Genomes of Endotrypanum monterogeii from Panama and Zelonia costaricensis from Brazil: Expansion of Multigene Families in Leishmaniinae Parasites That Are Close Relatives of Leishmania spp

The Leishmaniinae subfamily of the Trypanosomatidae contains both genus Zelonia (monoxenous) and Endotrypanum (dixenous). They are amongst the nearest known relatives of Leishmania, which comprises many human pathogens widespread in the developing world. These closely related lineages are models for the genomic biology of monoxenous and dixenous parasites. Herein, we used comparative genomics to identify the orthologous groups (OGs) shared among 26 Leishmaniinae species to investigate gene family expansion/contraction and applied two phylogenomic approaches to confirm relationships within the subfamily. The Endotrypanum monterogeii and Zelonia costaricensis genomes were assembled, with sizes of 29.9 Mb and 38.0 Mb and 9.711 and 12.201 predicted protein-coding genes, respectively. The genome of E. monterogeii displayed a higher number of multicopy cell surface protein families, including glycoprotein 63 and glycoprotein 46, compared to Leishmania spp. The genome of Z. costaricensis presents expansions of BT1 and amino acid transporters and proteins containing leucine-rich repeat domains, as well as a loss of ABC-type transporters. In total, 415 and 85 lineage-specific OGs were identified in Z. costaricensis and E. monterogeii. The evolutionary relationships within the subfamily were confirmed using the supermatrix (3384 protein-coding genes) and supertree methods. Overall, this study showed new expansions of multigene families in monoxenous and dixenous parasites of the subfamily Leishmaniinae.

Molecular detection of blood-borne agents in vampire bats from Brazil, with the first molecular evidence of Neorickettsia sp. in Desmodus rotundus and Diphylla ecaudata

Bats (Mammalia, Chiroptera) represent the second largest group of mammals. Due to their ability to fly and adapt and colonize different niches, bats act as reservoirs of several potentially zoonotic pathogens. In this context, the present work aimed to investigate, using molecular techniques, the occurrence of blood-borne agents (Anaplasmataceae, Coxiella burnetii, hemoplasmas, hemosporidians and piroplasmids) in 198 vampire bats sampled in different regions of Brazil and belonging to the species Desmodus rotundus (n=159), Diphylla ecaudata (n=31) and Diaemus youngii (n=8). All vampire bats liver samples were negative in PCR assays for Ehrlichia spp., Anaplasma spp., piroplasmids, hemosporidians and Coxiella burnetii. However, Neorickettsia sp. was detected in liver samples of 1.51% (3/198) through nested PCR based on the 16S rRNA gene in D. rotundus and D. ecaudata. This is the first study to report Neorickettsia sp. in vampire bats. Hemoplasmas were detected in 6.06% (12/198) of the liver samples using a PCR based on the 16S rRNA gene. The two 16S rRNA sequences obtained from hemoplasmas were closely related to sequences previously identified in vampire and non-hematophagous bats from Belize, Peru and Brazil. The genotypic analysis identified a high diversity of bat-associated hemoplasma genotypes from different regions of the world, emphasizing the need for studies on this subject, in order to better understand the mechanisms of co-evolution between this group of bacteria and their vertebrate hosts. The role of neotropical bat-associated Neorickettsia sp. and bats from Brazilian in the biological cycle of such agent warrant further investigation.

Vivaxin genes encode highly immunogenic, non-variant antigens on the Trypanosoma vivax cell-surface

Trypanosoma vivax is a unicellular hemoparasite, and a principal cause of animal African trypanosomiasis (AAT), a vector-borne and potentially fatal livestock disease across sub-Saharan Africa. Previously, we identified diverse T. vivax-specific genes that were predicted to encode cell surface proteins. Here, we examine the immune responses of naturally and experimentally infected hosts to these unique parasite antigens, to identify immunogens that could become vaccine candidates. Immunoprofiling of host serum shows that one particular family (Fam34) elicits a consistent IgG antibody response. This gene family, which we now call Vivaxin, encodes at least 124 transmembrane glycoproteins that display quite distinct expression profiles and patterns of genetic variation. We focused on one gene (viv-β8) that encodes one particularly immunogenic vivaxin protein and which is highly expressed during infections but displays minimal polymorphism across the parasite population. Vaccination of mice with VIVβ8 adjuvanted with Quil-A elicits a strong, balanced immune response and delays parasite proliferation in some animals but, ultimately, it does not prevent disease. Although VIVβ8 is localized across the cell body and flagellar membrane, live immunostaining indicates that VIVβ8 is largely inaccessible to antibody in vivo. However, our phylogenetic analysis shows that vivaxin includes other antigens shown recently to induce immunity against T. vivax. Thus, the introduction of vivaxin represents an important advance in our understanding of the T. vivax cell surface. Besides being a source of proven and promising vaccine antigens, the gene family is clearly an important component of the parasite glycocalyx, with potential to influence host-parasite interactions.

Animal African trypanosomiasis (AAT) is an important livestock disease throughout sub-Saharan Africa and beyond. AAT is caused by Trypanosoma vivax, among other species, a unicellular parasite that is spread by biting tsetse flies and multiplies in the bloodstream and other tissues, leading to often fatal neurological conditions if untreated. Although concerted drug treatment and vector eradication programmes have succeeded in controlling Human African trypanosomiasis, AAT continues to adversely affect animal health and impede efficient food production and economic development in many less-developed countries. In this study, we attempted to identify parasite surface proteins that stimulated the strongest immune responses in naturally infected animals, as the basis for a vaccine. We describe the discovery of a new, species-specific protein family in T. vivax, which we call vivaxin. We show that one vivaxin protein (VIVβ8) is surface expressed and retards parasite proliferation when used to immunize mice, but does not prevent infection. Nevertheless, we also reveal that vivaxin includes another protein previously shown to induce protective immunity (IFX/VIVβ1). Besides its great potential for novel approaches to AAT control, the vivaxin family is revealed as a significant component of the T. vivax cell surface and may have important, species-specific roles in host interactions.

The Importance of Glycerophospholipid Production to the Mutualist Symbiosis of Trypanosomatids

The symbiosis in trypanosomatids is a mutualistic relationship characterized by extensive metabolic exchanges between the bacterium and the protozoan. The symbiotic bacterium can complete host essential metabolic pathways, such as those for heme, amino acid, and vitamin production. Experimental assays indicate that the symbiont acquires phospholipids from the host trypanosomatid, especially phosphatidylcholine, which is often present in bacteria that have a close association with eukaryotic cells. In this work, an in-silico study was performed to find genes involved in the glycerophospholipid (GPL) production of Symbiont Harboring Trypanosomatids (SHTs) and their respective bacteria, also extending the search for trypanosomatids that naturally do not have symbionts. Results showed that most genes for GPL synthesis are only present in the SHT. The bacterium has an exclusive sequence related to phosphatidylglycerol production and contains genes for phosphatidic acid production, which may enhance SHT phosphatidic acid production. Phylogenetic data did not indicate gene transfers from the bacterium to the SHT nucleus, proposing that enzymes participating in GPL route have eukaryotic characteristics. Taken together, our data indicate that, differently from other metabolic pathways described so far, the symbiont contributes little to the production of GPLs and acquires most of these molecules from the SHT.

Remarkable kinetoplast, cytostome-cytopharynx complex, and storage-related structures as dissected by three-dimensional reconstruction of Trypanosoma sp. 858 isolated from a toad (Amphibia: Anura)

In Brazil, the Trypanosoma sp. 858 was isolated from a toad (Anura: Bufonidae: Rhinella ictericus) and successfully maintained in cultures. We previously demonstrated that this trypanosome is different but tightly clustered phylogenetically with other trypanosomes from anurans. In this study, we addressed the ultrastructural features of cultured epimastigotes of this new trypanosome. Our results showed very long and thin free motile forms exhibiting a long flagellum and remarkable large and loose K-DNA network. In addition, the anterior portion contained many acidocalcisomes and a well-developed spongiome tubules-contractile vacuole system. One of the main morphological features of this anuran trypanosome was the presence of a complex cytostome-cytopharynx with a specialized membrane coating at the entrance, which is often hidden by the flagellum. Other conspicuous features are the presence of lipid-like droplets, lamellar membrane limited inclusions, and one very large reservosome, all at the posterior portion of the cell body. This new trypanosome may constitute an excellent model for organelles studies related to endocytosis and lipid storage, as demonstrated herein using scanning and transmission electron microscopy and three-dimensional models obtained by either electron microscopy tomography or dual-beam slice and view series.

Trypanosoma rangeli Genetic, Mammalian Hosts, and Geographical Diversity from Five Brazilian Biomes

Trypanosoma rangeli is a generalist hemoflagellate that infects mammals and is transmitted by triatomines around Latin America. Due to its high genetic diversity, it can be classified into two to five lineages. In Brazil, its distribution outside the Amazon region is virtually unknown, and knowledge on the ecology of its lineages and on host species diversity requires further investigation. Here, we analyzed 57 T. rangeli samples obtained from hemocultures and blood clots of 1392 mammals captured in different Brazilian biomes. The samples were subjected to small subunit (SSU) rDNA amplification and sequencing to confirm T. rangeli infection. Phylogenetic inferences and haplotype networks were reconstructed to classify T. rangeli lineages and to infer the genetic diversity of the samples. The results obtained in our study highlighted both the mammalian host range and distribution of T. rangeli in Brazil: infection was observed in five new species (Procyon cancrivorous, Priodontes maximum, Alouatta belzebul, Sapajus libidinosus, and Trinomys dimidiatus), and transmission was observed in the Caatinga biome. The coati (Nasua nasua) and capuchin monkey (S. libidinosus) are the key hosts of T. rangeli. We identified all four T. rangeli lineages previously reported in Brazil (A, B, D, and E) and possibly two new genotypes.

Endosymbiont Capture, a Repeated Process of Endosymbiont Transfer with Replacement in Trypanosomatids Angomonas spp

Trypanosomatids of the subfamily Strigomonadinae bear permanent intracellular bacterial symbionts acquired by the common ancestor of these flagellates. However, the cospeciation pattern inherent to such relationships was revealed to be broken upon the description of Angomonas ambiguus, which is sister to A. desouzai, but bears an endosymbiont genetically close to that of A. deanei. Based on phylogenetic inferences, it was proposed that the bacterium from A. deanei had been horizontally transferred to A. ambiguus. Here, we sequenced the bacterial genomes from two A. ambiguus isolates, including a new one from Papua New Guinea, and compared them with the published genome of the A. deanei endosymbiont, revealing differences below the interspecific level. Our phylogenetic analyses confirmed that the endosymbionts of A. ambiguus were obtained from A. deanei and, in addition, demonstrated that this occurred more than once. We propose that coinfection of the same blowfly host and the phylogenetic relatedness of the trypanosomatids facilitate such transitions, whereas the drastic difference in the occurrence of the two trypanosomatid species determines the observed direction of this process. This phenomenon is analogous to organelle (mitochondrion/plastid) capture described in multicellular organisms and, thereafter, we name it endosymbiont capture.

Molecular epidemiological insights into Trypanosoma vivax in Argentina: From the endemic Gran Chaco to outbreaks in the Pampas

Argentina is a home to millions of beef and dairy cattle and is one of the world's major exporters of meat. In the present study, Trypanosoma vivax was prevalent (2016-2018) in two major livestock farming regions, the Gran Chaco and the Pampas. In the Gran Chaco, 29% and 51% of animals (n = 72, taurine x zebuine crossbreed) were, respectively, positive by TviCATL-PCR and the more sensitive fluorescent fragment length barcoding (FFLB) method. While 18.4/38.8% of breeding cows (n = 49) tested positive by PCR/FFLB, infection increased to 52.2/78.3% in an outbreak of acute infection in steers (n = 23, taurine breed) brought from a non-endemic area. In the Pampas, overall infection rates in dairy cows (n = 54, taurine breed) were comparable (p > .01) between PCR (66.7%) and FFLB (62.9%) and showed a remarkable increase (PCR / FFLB) from 48.3/44.8% in 2017 to 88/84% in 2018. Infected dairy cattle exhibited anaemia, fever, anorexia, enlarged lymph nodes, emaciation and neurological signs. In contrast, beef cows (taurine x zebuine crossbreed) from the Pampas (n = 30) were asymptomatic despite exhibiting 16.7% (PCR) and 53.3% (FFLB) infection rates. Microsatellite genotyping revealed a remarkable microheterogeneity, seven genotypes in the Gran Chaco, nine in the Pampas and five shared between both regions, consistent with regular movement of T. vivax infected livestock. Data gathered in our study support the Gran Chaco being an endemic area for T. vivax, whereas the Pampas emerged as an outbreak area of acute infection in dairy cattle with critical negative impact in milk production. To the best of our knowledge, this is the first molecular study of T. vivax in Argentina, and results indicated the need for preventive measures to control T. vivax spread from the Gran Chaco to vast livestock farming areas across Argentina.

Pan-American Trypanosoma (Megatrypanum) trinaperronei n. sp. in the white-tailed deer Odocoileus virginianus Zimmermann and its deer ked Lipoptena mazamae Rondani, 1878: morphological, developmental and phylogeographical characterisation

Background

The subgenus Megatrypanum Hoare, 1964 of Trypanosoma Gruby, 1843 comprises trypanosomes of cervids and bovids from around the world. Here, the white-tailed deer Odocoileus virginianus (Zimmermann) and its ectoparasite, the deer ked Lipoptena mazamae Rondani, 1878 (hippoboscid fly), were surveyed for trypanosomes in Venezuela.

Results

Haemoculturing unveiled 20% infected WTD, while 47% (7/15) of blood samples and 38% (11/29) of ked guts tested positive for the Megatrypanum-specific TthCATL-PCR. CATL and SSU rRNA sequences uncovered a single species of trypanosome. Phylogeny based on SSU rRNA and gGAPDH sequences tightly cluster WTD trypanosomes from Venezuela and the USA, which were strongly supported as geographical variants of the herein described Trypanosoma (Megatrypanum) trinaperronei n. sp. In our analyses, the new species was closest to Trypanosoma sp. D30 from fallow deer (Germany), both nested into TthII alongside other trypanosomes from cervids (North American elk and European fallow, red and sika deer), and bovids (cattle, antelopes and sheep). Insights into the life-cycle of T. trinaperronei n. sp. were obtained from early haemocultures of deer blood and co-culture with mammalian and insect cells showing flagellates resembling Megatrypanum trypanosomes previously reported in deer blood, and deer ked guts. For the first time, a trypanosome from a cervid was cultured and phylogenetically and morphologically (light and electron microscopy) characterised.

Conclusions

In the analyses based on SSU rRNA, gGAPDH, CATL and ITS rDNA sequences, neither cervids nor bovids trypanosomes were monophyletic but intertwined within TthI and TthII major phylogenetic lineages. One host species can harbour more than one species/genotype of trypanosome, but each trypanosome species/genotype was found in a single host species or in phylogenetically closely related hosts. Molecular evidence that L. mazamae may transmit T. trinaperronei n. sp. suggests important evolutionary constraints making tight the tripartite T. trinaperronei-WTD-deer ked association. In a plausible evolutionary scenario, T. trinaperronei n. sp. entered South America with North American white-tailed deer at the Pliocene-Pleistocene boundary following the closure of the Panama Isthmus.

Variant antigen diversity in Trypanosoma vivax is not driven by recombination

African trypanosomes (Trypanosoma) are vector-borne haemoparasites that survive in the vertebrate bloodstream through antigenic variation of their Variant Surface Glycoprotein (VSG). Recombination, or rather segmented gene conversion, is fundamental in Trypanosoma brucei for both VSG gene switching and for generating antigenic diversity during infections. Trypanosoma vivax is a related, livestock pathogen whose VSG lack structures that facilitate gene conversion in T. brucei and mechanisms underlying its antigenic diversity are poorly understood. Here we show that species-wide VSG repertoire is broadly conserved across diverse T. vivax clinical strains and has limited antigenic repertoire. We use variant antigen profiling, coalescent approaches and experimental infections to show that recombination plays little role in diversifying T. vivax VSG sequences. These results have immediate consequences for both the current mechanistic model of antigenic variation in African trypanosomes and species differences in virulence and transmission, requiring reconsideration of the wider epidemiology of animal African trypanosomiasis.

Expanding our knowledge on African trypanosomes of the subgenus Pycnomonas: A novel Trypanosoma suis-like in tsetse flies, livestock and wild ruminants sympatric with Trypanosoma suis in Mozambique

Among the subgenera of African tsetse-transmitted trypanosomes pathogenic to livestock, the least known is the subgenus Pycnomonas, which contains a single species, Trypanosoma suis (TSU), a pathogen of domestic pigs first reported in 1905 and recently rediscovered in Tanzania and Mozambique. Analysis by Fluorescent Fragment Length Barcoding (FFLB) revealed an infection rate of 20.3% (108 out of 530 tsetse flies) in a recent study in the Gorongosa and Niassa wildlife reserves in Mozambique, and demonstrated two groups of Pycnomonas trypanosomes: one (14.1%, 75 flies) showing an FFLB profile identical to the reference TSU from Tanzania, and the other (6.2%, 33 flies) differing slightly from reference TSU and designated Trypanosoma suis-like (TSU-L). Phylogenetic analyses tightly clustered TSU and TSU-L from Mozambique with TSU from Tanzania forming the clade Pycnomonas positioned between the subgenera Trypanozoon and Nannomonas. Our preliminarily exploration of host ranges of Pycnomonas trypanosomes revealed TSU exclusively in warthogs while TSU-L was identified, for the first time for a member of the subgenus Pycnomonas, in ruminants (antelopes, Cape buffalo, and in domestic cattle and goats). The preferential blood meal sources of tsetse flies harbouring TSU and TSU-L were wild suids, and most of these flies concomitantly harboured the porcine trypanosomes T. simiae, T. simiae Tsavo, and T. godfreyi. Therefore, our findings support the link of TSU with suids while TSU-L remains to be comprehensively investigated in these hosts. Our results greatly expand our knowledge of the diversity, hosts, vectors, and epidemiology of Pycnomonas trypanosomes. Due to shortcomings of available molecular diagnostic methods, a relevant cohort of trypanosomes transmitted by tsetse flies to ungulates, especially suids, has been neglected or most likely misidentified. The method employed in the present study enables an accurate discrimination of trypanosome species and genotypes and, hence, a re-evaluation of the "lost" subgenus Pycnomonas and of porcine trypanosomes in general, the most neglected group of African trypanosomes pathogenic to ungulates.

Zoonotic Trypanosomes in Rats and Fleas of Venezuelan Slums

Rattus spp. are reservoirs of many human zoonoses, but their role in domestic transmission cycles of human trypanosomiasis is underestimated. In this study, we report trypanosome-infected Rattus norvegicus and Rattus rattus in human dwellings in slums neighboring Maracay, a large city near Caracas, the capital of Venezuela. Blood samples of R. norvegicus and R. rattus examined by PCR and FFLB (fluorescent fragment length barcoding) revealed a prevalence of 6.3% / 31.1% for Trypanosoma lewisi (agent of rat- and flea-borne human emergent zoonosis), and 10.5% / 24.6% for Trypanosoma cruzi (agent of Chagas disease). Detection in flea guts of T. lewisi (76%) and, unexpectedly, T. cruzi (21.3%) highlighted the role of fleas as carriers and vectors of these trypanosomes. A high prevalence of rats infected with T. lewisi and T. cruzi and respective flea and triatomine vectors poses a serious risk of human trypanosomiasis in Venezuelan slums. Anthropogenic activities responsible for growing rat and triatomine populations within human dwellings drastically increased human exposure to trypanosomes. This scenario has allowed for the reemergence of Chagas disease as an urban zoonosis in Venezuela and can propitiate the emergence of atypical T. lewisi infection in humans.

Genetic diversity of Bartonella spp. in vampire bats from Brazil

Recently, an increasing number of Bartonella species have been emerged to cause human diseases. Among animal reservoirs for Bartonella spp., bats stand out due to their high mobility, wide distribution, social behaviour and long-life span. Although studies on the role of vampire bats in the epidemiology of rabies have been extensively investigated in Latin America, information on the circulation and genetic diversity of Bartonella species in these bat species is scarce. In the present work, 208 vampire bats, namely Desmodus rotundus (the common vampire bat; n = 167), Diphylla ecaudata (the hairy-legged vampire bat; n = 32) and Diaemus youngii (the white-winged vampire bat; n = 9) from 15 different states in Brazil were sampled. DNA was extracted from liver tissue samples and submitted to real-time PCR (qPCR) and conventional PCR (cPCR) assays for Bartonella spp. targeting five genetic loci, followed by phylogenetic and genotype network analyses. Fifty-one out of 208 liver samples (24.51%) were positive for Bartonella DNA in the ITS real-time PCR assay [40 (78.43%) of them were from D. rotundus from 11 states, and 11 (21.57%) samples from D. ecaudata from three states. Eleven genotypes were found for each gltA and rpoB genes. Several ITS sequences detected in the present study clustered within the lineage that includes B. bacilliformis and B. ancachensis. The Bayesian phylogenetic inference based on the gltA gene positioned the obtained sequences in six different clades, closely related to Bartonella genotypes previously detected in D. rotundus and associated ectoparasites sampled in Latin America. On the other hand, the Bartonella rpoB genotypes clustered together with the ruminant species, B. schoenbuchensis and B. chomelii. The present study describes for the first time the molecular detection of Bartonella spp. in D. ecaudata bats. It also indicates that Bartonella spp. of vampire bats are genetically diverse and geographically widespread in Brazil.

Shared species of crocodilian trypanosomes carried by tabanid flies in Africa and South America, including the description of a new species from caimans, Trypanosoma kaiowa n. sp

Background

The genus Trypanosoma Gruby, 1843 is constituted by terrestrial and aquatic phylogenetic lineages both harboring understudied trypanosomes from reptiles including an increasing diversity of crocodilian trypanosomes. Trypanosoma clandestinus Teixeira & Camargo, 2016 of the aquatic lineage is transmitted by leeches to caimans. Trypanosoma grayi Novy, 1906 of the terrestrial lineage is transmitted by tsetse flies to crocodiles in Africa, but the vectors of Neotropical caiman trypanosomes nested in this lineage remain unknown.

Results

Our phylogenetic analyses uncovered crocodilian trypanosomes in tabanids from South America and Africa, and trypanosomes other than T. grayi in tsetse flies. All trypanosomes found in tabanids clustered in the crocodilian clade (terrestrial lineage) forming six clades: Grayi (African trypanosomes from crocodiles and tsetse flies); Ralphi (trypanosomes from caimans, African and Brazilian tabanids and tsetse flies); Terena (caimans); Cay03 (caimans and Brazilian tabanids); and two new clades, Tab01 (Brazilian tabanid and tsetse flies) and Kaiowa. The clade Kaiowa comprises Trypanosoma kaiowa n. sp. and trypanosomes from African and Brazilian tabanids, caimans, tsetse flies and the African dwarf crocodile. Trypanosoma kaiowa n. sp. heavily colonises tabanid guts and differs remarkably in morphology from other caiman trypanosomes. This species multiplied predominantly as promastigotes on log-phase cultures showing scarce epimastigotes and exhibited very long flagellates in old cultures. Analyses of growth behavior revealed that insect cells allow the intracellular development of Trypanosoma kaiowa n. sp.

Conclusions

Prior to this description of Trypanosoma kaiowa n. sp., no crocodilian trypanosome parasitic in tabanid flies had been cultured, morphologically examined by light, scanning and transmission microscopy, and phylogenetically compared with other crocodilian trypanosomes. Additionally, trypanosomes thought to be restricted to caimans were identified in Brazilian and African tabanids, tsetse flies and the dwarf crocodile. Similar repertoires of trypanosomes found in South American caimans, African crocodiles and tabanids from both continents support the recent diversification of these transcontinental trypanosomes. Our findings are consistent with trypanosome host-switching likely mediated by tabanid flies between caimans and transoceanic migrant crocodiles co-inhabiting South American wetlands at the Miocene.

Electronic supplementary material

The online version of this article (10.1186/s13071-019-3463-2) contains supplementary material, which is available to authorized users.

Trypanosoma madeirae sp. n.: A species of the clade T. cruzi associated with the neotropical common vampire bat Desmodus rotundus

Molecular phylogenetic studies have revealed the growing diversity of bat trypanosomes. Here, 14 isolates from blood samples of the vampire bat Desmodus rotundus (Phyllostomidae) from Rio de Janeiro, Southeast Brazil, were cultivated, and morphologically and molecularly characterized. All isolates represent a novel species named Trypanosoma madeirae n. sp. positioned in the Neobat lineage of the clade T. cruzi. The Neobat lineage also comprises closely related trypanosomes of clades Neotropic 1, 2 and 3 from diverse phyllostomid species. Trypanosomes of Neotropic 1, found in Trachops cirrhosus and Artibeus jamaicensis (phyllostomids), likely represent a different species or genotype closely related to T. madeirae. Consistent with its phylogenetic positioning, T. madeirae differs from Trypanosoma cruzi in morphology of both epimastigote and trypomastigote culture forms and does not infect Triatoma infestans. Similar to its closest relatives of Neobat lineage, T. madeirae was unable to develop within mammalian cells. To date, PCR-surveys on archived blood/liver samples unveiled T. madeirae exclusively in D. rotundus from Southern to Northern Brazil. The description of a new species of bat trypanosome associated with vampire bats increases the repertoire of trypanosomes infecting D. rotundus, currently comprised of Trypanosoma cruzi, T. cruzi marinkellei, Trypanosoma dionisii, Trypanosoma rangeli, Trypanosoma pessoai, and Trypanosoma madeirae.

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Trypanosoma madeirae n. sp. was so far only detected in the vampire bat Desmodus rotundus.

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T. madeirae clustered with other Neotropical trypanosomes in the Neobat lineage of the clade T. cruzi.

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Several species of trypanosomes are hosted by Desmodus rotundus.

Genomic comparison of Trypanosoma conorhini and Trypanosoma rangeli to Trypanosoma cruzi strains of high and low virulence

Background

Trypanosoma conorhini and Trypanosoma rangeli, like Trypanosoma cruzi, are kinetoplastid protist parasites of mammals displaying divergent hosts, geographic ranges and lifestyles. Largely nonpathogenic T. rangeli and T. conorhini represent clades that are phylogenetically closely related to the T. cruzi and T. cruzi-like taxa and provide insights into the evolution of pathogenicity in those parasites. T. rangeli, like T. cruzi is endemic in many Latin American countries, whereas T. conorhini is tropicopolitan. T. rangeli and T. conorhini are exclusively extracellular, while T. cruzi has an intracellular stage in the mammalian host.

Results

Here we provide the first comprehensive sequence analysis of T. rangeli AM80 and T. conorhini 025E, and provide a comparison of their genomes to those of T. cruzi G and T. cruzi CL, respectively members of T. cruzi lineages TcI and TcVI. We report de novo assembled genome sequences of the low-virulent T. cruzi G, T. rangeli AM80, and T. conorhini 025E ranging from ~ 21–25 Mbp, with ~ 10,000 to 13,000 genes, and for the highly virulent and hybrid T. cruzi CL we present a ~ 65 Mbp in-house assembled haplotyped genome with ~ 12,500 genes per haplotype. Single copy orthologs of the two T. cruzi strains exhibited ~ 97% amino acid identity, and ~ 78% identity to proteins of T. rangeli or T. conorhini. Proteins of the latter two organisms exhibited ~ 84% identity. T. cruzi CL exhibited the highest heterozygosity. T. rangeli and T. conorhini displayed greater metabolic capabilities for utilization of complex carbohydrates, and contained fewer retrotransposons and multigene family copies, i.e. trans-sialidases, mucins, DGF-1, and MASP, compared to T. cruzi.

Conclusions

Our analyses of the T. rangeli and T. conorhini genomes closely reflected their phylogenetic proximity to the T. cruzi clade, and were largely consistent with their divergent life cycles. Our results provide a greater context for understanding the life cycles, host range expansion, immunity evasion, and pathogenesis of these trypanosomatids.

Electronic supplementary material

The online version of this article (10.1186/s12864-018-5112-0) contains supplementary material, which is available to authorized users.

Genome-wide identification of evolutionarily conserved Small Heat-Shock and eight other proteins bearing α-crystallin domain-like in kinetoplastid protists

Small Heat-Shock Proteins (sHSPs) and other proteins bearing alpha-crystallin domains (ACD) participate in defense against heat and oxidative stress and play important roles in cell cycle, cytoskeleton dynamics, and immunological and pathological mechanisms in eukaryotes. However, little is known about these proteins in early-diverging lineages of protists such as the kinetoplastids. Here, ACD-like proteins (ACDp) were investigated in genomes of 61 species of 12 kinetoplastid genera, including Trypanosoma spp. (23 species of mammals, reptiles and frogs), Leishmania spp. (mammals and lizards), trypanosomatids of insects, Phytomonas spp. of plants, and bodonids. Comparison of ACDps based on domain architecture, predicted tertiary structure, phylogeny and genome organization reveals a kinetoplastid evolutionarily conserved repertoire, which diversified prior to trypanosomatid adaptation to parasitic life. We identified 9 ACDp orthologs classified in 8 families of TryACD: four previously recognized (HSP20, Tryp23A, Tryp23B and ATOM69), and four characterized for the first time in kinetoplastids (TryACDP, TrySGT1, TryDYX1C1 and TryNudC). A single copy of each ortholog was identified in each genome alongside TryNudC1/TrypNudC2 homologs and, overall, ACDPs were under strong selection pressures at main phylogenetic lineages. Transcripts of all ACDPs were identified across the life stages of T. cruzi, T. brucei and Leishmania spp., but proteomic profiles suggested that most ACDPs may be species- and stage-regulated. Our findings establish the basis for functional studies, and provided evolutionary and structural support for an underestimated repertoire of ACDps in the kinetoplastids.

Genetic Diversity and Phylogenetic Relationships of Coevolving Symbiont-Harboring Insect Trypanosomatids, and Their Neotropical Dispersal by Invader African Blowflies (Calliphoridae)

This study is about the inter- and intra-specific genetic diversity of trypanosomatids of the genus Angomonas, and their association with Calliphoridae (blowflies) in Neotropical and Afrotropical regions. Microscopic examination of 3,900 flies of various families, mostly Calliphoridae, revealed that 31% of them harbored trypanosomatids. Small subunit rRNA (SSU rRNA) barcoding showed that Angomonas predominated (46%) over the other common trypanosomatids of blowflies of genera Herpetomonas and Wallacemonas. Among Angomonas spp., A. deanei was much more common than the two-other species, A. desouzai and A. ambiguus. Phylogenetic analyses based on SSU rRNA, glycosomal glyceraldehyde-3-phosphate dehydrogenase (gGAPDH) and internal transcribed spacer rDNA (ITS rDNA) sequences revealed a marked genetic diversity within A. deanei, which comprised four infraspecific genotypes (Dea1–Dea4), and four corresponding symbiont genotypes (Kcr1–Kcr4). Host and symbiont phylogenies were highly congruent corroborating their co-divergence, consistent with host-symbiont interdependent metabolism and symbiont reduced genomes shaped by a long coevolutionary history. We compared the diversity of Angomonas/symbionts from three genera of blowflies, Lucilia, Chrysomya and Cochliomyia. A. deanei, A. desouzai, and A. ambiguus were found in the three genera of blowflies in South America. In Africa, A. deanei and A. ambiguus were identified in Chrysomya. The absence of A. desouzai in Africa and its presence in Neotropical Cochliomyia and Lucilia suggests parasite spillback of A. desouzai into Chrysomya, which was most likely introduced four decades ago from Africa into the Neotropic. The absence of correlation between parasite diversity and geographic and genetic distances, with identical genotypes of A. deanei found in the Neotropic and Afrotropic, is consistent with disjunct distribution due to the recent human-mediated transoceanic dispersal of Angomonas by Chrysomya. This study provides the most comprehensive data gathered so far on the genetic repertoires of a genus of trypanosomatids found in flies from a wide geographical range.

Remarkable richness of trypanosomes in tsetse flies (Glossina morsitans morsitans and Glossina pallidipes) from the Gorongosa National Park and Niassa National Reserve of Mozambique revealed by fluorescent fragment length barcoding (FFLB)

Trypanosomes of African wild ungulates transmitted by tsetse flies can cause human and livestock diseases. However, trypanosome diversity in wild tsetse flies remains greatly underestimated. We employed FFLB (fluorescent fragment length barcoding) for surveys of trypanosomes in tsetse flies (3086) from the Gorongosa National Park (GNP) and Niassa National Reserve (NNR) in Mozambique (MZ), identified as Glossina morsitans morsitans (GNP/NNR=77.6%/90.5%) and Glossina pallidipes (22.4%/9.5%). Trypanosomes were microscopically detected in 8.3% of tsetse guts. FFLB of gut samples revealed (GNP/NNR): Trypanosoma congolense of Savannah (27%/63%), Kilifi (16.7%/29.7%) and Forest (1.0%/0.3%) genetic groups; T. simiae Tsavo (36.5%/6.1%); T. simiae (22.2%/17.7%); T. godfreyi (18.2%/7.0%); subgenus Trypanozoon (20.2%/25.7%); T. vivax/T. vivax-like (1.5%/5.2%); T. suis/T. suis-like (9.4%/11.9%). Tsetse proboscises exhibited similar species composition, but most prevalent species were (GNP/NNR): T. simiae (21.9%/28%), T. b. brucei (19.2%/31.7%), and T. vivax/T. vivax-like (19.2%/28.6%). Flies harboring mixtures of trypanosomes were common (~ 64%), and combinations of more than four trypanosomes were especially abundant in the pristine NNR. The non-pathogenic T. theileri was found in 2.5% while FFLB profiles of unknown species were detected in 19% of flies examined. This is the first report on molecular diversity of tsetse flies and their trypanosomes in MZ; all trypanosomes pathogenic for ungulates were detected, but no human pathogens were detected. Overall, two species of tsetse flies harbor 12 species/genotypes of trypanosomes. This notable species richness was likely uncovered because flies were captured in wildlife reserves and surveyed using the method of FFLB able to identify, with high sensitivity and accuracy, known and novel trypanosomes. Our findings importantly improve the knowledge on trypanosome diversity in tsetse flies, revealed the greatest species richness so far reported in tsetse fly of any African country, and indicate the existence of a hidden trypanosome diversity to be discovered in African wildlife protected areas.

Trypanosoma vivax in water buffalo of the Venezuelan Llanos: An unusual outbreak of wasting disease in an endemic area of typically asymptomatic infections

Trypanosoma vivax has been associated with asymptomatic infections in African and South American buffalo. In this study, T. vivax was analyzed in water buffalo (Bubalus bubalis) from Venezuela in a molecular survey involving 293 blood samples collected from 2006 to 2015 across the Llanos region. Results demonstrated constant infections (average 23%) during the years analyzed. In general, animals were healthy carriers of T. vivax with low levels of parasitemia and were diagnosed exclusively by TviCATL-PCR. However, an outbreak of severe acute infections mostly in dairy animals was reported during a prolonged drought affecting 30.4% of a buffalo herd (115 animals examined). During the outbreak, animals exhibiting anemia and neurological disorders developed fatal infections, and 7% of the herd died within nine months before treatment against trypanosomosis. Microsatellite locus genotyping (MLG) of T. vivax samples before and during the outbreak revealed similar genotypes, but outbreak isolates exhibited the most divergent MLG. Venezuelan samples from symptomless and sick buffalo did not share the MLGs previously detected in asymptomatic Brazilian buffalo. Trypanosoma evansi was not detected in the herd examined during the outbreak. However, as expected Babesia sp. (62.6%) and Anaplasma sp. (55.6%) infections were highly prevalent in asymptomatic buffalo in the studied areas. This is the first South American outbreak of highly lethal acute T. vivax infections in water buffalo. Our results suggest that chronically infected and asymptomatic buffalo living in areas of enzootic equilibrium can develop symptomatic/lethal disease triggered by stressful scarcity of green forage and water during long droughts, inappropriate management of herds and likely concomitant anaplasmosis and babesiosis. Altogether, these factors weaken buffalo immune defenses, allowing T. vivax to proliferate and, consequently, allowing for progression to wasting disease.

Phytomonas (Euglenozoa: Trypanosomatidae): Phylogenetic analyses support infrageneric lineages and a new species transmitted to Solanaceae fruits by a pentatomid hemipteran

The genus Phytomonas includes trypanosomatids transmitted to the fruits, latex, and phloem of vascular plants by hemipterans. We inferred the phylogenetic relationships of plant and insect isolates assigned to the previously defined genetic groups A-F and H of Phytomonas, particularly those from groups A, C and E comprising flagellates of Solanaceae fruits. Phylogenetic analyses using glycosomal Glyceraldehyde Phosphate Dehydrogenase (gGAPDH) and Small Subunit rRNA (SSU rRNA) genes strongly supported the monophyly of the genus Phytomonas and its division into seven main infrageneric phylogenetic lineages (Phy clades). Isolates from fruit or latex do not constitute monophyletic assemblages but disperse through more than one lineages. In this study, fruit flagellates were distributed in three clades: PhyA, formed by isolates from Solanaceae and phytophagous hemipterans; PhyC comprising flagellates from four plant families; and PhyE, which contains 15 fruit isolates from seven species of Solanaceae. The flagellates of PhyE are described as Phytomonas dolleti n. sp. according to their positioning in phylogenetic trees, complemented by data about their life cycle, and developmental and morphological characteristics in cultures, fruits of Solanum spp., and salivary glands of the vector, the phytophagous hemipteran Arvelius albopunctatus (Pentatomidae).

New insights into the evolution of the Trypanosoma cruzi clade provided by a new trypanosome species tightly linked to Neotropical Pteronotus bats and related to an Australian lineage of trypanosomes

Background

Bat trypanosomes are implicated in the evolution of the T. cruzi clade, which harbours most African, European and American trypanosomes from bats and other trypanosomes from African, Australian and American terrestrial mammals, including T. cruzi and T. rangeli, the agents of the American human trypanosomiasis. The diversity of bat trypanosomes globally is still poorly understood, and the common ancestor, geographical origin, and evolution of species within the T. cruzi clade remain largely unresolved.

Methods

Trypanosome sequences were obtained from cultured parasites and from museum archived liver/blood samples of bats captured from Guatemala (Central America) to the Brazilian Atlantic Coast. Phylogenies were inferred using Small Subunit (SSU) rRNA, glycosomal glyceraldehyde phosphate dehydrogenase (gGAPDH), and Spliced Leader (SL) RNA genes.

Results

Here, we described Trypanosoma wauwau n. sp. from Pteronotus bats (Mormoopidae) placed in the T. cruzi clade, then supporting the bat-seeding hypothesis whereby the common ancestor of this clade likely was a bat trypanosome. T. wauwau was sister to the clade T. spp-Neobats from phyllostomid bats forming an assemblage of trypanosome species exclusively of Noctilionoidea Neotropical bats, which was sister to an Australian clade of trypanosomes from indigenous marsupials and rodents, which possibly evolved from a bat trypanosome. T. wauwau was found in 26.5 % of the Pteronotus bats examined, and phylogeographical analysis evidenced the wide geographical range of this species. To date, this species was not detected in other bats, including those that were sympatric or shared shelters with Pteronotus. T. wauwau did not develop within mammalian cells, and was not infective to Balb/c mice or to triatomine vectors of T. cruzi and T. rangeli.

Conclusions

Trypanosoma wauwau n. sp. was linked to Pteronotus bats. The positioning of the clade T. wauwau/T.spp-Neobats as the most basal Neotropical bat trypanosomes and closely related to an Australian lineage of trypanosomes provides additional evidence that the T. cruzi clade trypanosomes likely evolved from bats, and were dispersed in bats within and between continents from ancient to unexpectedly recent times.

Electronic supplementary material

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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

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Bats, Trypanosomes, and Triatomines in Ecuador: New Insights into the Diversity, Transmission, and Origins of Trypanosoma cruzi and Chagas Disease

The generalist parasite Trypanosoma cruzi has two phylogenetic lineages associated almost exclusively with bats—Trypanosoma cruzi Tcbat and the subspecies T. c. marinkellei. We present new information on the genetic variation, geographic distribution, host associations, and potential vectors of these lineages. We conducted field surveys of bats and triatomines in southern Ecuador, a country endemic for Chagas disease, and screened for trypanosomes by microscopy and PCR. We identified parasites at species and genotype levels through phylogenetic approaches based on 18S ribosomal RNA (18S rRNA) and cytochrome b (cytb) genes and conducted a comparison of nucleotide diversity of the cytb gene. We document for the first time T. cruzi Tcbat and T. c. marinkellei in Ecuador, expanding their distribution in South America to the western side of the Andes. In addition, we found the triatomines Cavernicola pilosa and Triatoma dispar sharing shelters with bats. The comparisons of nucleotide diversity revealed a higher diversity for T. c. marinkellei than any of the T. c. cruzi genotypes associated with Chagas disease. Findings from this study increased both the number of host species and known geographical ranges of both parasites and suggest potential vectors for these two trypanosomes associated with bats in rural areas of southern Ecuador. The higher nucleotide diversity of T. c. marinkellei supports a long evolutionary relationship between T. cruzi and bats, implying that bats are the original hosts of this important parasite.

Phylogenetic and syntenic data support a single horizontal transference to a Trypanosoma ancestor of a prokaryotic proline racemase implicated in parasite evasion from host defences

Background

Proline racemase (PRAC) enzymes of Trypanosoma cruzi (TcPRAC), the agent of Chagas disease, and Trypanosoma vivax (TvPRAC), the agent of livestock trypanosomosis, have been implicated in the B-cells polyclonal activation contributing to immunosuppression and the evasion of host defences. The similarity to prokaryotic PRAC and the absence in Trypanosoma brucei and Trypanosoma congolense have raised many questions about the origin, evolution, and functions of trypanosome PRAC (TryPRAC) enzymes.

Findings

We identified TryPRAC homologs as single copy genes per haploid genome in 12 of 15 Trypanosoma species, including T. cruzi and T. cruzi marinkellei, T. dionisii, T. erneyi, T. rangeli, T. conorhini and T. lewisi, all parasites of mammals. Polymorphisms in TcPRAC genes matched T. cruzi genotypes: TcI-TcIV and Tcbat have unique genes, while the hybrids TcV and TcVI contain TcPRACA and TcPRACB from parental TcII and TcIII, respectively. PRAC homologs were identified in trypanosomes from anurans, snakes, crocodiles, lizards, and birds. Most trypanosomes have intact PRAC genes. T. rangeli possesses only pseudogenes, maybe in the process of being lost. T. brucei, T. congolense and their allied species, except the more distantly related T. vivax, have completely lost PRAC genes.

Conclusions

The genealogy of TryPRAC homologs supports an evolutionary history congruent with the Trypanosoma phylogeny. This finding, together with the synteny of PRAC loci, the relationships with prokaryotic PRAC inferred by taxon-rich phylogenetic analysis, and the absence in trypanosomatids of any other genera or in bodonids or euglenids suggest that a common ancestor of Trypanosoma gained PRAC gene by a single and ancient horizontal gene transfer (HGT) from a Firmicutes bacterium more closely related to Gemella and other species of Bacilli than to Clostridium as previously suggested. Our broad phylogenetic study allowed investigation of TryPRAC evolution over long and short timescales. TryPRAC genes diverged to become species-specific and genotype-specific for T. cruzi and T. rangeli, with resulting genealogies congruent with those obtained using vertically inherited genes. The inventory of TryPRAC genes described here is the first step toward the understanding of the roles of PRAC enzymes in trypanosomes differing in life cycles, virulence, and infection and immune evasion strategies.

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Biological and molecular characterization of a Trypanosoma cruzi isolate obtained from Panstrongylus megistus captured in Sao Paulo State, Brazil

An isolate of Trypanosoma cruzi obtained from P. megistus captured in the peridomicile area of a home in Santo Antonio do Jardim city in the State of Sao Paulo, denominated T. cruzi Mogi, was characterized biologically and molecularly. The RFLP analysis of the D7 divergent domain in the 24Sα rDNA and of the mini-exon positioned the T. cruzi isolate within the TcI group. Phylogenetic analysis performed with the trypanosomatid barcode confirmed that the isolate belongs to the TcI group, with high homology to the 3014 c1 T.cruzi strain. The biological characterization of the isolate in rats showed a prepatent period of about 8 days, low parasitemia and tropism for cardiac, skeletal and colonic muscles. In Swiss mice the T. cruzi Mogi isolate showed a prepatent period of about 22 days, intermittent parasitemia in some animals, and tropism for cardiac and colonic muscles. Despite the inherent difficulty of identifying correlations amongst the molecular and biological characteristics of different T. cruzi groups, the tropism for colonic muscle demonstrated by T. cruzi Mogi represented a peculiarity of this isolate within the TcI group.

Biosynthesis of vitamins and cofactors in bacterium-harbouring trypanosomatids depends on the symbiotic association as revealed by genomic analyses

Some non-pathogenic trypanosomatids maintain a mutualistic relationship with a betaproteobacterium of the Alcaligenaceae family. Intensive nutritional exchanges have been reported between the two partners, indicating that these protozoa are excellent biological models to study metabolic co-evolution. We previously sequenced and herein investigate the entire genomes of five trypanosomatids which harbor a symbiotic bacterium (SHTs for Symbiont-Haboring Trypanosomatids) and the respective bacteria (TPEs for Trypanosomatid Proteobacterial Endosymbiont), as well as two trypanosomatids without symbionts (RTsfor Regular Trypanosomatids), for the presence of genes of the classical pathways for vitamin biosynthesis. Our data show that genes for the biosynthetic pathways of thiamine, biotin, and nicotinic acid are absent from all trypanosomatid genomes. This is in agreement with the absolute growth requirement for these vitamins in all protozoa of the family. Also absent from the genomes of RTs are the genes for the synthesis of pantothenic acid, folic acid, riboflavin, and vitamin B_6. This is also in agreement with the available data showing that RTs are auxotrophic for these essential vitamins. On the other hand, SHTs are autotrophic for such vitamins. Indeed, all the genes of the corresponding biosynthetic pathways were identified, most of them in the symbiont genomes, while a few genes, mostly of eukaryotic origin, were found in the host genomes. The only exceptions to the latter are: the gene coding for the enzyme ketopantoate reductase (EC:1.1.1.169) which is related instead to the Firmicutes bacteria; and two other genes, one involved in the salvage pathway of pantothenic acid and the other in the synthesis of ubiquinone, that are related to Gammaproteobacteria. Their presence in trypanosomatids may result from lateral gene transfer. Taken together, our results reinforce the idea that the low nutritional requirement of SHTs is associated with the presence of the symbiotic bacterium, which contains most genes for vitamin production.

The phylogeography of trypanosomes from South American alligatorids and African crocodilids is consistent with the geological history of South American river basins and the transoceanic dispersal of Crocodylus at the Miocene

Background

Little is known about the diversity, phylogenetic relationships, and biogeography of trypanosomes infecting non-mammalian hosts. In this study, we investigated the influence of host species and biogeography on shaping the genetic diversity, phylogenetic relationship, and distribution of trypanosomes from South American alligatorids and African crocodilids.

Methods

Small Subunit rRNA (SSU rRNA) and glycosomal Glyceraldehyde Phosphate Dehydrogenase (gGAPDH) genes were employed for phylogenetic inferences. Trypanosomes from crocodilians were obtained by haemoculturing. Growth behaviour, morphology, and ultrastructural features complement the molecular description of two new species strongly supported by phylogenetic analyses.

Results

The inferred phylogenies disclosed a strongly supported crocodilian-restricted clade comprising three subclades. The subclade T. grayi comprised the African Trypanosoma grayi from Crocodylus niloticus and tsetse flies. The subclade T. ralphi comprised alligatorid trypanosomes represented by Trypanosoma ralphi n. sp. from Melanosuchus niger, Caiman crocodilus and Caiman yacare from Brazilian river basins. T. grayi and T. ralphi were sister subclades. The basal subclade T. terena comprised alligatorid trypanosomes represented by Trypanosoma terena n. sp. from Ca. yacare sharing hosts and basins with the distantly genetic related T. ralphi. This subclade also included the trypanosome from Ca. crocodilus from the Orinoco basin in Venezuela and, unexpectedly, a trypanosome from the African crocodilian Osteolaemus tetraspis.

Conclusion

The close relationship between South American and African trypanosomes is consistent with paleontological evidence of recent transoceanic dispersal of Crocodylus at the Miocene/Pliocene boundaries (4–5 mya), and host-switching of trypanosomes throughout the geological configuration of South American hydrographical basins shaping the evolutionary histories of the crocodilians and their trypanosomes.

Endosymbiosis in trypanosomatids: the genomic cooperation between bacterium and host in the synthesis of essential amino acids is heavily influenced by multiple horizontal gene transfers

BACKGROUND

Trypanosomatids of the genera Angomonas and Strigomonas live in a mutualistic association characterized by extensive metabolic cooperation with obligate endosymbiotic Betaproteobacteria. However, the role played by the symbiont has been more guessed by indirect means than evidenced. Symbiont-harboring trypanosomatids, in contrast to their counterparts lacking symbionts, exhibit lower nutritional requirements and are autotrophic for essential amino acids. To evidence the symbiont's contributions to this autotrophy, entire genomes of symbionts and trypanosomatids with and without symbionts were sequenced here.

RESULTS

Analyses of the essential amino acid pathways revealed that most biosynthetic routes are in the symbiont genome. By contrast, the host trypanosomatid genome contains fewer genes, about half of which originated from different bacterial groups, perhaps only one of which (ornithine cyclodeaminase, EC:4.3.1.12) derived from the symbiont. Nutritional, enzymatic, and genomic data were jointly analyzed to construct an integrated view of essential amino acid metabolism in symbiont-harboring trypanosomatids. This comprehensive analysis showed perfect concordance among all these data, and revealed that the symbiont contains genes for enzymes that complete essential biosynthetic routes for the host amino acid production, thus explaining the low requirement for these elements in symbiont-harboring trypanosomatids. Phylogenetic analyses show that the cooperation between symbionts and their hosts is complemented by multiple horizontal gene transfers, from bacterial lineages to trypanosomatids, that occurred several times in the course of their evolution. Transfers occur preferentially in parts of the pathways that are missing from other eukaryotes.

CONCLUSION

We have herein uncovered the genetic and evolutionary bases of essential amino acid biosynthesis in several trypanosomatids with and without endosymbionts, explaining and complementing decades of experimental results. We uncovered the remarkable plasticity in essential amino acid biosynthesis pathway evolution in these protozoans, demonstrating heavy influence of horizontal gene transfer events, from Bacteria to trypanosomatid nuclei, in the evolution of these pathways.

Genome evolution and phylogenomic analysis of Candidatus Kinetoplastibacterium, the betaproteobacterial endosymbionts of Strigomonas and Angomonas

It has been long known that insect-infecting trypanosomatid flagellates from the genera Angomonas and Strigomonas harbor bacterial endosymbionts (Candidatus Kinetoplastibacterium or TPE [trypanosomatid proteobacterial endosymbiont]) that supplement the host metabolism. Based on previous analyses of other bacterial endosymbiont genomes from other lineages, a stereotypical path of genome evolution in such bacteria over the duration of their association with the eukaryotic host has been characterized. In this work, we sequence and analyze the genomes of five TPEs, perform their metabolic reconstruction, do an extensive phylogenomic analyses with all available Betaproteobacteria, and compare the TPEs with their nearest betaproteobacterial relatives. We also identify a number of housekeeping and central metabolism genes that seem to have undergone positive selection. Our genome structure analyses show total synteny among the five TPEs despite millions of years of divergence, and that this lineage follows the common path of genome evolution observed in other endosymbionts of diverse ancestries. As previously suggested by cell biology and biochemistry experiments, Ca. Kinetoplastibacterium spp. preferentially maintain those genes necessary for the biosynthesis of compounds needed by their hosts. We have also shown that metabolic and informational genes related to the cooperation with the host are overrepresented amongst genes shown to be under positive selection. Finally, our phylogenomic analysis shows that, while being in the Alcaligenaceae family of Betaproteobacteria, the closest relatives of these endosymbionts are not in the genus Bordetella as previously reported, but more likely in the Taylorella genus.

Trypanosoma livingstonei: a new species from African bats supports the bat seeding hypothesis for the Trypanosoma cruzi clade

BACKGROUND

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.

METHODS

Trypanosomes 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.

RESULTS

New 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.

CONCLUSION

Phylogenetic 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.

Pathogenesis of reproductive failure induced by Trypanosoma vivax in experimentally infected pregnant ewes

The present study was aimed at investigating the effect of experimental infection by Trypanosoma vivax in different stages of pregnancy, determining the pathogenesis of reproductive failure, and confirming transplacental transmission. We used 12 pregnant ewes distributed into four experimental groups: G1, was formed by three ewes infected with T. vivax in the first third of pregnancy (30 days); G2 comprised three infected ewes in the final third of pregnancy (100 days); G3 and G4 were composed of three non-infected ewes with the same gestational period, respectively. Each ewe of G1 and G2 was inoculated with 1.25 × 10⁵ tripomastigotes. Clinical examination, determination of parasitemia, serum biochemistry (albumin, total protein, glucose, cholesterol, and urea), packed cell volume (PCV), serum progesterone, and pathological examination were performed. Placenta, amniotic fluid, blood and tissues from the fetuses and stillbirths were submitted to PCR. Two ewes of G1 (Ewe 1 and 3) presented severe infection and died in the 34^th and 35^th days post-infection (dpi), respectively; but both fetuses were recovered during necropsy. In G2, Ewe 5 aborted two fetuses on the 130^th day (30 dpi) of pregnancy; and Ewe 6 aborted one fetus in the 140^th day (40 dpi) of gestation. Ewes 2 and 4 delivered two weak lambs that died five days after birth. Factors possibly involved with the reproductive failure included high parasitemia, fever, low PCV, body score, serum glucose, total protein, cholesterol, and progesterone. Hepatitis, pericarditis, and encephalitis were observed in the aborted fetuses. The presence of T. vivax DNA in the placenta, amniotic fluid, blood, and tissues from the fetuses confirms the transplacental transmission of the parasite. Histological lesion in the fetuses and placenta also suggest the involvement of the parasite in the etiopathogenesis of reproductive failure in ewes.

Molecular phylogenetic redefinition of Herpetomonas (Kinetoplastea, Trypanosomatidae), a genus of insect parasites associated with flies

In order to review the taxonomy of the genus Herpetomonas through phylogenetic and morphological analyses we barcoded 527 insect trypanosomatids by sequencing the V7V8 region of the small subunit ribosomal RNA (SSU rRNA) gene. Fifty two flagellates, 90% of them from Diptera, revealed to be related to known species of Herpetomonas. Sequences of entire glycosomal glyceraldehyde phosphate dehydrogenase (gGAPDH) and SSU rRNA genes were employed for phylogenetic inferences including representatives of all genera of Trypanosomatidae. In the resulting phylogenetic trees, the selected flagellates clustered into a monophyletic assemblage that we are considering as the redefined genus Herpetomonas. Internal transcribed spacer 1 (ITS1) rDNA sequences and putative secondary structures of this region were compared for evaluation of inter- and intraspecific variability. The flagellates were classified in six already known species and five new species. In addition, two Leptomonas spp. were moved to Herpetomonas, now comprising 13 valid species, while four species were excluded from the genus. Light and electron microscopy revealed the extreme polymorphism of Herpetomonas, hindering genus and species identification by morphological characteristics. Our findings also showed that some species of Herpetomonas are generalist parasites of flies and appear to be as cosmopolitan as their hosts.

Follicular degeneration in the ovaries of goats experimentally infected with Trypanosoma vivax from the Brazilian semi-arid region

Infection by Trypanosoma vivax and other African trypanosomes plays an important role in reproductive disorders in male and female livestock. Outbreaks of T. vivax in the semi-arid region of northeastern Brazil are characterized by wasting disease in cattle, sheep and goats with hematological, cardiac and nervous compromises in addition to reproductive failures. Similar to reports from Africa, we previously observed a reduction in fertility rates and severe testicular degeneration and epididymitis in male sheep infected with T. vivax from this region. Although anestrus is frequently reported in goats and sheep infected with T. vivax, the effects of this infection on the female reproductive organs need clarification. In this study, we addressed this issue through a histopathological evaluation of ovarian follicular morphology and classification in goats experimentally infected with a T. vivax isolate from the Brazilian semi-arid region. The infected animals presented typical clinical signs of trypanosomosis by T. vivax, including anemia, hyperthermia, pallor of the mucous membranes, enlarged lymph nodes, and progressive loss of weight. All the infected goats remained anestrus throughout the experimental period and exhibited important disturbances in the ovaries, evidenced by reduced size and a smooth surface without follicles or corpora lutea, and abnormal follicular development. In addition, through PCR, we detected T. vivax DNA in the ovarian tissues of the infected goats. Our findings contributed to understand the female reproductive failure associated with trypanosomosis caused by T. vivax.

The evolution of Trypanosoma cruzi: the 'bat seeding' hypothesis

Recent discussions on the evolution of Trypanosoma cruzi have been dominated by the southern super-continent hypothesis, whereby T. cruzi and related parasites evolved in isolation in the mammals of South America, Antarctica and Australia. Here, we consider recent molecular evidence suggesting that T. cruzi evolved from within a broader clade of bat trypanosomes, and that bat trypanosomes have successfully made the switch into other mammalian hosts in both the New and Old Worlds. Accordingly, we propose an alternative hypothesis--the bat seeding hypothesis--whereby lineages of bat trypanosomes have switched into terrestrial mammals, thereby seeding the terrestrial lineages within the clade. One key implication of this finding is that T. cruzi may have evolved considerably more recently than previously envisaged.

Parasites reveal movement of bats between the New and Old Worlds

The global distribution of bat taxa indicates that the Atlantic and Pacific Oceans are effective barriers to movement between the Old and New Worlds. For instance, one of the major suborders, Yinpterochiroptera, has an exclusively Old World distribution, and within the other, Yangochiroptera, no species and only five genera are common to both. However, as bats are sometimes blown out to sea, and have colonised isolated islands, occasional natural movement between the New and Old Worlds does appear to be possible. Here we identify new genotypes of a blood parasite, Trypanosoma dionisii, in Old World bats that are closely related to South American strains. Using highly conservative calibration points, divergence of Old and New World strains is estimated to have occurred 3.2–5.0 million years ago (MYA), depending on the method used (upper 95% CL for maximum time 11.4 MYA). The true date of divergence is likely to be considerably more recent. These results demonstrate that taxon-specific parasites can indicate historical movements of their hosts, even where their hosts may have left no lasting phylogenetic footprint.

The revised Trypanosoma cruzi subspecific nomenclature: rationale, epidemiological relevance and research applications

The protozoan Trypanosoma cruzi, its mammalian reservoirs, and vectors have existed in nature for millions of years. The human infection, named Chagas disease, is a major public health problem for Latin America. T. cruzi is genetically highly diverse and the understanding of the population structure of this parasite is critical because of the links to transmission cycles and disease. At present, T. cruzi is partitioned into six discrete typing units (DTUs), TcI-TcVI. Here we focus on the current status of taxonomy-related areas such as population structure, phylogeographical and eco-epidemiological features, and the correlation of DTU with natural and experimental infection. We also summarize methods for DTU genotyping, available for widespread use in endemic areas. For the immediate future multilocus sequence typing is likely to be the gold standard for population studies. We conclude that greater advances in our knowledge on pathogenic and epidemiological features of these parasites are expected in the coming decade through the comparative analysis of the genomes from isolates of various DTUs.

Trypanosoma (Megatrypanum) melophagium in the sheep ked Melophagus ovinus from organic farms in Croatia: phylogenetic inferences support restriction to sheep and sheep keds and close relationship with trypanosomes from other ruminant species

Trypanosoma (Megatrypanum) melophagium is a parasite of sheep transmitted by sheep keds, the sheep-restricted ectoparasite Melophagus ovinus (Diptera: Hippoboscidae). Sheep keds were 100% prevalent in sheep from five organic farms in Croatia, Southeastern Europe, whereas trypanosomes morphologically compatible with T. melophagium were 86% prevalent in the guts of the sheep keds. Multilocus phylogenetic analyses using sequences of small subunit rRNA, glycosomal glyceraldehyde-3-phosphate dehydrogenase, spliced leader, and internal transcribed spacer 1 of the rDNA distinguished T. melophagium from all allied trypanosomes from other ruminant species and placed the trypanosome in the subgenus Megatrypanum. Trypanosomes from sheep keds from Croatia and Scotland, the only available isolates for comparison, shared identical sequences. All biologic and phylogenetic inferences support the restriction of T. melophagium to sheep and, especially, to the sheep keds. The comparison of trypanosomes from sheep, cattle, and deer from the same country, which was never achieved before this work, strongly supported the host-restricted specificity of trypanosomes of the subgenus Megatrypanum. Our findings indicate that with the expansion of organic farms, both sheep keds and T. melophagium may re-emerge as parasitic infections of sheep.

Multilocus phylogeographical analysis of Trypanosoma (Megatrypanum) genotypes from sympatric cattle and water buffalo populations supports evolutionary host constraint and close phylogenetic relationships with genotypes found in other ruminants

Species of the subgenus Trypanosoma (Megatrypanum) have been reported in cattle and other domestic and wild ruminants worldwide. A previous study in Brazil found at least four genotypes infecting cattle (Bos taurus), but only one in water buffalo (Bubalus bubalis). However, the small number of isolates examined from buffalo, all inhabiting nearby areas, has precluded evaluation of their diversity, host associations and geographical structure. To address these questions, we evaluated the genetic diversity and phylogeographical patterns of 25 isolates from water buffalo and 28 from cattle from four separate locations in Brazil and Venezuela. Multigene phylogenetic analyses of ssrRNA, internal transcribed spacer of rDNA (ITSrDNA), 5SrRNA, glycosomal glyceraldehyde 3-phosphate dehydrogenase (gGAPDH), mitochondrial cytochrome b (Cyt b), spliced leader (SL) and cathepsin L-like (CATL) sequences positioned all isolates from sympatric and allopatric buffalo populations into the highly homogeneous genotype TthIA, while the cattle isolates were assigned to three different genotypes, all distinct from TthIA. Polymorphisms in all of these sequences separated the trypanosomes infecting water buffalo, cattle, sheep, antelope and deer, and suggested that they correspond to separate species. Congruent phylogenies inferred with all genes indicated a predominant clonal structure of the genotypes. The multilocus analysis revealed one monophyletic assemblage formed exclusively by trypanosomes of ruminants, which corresponds to the subgenus T. (Megatrypanum). The high degree of host specificity, evidenced by genotypes exclusive to each ruminant species and lack of genotype shared by different host species, suggested that the evolutionary history of trypanosomes of this subgenus was strongly constrained by their ruminant hosts. However, incongruence between ruminant and trypanosome phylogenies did not support host-parasite co-evolution, indicating that host switches have occurred across ruminants followed by divergences, giving rise to new trypanosome genotypes adapted exclusively to one host species.

Genome size, karyotype polymorphism and chromosomal evolution in Trypanosoma cruzi

Background

The Trypanosoma cruzi genome was sequenced from a hybrid strain (CL Brener). However, high allelic variation and the repetitive nature of the genome have prevented the complete linear sequence of chromosomes being determined. Determining the full complement of chromosomes and establishing syntenic groups will be important in defining the structure of T. cruzi chromosomes. A large amount of information is now available for T. cruzi and Trypanosoma brucei, providing the opportunity to compare and describe the overall patterns of chromosomal evolution in these parasites.

Methodology/Principal Findings

The genome sizes, repetitive DNA contents, and the numbers and sizes of chromosomes of nine strains of T. cruzi from four lineages (TcI, TcII, TcV and TcVI) were determined. The genome of the TcI group was statistically smaller than other lineages, with the exception of the TcI isolate Tc1161 (José-IMT). Satellite DNA content was correlated with genome size for all isolates, but this was not accompanied by simultaneous amplification of retrotransposons. Regardless of chromosomal polymorphism, large syntenic groups are conserved among T. cruzi lineages. Duplicated chromosome-sized regions were identified and could be retained as paralogous loci, increasing the dosage of several genes. By comparing T. cruzi and T. brucei chromosomes, homologous chromosomal regions in T. brucei were identified. Chromosomes Tb9 and Tb11 of T. brucei share regions of syntenic homology with three and six T. cruzi chromosomal bands, respectively.

Conclusions

Despite genome size variation and karyotype polymorphism, T. cruzi lineages exhibit conservation of chromosome structure. Several syntenic groups are conserved among all isolates analyzed in this study. The syntenic regions are larger than expected if rearrangements occur randomly, suggesting that they are conserved owing to positive selection. Mapping of the syntenic regions on T. cruzi chromosomal bands provides evidence for the occurrence of fusion and split events involving T. brucei and T. cruzi chromosomes.

Identification and phylogenetic analysis of heme synthesis genes in trypanosomatids and their bacterial endosymbionts

It has been known for decades that some insect-infecting trypanosomatids can survive in culture without heme supplementation while others cannot, and that this capability is associated with the presence of a betaproteobacterial endosymbiont in the flagellate's cytoplasm. However, the specific mechanisms involved in this process remained obscure. In this work, we sequence and phylogenetically analyze the heme pathway genes from the symbionts and from their hosts, as well as from a number of heme synthesis-deficient Kinetoplastida. Our results show that the enzymes responsible for synthesis of heme are encoded on the symbiont genomes and produced in close cooperation with the flagellate host. Our evidence suggests that this synergistic relationship is the end result of a history of extensive gene loss and multiple lateral gene transfer events in different branches of the phylogeny of the Trypanosomatidae.

Association of Trypanosoma vivax in extracellular sites with central nervous system lesions and changes in cerebrospinal fluid in experimentally infected goats

Changes in cerebrospinal fluid (CSF) and anatomical and histopathological central nervous system (CNS) lesions were evaluated, and the presence of Trypanosoma vivax in CNS tissues was investigated through PCR. Twelve adult male goats were divided into three groups (G): G1, infected with T. vivax and evaluated during the acute phase; G2, infected goats evaluated during the chronic phase; and G3, consisting of non-infected goats. Each goat from G1 and G2 was infected with 1.25 × 10⁵ trypomastigotes. Cerebrospinal fluid (CSF) analysis and investigation of T. vivax was performed at the 15^th day post-infection (dpi) in G1 goats and on the fifth day after the manifestation of nervous system infection signs in G2 goats. All goats were necropsied, and CNS fragments from G1 and G2 goats were evaluated by PCR for the determination of T. vivax. Hyperthermia, anemia and parasitemia were observed from the fifth dpi for G1 and G2, with the highest parasitemia peak between the seventh and 21^st dpi. Nervous system infection signs were observed in three G2 goats between the 30^th and 35^th dpi. CSF analysis revealed the presence of T. vivax for G2. Meningitis and meningoencephalitis were diagnosed in G2. PCR were positive for T. vivax in all the samples tested. In conclusion, T. vivax may reach the nervous tissue resulting in immune response from the host, which is the cause of progressive clinical and pathological manifestations of the CNS in experimentally infected goats.

Phylogenetic validation of the genera Angomonas and Strigomonas of trypanosomatids harboring bacterial endosymbionts with the description of new species of trypanosomatids and of proteobacterial symbionts

We comparatively examined the nutritional, molecular and optical and electron microscopical characteristics of reference species and new isolates of trypanosomatids harboring bacterial endosymbionts. Sequencing of the V7V8 region of the small subunit of the ribosomal RNA (SSU rRNA) gene distinguished six major genotypes among the 13 isolates examined. The entire sequences of the SSU rRNA and glycosomal glyceraldehyde phosphate dehydrogenase (gGAPDH) genes were obtained for phylogenetic analyses. In the resulting phylogenetic trees, the symbiont-harboring species clustered as a major clade comprising two subclades that corresponded to the proposed genera Angomonas and Strigomonas. The genus Angomonas comprised 10 flagellates including former Crithidia deanei and C. desouzai plus a new species. The genus Strigomonas included former Crithidia oncopelti and Blastocrithidia culicis plus a new species. Sequences from the internal transcribed spacer of ribosomal DNA (ITS rDNA) and size polymorphism of kinetoplast DNA (kDNA) minicircles revealed considerable genetic heterogeneity within the genera Angomonas and Strigomonas. Phylogenetic analyses based on 16S rDNA and ITS rDNA sequences demonstrated that all of the endosymbionts belonged to the Betaproteobacteria and revealed three new species. The congruence of the phylogenetic trees of trypanosomatids and their symbionts support a co-divergent host-symbiont evolutionary history.

Horses naturally infected by Trypanosoma vivax in southern Brazil

In this study, we reported the first outbreak of the infection by Trypanosoma vivax in horses in southern Brazil, a non-endemic region where bovines have only recently been found infected by this trypanosome species. We evaluated 12 horses from a farm in southern Brazil, where four horses displayed pale mucous membranes, fever, weight loss, and swelling of abdomen, prepuce, or vulva. The diagnosis of T. vivax was confirmed in four horses by morphological parameters of trypomastigotes in blood smears and species-specific PCR. All T. vivax-infected animals showed anemia, and most showed increased levels of beta-1, beta-2, and gamma globulins. Horses were treated with diminazene aceturate, but cure was not achieved, and the disease relapsed after therapy. These findings demonstrated that Brazilian T. vivax isolates, which were already reported infecting cattle, buffaloes, goats, and sheep, can be highly pathogenic for horses, causing severe disease and even death of the animals due to the recurrence of the infection.

Cysteine proteases of Trypanosoma (Megatrypanum) theileri: cathepsin L-like gene sequences as targets for phylogenetic analysis, genotyping diagnosis

Although Trypanosomatheileri and allied trypanosomes are the most widespread trypanosomes in bovids little is known about proteolytic enzymes in these species. We have characterized genes encoding for cathepsin L-like (CATL) cysteine proteases from isolates of cattle, water buffalo and deer that largely diverged from homologues of other trypanosome species. Analysis of 78 CATL catalytic domain sequences from 22 T. theileri trypanosomes disclosed 6 genotypes tightly clustered together into the T. theileri clade. The CATL genes in these trypanosomes are organized in tandem arrays of approximately 1.7kb located in 2 chromosomal bands of 600-720kb. A diagnostic PCR assay targeting CATL sequences detected T. theileri of all genotypes from cattle, buffaloes and cervids and also from tabanid vectors. Expression of T. theileri cysteine proteases was demonstrated by proteolytic activity in gelatin gels and hydrolysis of Z-Phe-Arg-AMC substrate. Results from this work agree with previous data using ribosomal and spliced leader genes demonstrating that CATL gene sequences are useful for diagnosis, population genotyping and evolutionary studies of T. theileri trypanosomes.

Phylogenetic, morphological and behavioural analyses support host switching of Trypanosoma (Herpetosoma) lewisi from domestic rats to primates

We characterized four Brazilian trypanosomes isolated from domestic rats and three from captive non-human primates that were morphologically similar to T. lewisi, a considered non-pathogenic species restricted to rodents and transmitted by fleas, despite its potential pathogenicity for infants. These isolates were identified as T. lewisi by barcoding using V7V8 SSU rDNA sequences. In inferred phylogenetic trees, all isolates clustered tightly with reference T. lewisi and T. lewisi-like trypanosomes from Europe, Asia and Africa and despite their high sequence conservation formed a homogeneous clade separate from other species of the subgenus T. (Herpetosoma). With the aim of clearly resolving the relationships between the Brazilian isolates from domestic rats and primates, we compared sequences from more polymorphic ITS rDNA. Results corroborated that isolates from Brazilian rats and monkeys were indeed of the same species and quite close to T. lewisi isolates of humans and rats from different geographical regions. Morphology of the monkey isolates and their behaviour in culture and in experimentally infected rats were also compatible with T. lewisi. However, infection with T. lewisi is rare among monkeys. We have examined more than 200 free-ranging and 160 captive monkeys and found only three infected individuals among the monkeys held in captivity. The findings of this work suggest that proximity of monkeys and infected rats and their exposure to infected fleas may be responsible for the host switching of T. lewisi from their natural rodent species to primates. This and previous studies reporting T. lewisi in humans suggest that this trypanosome can cause sporadic and opportunistic flea-borne infection in primates.

Phylogenetic analyses based on small subunit rRNA and glycosomal glyceraldehyde-3-phosphate dehydrogenase genes and ultrastructural characterization of two snake Trypanosomes: Trypanosoma serpentis n. sp. from Pseudoboa nigra and Trypanosoma cascavelli from Crotalus durissus terrificus

We sequenced the small subunit (SSU) rRNA and glycosomal glyceraldehyde-3-phosphate dehydrogenase (gGAPDH) genes of two trypanosomes isolated from the Brazilian snakes Pseudoboa nigra and Crotalus durissus terrificus. Trypanosomes were cultured and their morphometrical and ultrastructural features were characterized by light microscopy and scanning and transmission electron microscopy. Phylogenetic trees inferred using independent or combined SSU rRNA and gGAPDH data sets always clustered the snake trypanosomes together in a clade closest to lizard trypanosomes, forming a strongly supported monophyletic assemblage (i.e. lizard-snake clade). The positioning in the phylogenetic trees and the barcoding based on the variable V7-V8 region of the SSU rRNA, which showed high sequence divergences, allowed us to classify the isolates from distinct snake species as separate species. The isolate from P. nigra is described as a new species, Trypanosoma serpentis n. sp., whereas the isolate from C. d. terrificus is redescribed here as Trypanosoma cascavelli.

Infection by Trypanosoma vivax in goats and sheep in the Brazilian semiarid region: from acute disease outbreak to chronic cryptic infection

A study was undertaken to investigate the role of Trypanosoma vivax in sheep and goat mortality and abortions in the Brazilian semiarid region, where outbreaks had been previously reported in bovines. For this purpose, 177 goats and 248 sheep (20% of herds) were randomly sampled on four farms in the State of Paraiba in May and October 2008. The animals were screened for trypanosomes by the buffy coat technique (BCT) and PCR. Infected animals, approximately 25% in both surveys, manifested apathy, pale mucous membranes, enlarged lymph nodes, weakness, weight loss, opacity of the cornea, blindness and abortion. However, the animals with acute and severe disease showing the highest levels of parasitemia and fever, which many times resulted in death, were only detected in the first survey. These severely diseased animals exhibited progressive weight loss and had the smallest packed cell volume (PCV) values. During survey 2, done in October 2008 on the same farms, only animals with low parasitemia and normal temperatures, PCV values and body weights were detected. Therefore, animals that spontaneously recovered from acute infection developed chronic and asymptomatic disease. This finding demonstrated for the first time that sheep and goats, which are the most important livestock in the semiarid region of Brazil, may be severely injured by T. vivax infection and also play a role as asymptomatic carriers and important sources of T. vivax to ruminants in general.

Rural Triatoma rubrovaria from southern Brazil harbors Trypanosoma cruzi of lineage IIc

Triatoma infestans, the main vector of Chagas disease, has nearly been eliminated from Brazil. Nevertheless, other triatominae species are involved in the domiciliation process, including Triatoma rubrovaria in Rio Grande do Sul State (RS). Previous studies showed that 1.6% of the T. rubrovaria specimens collected at the rural district of Quaraí, RS, were naturally infected by Trypanosoma cruzi. In this study, five T. cruzi isolates obtained from infected triatomines were characterized molecularly and biologically. Genotyping of the T. cruzi isolates showed that they belong to lineage IIc of T. cruzi (TCIIc). Biological characterization showed miotropism and myositis during acute and chronic phases of infection, respectively. Virulence and mortality rates were variable among isolates. To our knowledge, this study corresponds to the first characterization of T. cruzi isolates from T. rubrovaria and the first description of TCIIc in the sylvatic cycle of T. cruzi from the southern region of Brazil.