Characterization of a blood activated chitinolytic system in the midgut of the sand fly vectors Lutzomyia longipalpis and Phlebotomus papatasi

Abstract
We characterized a cDNA from Phlebotomus papatasi, PpChit1, which encodes a midgut specific chitinase and show the presence of a functional, blood‐induced chitinolytic system in sand flies. PpChit1 is detected only in the midgut and is regulated by blood feeding. A recombinant protein (rPpChit1) produced in HEK 293‐F cells exhibited a similar activity profile to that found in the native protein against several specific substrates, including an oligomeric glycol chitin and synthetic 4‐methyl‐umbelliferone labelled substrates. Western blotting showed that the native protein is recognized by mouse polyclonal antibodies against rPpChit1. Additionally, the rPpChit1 and the native chitinase displayed similar retention times in a HPLC size fractionation column. When added to rPpChit1 or to midgut lysates, PpChit1 sera reduced chitinolytic activity by 65–70%.