Abstract
Sandflies (Diptera: Psychodidae) are important disease vectors of parasites of the genus Leishmania, as well as bacteria and viruses. Following studies of the midgut transcriptome of Phlebotomus papatasi, the principal vector of Leishmania major, two non-classical Kazal-type serine proteinase inhibitors were identified (PpKzl1 and PpKzl2). Analyses of expression profiles indicated that PpKzl1 and PpKzl2 transcripts are both regulated by blood-feeding in the midgut of P. papatasi and are also expressed in males, larva and pupa. We expressed a recombinant PpKzl2 in a mammalian expression system (CHO-S free style cells) that was applied to in vitro studies to assess serine proteinase inhibition. Recombinant PpKzl2 inhibited α-chymotrypsin to 9.4% residual activity and also inhibited α-thrombin and trypsin to 33.5% and 63.9% residual activity, suggesting that native PpKzl2 is an active serine proteinase inhibitor and likely involved in regulating digestive enzymes in the midgut. Early stages of Leishmania are susceptible to killing by digestive proteinases in the sandfly midgut. Thus, characterising serine proteinase inhibitors may provide new targets and strategies to prevent transmission of Leishmania.
Highlights
Sandflies (Diptera: Psychodidae) are important disease vectors of parasites of the genus Leishmania, as well as bacteria and viruses
In PpKzl1 an arginine residue is in the deduced P1 site, the predicted active site for Kazal-type inhibitors (Fig. 1A) and PpKzl2 contains a tyrosine in the P1 site (Fig. 1B)
PpKzl1 has 81% similarity and 73% identity to a putative protein identified in the New World sandfly L. longipalpis, vector of Leishmania infantum chagasi (Jochim et al 2008, Pitaluga et al 2009) (Fig. 1A)
Summary
Sandflies (Diptera: Psychodidae) are important disease vectors of parasites of the genus Leishmania, as well as bacteria and viruses. Following studies of the midgut transcriptome of Phlebotomus papatasi, the principal vector of Leishmania major, two non-classical Kazal-type serine proteinase inhibitors were identified (PpKzl and PpKzl). Several serine proteinase inhibitors have been identified in blood-feeding arthropods and linked to inhibition of thrombin and other components of the coagulation cascade to facilitate fluidity in the mouth parts and midgut following blood-feeding on a host [reviewed by Tanaka-Azevedo et al (2010)]. Many of these thrombin inhibitors belong to the family of Kazal-type serine proteinase inhibitors. Transmission of Leishmania to suitable vertebrate hosts generally occurs during blood-feeding through the bite site of an infected sandfly vector [reviewed by Ramalho-Ortigão et al (2010)]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
