Abstract
BackgroundBat trypanosomes have been implicated in the evolutionary history of the T. cruzi clade, which comprises species from a wide geographic and host range in South America, Africa and Europe, including bat-restricted species and the generalist agents of human American trypanosomosis T. cruzi and T. rangeli.MethodsTrypanosomes from bats (Rhinolophus landeri and Hipposideros caffer) captured in Mozambique, southeast Africa, were isolated by hemoculture. Barcoding was carried out through the V7V8 region of Small Subunit (SSU) rRNA and Fluorescent Fragment Length barcoding (FFLB). Phylogenetic inferences were based on SSU rRNA, glyceraldehyde phosphate dehydrogenase (gGAPDH) and Spliced Leader (SL) genes. Morphological characterization included light, scanning and transmission electron microscopy.ResultsNew trypanosomes from bats clustered together forming a clade basal to a larger assemblage called the T. cruzi clade. Barcoding, phylogenetic analyses and genetic distances based on SSU rRNA and gGAPDH supported these trypanosomes as a new species, which we named Trypanosoma livingstonei n. sp. The large and highly polymorphic SL gene repeats of this species showed a copy of the 5S ribosomal RNA into the intergenic region. Unique morphological (large and broad blood trypomastigotes compatible to species of the subgenus Megatrypanum and cultures showing highly pleomorphic epimastigotes and long and slender trypomastigotes) and ultrastructural (cytostome and reservosomes) features and growth behaviour (when co-cultivated with HeLa cells at 37°C differentiated into trypomastigotes resembling the blood forms and do not invaded the cells) complemented the description of this species.ConclusionPhylogenetic inferences supported the hypothesis that Trypanosoma livingstonei n. sp. diverged from a common ancestral bat trypanosome that evolved exclusively in Chiroptera or switched at independent opportunities to mammals of several orders forming the clade T. cruzi, hence, providing further support for the bat seeding hypothesis to explain the origin of T. cruzi and T. rangeli.
Highlights
Bat trypanosomes have been implicated in the evolutionary history of the T. cruzi clade, which comprises species from a wide geographic and host range in South America, Africa and Europe, including bat-restricted species and the generalist agents of human American trypanosomosis T. cruzi and T. rangeli
Trypanosomes in blood samples and haemocultures from bats In this study, we evaluated trypanosome infection in 79 bats from Mozambique: 48 Rhinolophus landeri from Chupanga, and 31 Hipposideros caffer from Gorongosa (Table 1; Figure 1)
The trypomastigotes we found in blood smears from bats infected with T. livingstonei resembled those denominated as T. heybergi-type and described for the African Megatrypanum trypanosomes T. leleupi, T. mpapuense, T. morinorum and T. thomasi
Summary
Bat trypanosomes have been implicated in the evolutionary history of the T. cruzi clade, which comprises species from a wide geographic and host range in South America, Africa and Europe, including bat-restricted species and the generalist agents of human American trypanosomosis T. cruzi and T. rangeli. Large blood trypanosomes of the subgenus Megatrypanum, followed by small blood forms of the subgenus Schizotrypanum, comprise the majority of the trypanosomes reported in bats throughout South America, Asia, Europe and, especially, Africa [1,3,5,7,8,10,11,12,13,14]. The subgenus Megatrypanum, originally comprising large blood trypanosomes from artiodactyls [15], was amended exclusively on a morphological basis to include any large trypanosome found in bats, monkeys and rodents [1,2,4,6]. In the reappraisal of this subgenus, other species from nonruminant hosts that putatively belong to this subgenus need to be phylogenetically positioned, especially those from bats, which together with trypanosomes from artiodactyls, account for most of the species assigned to this subgenus [1,4,7]
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