Inducible Antibacterial Defense System in C. elegans
Mallo G.V., Kurz C.L., Couillault C., Pujol
N., Granjeaud S., Kohara Y. and Ewbank J. J.
Current Biology 12, 1209-1214. (2002)
The term innate immunity refers to a number of evolutionary
ancient mechanisms that serve to defend animals and plants against
infection. Genetically tractable model organisms, especially Drosophila,
have contributed greatly to advances in our understanding of mammalian
innate immunity. Essentially, nothing is known about immune responses
in the nematode Caenorhabditis elegans. Using high-density
cDNA microarrays, we show here that infection of C. elegans
by the Gram-negative bacterium Serratia marcescens provokes
a marked upregulation of the expression of many genes. Among the
most robustly induced are genes encoding lectins and lysozymes,
known to be involved in immune responses in other organisms. Certain
infection-inducible genes are under the control of the DBL-1/TGFb pathway. We found that dbl-1 mutants
exhibit increased susceptibility to infection. Conversely, overexpression
of the lysozyme gene lys-1 augments the resistance of C.
elegans to S. marcescens. These results constitute
the first demonstration of inducible antibacterial defenses in
C. elegans and open new avenues for the investigation of
evolutionary conserved mechanisms of innate immunity.