A novel Leishmania infantum reference strain for gene editing and the study of visceral leishmaniasis

Parasites of the Leishmania donovani complex are responsible for visceral leishmaniasis, a vector-borne disease transmitted through the bite of female phlebotomine sand flies. As well as the human hosts, these parasites infect many mammals which can serve as reservoirs. Dogs are particularly important reservoirs in Europe. Transmission is widespread across Asia, Africa, the Americas, and the Mediterranean basin, including South of France. Visceral leishmaniasis poses a fatal threat if left untreated. Research into the pathophysiology of this neglected disease is of prime importance, as is the development of new drugs. In this study, we evaluated the growth, differentiation, and macrophage infectivity of four L. donovani complex strains and identified L. infantum S9F1 (MHOM/MA/67/ITMAP263, clone S9F1) as a well-adapted strain for genetic engineering studies. We present here the genome sequence and annotation of L infantum S9F1 T7 Cas9, providing the scientific community with easy access to its genomic information. The data has been integrated into the LeishGEdit online resource to support primer design for CRISPR-Cas9 experiments. We now aim to make this strain widely available to foster pathogenesis studies of visceral leishmaniasis. AUTHOR SUMMARYVisceral leishmaniasis is a disease caused by parasites of the Leishmania donovani complex. These parasites are spread to humans and animals through the bites of sand flies, and this disease affects millions of people worldwide, particularly in regions such as the Americas, Asia, Africa, and the Mediterranean basin. If left untreated, it can be fatal. Researchers need to study the biology of the parasite that causes the disease to better understand how it develops and progresses. In this study, we identified a L. infantum strain that is amenable to genetic modification in the laboratory and may serve as a representative model of the causative agent of visceral leishmaniasis. We tested two CRISPR-Cas9 strategies on this strain, re-sequenced and annotated its genome, and made the data available on the LeishGEdit website. By sharing this strain with the research community, we aim to support further studies on the pathogenesis of visceral leishmaniasis.