Genomic Analysis of Two Phlebotomine Sand Fly Vectors of Leishmania from the New and Old World

Abstract

Phlebotomine sand flies are of global significance as important vectors of human disease, transmitting bacterial, viral, and protozoan pathogens, including the devastating kinetoplastid parasites of the genus Leishmania, the causative agents of diseases collectively termed leishmaniasis. More than 40 pathogenic Leishmania species are transmitted to humans by approximately 35 sand fly species in 98 countries with hundreds of millions of people at risk around the world. As no approved efficacious vaccine exists, available drugs are expensive and/or toxic, and resistance is emerging, management of sand fly populations to break transmission is currently the most effective disease control strategy. To better understand the biology of sand flies, including the mechanisms involved in their vectorial capacity, insecticide resistance, and population structures we sequenced the genomes of two of the most important sand fly species: Phlebotomus papatasi, a cutaneous leishmaniasis vector, (distributed in the Middle East and North Africa) and Lutzomyia longipalpis, a visceral leishmaniasis vector (distributed across Central and South America). We categorized and curated genes involved in processes important to their roles as disease vectors, including chemosensation, blood feeding, circadian rhythm, immunity, and detoxification, as well as mobile genetic elements. We also defined gene orthology and observed micro-synteny among the genomes. Finally, we present the genetic diversity and population structure of these species in their respective geographical areas. These genomes will be a foundation on which to base future efforts to prevent vector-borne transmission of Leishmania parasites. Author SummaryThe leishmaniases are a group of neglected tropical diseases caused by protist parasites from the Genus Leishmania. Different Leishmania species present a wide clinical profile, ranging from mild, often self-resolving cutaneous lesions that can lead to protective immunity, to severe metastatic mucosal disease, to visceral disease that is ultimately fatal. Leishmania parasites are transmitted by the bites of sand flies, and as no approved vaccine exists, available drugs are toxic and/or expensive and resistance is emerging, new dual control strategies to combat these diseases must be developed, combining interventions on human infections and integrated sand fly population management. Effective vector control requires a good understanding of the biology of sand flies. To this end, we sequenced and annotated the genomes of two sand fly species that are important leishmaniasis vectors from the Old and New Worlds. These genomes allow us to better understand, at the genetic level, processes important in the vector biology of these species, such as finding hosts, blood-feeding, immunity, and detoxification. These genomic resources highlight the driving forces of evolution of two major Leishmania vectors and provide foundations for future research on how to better prevent leishmaniasis by control of the sand fly vectors.