Project description:Gene expression profiling to address the effects of infection with Leishmania infantum during distinct clinical outcomes as active visceral leishmaniasis (VL), remission of disease and asymptomatic infection.
Project description:The genomic DNAs of strains JPCM5 and 263 of L. infantum, strains LV39 and Friedlin of L. major and strains Parrot-TarII and S125 of L. tarentolae were used in comparative genomic hybridizations to reveal the intra-species and inter-species gene content, and to validate L. tarentolae Parrot-TarII genome sequencing results. Leishmania (Sauroleishmania) tarentolae was first isolated in the lizard Tarentola mauritanica. This species is not known to be pathogenic to humans but is often used as a model organism for molecular analyses or protein overproduction. The Leishmania tarentolae Parrot-TarII strain genome sequence was resolved by high-throughput sequencing technologies. The L. tarentolae genome was first assembled de novo and then aligned against the reference L. major Friedlin genome to facilitate contig positioning and annotation, providing a 23-fold coverage of the genome. This is the first non-pathogenic to humans kinetoplastid protozoan genome to be described, and it provides an opportunity for comparison with the completed genomes of the pathogenic Leishmania species. A high synteny was observed in de novo assembled contigs between all sequenced Leishmania species. A number of limited chromosomal regions diverged between L. tarentolae and L. infantum, while remaining syntenic with L. major. Globally, over 90% of the L. tarentolae gene content was shared with the other Leishmania species. There were 250 L. major genes absent from L. tarentolae, and interestingly these missing genes were primarily expressed in the intracellular amastigote stage of the pathogenic parasites. This implies that L. tarentolae may have impaired ability to survive as an intracellular parasite. In contrast to other Leishmania genomes, two gene families were expanded in L. tarentolae, namely the leishmanolysin (GP63) and a gene related to the promastigote surface antigen (PSA31C). Overall, L. tarentolae appears to have a gene content more adapted to the insect stage rather than the mammalian one. This may partly explain its inability to replicate within mammalian macrophages and its suspected preferred life style as promastigote in the lizards.
Project description:The DEAD/H RNA helicase LINF_220021200 (DEVH1) gene from Leishmania infantum (Kinetoplastida:Trypanosomatidae) was cloned in the pTEX expression plasmid vector for trypanosomatids. Leishmania infantunm promastigotes were transfected and a knock-in L. infantum promastigote cell line was selected with geneticin (G418). A pTEX control promastigote line was also generated. Then, three independent biological replicate cultures of each pTEX-DEVH1 and pTEX promastigote lines were performed in the presence of the selective agent. The parasites were harvested on day 7 (stationary phase). Total mRNA samples were obtained. Cyanine dye-labelled samples were obtained from the knock-in and the control line (Cy5 and Cy3, respectively) and they were hybridized with custom whole-genome L. infantum DNA microarrays. This platform is included in GEO (GPL6781) and has also been repeatedly used in different experiments from 2009. Hybridization analysis allowed for finding differentially expressed genes due to the effect of induced over-expression of the DEVH1-encoding gene in the knock-in promastigote line compared to the control line. Genes involved in parasite infectivity and survival such as the HASP/SHERP gene cluster and an amastin gene or redox homeostasis genes are significantly down-regulated in the pTEX-DEVH1 knock-in promastigote line, whereas genes related to growth are up-regulated. This is in agreement with previous experimental data supporting that L. infantum DEVH1 knock-in promastigotes are able to recover the growth rate when stress conditions are removed.