Cloning and expression analysis of two novel paraflagellar rod domain genes found in Trypanosoma cruzi

Trypanosoma vivax infection in sheep: Different patterns of virulence and pathogenicity associated with differentially expressed proteomes

•

Trypanosoma vivax strains exhibit different virulence and pathogenicity patterns.

•

TvMT1 strain showed low virulence and high pathogenicity.

•

TvLIEM176 strain showed high virulence and moderate pathogenicity.

•

Protein expression varies in high virulence/moderate pathogenicity strain vs low virulence/high pathogenicity strain.

Cattle trypanosomosis caused by Trypanosoma vivax is a widely distributed disease in Africa and Latin America. It causes significant losses in the livestock industry and is characterized by fluctuating parasitemia, anemia, fever, lethargy, and weight loss. In this study we evaluated the virulence (capacity to multiply inside the host and to modulate the host response) and pathogenicity (ability to produce disease and/or mortality) patterns of two T. vivax strains (TvMT1 and TvLIEM176) in experimentally-infected sheep and determined the proteins differentially expressed in the proteomes of these two strains. Hematological and clinical parameters were monitored in experimentally-infected versus non-infected sheep for 60 days. All the infected animals developed discernable parasitemia at 3 days post-infection (dpi), and the first parasitemia peak was observed at 6 dpi. The maximum average value of parasitemia was 1.3 × 10⁷ (95% CI, 7.9 × 10⁵–2 × 10⁸) parasites/ml in TvLIEM176-infected animals, and 2.5 × 10⁶ (95% CI, 1.6 × 10⁵–4 × 10⁷) parasites/ml in TvMT1-infected ones. Anemia and clinical manifestations were more severe in the animals infected by TvMT1 strain than in those infected by TvLIEM176. In the proteomic analysis, a total of 29 proteins were identified, of which 14 exhibited significant differences in their expression levels between strains. Proteins with higher expression in TvLIEM176 were: alpha tubulin, beta tubulin, arginine kinase, glucose-regulated protein 78, paraflagellar protein 3, and T-complex protein 1 subunit theta. Proteins with higher expression in TvMT1 were: chaperonin HSP60, T-complex protein 1 subunit alpha, heat shock protein 70, pyruvate kinase, glycerol kinase, inosine-5'-monophosphate dehydrogenase, 73 kDa paraflagellar rod protein, and vacuolar ATP synthase. There was a difference in the virulence and pathogenicity between the T. vivax strains: TvLIEM176 showed high virulence and moderate pathogenicity, whereas TvMT1 showed low virulence and high pathogenicity. The proteins identified in this study are discussed for their potential involvement in strains’ virulence and pathogenicity, to be further defined as biomarkers of severity in T. vivax infections.

Performance of Leishmania PFR1 recombinant antigen in serological diagnosis of asymptomatic canine leishmaniosis by ELISA

Background

Leishmania infantum is a protozoan parasite transmitted by phlebotomine sand flies that causes life-threatening disease in humans and dogs. The dog is the primary reservoir of the parasite and early diagnosis of canine leishmaniosis is crucial at the clinical and epidemiological level. The currently available serological tests for CanL diagnostic show limitations therefore the aim of the present study was to investigate the diagnostic performance of an indirect antibody ELISA based on the Leishmania infantum recombinant antigen PFR1 in asymptomatically infected dogs. One hundred fifty-six dogs including Leishmania-free experimental Beagles and pet dogs from England, Scotland and Leishmania-endemic Murcia in Spain, were tested with the assay. The later were also tested with two commercial L. infantum crude antigen ELISAs (INgezim and Civtest, respectively) and a real-time kinetoplast PCR test.

Results

Anti-PFR1 antibodies were detected in the four groups of dogs, and the mean log-transformed optical density (OD) values were lowest in Beagles and in dogs from England and highest among dogs from Murcia (p < 0.05). Using the highest OD in beagles as the PFR1 ELISA cut-off point, the estimated seroprevalence was 27% (14-40%) in dogs from Murcia, 4% (0-9%) in dogs from Scotland and 3% (0-8%) in dogs from England (p < 0.05). Seroprevalence in dogs from Murcia according to the INgezim and Civtest ELISAs were 24% (12-37%) and 31% (18-45%), respectively, whilst the prevalence of infection based on PCR in these dogs was 73% (60-86). The percentages of PFR1-positive dogs that tested negative on the INgezim and Civtest ELISAs were 30% and 35%, respectively, and all of them tested positive on the PCR test. Relative to the PCR, the specificity, sensitivity and area under the ROC curve of the PFR1 ELISA were 100%, 36% and 0.74 (0.63-0.86), respectively.

Conclusions

The ability shown by the PFR1 ELISA to detect infected dogs that go undetected by the crude antigen ELISAs is clinically and epidemiologically useful and PFR1 could be considered a candidate for a multi-antigen-based immunoassay for early detection of L. infantum infected dogs.

Electronic supplementary material

The online version of this article (10.1186/s12917-017-1224-z) contains supplementary material, which is available to authorized users.

An overview on kinetoplastid paraflagellar rod

Kinetoplastids, the evolutionary ancient organisms exhibit a rich and diverse biology which epitomizes many of the fascinating topics of recent interest and study. These organisms possess a multifunctional organelle, the flagellum containing a canonical 9 + 2 axoneme which is involved in vital roles, viz. parasite cell division, morphogenesis, motility and immune evasion. Since Antony Van Leeuwenhoek's innovative explanation of 'little legs' helping the movements of microbes in 1975, this biological nanomachine has captured the thoughts of scientists. The core structure of kinetoplastid flagellum is embroidered with a range of extra-axonemal structures such as paraflagellar rod (PFR), a large lattice like structure which extends alongside the axoneme from the flagellar pocket to the flagellar tip. The coding sequences for significant components of PFR are highly conserved throughout the Kinetoplastida and Euglenida. The high order organization and restricted evolutionary distribution of the PFR components and structure makes the PFR a particularly valuable therapeutic and prophylactic target. This review focuses on the recent developments in identification of ultra structural components of PFR in order to understand the function of this intriguing organelle and devising strategies for therapeutic interventions.

The eukaryotic flagellum makes the day: novel and unforeseen roles uncovered after post-genomics and proteomics data

This review will summarize and discuss the current biological understanding of the motile eukaryotic flagellum, as posed out by recent advances enabled by post-genomics and proteomics approaches. The organelle, which is crucial for motility, survival, differentiation, reproduction, division and feeding, among other activities, of many eukaryotes, is a great example of a natural nanomachine assembled mostly by proteins (around 350-650 of them) that have been conserved throughout eukaryotic evolution. Flagellar proteins are discussed in terms of their arrangement on to the axoneme, the canonical “9+2” microtubule pattern, and also motor and sensorial elements that have been detected by recent proteomic analyses in organisms such as Chlamydomonas reinhardtii, sea urchin, and trypanosomatids. Such findings can be remarkably matched up to important discoveries in vertebrate and mammalian types as diverse as sperm cells, ciliated kidney epithelia, respiratory and oviductal cilia, and neuro-epithelia, among others. Here we will focus on some exciting work regarding eukaryotic flagellar proteins, particularly using the flagellar proteome of C. reinhardtii as a reference map for exploring motility in function, dysfunction and pathogenic flagellates. The reference map for the eukaryotic flagellar proteome consists of 652 proteins that include known structural and intraflagellar transport (IFT) proteins, less well-characterized signal transduction proteins and flagellar associated proteins (FAPs), besides almost two hundred unannotated conserved proteins, which lately have been the subject of intense investigation and of our present examination.

Previous exposure to a low infectious dose of Leishmania major exacerbates infection with Leishmania infantum in the susceptible BALB/c mouse

The geographic distribution of Leishmania major overlaps with several other species of Leishmania. This study seeks to examine what effect previous exposure to L. major has on the outcome of infection with Leishmania infantum, the agent of virulent visceral leishmaniasis. The L. major immune response is well characterized by a strong Th1 response leading to resolution and protection against subsequent re-infection. A contrasting Th2 immune response leads to disseminated disease, while the role Th17 cytokines may play in Leishmania infection is still being explored. The cytokine profile, antibody titer, and parasite burden were evaluated in the susceptible BALB/c mouse after L. infantum infection in either naïve mice or those previously infected with a low/self-healing dose of L. major. Only IL-4 expression in mice previously exposed to L. major was found to be significantly increased over controls, a cytokine with an ambiguous role in L. infantum infection. However, disease exacerbation, with a notably higher parasite burden, was observed in the L. major exposed mice compared to the L. infantum only. Cross-reactive antibodies were seen in both groups of infected mice regardless of their immune history. Studies have shown a role for opsonizing antibodies leading to increased disease in visceral leishmaniasis. We speculate that cross-reactive antibodies may be playing a role in augmenting visceral disease in mice with immunological memory to L. major.

Transfusion transmitted Chagas disease: is it really under control?

Transfusion transmitted Chagas disease was recognized as a medical problem more than 50 years ago. However, little attention was paid to it by Transfusion Medicine, medical authorities or regulatory agencies as a major problem and threat (especially after the advent of HIV/AIDS); perhaps because it was mainly restricted to tropical regions, usually in less developed countries. With the intense human migratory movement from developing to developed countries, it became more common and evident. The scope of this review is to cover the main transfusional aspects of American trypanosomiasis (Chagas disease), including the main strategies to prevent it through donor questionnaires, specific serological testing and alternative methods such as leukofiltration and pathogen reduction procedures, in order to increase the blood safety in both developing and developed countries.

The paraflagellar rod of kinetoplastid parasites: from structure to components and function

The role of the eukaryotic flagellum in cell motility is well established but its importance in many other aspects of cell biology, from cell signalling to developmental regulation, is becoming increasingly apparent. In addition to this diversity of function the core structure of the flagellum, which has been inherited from the earliest ancestor of all eukaryotes, is embellished with a range of extra-axonemal structures in many organisms. One of the best studied of these structures is the paraflagellar rod of kinetoplastid protozoa in which the morphological characteristics have been well defined and some of the major protein constituents have been identified. Here we discuss recent advances in the identification of further molecular components of the paraflagellar rod, how these impact on our understanding of its function and regulation and the implications for therapeutic intervention in a number of devastating human pathologies.

Combining RNA interference mutants and comparative proteomics to identify protein components and dependences in a eukaryotic flagellum

Eukaryotic flagella from organisms such as Trypanosoma brucei can be isolated and their protein components identified by mass spectrometry. Here we used a comparative approach utilizing two-dimensional difference gel electrophoresis and isobaric tags for relative and absolute quantitation to reveal protein components of flagellar structures via ablation by inducible RNA interference mutation. By this approach we identified 20 novel components of the paraflagellar rod (PFR). Using epitope tagging we validated a subset of these as being present within the PFR by immunofluorescence. Bioinformatic analysis of the PFR cohort reveals a likely calcium/calmodulin regulatory/signaling linkage between some components. We extended the RNA interference mutant/comparative proteomic analysis to individual novel components of our PFR proteome, showing that the approach has the power to reveal dependences between subgroups within the cohort.

Trypanosoma evansi: Paraflagellar rod protein 1 and 2 are similar but lack common B cell epitopes

In an attempt to identify invariant proteins with vaccine potential against African trypanosomes, we investigated the existence of PFR1 protein in Trypanosoma evansi and compared its B cell epitope with that of PFR2 protein of T. evansi using Western blotting and immuno-precipitation assays. The PFR1 gene of T. evansi was amplified by RT-PCR using primers designed based on the open reading frame of PFR1 gene of Trypanosoma brucei. The cloned PFR1 gene of T.evansi was similar to PFR1 genes of T. brucei and Trypanosoma cruzi. The expressed protein from the PFR1 gene was 68.4% homologous to the PFR2 protein of T. evansi, and showed 99.8%, 87%, 77.9% and 77.5% homologous to the PFR1 protein of T. brucei, T. cruzi, Leishmania mexicana and Leishmania major, respectively. Western blot and immuno-precipitation assays showed that antibodies raised against PFR1 and 2 proteins in BALB/c mice recognized the PFR1 and 2 proteins, respectively, with no cross-reactivity. Immuno-agglutination assay showed trypanolytic properties of the anti-PFR1, anti-PFR2 and anti-native PFR sera. These results suggest that PFR1 and PFR2 proteins are components of native PFR antigen and do not share common B cell epitopes.

Evidence for the existence of paraflagellar rod protein 2 (PFR2) gene in Trypanosoma evansi and its conservation among other kinetoplastid parasites

Paraflagellar rod proteins required for cell motility are unique among the kinetoplastids and their heteropolymers provide the building block of the flagellum. We investigated the existence of the paraflagellar rod protein 2 (PFR2) gene in Trypanosoma evansi by reverse transcription-polymerase chain reaction (RT-PCR) using primers designed based on the open reading frame of the PFR2 gene of Trypanosoma brucei. The PFR2 gene was cloned and the PFR2-encoded protein was expressed in bacteria. The expressed His-tag protein was purified using nickel affinity chromatography and confirmed by gel electrophoresis and Western blotting. The nucleotide sequence of the PFR2 gene of T. evansi showed 100% identity with the sequence of the PFR2 gene of T. brucei and 83.4% and 76.6% similarity with that of Trypanosoma cruzi and Leishmania mexicana, respectively. The conserved domain among various PFR2 genes present in kinetoplastids could be used as a target for the development of vaccines against multiple Trypanosoma species.