Two genotypic groups of morphologically similar fish trypanosomes from the Okavango Delta, Botswana

The neglected diversity: Description and molecular characterisation of Trypanosoma haploblephari Yeld and Smit, 2006 from endemic catsharks (Scyliorhinidae) in South Africa, the first trypanosome sequence data from sharks globally

With over 200 species of sharks reported from South African waters, the potential of discovering new blood parasites is very high. Unfortunately, this remains a poorly explored area of research, particularly in this biogeographical region. To date, only a single trypanosome species, Trypanosoma haploblephari Yeld and Smit, 2006, has been described from elasmobranchs off the coast of South Africa infecting the catsharks Haploblepharus pictus (Müller & Henle) and Haploblepharus edwardsii (Schinz). With only a single trypanosome species described and absence of molecular information, a study was conducted to provide further morphological and molecular information on T. haploblephari, a species considered not to demonstrate any pleomorphism. Thin blood smears were prepared, and blood was collected in molecular-grade ethanol from the caudal vein of two shark species, H. pictus and Poroderma pantherinum (Müller & Henle). Trypanosomes were morphologically described and molecularly characterised based on analysis of fragments of the 18S ribosomal gene. The presence of T. haploblephari in H. pictus was confirmed using the original description based on morphology, type host and locality, which allowed for the molecular characterisation of the species. In addition, this species was found parasitising P. pantherinum, its morphology considerably different in this host species as compared to that in the species of Haploblepharus, demonstrating that T. haploblephari may show extreme pleomorphism. This paper provides both morphological and molecular data for both morphotypes of T. haploblephari, with molecular comparisons to the only two other elasmobranch species of trypanosome for which sequence data is available. To elucidate the relationship of trypanosomes from aquatic hosts in general, more efforts need to be placed on elasmobranchs, as current phylogenetic studies are predominantly focused on trypanosomes infecting freshwater fishes.

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First molecular characterization of trypanosomes in endemic sharks in South Africa.

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Illustration of extreme morphological plasticity in trypanosomes.

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Phylogenetic analysis of marine and freshwater fish trypanosomes.

Morphological and molecular characterization of an African freshwater fish trypanosome, including its development in a leech vector

Trypanosomes are ubiquitous blood parasites of fishes and at least 16 species were originally described infecting African freshwater fishes. This number was later reduced to six and in the late 1990s it was proposed that most records of freshwater fish trypanosomes across Africa are Trypanosoma mukasai Hoare, 1932. Recently, results from a molecular analysis of fish trypanosomes from the Okavango Delta, Botswana, reported the presence of at least two genotypic groups and concluded that the identification of T. mukasai remains problematic. The aims of the present study were thus to elucidate the life cycle of a freshwater fish trypanosome from southern Africa and to do a morphological and molecular characterization of this parasite from both the fish host and leech vector. To locate trypanosome stages, leeches were removed from fishes captured in the Phongolo River, South Africa, and fish blood films and leech squashes were Giemsa-stained and screened. To determine whether trypanosome stages in fishes and leeches were of the same genotype, DNA was extracted and fragments of the 18S rDNA gene were amplified and sequenced. Trypanosomes were detected in the fish families Cichlidae, Clariidae, Mochokidae and Schilbeidae. Sequence data showed that the trypanosome from one of the leeches, identified as Batracobdelloides tricarinata (Blanchard, 1897), was highly similar to those obtained from the plain squeaker, Synodontis zambezensis, with 0.7% difference recorded between them. From morphological and molecular data presented here, it is clear that the trypanosomes from Phongolo are closely related to those of the Okavango and should be considered as a single diverse species with genetic differentiation between 0.4-2.9%, under the 3-5% differences expected to be seen between true distinct species within the rRNA. Developmental stages of the trypanosome found in the leech B. tricarinata supports its status as the vector and the molecular evidence shows the relationship between the trypanosome in the fish and leech, but also illustrates the exceptional genetic and morphological diversity of a single species of trypanosome between host species. The work presented here provides us with clear information to take further steps in resolving the taxonomy and systematics of African freshwater fish trypanosomes.

First report of trypanosomiasis in farmed largemouth bass (Micropterus salmoides) from China: pathological evaluation and taxonomic status

The aim of this study was to evaluate the effect of trypanosomes on cultured largemouth bass (Micropterus salmoides) and describe the taxonomic identification of the parasite. The effects of the parasite on M. salmoides were examined based on clinical symptoms, hemograms, histopathology, and serum biochemistry. Diseased fish showed typical clinical symptoms of trypanosomiasis, which included lethargy, anorexia, and histopathological lesions in the liver, head kidney, and spleen. The serum of diseased fish had significantly lower concentrations of glucose, triglyceride, and low-density lipoprotein, and significantly higher alanine transaminase (ALT), aspartate transaminase (AST), and lactate dehydrogenase (LDH) activities. The morphology of the trypanosomes was also analyzed using light microscopy, and their 18S rDNA sequence was analyzed to establish genetic relationships with other known strains. We found that the trypomastigote form of the trypanosomes from M. salmoides was similar to those isolated from Pelteobagrus fulvidraco. The trypanosomes had a slender and narrow body with a relatively long free flagellum, not well-developed undulating membrane, and an oval kinetoplast located near the subterminal posterior end of the body. The 18S rDNA sequences of the trypanosome from M. salmoides had the highest similarity (99.8%) with that of P. fulvidraco, suggesting they are identical species. Based on the differences in morphological characteristics and 18S rDNA sequence compared to trypanosomes isolated from other freshwater fish, it is considered as a new species and we propose the name Trypanosoma micropteri n. sp.

Trypanosomatids (Protozoa: Kinetoplastida) in three species of Armored Catfish from Mogi-Guaçu river, Pirassununga, São Paulo, Brazil

Trypanosome infections have been reported in several species of fish, in majority of cases described on the basis of morphological characteristics. Trypanosomes in fish are heteroxenous and transmitted by hirudineans. This study aims to evaluate the prevalence and density of infections by Trypanosoma sp. in blood from three species of catfish, Hypostomus regani, H. strigaticeps, H. albopunctatus, from the Mogi Guaçu River, Pirassununga, São Paulo, Brazil. Further, this study intends to characterize the Trypanosoma specimens found in the blood of these fish by morphological and molecular techniques. The trypanosomes overall prevalence observed was 47.6% with a general average density of 0.75 parasites/µl of blood. Hypostomus regani and Hypostomus strigaticeps showed a significant difference in prevalence. The average densities of parasites were not significantly different among the three fish species. Similar findings were observed for the monthly variations in densities. The parasites found in the three species of catfish studied showed similar morphological characteristics. The morphological data and the statistical analyses used in this study didn't show the formation of groups. The analyses provided evidence of the presence of pleomorphisms in the trypanosomes found in the three studied fish.

Phylogenetic and morphological characterization of trypanosomes from Brazilian armoured catfishes and leeches reveal high species diversity, mixed infections and a new fish trypanosome species

Background

Several Trypanosoma species transmitted by leeches infect marine and freshwater fish worldwide. To date, all South American fish trypanosome species identified have been based on unreliable morphological parameters. We recently isolated and cultured trypanosomes from the Brazilian armoured catfishes Hypostomus luetkeni and H. affinis. Here, we report the first phylogenetic analyses of South American (Brazilian) trypanosomes isolated from fish, and from leeches removed from these fish. We also analysed morphologically and morphometrically the different forms of fish, leech and cultured trypanosomes.

Methods

V7V8 SSU rRNA and gGAPDH sequences were used for phylogenetic analysis of Brazilian fish and leech trypanosomes. Trypanosomes from cultures, fish blood and leech samples were also characterized morphologically and morphometrically by light and electron microscopy.

Results

In blood smears from fish high trypanosome prevalence (90–100 %) and parasitemia (0.9-1.0x10²) were observed. Phylogenetic relationships using SSU rRNA and gGAPDH showed that, despite relevant sequence divergence, all Brazilian fish (and derived cultures) and leech trypanosomes clustered together into a single clade. The Brazilian clade clustered with European, North American and African fish trypanosomes. Based on sequence analysis, we uncovered a new species of Brazilian fish trypanosome, Trypanosoma abeli n. sp. Trypanosoma abeli cultures contained pleomorphic epimastigotes, small trypomastigotes and rare sphaeromastigotes. Ultrastructural features of T. abeli included a cytostome-cytopharynx complex in epi- and trypomastigotes, a compact rod-like kinetoplast, lysosome-related organelles (LROs) and multivesicular bodies. Trypanosomes found in fish blood smears and leech samples were highly pleomorphic, in agreement with sequence data suggesting that catfishes and leeches often have mixed trypanosome infections.

Conclusions

Trypanosoma abeli n. sp. is the first trypanosome from South American fishes isolated in culture, positioned in phylogenetic trees and characterized at the ultrastructural level. Trypanosoma abeli n. sp. is highly prevalent in H. luetkeni and H. affinis armoured catfish from the Atlantic Forest biome, and in other catfish species from the Amazon and the Pantanal. Sequencing data suggested that Brazilian catfish often have mixed trypanosome infections, highlighting the importance of molecular characterization to identify trypanosome species in fishes and leeches.

Electronic supplementary material

The online version of this article (doi:10.1186/s13071-015-1193-7) contains supplementary material, which is available to authorized users.

Phylogeny and Morphological Variability of Trypanosomes from African Pelomedusid Turtles with Redescription of Trypanosoma mocambicum Pienaar, 1962

Little is known about host specificity, genetic diversity and phylogenetic relationships of African turtle trypanosomes. Using PCR targeting the SSU rRNA gene, we detected trypanosomes in 24 of 134 (17.9%) wild caught African pelomedusid turtles: Pelusios upembae (n=14), P. bechuanicus (n=1), P. rhodesianus (n=3) and P. subniger (n=6). Mixed infection of Trypanosoma species was confirmed by PCR in three specimens of P. upembae, and in one specimen each of P. bechuanicus, P. rhodesianus, and P. subniger. Microscopic examination of stained blood smears revealed two distinct forms (broad and slender) of trypomastigotes. The broad form coincided in morphology with T. mocambicumPienaar, 1962. Accordingly, we have designated this form as the neotype of T. mocambicum. In phylogenetic analysis of the SSU rRNA gene, all the new turtle trypanosome sequences grouped in a single clade within the strongly supported "aquatic" clade of Trypanosoma species. The turtle trypanosome clade was further subdivided into two subclades, which did not correlate with host turtle species or trypanosome morphology. This study provides the first sequence data of Trypanosoma species isolated from freshwater turtles from tropical Africa and extends knowledge on diversity of trypanosomes in the Afrotropical zoogeographical realm.

Haematological response of snow barbell, Schizothorax plagiostomus Heckel, naturally infected with a new Trypanosoma species

The present study deals with the description of a new piscine trypanosome species found infecting the fresh water fish Schizothorax plagiostomus Heckel from river Jhelum, Srinagar, J&K, India and evaluating the haematological parameters of the infected fish. Haematological examination of S. plagiostomus revealed 61.1 % infection with an intensity of 1-9 trypanosomes/100 RBC's. Small (26.9 ± 1.39 µm) and large (47.17 ± 3.50 µm) forms of the trypanosome were observed in light microscopy investigations, revealing the dimorphic nature of the species. The trypanosome species was found to be distinct from the other related dimorphic species in morphometric dimensions including cell length, cell breadth, kinetoplast index, flagellar index, and cytological peculiarities, respectively. The detailed descriptions of the two morphological forms found in the blood of S. plagiostomus are provided. Based on the geographical location, morphometrics, cytological peculiarities, host status and comparative study, the new species is named Trypanosoma kashmirensis n. sp. The parasitic infestation caused a significant decrease (p < 0.05) in red blood cell counts, haematocrit and haemoglobin concentrations while, the leucocyte (WBC) count, mean cellular volume and mean cellular haemoglobin showed a significant increase (p < 0.05) in the infected fish as compared to the non-infected. The above alterations of the haematological parameters could be used as an important tool for the indication of Trypanosoma infection in the fish.

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

Background

Trypanosomes 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.

Methods

To 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.

Results

Trypanosomes 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.

Conclusions

Combined 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.

Notes on the occurrence of Trypanosoma sp. (Kinetoplastida: Trypanosomatidae) in freshwater fishes from South Africa

A total of 257 fishes from four families, Clariidae, Cichlidae, Cyprinidae and Schilbeidae were collected from three localities: the Sand River Dam, Swaziland; the Nylsvlei Nature Reserve, South Africa and the Vaal Dam and Vaal River Barrage, South Africa. Only fishes (n= 154) from Clariidae and Cichlidae were found to be infected with trypanosomes. A total of 221 Clarias gariepinus (Burchell 1822) were collected from the Vaal Dam and Vaal Barrage area, South Africa. Of these, 74%(89/121) were infected with trypanosomes from the Vaal Dam and 63%(63/100) from the Vaal River Barrage, with no seasonal infection pattern. A prevalence of 25%(1/4) was found in C. gariepinus from the Sand River Dam, Swaziland, and a 50% (1/2) prevalence was found in Tilapia sparrmanii from the Nylsvlei Nature Reserve, South Africa. Standard measurements conformed closely to the morphometric and morphological descriptions of Trypanosoma mukasai. This article provides new locality records for T. mukasai from the Vaal Dam, Vaal River Barrage and Nylsvlei Nature Reserve (South Africa) and the Sand River Dam (Swaziland). Tilapia sparrmanii collected in the Sand River Dam in Swaziland is also noted as a new host record.

Phylogenetic position of the freshwater fish trypanosome, Trypanosoma ophiocephali (Kinetoplastida) inferred from the complete small subunit ribosomal RNA gene sequence

The complete small subunit rRNA (SSrRNA) gene sequence (2,142 nucleotides) of the freshwater fish trypanosome Trypanosoma ophiocephali Chen (1964) was determined. The phylogenetic analysis deduced using neighbor-joining, maximum parsimony, and Bayesian methods demonstrated the existence of an “aquatic clade”. T. ophiocephali was revealed to be a member of the freshwater fish trypanosomes and form the sister species with Trypanosoma siniperca and Trypanosoma sp. Carpio with high bootstrap values (98% MP, 100% NJ, 100% Bay). The high similarity of SSrRNA gene sequences and morphometric characters showed that T. ophiocephali, T. siniperca and T. sp. Carpio probably were the same species. The phylogenetic trees further suggested that Chinese freshwater fish trypanosome might be paraphyletic, and fish trypanosomes should have low host specificity.

Morphological and genetic differences of Trypanosoma in some Chinese freshwater fishes: difficulties of species identification

Blood smears and purified trypanosome from freshwater fishes yellow catfish (Pseudobagras fulvidraco) and common carp (Cyprinus carpio) captured from Niushan Lake, Hubei Province were examined to determine whether all of their trypanosomes were Trypanosoma pseudobagri, a species of supposed host specificity and widespread existence across China. Trypanosomes occurred in 16/16 blood smears, and morphometric character analysis of trypanosomes from these smears showed that there were three morphospecies, Trypanosoma sp Carpio, T. sp Pseudobagri, and T. sp. 18S rDNA sequences of trypanosomes from 16 samples revealed three genetic groups among these fish trypanosomes. Group 1 was from C. carpio containing T. sp Carpio; groups 2 and 3 were from P. fulvidraco containing T. sp Pseudobagri and T. sp, respectively. The high similarity of morphometric characters and 18S rDNA sequences showed that T. sp Carpio and T. siniperca probably were the same species. T. sp Pseudobagri was the first occurrence in China. Sequence comparison showed that T. sp Pseudobagri sequence was most similar to that of clone Marv, whereas T. sp sequence differ from those of T. sp Carpio and T. sp Pseudobagri by 5.4 and 5.8%, respectively, and tentatively identified as T. pseudobagri. It was concluded that three species of trypanosomes, at least three genotypes occur in Niushan Lake fishes, and P. fulvidraco in this region appear to contain both types, although the identification of T. pseudobagri remains a problem.

Redescription of Trypanosoma siniperca Chang 1964 from freshwater fish of China based on morphological and molecular data

During the parasite fauna investigation within 2005, the freshwater fish trypanosome Trypanosoma siniperca Chang 1964 was isolated from the blood of Mandarin carp (Siniperca chuatsi) from Niushan Lake, Hubei Province, central China. Blood trypomastigotes were observed only, and the density of infection was low. Light microscopy examinations of this material made it possible to study in detail the morphology of this parasite and redescribe it according to current standards. T. siniperca is characterized also on the molecular level using the sequences of SSU rRNA gene. Phylogenetic analyses based on these sequences allowed clearer phylogenetic relationships to be established with other fish trypanosomes sequenced to date.

Redescription of Trypanosoma ophiocephali Chen 1964 (Kinetoplastida: Trypanosomatina: Trypanosomatidae) and first record from the blood of dark sleeper (Odontobutis obscura Temminck and Schlegel) in China

During the parasite fauna investigation within 2004 and 2005, the freshwater fish trypanosomes were isolated from the blood of dark sleeper (Odontobutis obscura Temminck and Schlegel) and snakehead fish (Ophiocephalus argus Cantor) from Niushan Lake, Hubei Province, China. Blood trypomastigotes were used for light microscopy investigations. The detailed descriptions of three morphological groups of the genus Trypanosoma: Trypanosoma sp. I and Trypanosoma sp. II found in blood of O. obscura, and Trypanosoma sp. III found in blood of O. argus were provided. Morphological features and host species show Trypanosoma sp. III belong to Trypanosoma ophiocephali Chen 1964, an incompletely described species. Infection with trypanosomes of O. obscura was recorded for the first time. According to the size and appearance, the trypanosomes in O. obscura were also tentatively identified as T. ophiocephali Chen 1964.