Chourabi, K. | Search bioRxiv

bioRxiv2025

Genomic evidence for co-evolution and sporadic host shifts in leishmaniaviruses

The association between Leishmania parasites and the double-stranded RNA virus, Leishmaniavirus (LRV), significantly impacts human health by modulating disease severity. Despite its clinical importance, the evolutionary history of this symbiosis remains largely unknown. This study presents one of the first formal investigations of their co-phylogenetic history across different taxonomic hierarchical levels; based on total RNA sequencing of cultivated isolates, simultaneously capturing the parasite`s transcriptome and the viral genome. We found strong support for phylogenetic congruence between Leishmania and LRV at both the subgenus and species level; based on genetic distance correlations and formal co-phylogenetic statistics. Focusing on the interactions of L. (V.) braziliensis and L. (V.) guyanensis with LRV1, we observed weaker co-phylogenetic signals though frequent instances of intraspecific host switching. Together, our findings indicate that LRV has been a persistent evolutionary partner of Leishmania, providing a framework for understanding the emergence and maintenance of virus-mediated disease phenotypes.

evolutionary biology↗

bioRxiv2024

Evolutionary genomics of a zoonotic parasite across the Neotropical Realm

The Neotropical realm, one of the most biodiverse regions on Earth, houses a broad range of zoonoses that pose serious public health threats. Protozoan parasites of the Leishmania (Viannia) braziliensis species complex cause zoonotic leishmaniasis in Latin America with clinical symptoms ranging from simple cutaneous to destructive, disfiguring mucosal lesions. We present the first comprehensive genome-wide continental study including 257 cultivated isolates representing most of the geographical distribution of this major human pathogen. The L. braziliensis species complex is genetically highly heterogeneous, consisting of divergent parasite groups that are associated with different environments and vary greatly in diversity. Apart from several small ecologically isolated groups with little diversity, our sampling identifies two major parasite groups, one associated with the Amazon and the other with the Atlantic Forest biomes. These groups show different recombination histories, as suggested by high levels of heterozygosity and effective population sizes in the Amazonian group in contrast to high levels of linkage and clonality in the Atlantic group. We argue that these differences are linked to strong eco-epidemiological differences between the two regions. In contrast to geographically focused studies, our study provides a broad understanding of the molecular epidemiology of zoonotic parasites circulating in tropical America.

evolutionary biology↗