The Maze Pathway of Coevolution: A Critical Review over the Leishmania and its Endosymbiotic History

The description of the genus Leishmania as causative agents of leishmaniasis occurred during this modern age. But evolutionary studies suggest that the origin of Leishmania can be traced back to the Mesozoic era. Subsequently, during its evolutionary process, it sustained a worldwide dispersion predating the breakup of the Gondwana supercontinent. It is assumed that this parasite evolved from monoxenic Trypanosomatidae. Phylogenetic studies locate the dixenous Leishmania in a well-supported clade, recently named subfamily Leishmaniinae, which includes also monoxenous trypanosomatids. Virus-Like Particles were reported in many species of this family. So far, several Leishmania species have been reported as infected by Leishmania RNA Virus (LRV) and Leishbunyavirus (LBV). Since the first descriptions of LRV decades ago, differences in its genomic structure have been highlighted, leading to the designation of a LRV1 in L. (Viannia) species and a LRV2 in other L. (Leishmania) species. There are strong indications of virus infecting Leishmania spp. ability to enhance parasitic survival both in human and experimental infections, through highly complex and specialized mechanisms. Phylogenetic analyzes of these viruses have shown that their genomic differences correlate with the infected parasite species, suggesting a coevolutionary process. Herein, we will present unpublished results regarding the relationship Leishmania – endosymbiotic Leishmania viruses and will explore what has been described in the literature, and what is known about this association that could contribute to discussions about the worldwide dispersion of Leishmania.