Morphological and molecular characterization of a marine fish trypanosome from South Africa, including its development in a leech vector

Abstract

BackgroundTrypanosomes are ubiquitous blood parasites of marine and freshwater fishes, typically transmitted by aquatic leeches. Phylogenetic studies have been dominated by examples derived from freshwater fishes, with few marine representatives. Furthermore, life cycle studies on marine fish trypanosomes have focused on those of the northern hemisphere. In this investigation, we have examined the life cycle and molecular taxonomy of a marine fish trypanosome from South Africa.MethodsTo locate trypanosome stages, leeches were removed from fishes captured on the west and south coasts of South Africa, and fish blood films and leech squashes were Giemsa-stained and screened; leeches were also examined histologically. To determine whether trypanosome stages in fishes and leeches were of the same genotype, DNA was extracted from Giemsa-stained fish blood films and leech squashes, and from fish whole blood. Fragments of the 18S rRNA gene were amplified by PCR using trypanosome-specific primers and sequenced. Resulting sequence data were compared with each other and with published trypanosome 18S rDNA sequences, and used for phylogenetic analysis.ResultsTrypanosomes were detected in blood films from fishes of the families Clinidae, Blenniidae and Gobiidae. The flagellates ranged in size and staining properties within the films and across fish hosts. In squashes and histological sections of adult and juvenile leeches, identified as Zeylanicobdella arugamensis, trypanosome developmental stages were predominantly slender epimastigotes. Sequence data showed that trypanosomes derived from fishes were identical, irrespective of whether they were small or large forms; sequences derived largely from leech epimastigotes were also identical to those obtained from fish trypanosomes. Fish and leech trypanosome sequences fell into a marine fish aquatic clade, and aligned most closely with two trypanosome sequences from marine fishes off Norway.ConclusionsCombined morphological and molecular methods indicate that the trypanosomes examined here represent a single pleomorphic species, rather than the three species described originally. This species is identified as Trypanosoma nudigobii Fantham, 1919 with the leech Z. arugamensis as its vector, and T. capigobii Fantham, 1919 and T. blenniclini Fantham, 1930 are regarded as junior synonyms of the species. Phylogenetic analysis establishes its affinity with marine fish trypanosomes off Norway.

Blood parasite biodiversity of reef-associated fishes of the eastern Caribbean

“…Perkins et al 2009). However, except for trypano somes (Hayes et al 2014), such tools remain in developmental stages for marine fish blood parasites, where the parasite DNA is so heavily 'diluted' by host DNA and where phylogenetic affiliations are so poorly known.…”

“…All fish were measured prior to sampling (standard, fork, and total length). Fish were also visually inspected for any ectoparasites that have previously been shown to act as potential vectors of blood parasites; these include specifically leeches (Hayes et al 2006, Hayes et al 2014) and gnathiid isopods , Curtis et al 2013.…”

Infections of Hypostomus spp. by Trypanosoma spp. and leeches: a study of hematology and record of these hirudineans as potential vectors of these hemoflagellates

“…Many members of this family are heteroxenous, living one phase of life in the bloodstream or in a variety of tissues of different species of aquatic vertebrates (fish, amphibians and reptiles), and another phase in the intestine of bloodsucking invertebrates. Trypanosoma species (Gruby, 1843) are almost all heteroxenous and parasites of the blood of all classes of vertebrates, including marine and freshwater teleost and elasmobranch fish all over the world (WOO, 1998;EIRAS et al, 2008;ROBERTS & JANOVY, 2013;HAYES et al, 2014). Today, more than 200 species are known to parasite fish around the world (GUPTA & GUPTA, 2012).…”

Spliced Leader (SL) RNA: análises de genes e regiões intergênicas com aportes na filogenia, taxonomia e genotipagem de <i>Trypanosoma</i> spp. de todas as classes de vertebrados.

“…Todos os tripanossomas de peixe formam um único clado dividido em três subclados: peixes marinhos, peixes de água doce e o terceiro formado por isolados de tartaruga e ornitorrinco (Figura 8; Hayes et al, 2014;Lemos et al, 2015). No subclado de água doce, também se observam subgrupos, um deles correspondendo a isolados de bagres brasileiros e sanguessugas neles colhidas, formando um grupo pouco heterogêneo e separado de isolados de peixes da Europa, Ásia e África (Lemos et al, 2015).…”