Authors

E Cupolillo¹; L Motta Cantanhêde¹; K Chourabi¹; M Côrtes Boité¹; C Dujardin²; S Heeren²; F Van den Broeck²;  ¹ Leishmaniasis Research Laboratory, Instituto Oswaldo Cruz, Brazil;  ² Department of Biomedical Sciences, Institute of Tropical Medicine, Belgium

Discussion

The parasitic flagellates of the Leishmania genus (Family Trypanosomatidae) cause leishmaniasis, a vector-borne disease with diverse clinical manifestations. Dixenous Leishmania parasites likely evolved from monoxenic Trypanosomatidae, with phylogenetic studies placing them in the Leishmaniinae subfamily. Their origin dates back to the Mesozoic era, dispersing globally before the Gondwana supercontinent breakup. These protists host negative-sense single-stranded RNA viruses (Family Leishbunyaviridae) and double-stranded RNA viruses (Family Totiviridae). Leishmania martiniquensis leishbunyavirus 1 (LmarLBV1) enhance infectivity in vitro and is the only known bunyavirus in Leishmania, found in the Mundinia subgenus, represented by worldwide dispersed Leishmania species. Totiviridae, commonly known as myco-viruses, infect also several protists. Leishmania RNA virus (LRV) includes LRV1 and LRV2, infecting Viannia and Leishmania subgenera, respectively. LRV1, influencing infection pathology, exhibits regional specificity, with Northern South American strains predominantly infected. Population genetic studies reveal LRV1 distribution aligning with Brazilian Amazon strains, emphasizing the importance of LRV surveys due to their impact on infection outcomes. LRVs provide Leishmania a survival advantage by suppressing anti-leishmanial immunity in vertebrate hosts. LRV1's interaction with the TLR3 endosomal receptor promotes chronic inflammation and facilitates Leishmania spread, causing persistent "metastatic" infection. The presence of viruses in certain Leishmania spp. may result from recent horizontal transfers, supported by experimental evidence of LRV transmission via exosomes. Understanding the co-evolution of LRV1 and Leishmania (Viannia) parasites, their species-specific relationships, and the endosymbiont's impact on parasite biology is crucial for comprehending Leishmania infection dynamics in hosts.