Field and experimental evidence of a new caiman trypanosome species closely phylogenetically related to fish trypanosomes and transmitted by leeches

Abstract

Trypanosoma terena and Trypanosoma ralphi are known species of the South American crocodilians Caiman crocodilus, Caiman yacare and Melanosuchus niger and are phylogenetically related to the tsetse-transmitted Trypanosoma grayi of the African Crocodylus niloticus. These trypanosomes form the Crocodilian clade of the terrestrial clade of the genus Trypanosoma. A PCR-survey for trypanosomes in caiman blood samples and in leeches taken from caimans revealed unknown trypanosome diversity and frequent mixed infections. Phylogenies based on SSU (small subunit) of rRNA and gGAPDH (glycosomal Glyceraldehyde Phosphate Dehydrogenase) gene sequences revealed a new trypanosome species clustering with T. terena and T. ralphi in the crocodilian clade and an additional new species nesting in the distant Aquatic clade of trypanosomes, which is herein named Trypanosoma clandestinus n. sp. This new species was found in Caiman yacare, Caiman crocodilus and M. niger from the Pantanal and Amazonian biomes in Brazil. Large numbers of dividing epimastigotes and unique thin and long trypomastigotes were found in the guts of leeches (Haementeria sp.) removed from the mouths of caimans. The trypanosomes recovered from the leeches had sequences identical to those of T. clandestinus of caiman blood samples. Experimental infestation of young caimans (Caiman yacare) with infected leeches resulted in long-lasting T. clandestinus infections that permitted us to delineate its life cycle. In contrast to T. terena, T. ralphi and T. grayi, which are detectable by hemoculturing, microscopy and standard PCR of caiman blood, T. clandestinus passes undetected by these methods due to very low parasitemia and could be detected solely by the more sensitive nested PCR method. T. clandestinus n. sp. is the first crocodilian trypanosome known to be transmitted by leeches and positioned in the aquatic clade closest to fish trypanosomes. Our data show that caimans can host trypanosomes of the aquatic or terrestrial clade, sometimes simultaneously.

Developmental and Ultrastructural Characterization and Phylogenetic Analysis of Trypanosoma herthameyeri n. sp. of Brazilian Leptodactilydae Frogs

“…Phylogeographical analyses of crocodilian trypanosomes also suggested their dispersion through the largely connected wetlands that existed before the present day configuration of the South American hydrographic basins (Fermino et al. , ).…”

“…Amplified DNA fragments were cloned in pGEM‐T‐easy, and ~5 clones were sequenced for each isolate, except for the isolate TCC316 for which a total of 7 and 12 clones of SSU rRNA and gGAPDH sequences, respectively, obtained from two independent PCR reactions were sequenced aiming at detecting mixed trypanosome infections (Fermino et al. ; Lemos et al. ).…”

“…An increasing number of trypanosome species from non‐mammalian hosts, including anurans, snakes, and crocodilians, have been cultivated and described using a combination of phylogenetic, morphological, and ultrastructural approaches (Fermino et al. , ; Viola et al. ).…”

“…), which also comprises trypanosomes from fishes, platypus, turtles and caimans transmitted by aquatic leeches (Fermino et al. , ; Hayes et al. ; Jakes et al.…”

“…Data about the host species, geographical ranges, vectors, experimental infections, pathogenicity, and possible evolutionary scenarios comprises complementary information that improves the description of any trypanosome species, and have been employed for the description of new trypanosome species (Fermino et al. , ; Lemos et al. ; Lima et al.…”