Mhaidi, I. | Search bioRxiv

bioRxiv2023

Establishment and maintenance of two sand fly colonies (Phlebotomus perniciosus and Phlebotomus papatasi) to implement experimental infections

Sand flies are vectors of Leishmania and Phlebovirus, pathogens responsible for public health concerns in numerous countries. Sand fly colonies are essential for research on vector-pathogen interactions. Methods for establishing and maintaining sand fly colonies have been well described in the literature. However, very few colonies of these considerable vectors currently exist. In order to encourage the creation of new colonies, we provide a timeline for researchers who want to implement colonies of Phlebotomus perniciosus and Phlebotomus papatasi. In this study, we set up colonies of both species to test and optimize their breeding conditions. For Ph. perniciosus, we reached a stable production of 800 individuals per week, one year after the start of the colony. For Ph. papatasi, a stable production of 400 individuals per week was reached 11 months after establishing the colony. Moreover, we have successfully conducted experiments within a year of establishing the colonies. In conclusion, our data on these two species showed that colonies could be established without difficulty with 1000-1500 eggs. It is possible to reach a stable weekly production of 800 individuals one year after starting the colony. We also describe colony settings and breeding recommendations to facilitate this procedure for other laboratories.

ecology↗

bioRxiv2023

A comparative genomics approach reveals a local genetic signature of Leishmania tropica in Morocco

In Morocco, cutaneous leishmaniasis (CL) caused by Leishmania (L.) tropica is an important health problem. Despite its high incidence in the country, the genomic heterogeneity of these parasites is still incompletely understood. In this study, we sequenced the genomes of 14 Moroccan isolates of L. tropica collected from confirmed cases of CL to investigate their genomic heterogeneity. Comparative genomics analyses were conducted by applying the recently established Genome Instability Pipeline (GIP), which allowed us to conduct phylogenomic and PCA analyses, and to assess genomic variations at the levels of the karyotype, gene copy number, and single nucleotide polymorphisms (SNPs). The results identified a core group of 12 isolates that were genetically highly related but evolutionarily distant to the reference genome as judged by the presence of over 100,000 SNPs, 75% of which were shared inside this core group. In addition, we identified two highly divergent strains, M3015 and Ltr_16, that were phylogenetically distinct between each other as well as to the core group and the reference genome. Read-depth analysis revealed important karyotypic variations across all isolates and uncovered important differences in gene copy number between the isolates of the core group and the L. tropica reference genome, as well as between the core group and M3015. In conclusion, our NGS results suggest the presence of a local SNP signature that distinguishes Moroccan L. tropica from other endemic regions and from the reference genome. These results pave the way for future research with a larger number of strains that will allow to correlate diverse phenotypes (resistance to treatments, virulence) and origins (geography, host species, year of isolation) to defined genomic signals that may represent interesting biomarker candidates.

genomics↗