Induction of a putative serine protease transcript in immune challenged Drosophila.

In an effort to identify serine proteases involved in the insect's immune response, we used a degenerate PCR approach to amplify putative serine protease gene fragments in Drosophila. Sequencing of the cloned PCR products identified one serine protease previously isolated in D. melanogaster (SER1/SER2), as well as two novel putative serine protease gene fragments (SP2, SP3). The involvement of the corresponding genes in the immune response was examined by analyzing their expression in larval mRNA following both parasitic and bacterial exposures. The overexpression of one of the serine proteases-related mRNAs in immune challenged larvae suggests its involvement in the Drosophila immune response.