Leptomonas seymouri: Adaptations to the Dixenous Life Cycle Analyzed by Genome Sequencing, Transcriptome Profiling and Co-infection with Leishmania donovani

Abstract

The co-infection cases involving dixenous Leishmania spp. (mostly of the L. donovani complex) and presumably monoxenous trypanosomatids in immunocompromised mammalian hosts including humans are well documented. The main opportunistic parasite has been identified as Leptomonas seymouri of the sub-family Leishmaniinae. The molecular mechanisms allowing a parasite of insects to withstand elevated temperature and substantially different conditions of vertebrate tissues are not understood. Here we demonstrate that L. seymouri is well adapted for the environment of the warm-blooded host. We sequenced the genome and compared the whole transcriptome profiles of this species cultivated at low and high temperatures (mimicking the vector and the vertebrate host, respectively) and identified genes and pathways differentially expressed under these experimental conditions. Moreover, Leptomonas seymouri was found to persist for several days in two species of Phlebotomus spp. implicated in Leishmania donovani transmission. Despite of all these adaptations, L. seymouri remains a predominantly monoxenous species not capable of infecting vertebrate cells under normal conditions.

Isolation of Novel Trypanosomatid, Zelonia australiensis sp. nov. (Kinetoplastida: Trypanosomatidae) Provides Support for a Gondwanan Origin of Dixenous Parasitism in the Leishmaniinae

“…Genome sequencing and transcriptome profiling identified several adaptations in L . seymouri that allow it to persist in the vertebrate host environment [100]. Furthermore, L .…”

“…Furthermore, L . seymouri survived for several days in two species of phlebotamine sand fly [100]. Given their close relationship with Leishmania , Leptomonas spp.…”

“…Given their close relationship with Leishmania , Leptomonas spp. represent interesting models for studying the transition from a monoxenous to dixenous life cycle, including the evolutionary innovations that enable parasitism of vertebrate hosts [98, 100]. Moreover, the ability of L .…”

T7 polymerase-driven transcription is downregulated in metacyclic promastigotes and amastigotes of Leishmania mexicana

“…This is one of the most potent enzymes on the Earth with Kcat reaching 10 7 molecules of H 2 0 2 per second. Its presence in all monoxenous relatives of Leishmania (species of Leptomonas Kent, 1880, Crithidia Léger, 1902 and Lotmaria Evans et Schwarz, 2014 of the subfamily Leishmaniinae -see Jirků et al 2012) requires further investigation (Kraeva et al 2015, Flegontov et al 2016. The entire open reading frame of the catalase gene, PCR-amplified from DNA of the H10 isolate of Leptomonas pyrrhocoris Zotta, 1912(Votýpka et al 2012, was integrated into the β-tubulin locus and expressed in a T7 polymerase-dependent, Tet-inducible way.…”

“…To verify that the decrease of gene expression in metacyclics and amastigotes is not sequence-specific, we replaced the T7 polymerase open reading frame by that of mCherry as described previously (Kraeva et al 2015). The construct was integrated into the same 18S rRNA locus (Kushnir et al 2005) and expression of the mCherry protein was confirmed by fluorescence microscopy (data not shown).…”