Cloning of a family of serine protease genes from the cat flea Ctenocephalides felis

Serine protease gene fragments approximately 480 nucleotides in length were amplified from Ctenocephalides felis larval and adult cDNA libraries using degenerate oligonucleotide PCR primers. Partial clones of thirty-eight dis tinct serine protease encoding sequences were isolated, and nineteen differ ent full-length cDNAs encoding mature serine proteases were subsequently cl oned and sequenced. All of the mature proteases contained the histidine, as partic acid and serine amino acids of the catalytic triad characteristic of serine proteases. The mature C. felis serine proteases had amino acid sequ ences that were at most 29-53% identical to those known insect and arachnid serine proteases. Two of the C. felis gene sequences had similarity with t he Drosophila melanogaster developmental genes snake and stubble. mRNA expr ession of selected serine protease genes was examined in different life sta ges, tissues, genders, and in response to bloodfeeding.