Project description:A laboratory colony of Phlebotomus perniciosus sand flies was maintained. Sand flies were infected with cultured Leishmania infantum promastigotes in stationary phase. Ten infected sand flies were dissected after 5 days and promastigotes within the gut pooled. The cells were immediately washed in PBS once and lysed in TRIzol reagent (Life Technologies). RNA isolation was completed according to the manufacturer's instructions, obtaining 63ng. RNA-seq libraries were generated using the spliced leader sequence for second strand synthesis (Cuypers et al., 2017; Haydock et al., 2015), thus allowing for specific amplification of sequences from L. infantum promastigotes, thus avoiding contamination with material from the sand fly gut. Single-end sequencing was performed in an Illumina HiSeq2500 instrument and data analysis was conducted using bowtie2, samtools, featureCounts and Geneious. The main findings are: i) substantial differences in differential gene expression between sand fly-derived (sfPro) and cultured (acPro) promastigotes; and ii) over-expression of genes involved in metacyclogenesis in sfPro vs. acPro, including gp63 genes, autophagy genes, etc.
Project description:The debilitating disease kala-azar or visceral leishmaniasis (VL) is caused by the kinetoplastid protozoan parasite Leishmania donovani. The parasite is transmitted by the hematophagous sandfly vector of the genus Phlebotomus in the old world and Lutzomyia in the new world. The predominant Phlebotomine species associated with transmission of kala-azar are Phlebotomus papatasi and Phlebotomus argentipes. The infected female sandfly transmits the parasite when it takes a blood meal. Understanding the molecular interaction of the sand fly-Leishmania during the development of parasite within the gut of the sandfly is crucial to understanding parasite life cycle. The complete genome sequences of sandfly vectors (Phlebotomus and Lutzomyia) are currently not available and sequencing efforts are underway. Non-availability of genome sequence can hamper identification of proteins in the sandfly vector. In the present study we have carried out proteogenomic analysis of unsequenced sandfly vector P. paptasi cell line using high-resolution mass spectrometry and comparative homology-based searches using related dipteran protein data (mosquitoes and fruit fly). This study resulted in identification of 1,312 proteins from P. papatasi based on homology. Our study demonstrates the power of proteogenomic approaches in mapping the proteomes of unsequenced organisms.
Project description:The leishmaniases are globally important parasitic diseases for which no human vaccines are currently available. To facilitate vaccine development, we conducted an open label observational study to establish a controlled human infection model of sand fly-transmitted cutaneous leishmaniasis caused by L. major. Between 24th January and 12th August 2022, we exposed 14 (8F, 6M) participants to infected sand flies. The primary objective was to demonstrate effectiveness (attack rate) and safety (absence of CL lesion at 12 months), whereas secondary and exploratory objectives included rate of lesion development, parasite load and analysis of local immune responses using immunohistology and spatial transcriptomics. We estimated a take rate for CL development of 64% (9/14) based on all participants, increasing to 82% (9/11) if only participants with confirmed bites are included. Lesion development was terminated by therapeutic biopsy in 10 participants with confirmed bites. 30% (3/10) had either one (2/10) or two (1/10) lesion recurrences between 4-8 months after biopsy that were treated successfully with cryotherapy. No severe or serious adverse events were recorded, but scarring was evident as expected. All participants were lesion-free at long-term (>12 month) follow up. We provide the first comprehensive map of immune cell distribution and cytokine/chemokine expression in human CL lesions, revealing discrete immune niches. This controlled human infection model offers opportunities for rapid vaccine candidate selection and a greater understanding of immune-mediated protection and pathology.
Project description:Leishmania infantum (Kinetoplastida:Trypanosomatidae) is the etiological agent of zoonotic visceral leishmaniasis in the Mediterranean basin. The motile promastigote stage infects the hematophagous sand fly vector host and amastigotes survives and multiplies within phagocytes of the mammalian host. Promastigotes are routinely cultured in liquid undefined media and are considered to mimic the environment within the sand fly gut. We have put this to the test by high-throughput gene expression profiling by shotgun DNA microarrays generated in our laboratory. This has been possible thanks to RNA amplification.