to allow survival in noxious
environments.
