The characterization of the Phlebotomus papatasi transcriptome.

Area of Science:

• * Entomology
• * Molecular Biology
• * Parasitology

Background:

• * Phlebotomine sand flies are critical vectors for numerous human diseases globally.
• * Leishmaniases, transmitted by sand flies, cause substantial mortality and morbidity.
• * Understanding sand fly biology is key to controlling disease transmission.

Purpose of the Study:

• * To perform the first global transcriptome analysis of *Phlebotomus papatasi*, an Old World vector of cutaneous leishmaniasis.
• * To compare the *P. papatasi* transcriptome with that of *Lutzomyia longipalpis*, a New World vector of visceral leishmaniasis.
• * To identify genes involved in key physiological processes relevant to sand fly vector competence.

Main Methods:

• * Construction of a normalized cDNA library from *Phlebotomus papatasi* across various life stages and feeding conditions (sugar, blood, infected blood).
• * High-throughput sequencing, data cleaning, and assembly of unique transcripts.
• * Gene Ontology (GO) classification and in-depth analysis of identified sequences.

Main Results:

• * Generation and assembly of 17,120 unique transcripts from *P. papatasi*.
• * 50% of sequences were classified using GO terms, indicating a comprehensive dataset.
• * Identification of 245 sequences with homology to proteins involved in blood/sugar digestion, immune response, and peritrophic matrix formation.
• * Discovery of 12 novel genes (trypsins, peptidoglycan recognition proteins (PGRP), chymotrypsins) with higher expression in larval stages.
• * Identification of two novel chymotrypsins and one novel PGRP with high expression after blood feeding.

Conclusions:

• * This study provides a comprehensive transcriptome resource for *Phlebotomus papatasi*, significantly enhancing genomic information.
• * Identified genes offer insights into the physiological adaptations of sand flies for vector competence.
• * Findings are crucial for future genome annotation and for developing strategies to control leishmaniasis transmission.