Apicomplexa micropore: history, function, and formation

The micropore, a mysterious structure found in apicomplexan species, was recently shown to be essential for nutrient acquisition in Plasmodium falciparum and Toxoplasma gondii. However, the differences between the micropores of these two parasites questions the nature of a general apicomplexan micropore structure and whether the formation process model from Plasmodium can be applied to other apicomplexans. We analyzed the literature on different apicomplexan micropores and found that T. gondii probably harbors a more representative micropore type than the more widely studied ones in Plasmodium. Using recent knowledge of the Kelch 13 (K13) protein interactome and gene depletion phenotypes in the T. gondii micropore, we propose a model of micropore formation, thus enriching our wider understanding of micropore protein function.

The Toxoplasma monocarboxylate transporters are involved in the metabolism within the apicoplast and are linked to parasite survival

The apicoplast is a four-membrane plastid found in the apicomplexans, which harbors biosynthesis and organelle housekeeping activities in the matrix. However, the mechanism driving the flux of metabolites, in and out, remains unknown. Here, we used TurboID and genome engineering to identify apicoplast transporters in Toxoplasma gondii. Among the many novel transporters, we show that one pair of apicomplexan monocarboxylate transporters (AMTs) appears to have evolved from a putative host cell that engulfed a red alga. Protein depletion showed that AMT1 and AMT2 are critical for parasite growth. Metabolite analyses supported the notion that AMT1 and AMT2 are associated with biosynthesis of isoprenoids and fatty acids. However, stronger phenotypic defects were observed for AMT2, including in the inability to establish T. gondii parasite virulence in mice. This study clarifies, significantly, the mystery of apicoplast transporter composition and reveals the importance of the pair of AMTs in maintaining the apicoplast activity in apicomplexans.

The transplant rejection response involves neutrophil and macrophage adhesion-mediated trogocytosis and is regulated by NFATc3

The anti-foreign tissue (transplant rejection) response, mediated by the immune system, has been the biggest obstacle to successful organ transplantation. There are still many enigmas regarding this process and some aspects of the underlying mechanisms driving the immune response against foreign tissues remain poorly understood. Here, we found that a large number of neutrophils and macrophages were attached to the graft during skin transplantation. Furthermore, both types of cells could autonomously adhere to and damage neonatal rat cardiomyocyte mass (NRCM) in vitro. We have demonstrated that Complement C3 and the receptor CR3 participated in neutrophils/macrophages-mediated adhesion and damage this foreign tissue (NRCM or skin grafts). We have provided direct evidence that the damage to these tissues occurs by a process referred to as trogocytosis, a damage mode that has never previously been reported to directly destroy grafts. We further demonstrated that this process can be regulated by NFAT, in particular, NFATc3. This study not only enriches an understanding of host-donor interaction in transplant rejection, but also provides new avenues for exploring the development of novel immunosuppressive drugs which prevent rejection during transplant therapy.

Prevalence of Eimeria Species, Detected by ITS1-PCR Immobilized on FTA Cards, in Future Laying Hens and Breeding Hens in Six Provinces in Northeastern Algeria

PURPOSE

Avian coccidiosis is an important and widely distributed disease that affects global agricultural economies through losses. In Algeria, there is limited epidemiological and ecological knowledge about this disease and this hinders implementation of control strategies. A recent study, in Algeria, demonstrated a high prevalence and diversity of Eimeria species in broiler chickens. However, very little is known about the Eimeria species that exist on chicken farms raised on the floor and older than broiler chickens (for example, future laying hens and breeding hens) in Algeria.

METHODS

Samples were collected from 32 poultry farms located in 6 northeastern Algerian provinces (Algiers, Batna, Bejaia, Bordj Bou Arréridj, Jijel, Mila). These included 22 pre-laying pullet farms, with hens aged between 11 and 17 weeks, and 10 breeding hen farms with older hens (over 20 weeks). FTA cards were used to capture DNA and internal transcribed Spacer 1 PCR (ITS1-PCR) was used to determine the prevalence and composition of Eimeria species in the chickens.

RESULTS

This showed the presence of six species of Eimeria with a diverse prevalence range. Eimeria necatrix (63%) was the most common species, followed by E. maxima (53%), E. tenella (31%), E. brunetti (19%), E. acervulina and E. mitis (both 0.3%). Eimeria praecox was absent. Eimeria infection affected all farms studied where co-infections by different Eimeria species (63%) were more frequent than single infections (38%). The number of oocyts, per ml of enriched oocyst suspension was higher in breeding hen farms compared to pre-laying pullet farms.

CONCLUSION

This study, taken alongside a previous study involving broiler farms, demonstrated that the infection with this parasite is a significant problem in Algeria.

Macrophage-mediated trogocytosis contributes to destroying human schistosomes in a non-susceptible rodent host, Microtus fortis

Schistosoma parasites, causing schistosomiasis, exhibit typical host specificity in host preference. Many mammals, including humans, are susceptible to infection, while the widely distributed rodent, Microtus fortis, exhibits natural anti-schistosome characteristics. The mechanisms of host susceptibility remain poorly understood. Comparison of schistosome infection in M. fortis with the infection in laboratory mice (highly sensitive to infection) offers a good model system to investigate these mechanisms and to gain an insight into host specificity. In this study, we showed that large numbers of leukocytes attach to the surface of human schistosomes in M. fortis but not in mice. Single-cell RNA-sequencing analyses revealed that macrophages might be involved in the cell adhesion, and we further demonstrated that M. fortis macrophages could be mediated to attach and kill schistosomula with dependence on Complement component 3 (C3) and Complement receptor 3 (CR3). Importantly, we provided direct evidence that M. fortis macrophages could destroy schistosomula by trogocytosis, a previously undescribed mode for killing helminths. This process was regulated by Ca2+/NFAT signaling. These findings not only elucidate a novel anti-schistosome mechanism in M. fortis but also provide a better understanding of host parasite interactions, host specificity and the potential generation of novel strategies for schistosomiasis control.

Functional screening reveals Toxoplasma prenylated proteins required for endocytic trafficking and rhoptry protein sorting

In the apicomplexans, endocytosed cargos (e.g., hemoglobin) are trafficked to a specialized organelle for digestion. This follows a unique endocytotic process at the micropore/cytostome in these parasites. However, the mechanism underlying endocytic trafficking remains elusive, due to the repurposing of classical endocytic proteins for the biogenesis of apical organelles. To resolve this issue, we have exploited the genetic tractability of the model apicomplexan Toxoplasma gondii, which ingests host cytosolic materials (e.g., green fluorescent protein[GFP]). We determined an association between protein prenylation and endocytic trafficking, and using an alkyne-labeled click chemistry approach, the prenylated proteome was characterized. Genome editing, using clustered regularly interspaced short palindromic repaet/CRISPR-associated nuclease 9 (CRISPR/Cas9), was efficiently utilized to generate genetically modified lines for the functional screening of 23 prenylated candidates. This identified four of these proteins that regulate the trafficking of endocytosed GFP vesicles. Among these proteins, Rab1B and YKT6.1 are highly conserved but are non-classical endocytic proteins in eukaryotes. Confocal imaging analysis showed that Rab1B and Ras are substantially localized to both the trans-Golgi network and the endosome-like compartments in the parasite. Conditional knockdown of Rab1B caused a rapid defect in secretory trafficking to the rhoptry bulb, suggesting a trafficking intersection role for the key regulator Rab1B. Further experiments confirmed a critical role for protein prenylation in regulating the stability/activity of these proteins (i.e., Rab1B and YKT6.1) in the parasite. Our findings define the molecular basis of endocytic trafficking and reveal a potential intersection function of Rab1B on membrane trafficking in T. gondii. This might extend to other related protists, including the malarial parasites. IMPORTANCE The protozoan Toxoplasma gondii establishes a permissive niche, in host cells, that allows parasites to acquire large molecules such as proteins. Numerous studies have demonstrated that the parasite repurposes the classical endocytic components for secretory sorting to the apical organelles, leaving the question of endocytic transport to the lysosome-like compartment unclear. Recent studies indicated that endocytic trafficking is likely to associate with protein prenylation in malarial parasites. This information promoted us to examine this association in the model apicomplexan T. gondii and to identify the key components of the prenylated proteome that are involved. By exploiting the genetic tractability of T. gondii and a host GFP acquisition assay, we reveal four non-classical endocytic proteins that regulate the transport of endocytosed cargos (e.g., GFP) in T. gondii. Thus, we extend the principle that protein prenylation regulates endocytic trafficking and elucidate the process of non-classical endocytosis in T. gondii and potentially in other related protists.

Investigation into the potential of using UV-treated sporulated oocysts of Eimeria tenella as a local solution to immunization of chickens against caecal coccidiosis

In this study, we aim to evaluate the immune response of chickens to UV-treated sporulated oocysts as a means of protection against caecal coccidiosis caused by field strains of Eimeria tenella. Two groups of chicks were immunized using prepared UV-treated oocysts of E. tenella and challenged at day 20 post hatching. The first group was immunized only once at day 1 post hatching, the second group was immunized twice (day 1 and day 8 post hatching). Two non-immunized control groups were used: the first group was challenged with E. tenella, while the second group remained uninfected. The effectiveness of immunization on production and animal health was evaluated by the following criteria: body weight, feed conversion ratio, blood in faeces, mortality, lesion scores and oocyst output. The two immunized groups showed a significantly better performance in body weight, weight gain and lesion scores than the non-immunized group. However, all three groups performed significantly worse than the unchallenged group. The mortality of the non-immunized infected group was high (70%) while mortality in both immunized and unchallenged groups of chickens was significantly lower (range 2.2 to 4.4%) than the infected group (p < 0.05). The production of oocysts in faeces, post-infection, was significantly higher in the non-immunized group compared to the immunized group (p < 0.05) and both were significantly higher than the uninfected group (p < 0.05). In conclusion, immunization by prepared UV-irradiated oocysts is effective in stimulating at least a partial protective immunity in immunized chickens against caecal coccidiosis.

The Toxoplasma micropore mediates endocytosis for selective nutrient salvage from host cell compartments

Apicomplexan parasite growth and replication relies on nutrient acquisition from host cells, in which intracellular multiplication occurs, yet the mechanisms that underlie the nutrient salvage remain elusive. Numerous ultrastructural studies have documented a plasma membrane invagination with a dense neck, termed the micropore, on the surface of intracellular parasites. However, the function of this structure remains unknown. Here we validate the micropore as an essential organelle for endocytosis of nutrients from the host cell cytosol and Golgi in the model apicomplexan Toxoplasma gondii. Detailed analyses demonstrated that Kelch13 is localized at the dense neck of the organelle and functions as a protein hub at the micropore for endocytic uptake. Intriguingly, maximal activity of the micropore requires the ceramide de novo synthesis pathway in the parasite. Thus, this study provides insights into the machinery underlying acquisition of host cell-derived nutrients by apicomplexan parasites that are otherwise sequestered from host cell compartments.

PAG3 promotes the differentiation of bloodstream forms in Trypanosoma brucei and reveals the evolutionary relationship among the Trypanozoon trypanosomes

Introduction

Trypanosoma brucei, T. evansi and T. equiperdum are members of the subgenus Trypanozoon and are highly similar morphologically and genetically. The main differences between these three species are their differentiation patterns in the hosts and the role of vectors in their life cycles. However, the mechanisms causing these differences are still controversial.

Methods

PAG3 gene was accessed by PCR amplification in 26 strains of Trypanozoon and sequences were then analyzed by BLAST accompanied with T. evansitype B group. RNA interference and CRISPR/Cas9 were used for revealing possible role of PAG3 in slender to stumpy transformation.

Results

The procyclin associated gene 3 (PAG3) can be found in the pleomorphicspecies, T.brucei, which undergoes differentiation of slender forms to the stumpy form. This differentiation process is crucial for transmission to the tsetse fly vector. However, a homologue of PAG3 was not detected in either T. evansi or in the majority of T. equiperdum strains which are allmonomorphic. Furthere xperiments in T. brucei demonstrated that, when PAG3 was down-regulated or absent, there was a significant reduction in the differentiation from slender to stumpy forms.

Conclusion

Therefore, we conclude that PAG3 is a key nuclear gene involved in the slender to stumpy differentiation pathway of T.brucei in the mammalian host. Loss of this gene might also offer a simple evolutionary mechanism explaining why T. evansi and some T. equiperdum have lost the ability to differentiate and have been driven to adapt to transmission cycles that by pass the tsetse vector or mechanical contact.

The British Athletics Muscle Injury Classification grading system as a predictor of return to play following hamstrings injury in professional football players

OBJECTIVES

Investigate the British Athletics Muscle Injury Classification (BAMIC) grading system as a predictor of return to play (RTP) following primary hamstring strain injury (HSI) and its agreement with the Peetron's classification system in professional footballers.

METHODS

A retrospective cohort study of 39 hamstrings strains in a professional English football club were identified. Two musculoskeletal radiologists reviewed historical MRI's and classified them against the BAMIC and Peetron's grading system. Classification, oedema length and cross-sectional area were compared against RTP.

RESULTS

Pearson's correlation coefficient demonstrated a weak but statistically significant correlation between BAMIC and RTP (r = 0.32; 95%CI 0.01 to 0.58; p = 0.05). Maximum length of intramuscular oedema demonstrated weak correlations with RTP (r = 0.3; 95%CI -0.02 to 0.56; p = 0.06). Percentage cross sectional demonstrated a weak correlation with RTP (r = 0.02; 95%CI -0.3 to 0.33; p = 0.91). Multiple regression demonstrated that 16% of the variance in RTP was explained by the model. Kappa for the agreement between BAMIC and Peetron's was 0.21 (95%CI 0 to 0.42).

CONCLUSIONS

A significant association between the grade of HSI on the BAMIC system and RTP was found. Findings suggest BAMIC could provide valuable prognostic information on the RTP.

Prevalence of Eimeria species, detected by ITS1-PCR, in broiler poultry farms located in seven provinces of northeastern Algeria

Coccidiosis is an important global chickens' disease which can cause serious economic losses in the poultry industry worldwide. Little is known about the extent of infection or diversity, of the causative agent Eimeria spp., in Algeria. A priority, therefore, is to determine the prevalence and species composition to inform strategies on treatments and control measures. Samples were collected from 187 broiler farms, located in 7 Northeastern Algerian provinces (Jijel, Constantine, Skikda, Mila, Setif, Batna, Bordj bou-Arreridj), and Internal Transcribed Spacer 1 PCR (ITS1-PCR) was used to determine the prevalence and composition of Eimeria species in chickens. The survey revealed the presence of all seven species of Eimeria at different prevalences (E. maxima (69%), E. acervulina (68.4%), E. necatrix (11.2%), E. tenella (8%), E. praecox (4.3%), E. mitis (2.1%), E. brunetti (2.1%). Multiple infections, with up to 4 different Eimeria species present on a single farm, were the most frequent situation in our samples (51.9% mixed infections versus 47.6% single infections). All farms revealed infected samples, and we conclude that this parasite is a significant problem in these provinces.

iNOS is essential to maintain a protective Th1/Th2 response and the production of cytokines/chemokines against Schistosoma japonicum infection in rats

Humans and a wide range of mammals are generally susceptible to Schistosoma infection, while some rodents such as Rattus rats and Microtus spp are not. We previously demonstrated that inherent high expression levels of nitric oxide (NO), produced by inducible nitric oxide synthase (iNOS), plays an important role in blocking the growth and development of Schistosoma japonicum in wild-type rats. However, the potential regulatory effects of NO on the immune system and immune response to S. japonicum infection in rats are still unknown. In this study, we used iNOS-knockout (KO) rats to determine the role of iNOS-derived NO in the immune system and immunopathological responses to S. japonicum infection in rats. Our data showed that iNOS deficiency led to weakened immune activity against S. japonicum infection. This was characterized by the impaired T cell responses and a significant decrease in S. japonicum-elicited Th2/Th1 responses and cytokine and chemokine-producing capability in the infected iNOS-KO rats. Unlike iNOS-KO mice, Th1-associated cytokines were also decreased in the absence of iNOS in rats. In addition, a profile of pro-inflammatory and pro-fibrogenic cytokines was detected in serum associated with iNOS deficiency. The alterations in immune responses and cytokine patterns were correlated with a slower clearance of parasites, exacerbated granuloma formation, and fibrosis following S. japonicum infection in iNOS-KO rats. Furthermore, we have provided direct evidence that high levels of NO in rats can promote the development of pulmonary fibrosis induced by egg antigens of S. japonicum, but not inflammation, which was negatively correlated with the expression of TGF-β3. These studies are the first description of the immunological and pathological profiles in iNOS-KO rats infected with S. japonicum and demonstrate key differences between the responses found in mice. Our results significantly enhance our understanding of the immunoregulatory effects of NO on defensive and immunopathological responses in rats and the broader nature of resistance to pathogens such as S. japonicum.

Schistosomiasis is a zoonosis that affects more than 200 million people worldwide. A wide range of mammals, including mice, are permissive hosts of Schistosoma and develop chronic disease characterized by egg-granuloma formation and fibrosis after infection. Rats, on the other hand, are non-permissive hosts and develop efficient immune responses to eliminate the worms. Interestingly, schistosome eggs elicit a dominant Th2 immune response within mouse hosts, whereas rats with schistosomiasis develop a significant Th2 response in the absence of available egg production. The Th2 response in rats seems to play an essential role in the protection of the host against Schistosoma. So far, the factors that lead to the different immune responses to Schistosoma infection in both hosts have not been demonstrated. In this study, our results show that an iNOS-dependent mechanism maintains the function of the immune system in rats by modulating CD4⁺ T cell-mediated Th1/Th2-associated cytokine responses and chemokine production. Additionally, the absence of iNOS led to slow clearance of parasites, increases in the development of worms, and an exacerbation of granuloma formation and fibrosis in rats. Furthermore, high levels of NO in rats can promote the development of fibrosis induced by inflammation (rapid inflammatory repair). Therefore, this study demonstrates that the difference in iNOS levels between mice and rats is responsible for the different immune responses and outcomes induced by schistosome infection in both hosts.

Transplantation of Gut Microbiota From High-Fat-Diet-Tolerant Cynomolgus Monkeys Alleviates Hyperlipidemia and Hepatic Steatosis in Rats

Emerging evidence has been reported to support the involvement of the gut microbiota in the host's blood lipid and hyperlipidemia (HLP). However, there remains unexplained variation in the host's blood lipid phenotype. Herein a nonhuman primate HLP model was established in cynomolgus monkeys fed a high-fat diet (HFD) for 19 months. At month 19%, 60% (3/5) of the HFD monkeys developed HLP, but surprisingly 40% of them (2/5) exhibited strong tolerance to the HFD (HFD-T) with their blood lipid profiles returning to normal levels. Metagenomic analysis was used to investigate the compositional changes in the gut microbiota in these monkeys. Furthermore, the relative abundance of Megasphaera remarkably increased and became the dominant gut microbe in HFD-T monkeys. A validation experiment showed that transplantation of fecal microbiota from HFD-T monkeys reduced the blood lipid levels and hepatic steatosis in HLP rats. Furthermore, the relative abundance of Megasphaera significantly increased in rats receiving transplantation, confirming the successful colonization of the microbe in the host and its correlation with the change of the host's blood lipid profiles. Our results thus suggested a potentially pivotal lipid-lowering role of Megasphaera in the gut microbiota, which could contribute to the variation in the host's blood lipid phenotype.

The Occurrence of Malignancy in Trypanosoma brucei brucei by Rapid Passage in Mice

Pleomorphic Trypanosoma brucei are best known for their tightly controlled cell growth and developmental program, which ensures their transmissibility and host fitness between the mammalian host and insect vector. However, after long-term adaptation in the laboratory or by natural evolution, monomorphic parasites can be derived. The origin of these monomorphic forms is currently unclear. Here, we produced a series of monomorphic trypanosome stocks by artificially syringe-passage in mice, creating snapshots of the transition from pleomorphism to monomorphism. We then compared these artificial monomorphic trypanosomes, alongside several naturally monomorphic T. evansi and T. equiperdum strains, with the pleomorphic T. brucei. In addition to failing to generate stumpy forms in animal bloodstream, we found that monomorphic trypanosomes from laboratory and nature exhibited distinct differentiation patterns, which are reflected by their distinct differentiation potential and transcriptional changes. Lab-adapted monomorphic trypanosomes could still be induced to differentiate, and showed only minor transcriptional differences to that of the pleomorphic slender forms but some accumulated differences were observed as the passages progress. All naturally monomorphic strains completely fail to differentiate, corresponding to their impaired differentiation regulation. We propose that the natural phenomenon of trypanosomal monomorphism is actually a malignant manifestation of protozoal cells. From a disease epidemiological and evolutionary perspective, our results provide evidence for a new way of thinking about the origin of these naturally monomorphic strains, the malignant evolution of trypanosomes may raise some concerns. Additionally, these monomorphic trypanosomes may reflect the quantitative and qualitative changes in the malignant evolution of T. brucei, suggesting that single-celled protozoa may also provide the most primitive model of cellular malignancy, which could be a primitive and inherent biological phenomenon of eukaryotic organisms from protozoans to mammals.

Species identification and phylogenetic analysis of Leishmania isolated from patients, vectors and hares in the Xinjiang Autonomous Region, The People's Republic of China

Background

Visceral leishmaniasis (VL) has been declared as one of the six major tropical diseases by the World Health Organization. This disease has been successfully controlled in China, except for some areas in the western region, such as the Xinjiang Autonomous Region, where both anthroponotic VL (AVL) and desert type zoonotic VL (DT-ZVL) remain endemic with sporadic epidemics.

Methodology/Principal findings

Here, an eleven-year survey (2004–2014) of Leishmania species, encompassing both VL types isolated from patients, sand-fly vectors and Tarim hares (Lepus yarkandensis) from the Xinjiang Autonomous Region was conducted, with a special emphasis on the hares as a potential reservoir animal for DT-ZVL. Key diagnostic genes, ITS1, hsp70 and nagt (encoding N-acetylglucosamine-1-phosphate transferase) were used for phylogenetic analyses, placing all Xinjiang isolates into one clade of the L. donovani complex. Unexpectedly, AVL isolates were found to be closely related to L. infantum, while DT-ZVL isolates were closer to L. donovani. Unrooted parsimony networks of haplotypes for these isolates also revealed their relationship.

Conclusions/Significance

The above analyses of the DT-ZVL isolates suggested their geographic isolation and independent evolution. The sequence identity of isolates from patients, vectors and the Tarim hares in a single DT-ZVL site provides strong evidence in support of this species as an animal reservoir.

Black faver, also known as visceral leishmaniasis (VL), is caused by pathogens of Leishmania species, spread by the bites of infected sand flies. This disease has been successfully controlled in China, except for some areas in the western region, such as Xinjiang. However, the knowledge on Leishmania in these areas remains a few important gaps. Particularly, what is the animal reservoir for desert type zoonotic VL (DT-ZVL), as sand flies get infected in areas free of patients or infected dogs? To address this question, an eleven-year survey (2004–2014) in Xinjiang for Leishmania species was carried out. We found that VLs in Xinjiang are contributed to Leishmania donovani complex, and Tarim hares is likely the reservoir animal for DT-ZVL.

Circulating tumour DNA is a promising biomarker for risk stratification of central chondrosarcoma with IDH1/2 and GNAS mutations

Chondrosarcoma (CS) is a rare tumour type and the most common primary malignant bone cancer in adults. The prognosis, currently based on tumour grade, imaging and anatomical location, is not reliable, and more objective biomarkers are required. We aimed to determine whether the level of circulating tumour DNA (ctDNA) in the blood of CS patients could be used to predict outcome. In this multi-institutional study, we recruited 145 patients with cartilaginous tumours, of which 41 were excluded. ctDNA levels were assessed in 83 of the remaining 104 patients, whose tumours harboured a hotspot mutation in IDH1/2 or GNAS. ctDNA was detected pre-operatively in 31/83 (37%) and in 12/31 (39%) patients postoperatively. We found that detection of ctDNA was more accurate than pathology for identification of high-grade tumours and was associated with a poor prognosis; ctDNA was never associated with CS grade 1/atypical cartilaginous tumours (ACT) in the long bones, in neoplasms sited in the small bones of the hands and feet or in tumours measuring less than 80 mm. Although the results are promising, they are based on a small number of patients, and therefore, introduction of this blood test into clinical practice as a complementary assay to current standard-of-care protocols would allow the assay to be assessed more stringently and developed for a more personalised approach for the treatment of patients with CS.

A new species of mammalian trypanosome, Trypanosoma (Megatrypanum) bubalisi sp. nov., found in the freshwater leech Hirudinaria manillensis

Leeches have long been considered potential vectors for the aquatic lineage of trypanosomes, while bloodsucking insects are generally considered as the vectors for the terrestrial lineage of trypanosomes. The freshwater leech, Hirudinaria manillensis, is a widely distributed species in southern China and could potentially act as the vector for trypanosomes. Prior to this study, no trypanosomes had been reported from this leech. However, in this study, leeches were collected from three different places in Guangdong province, China, and a large number of flagellates were isolated and successfully cultured in vitro. Based on morphology, these flagellates looked like a typical trypanosome species. Analysis was carried out on the molecular sequences of the 18S rRNA gene and the glycosomal glyceraldehyde-3-phosphate dehydrogenase (gGAPDH) gene. To our surprise, these flagellates were identified as likely to be a mammalian trypanosome belonging to the clade containing Trypanosoma (Megatrypanum) theileri but they are significantly different from the typical TthI and TthII stocks. Analyses of blood composition indicated that the source of the blood meal in these leeches was from the water buffalo (Bubalus bubalis). To further test if this flagellate from the freshwater leech was indeed a mammalian trypanosome, we transferred the trypanosomes cultured at 27-37 °C and they were able to successfully adapt to this mammalian body temperature, providing further supporting evidence. Due to the significant genetic differences from other related trypanosomes in the subgenus Megatrypanum, we propose that this flagellate, isolated from H. manillensis, is a new species and have named it Trypanosoma bubalisi. Our results indicate that freshwater leeches may be a potential vector of this new mammalian trypanosome.

High resistance to Toxoplasma gondii infection in inducible nitric oxide synthase knockout rats

Nitric oxide (NO) is an important immune molecule that acts against extracellular and intracellular pathogens in most hosts. However, after the knockout of inducible nitric oxide synthase (iNOS^−/−) in Sprague Dawley (SD) rats, these iNOS^−/− rats were found to be completely resistant to Toxoplasma gondii infection. Once the iNOS^−/− rat peritoneal macrophages (PMs) were infected with T. gondii, they produced high levels of reactive oxygen species (ROS) triggered by GRA43 secreted by T. gondii, which damaged the parasitophorous vacuole membrane and PM mitochondrial membranes within a few hours post-infection. Further evidence indicated that the high levels of ROS caused mitochondrial superoxide dismutase 2 depletion and induced PM pyroptosis and cell death. This discovery of complete resistance to T. gondii infection, in the iNOS^−/−-SD rat, demonstrates a strong link between NO and ROS in immunity to T. gondii infection and showcases a potentially novel and effective backup innate immunity system.

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iNOS^−/−-SD rats show strong resistance to Toxoplasma gondii infection

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iNOS^−/−-SD rat PMs resist T. gondii infection through ROS upregulation

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The T. gondii infection results in PM pyroptosis in iNOS^−/−-SD rats

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GRAs play a key role in the activation of resistance in iNOS^−/−-SD rat PMs

Innate Resistance to Leishmania amazonensis Infection in Rat Is Dependent on NOS2

Leishmania infection causes diverse clinical manifestations in humans. The disease outcome is complicated by the combination of many host and parasite factors. Inbred mouse strains vary in resistance to Leishmania major but are highly susceptible to Leishmania amazonensis infection. However, rats are highly resistant to L. amazonensis infection due to unknown mechanisms. We use the inducible nitric oxide synthase (Nos2) gene knockout rat model (Nos2^−/− rat) to investigate the role of NOS2 against leishmania infection in rats. Our results demonstrated that diversion toward the NOS2 pathway is the key factor explaining the resistance of rats against L. amazonensis infection. Rats deficient in NOS2 are susceptible to L. amazonensis infection even though their immune response to infection is still strong. Moreover, adoptive transfer of NOS2 competent macrophages into Nos2^−/− rats significantly reduced disease development and parasite load. Thus, we conclude that the distinct L-arginine metabolism, observed in rat macrophages, is the basis of the strong innate resistance to Leishmania. These data highlight that macrophages from different hosts possess distinctive properties and produce different outcomes in innate immunity to Leishmania infections.

Identification of an orally active carbazole aminoalcohol derivative with broad-spectrum anti-animal trypanosomiasis activity

Animal trypanosomiasis, caused by the members of subgenus Trypanozoon (Trypanosoma brucei brucei, T. evansi and T. equiperdum), has reduced animal productivity leading to significant negative economic impacts in endemic regions. Due to limited drug discovery and the emergence of drug-resistance over many recent decades, novel and effective compounds against animal trypanosomiasis are urgently required. This study was conducted to evaluate the antitrypanosomal potential of a batch of carbazole aminoalcohol derivatives. Among them, we found that the most effective compound was H1402, which exhibited potent trypanocidal efficacy against the bloodstream-form of T. b. brucei (EC₅₀ = 0.73 ± 0.05 µM) and presented low cytotoxicity against two mammalian cell lines with CC₅₀ > 30 µM. Using a murine model of acute infection, oral administration with H1402 demonstrated a complete clearance of T. b. brucei and all the infected mice were cured when they were treated twice daily for 5 days at a dose of 100 mg/kg. Furthermore, parasites were not detected in mice infected with T. evansi and T. equiperdum (the causative agents of surra and dourine, respectively, in animals) within 30 days following the same regimen with H1402. In addition, H1402 caused severe morphological and ultrastructural destruction to trypanosomes, as well as causing phosphatidylserine externalization, which are suggested to be the most likely cause of cell death. Overall, the present data demonstrated that H1402 could be promising as a rapid, safe and orally active lead compound for the development of new chemotherapeutics for animal trypanosomiasis.

Infection with Trypanosoma lewisi or Trypanosoma musculi may promote the spread of Toxoplasma gondii

Toxoplasma gondii can infect almost all warm-blooded vertebrates with pathogensis being largely influenced by the host immune status. As important epidemiological hosts, rodents are globally distributed and are also commonly found infected with haemoflagellates, such as those in the genus Trypanosoma. We here address whether and how co-infection with trypanosomes can influence T. gondii infection in laboratory models. Rats of five strains, co-infected with T. lewisi and mice of four strains, co-infected with T. musculi, were found to be more or less susceptible to T. gondii infection, respectively, with corresponding increased or decreased brain cyst burdens. Downregulation of iNOS expression and decreased NO production or reverse were observed in the peritoneal macrophages of rats or mice, infected with trypanosomes, respectively. Trypanosoma lewisi and T. musculi can modulate host immune responses, either by enhancement or suppression and influence the outcome of Toxoplasma infection.

Long-term trends in helminth infections of wood mice (Apodemus sylvaticus) from the vicinity of Malham Tarn in North Yorkshire, England

Helminth infections in wood mice (n = 483), trapped over a period of 26 years in the woods surrounding Malham Tarn in North Yorkshire, were analysed. Although 10 species of helminths were identified, the overall mean species richness was 1.01 species/mouse indicating that the helminth community was relatively depauperate in this wood mouse population. The dominant species was Heligmosomoides polygyrus, the prevalence (64.6%) and abundance (10.4 worms/mouse) of which declined significantly over the study period. Because of the dominance of this species, analyses of higher taxa (combined helminths and combined nematodes) also revealed significantly declining values for prevalence, although not abundance. Helminth species richness (HSR) and Brillouin's index of diversity (BID) did not show covariance with year, neither did those remaining species whose overall prevalence exceeded 5% (Syphacia stroma, Aonchotheca murissylvatici and Plagiorchis muris). Significant age effects were detected for the prevalence and abundance of all higher taxa, H. polygyrus and P. muris, and for HSR and BID, reflecting the accumulation of helminths with increasing host age. Only two cases of sex bias were found; male bias in abundance of P. muris and combined Digenea. We discuss the significance of these results and hypothesize about the underlying causes.

Novel organization of mitochondrial minicircles and guide RNAs in the zoonotic pathogen Trypanosoma lewisi

Kinetoplastid flagellates are known for several unusual features, one of which is their complex mitochondrial genome, known as kinetoplast (k) DNA, composed of mutually catenated maxi- and minicircles. Trypanosoma lewisi is a member of the Stercorarian group of trypanosomes which is, based on human infections and experimental data, now considered a zoonotic pathogen. By assembling a total of 58 minicircle classes, which fall into two distinct categories, we describe a novel type of kDNA organization in T. lewisi. RNA-seq approaches allowed us to map the details of uridine insertion and deletion editing events upon the kDNA transcriptome. Moreover, sequencing of small RNA molecules enabled the identification of 169 unique guide (g) RNA genes, with two differently organized minicircle categories both encoding essential gRNAs. The unprecedented organization of minicircles and gRNAs in T. lewisi broadens our knowledge of the structure and expression of the mitochondrial genomes of these human and animal pathogens. Finally, a scenario describing the evolution of minicircles is presented.

Temperature is a key factor influencing the invasion and proliferation of Toxoplasma gondii in fish cells

Toxoplasma gondii has long been considered a ubiquitous parasite possessing the capacity of infecting virtually all warm-blooded animals globally. Occasionally, this parasite can also infect cold-blooded animals such as fish if their body temperature reaches 37 °C. However, we are currently lacking an understanding of key details such as the minimum temperature required for T. gondii invasion and proliferation in these cold-blooded animals and their cells. Here, we performed in vitro T. gondii infection experiments with rat embryo fibroblasts (REF cells), grouper (Epinephelus coioides) splenocytes (GS cells) and zebra fish (Danio rerio) hepatocytes (ZFL cells), at 27 °C, 30 °C, 32 °C, 35 °C and 37 °C, respectively. We found that T. gondii tachyzoites could penetrate REF, GS nd ZFL cells at 27 °C but clear inhibition of multiplication was observed. Intriguingly, the intracellular tachyzoites retained the ability to infect mice after 12 days of incubation in GS cells cultured at 27 °C as demonstrated by bioassay. At 30 °C, 32 °C and 35 °C, we observed that the mammalian cells (REF cells) and fish cells (GS and ZFL cells) could support T. gondii invasion and replication, which showed a temperature-dependent relationship in infection and proliferation rates. Our data demonstrated that the minimum temperature for T. gondii invasion and replication was 27 °C and 30 °C respectively, which indicated that temperature should be a key factor for T. gondii invasion and proliferation in host cells. This suggests that temperature-dependent infection determines the differences in the capability of T. gondii to infect cold- and warm-blooded vertebrates.

Vacuolar ATPase depletion contributes to dysregulation of endocytosis in bloodstream forms of Trypanosoma brucei

Background

Vacuolar H⁺-ATPase (V-ATPase) is a highly conserved protein complex which hydrolyzes ATP and pumps protons to acidify vacuolar vesicles. Beyond its role in pH maintenance, the involvement of V-ATPase in endocytosis is well documented in mammals and plants but is less clear in Trypanosoma brucei.

Methods

In this study, the subcellular localization of V-ATPase subunit B (TbVAB) of T. brucei was assessed via in situ N-terminal YFP-tagging and immunofluorescence assays. Transgenic bloodstream forms (BSF) of T. brucei were generated which comprised either a V-ATPase subunit B (TbVAB) conditional knockout or a V-ATPase subunit A (TbVAA) knockdown. Acridine orange and BCECF-AM were employed to assess the roles of V-ATPase in the pH regulation of BSF T. brucei. The endocytic activities of three markers were also characterized by flow cytometry analyses. Furthermore, trypanosomes were counted from trypanolysis treatment groups (either containing 1% or 5% NHS) and endocytosed trypanosome lytic factor (TLF) was also analyzed by an immunoblotting assay.

Results

TbVAB was found to localize to acidocalcisomes, lysosomes and probably also to endosomes of BSF of T. brucei and was demonstrated to be essential for cell growth. TbVAB depletion neutralized acidic organelles at 24 hours post-tetracycline depletion (hpd), meanwhile the steady state intracellular pH increased from 7.016 ± 0.013 to 7.422 ± 0.058. Trypanosomes with TbVAB depletion at 24 hpd were found to take up more transferrin (2.068 ± 0.277 fold) but less tomato lectin (49.31 ± 22.57%) by endocytosis, while no significant change was detected in dextran uptake. Similar endocytic dysregulated phenotypes were also observed in TbVAA knockdown cells. In addition, TbVAB depleted trypanosomes showed a low uptake of TLF and exhibited less sensitive to lysis in both 1% and 5% NHS treatments.

Conclusions

TbVAB is a key component of V-ATPase and was found to play a key function in endocytosis as well as exhibiting different effects in a receptor/cargo dependent manner in BSF of T. brucei. Besides vacuolar alkalinization, the dysregulation of endocytosis in TbVAB depleted T. brucei is considered to contribute to the reduced sensitivity to lysis by normal human serum.

Improved mediolateral load distribution without adverse laxity pattern in robot-assisted knee arthroplasty compared to a standard manual measured resection technique

PURPOSE

Robot-assisted total knee arthroplasty (rTKA) remains in its infancy, is expensive but offers the promise of improved kinematic performance through precise bone cuts, with minimal soft tissue disruption, based on pre-resection soft tissue behaviour. This cadaveric study examined load transfer, soft tissue performance and radiographic indices for conventional (sTKA) versus rTKA. The null hypothesis was there would be no difference between the two modes of implantation.

METHODS

Whole (ten) cadaveric limbs were randomised to receive either robotic (rTKA, N = 5) or conventional measured resection (sTKA, N = 5) knee arthroplasty. Laxity patterns were established using validated fixed sensors (Verasense) with manual maximum displacement for six degrees of freedom. Tibiofemoral load and contact points were determined dynamically using remote sensor technology for medial and lateral compartments through a functional arc of motion (0-110 degrees of motion). Final component position was assessed using pre- and post-implantation CT.

RESULTS

No significant intergroup differences for laxity were found (n.s.). The rTKA group exhibited consistently balanced mediolateral load throughout the full arc with significantly reduced overall total load across the joint (for distinct points of measurement, p < 0.05). Despite using flexion-extension and mediolateral gap balancing with measured resection, the sTKA group failed to achieve balance in at least three points of the flexion arc. Post-operative CT confirmed satisfactory component alignment with no significant differences for positioning between the two groups.

CONCLUSION

This work found improved load sharing for rTKA when compared to conventional surgery for same donor knees. Laxity and CT determined final component positioning was not significantly different. The work supports the contention that robot-assisted TKA delivers improved tibiofemoral load sharing in time zero studies under defined conditions but such offers the promise of improved clinical performance and reduced implant wear.

Mat Seroprevalence Infers Low Rates of Toxoplasma gondii in Domestic Pigs from Yucatan, Mexico

Toxoplasma gondii is a zoonotic parasite of worldwide distribution. The consumption of infected pork meat has been suggested to be an important source for human infection in the tropical area of Yucatan, Mexico. We performed a cross-sectional study of 12 farms across the state to investigate the seroprevalence of Toxoplasma gondii infection in domestic pigs. In total, 632 samples were obtained from 2 different environmental zones (tropical deciduous low forest and tropical sub-deciduous medium forest) and 2 abattoirs. The modified agglutination test (MAT) was used to assess the seroprevalence of T. gondii in pigs and to evaluate 2 globally used serological tests, the Dye test (DT) and ID Screen® ELISA multi-species, and a commercial ELISA kit (Human Toxo IgG, Human-diagnostics), which is widely used locally in this geographical area. The overall prevalence obtained with the MAT (cut-off ≥1:25) among the 632 pigs was 1.4% (95% CI, 0.6-2.7%). The seroprevalence obtained for the different age groups was 0.6%, 0.7%, 1.8%, and 6.8% among 2-3, 3-4, 4-5, and ≥5-mo-old pigs. This increase in the seroprevalence was statistically significant for the 2 older groups (odds ratio [OR] 3.9-7.1, P < 0.05) in comparison with younger groups. DT at >4 IU dilution had a perfect agreement and 100% of sensitivity and specificity when compared with the MAT. Although ID Screen® had only a fair agreement (κ = 0.389) with the MAT, the McNemar test showed that the results of these tests were comparable (P = 0.29). The Human Toxo ELISA showed no agreement with MAT, ID Screen®, and DT (κ = 0.000-0.023, McNemar P < 0.05). This ELISA was lacking in specificity, accuracy, and precision; hence, we do not recommend its use for T. gondii diagnosis in pig serum.

High frequency of infection of lung cancer patients with the parasite Toxoplasma gondii

Background

Toxoplasma gondii is an intracellular protozoan parasite that can cause a wide range of clinical conditions, including miscarriage and pneumonia. The global prevalence is 30% in humans, but varies by locality (e.g. in the UK it is typically 10%). The association between lung cancer and T. gondii infection was investigated by direct detection in lung tissue samples.

Methods

Lung tissue samples were taken from patients undergoing lung resection surgery (n=72) for suspected lung cancer (infection prevalence 100% (95% CI: 93.9–100%)). All 72 participants were confirmed as having lung cancer following subsequent diagnostic tests. In addition, bronchial biopsy samples were collected from non-lung cancer healthy control subjects (n=10). Samples were tested for T. gondii using PCR amplification of T. gondii specific gene markers and T. gondii specific immunohistochemistry.

Results

All 72 lung cancer patients were infected with T. gondii (prevalence 100% (95% CI: 93.9–100%)). Of which, 95.8% (n=69) of patients showed evidence of active parasite stages. Infection prevalence in the controls (10%) was significantly lower (p<0.0001).

Conclusions

Clinicians treating lung cancer patients should be aware of the potential presence of the parasite, the potential for induction of symptomatic complications and interference with treatment success.

Toxoplasma gondii infection was found to be present in all lung tissue samples taken from 72 cancer patients (including active parasite stages in 96% of samples)http://bit.ly/2DhPPRN

The association between Toxoplasma gondii infection and postpartum blues

INTRODUCTION AND AIM

Toxoplasma gondii is an intracellular protozoan parasite infecting approximately 30% of the global human population. It has often been suggested that chronic infection with T. gondii is related to personality changes and various mental disorders including depression. It is not known whether this includes post-partum blues or depression. In this study, we test the hypothesis that there is a relationship between T. gondii infection and post-partum blues by measuring the association between infection and postpartum blues.

METHODS

A total of 475 Chinese women who have just given birth were detected serology for Toxoplasma IgG and IgM antibodies, and evaluated the degree of depression by Hamilton Depression Scale (HAMD) score. Data were analyzed by Chi-square or Fisher's Exact tests using SPSS software.

RESULTS

We found an overall Toxoplasma seroprevalence of 5.68% (27/475; 95% CI: 3.59-7.77) which was broken down into a prevalence of 6.60% (7/106; 95% CI: 1.80-11.41) in mothers with post-partum blues and 5.42% (20/369; 95% CI: 3.10-7.74) in non-affected mothers. There was no significant association between infection and post-partum blues (p = 0.64).

CONCLUSION

The results suggest that there is no relationship between T. gondii infection and postpartum blues, at least in this sample of patients from China.

Cell cycle and cleavage events during in vitro cultivation of bloodstream forms of Trypanosoma lewisi, a zoonotic pathogen

Trypanosoma (Herpetosoma) lewisi is a globally distributed rat trypanosome, currently considered as a zoonotic pathogen; however, a detailed understanding of the morphological events occurring during the cell cycle is lacking. This study aimed to investigate the cell cycle morphology and cleavage events of Trypanosoma lewisi (T. lewisi) during in vitro cultivation. By establishing in vitro cultivation of T. lewisi at 37°C, various cell morphologies and stages could be observed. We have provided a quantitative analysis of the morphological events during T. lewisi proliferation. We confirmed a generation time of 12.14 ± 0.79 hours, which is similar to that in vivo (12.21 ± 0.14 hours). We also found that there are two distinct cell cycles, with a two-way transformation connection in the developmental status of this parasite, which was contrasted with the previous model of multiple division patterns seen in T. lewisi. We quantified the timing of cell cycle phases (G1n, 0.56 U; Sn, 0.14 U; G2n, 0.16 U; M, 0.06 U; C, 0.08 U; G1k, 0.65 U; Sk, 0.10 U; G2k, 0.17 U; D, 0.03 U; A, 0.05 U) and their morphological characteristics, particularly with respect to the position of kinetoplast(s) and nucleus/nuclei. Interestingly, we found that both nuclear synthesis initiation and segregation in T. lewisi occurred prior to kinetoplast, different to the order of replication found in Trypanosoma brucei and Trypanosoma cruzi, implicating a distinct cell cycle control mechanism in T. lewisi. We characterized the morphological events during the T. lewisi cell cycle and presented evidence to support the existence of two distinct cell cycles with two-way transformation between them. These results provide insights into the differentiation and evolution of this parasite and its related species.

Genotyping of Toxoplasma gondii from pigs in Yucatan, Mexico

Toxoplasmosis is a zoonotic disease of worldwide distribution. The parasite exhibits strong geographical patterns of strain variation with contrasting high levels of diversity across South America and restricted variation across North America. Little is known about the diversity of strains in the transitional area between the two continents. Here we present data on the prevalance and diversity of Toxoplasma gondii in the Yucatan peninsula of Mexico, through a study in commercially reared pigs. A survey of 12 farms found evidence of circulating T. gondii DNA in 125 of 632 blood samples (19.8%, CI: 16.7%-23%). In addition, 46 tongue samples were collected from culled animals and 16 of these were positive for T. gondii DNA and 3 were positive in mouse bioassay. PCR-sequencing was used to generate genotyping data from blood and tissue samples. Four loci (SAG1, 2, 3 and GRA6) were reliably amplified and revealed a high diversity among Yucatan strains with evidence of recombination and novel alleles. Sequencing data from the four loci was achieved in eight samples each of which had a different genotype. The predominant allelic type was atypical, in relation to the dominant strain types (I, II, III), the number of allelic variants being 27 (I, II-III, u-1-25), 20 (I, III, u1-18), 6 (I, III, u1-4) and 11 (I, II, u1-9) for the SAG1, SAG2, SAG3 and GRA6 loci respectively. Phylogenetic analysis showed that T. gondii strains from Yucatan shared alleles with strains originating from both North and South America. Our findings are consistent with data from other regions of Central America and suggest the genetic population structure of the parasite, with significant levels of allelic variation and recombination, constitutes a reservoir from which new strains may emerge. Positive bioassay results (7.5%) indicate that consumption of undercooked pork could be a potential T. gondii infection risk to humans.

Investigation into the genetic diversity in toll-like receptors 2 and 4 in the European badger Meles meles

The Toll-like receptor (TLR) genes are a conserved family of genes central to the innate immune response to pathogen infection. They encode receptor proteins, recognise pathogen associated molecular patterns (PAMPs) and trigger initial immune responses. In some host-pathogen systems, it is reported that genetic differences, such as single nucleotide polymorphisms (SNPs), associate with disease resistance or susceptibility. Little is known about TLR gene diversity in the European badger (Meles meles). We collected DNA from UK badgers, carried out PCR amplification of the badger TLR2 gene and exon 3 of TLR4 and determined DNA sequences for individual badgers for TLR2 (n = 61) and TLR4 exon 3 (n = 59). No polymorphism was observed in TLR4. Three TLR2 amino acid haplotype variants were found. Ninety five percent of badgers were homozygous for one common haplotype (H1), the remaining three badgers had genotypes H1/H3, H1/H2 and H2/H2. By broad comparison with other species, diversity in TLR genes in badgers seems low. This could be due to a relatively localised sampling or inherent low genetic diversity. Further studies are required to assess the generality of the low observed diversity and the relevance to the immunological status of badgers.

The effect of normal human serum on the mouse trypanosome Trypanosoma musculi in vitro and in vivo

Trypanosoma musculi, a common blood flagellate found in mice, is similar in morphology and life cycle to the rat trypanosome T. lewisi. Both species belong to the subgenus Herpetosoma, and as T. lewisi has recently been shown to be a zoonotic pathogen, there is concern that T. musculi could also be potentially infective to humans. To test this hypothesis, a well-established method, the normal human serum (NHS) incubation test, was carried out which distinguishes human and non-human infective trypanosomes. We found that T. musculi could grow in 0.31% NHS in vitro, and even kept their infectivity to mice after incubation with 10% NHS for 24 h. In in vivo experiments, T. musculi were only slightly affected by NHS injection, confirming that it was less sensitive to the NHS than T. b. brucei, but more sensitive than T. lewisi. This resistance probably does not rely on a restricted uptake of ApoL-1. Due to this partial resistance, we cannot definitively confirm that T. musculi has the potential for infection to humans. As resistance is less than that of T. lewisi, our data suggest that it is unlikely to be a zoonotic pathogen although we would advise caution in the case of immunocompromised people such as AIDS and cancer patients.

Role of vertical transmission of Toxoplasma gondii in prevalence of infection

The parasite, Toxoplasma gondii, is a highly successful pathogen that infects around 30% of the global human population. Additionally, it is able to infect all warm blooded animals with high prevalence. This is surprising as it is a parasite of the cat and can only complete its full sexual cycle in that host. This review examines the important key routes of transmission: infective oocysts from the cat, ingestion of raw infected tissue and vertical transmission. The latter route of transmission has traditionally been thought to be rare. In this review, this assumption is examined and discussed in the light of the current literature. The available evidence points to the possibility that vertical transmission occurs frequently in natural populations of mice however the evidence in sheep is currently ambivalent and controversial. In humans, the situation appears as though vertical transmission may be rare although there is still much that is unexplained.

Further evidence from SSCP and ITS DNA sequencing support Trypanosoma evansi and Trypanosoma equiperdum as subspecies or even strains of Trypanosoma brucei

The subgenus Trypanozoon includes three species Trypanosoma brucei, Trypanosoma evansi and Trypanosoma equiperdum, which are morphologically identical and indistinguishable even using some molecular methods. In this study, PCR-based single strand conformation polymorphism (PCR-SSCP) was used to analyze the ribosomal DNA of the Trypanozoon species. Data indicate different patterns of ITS2 fragments between T. brucei, T. evansi and T. equiperdum by SSCP. Furthermore, analysis of total ITS sequences within these three members of the subgenus Trypanozoon showed a high degree of homology using phylogenetic analysis but were polyphyletic in haplotype networks. These data provide novel nuclear evidence to further support the notion that T. evansi and T. equiperdum should be subspecies or even strains of T. brucei.

Analysis of the mitochondrial maxicircle of Trypanosoma lewisi, a neglected human pathogen

BACKGROUND

The haemoflagellate Trypanosoma lewisi is a kinetoplastid parasite which, as it has been recently reported to cause human disease, deserves increased attention. Characteristic features of all kinetoplastid flagellates are a uniquely structured mitochondrial DNA or kinetoplast, comprised of a network of catenated DNA circles, and RNA editing of mitochondrial transcripts. The aim of this study was to describe the kinetoplast DNA of T. lewisi.

METHODS/RESULTS

In this study, purified kinetoplast DNA from T. lewisi was sequenced using high-throughput sequencing in combination with sequencing of PCR amplicons. This allowed the assembly of the T. lewisi kinetoplast maxicircle DNA, which is a homologue of the mitochondrial genome in other eukaryotes. The assembly of 23,745 bp comprises the non-coding and coding regions. Comparative analysis of the maxicircle sequence of T. lewisi with Trypanosoma cruzi, Trypanosoma rangeli, Trypanosoma brucei and Leishmania tarentolae revealed that it shares 78%, 77%, 74% and 66% sequence identity with these parasites, respectively. The high GC content in at least 9 maxicircle genes of T. lewisi (ATPase6; NADH dehydrogenase subunits ND3, ND7, ND8 and ND9; G-rich regions GR3 and GR4; cytochrome oxidase subunit COIII and ribosomal protein RPS12) implies that their products may be extensively edited. A detailed analysis of the non-coding region revealed that it contains numerous repeat motifs and palindromes.

CONCLUSIONS

We have sequenced and comprehensively annotated the kinetoplast maxicircle of T. lewisi. Our analysis reveals that T. lewisi is closely related to T. cruzi and T. brucei, and may share similar RNA editing patterns with them rather than with L. tarentolae. These findings provide novel insight into the biological features of this emerging human pathogen.

High prevalence of trypanosomes in European badgers detected using ITS-PCR

Background

Wildlife can be important sources and reservoirs for pathogens. Trypanosome infections are common in many mammalian species, and are pathogenic in some. Molecular detection tools were used to measure trypanosome prevalence in a well-studied population of wild European badgers (Meles meles).

Findings

A nested ITS-PCR system, that targeted the ribosomal RNA gene locus, has been widely used to detect pathogenic human and animal trypanosomes in domestic animals in Africa and some wildlife hosts. Samples from a long-term DEFRA funded capture-mark-recapture study of wild badgers at Woodchester Park (Gloucestershire, SW England) were investigated for trypanosome prevalence. A total of 82 badger blood samples were examined by nested ITS-PCR. Twenty-nine of the samples were found to be positive for trypanosomes giving a prevalence of 35.4 % (25.9 % - 46.2 %; 95 % CI). Infection was not found to be linked to badger condition, sex or age. Analysis of DNA sequence data showed the badgers to be infected with Trypanosoma (Megatrypanum) pestanai and phylogenetic analysis showed the Woodchester badger trypanosomes and T. pestanai to cluster in the Megatrypanum clade.

Conclusions

The results show that the ITS Nested PCR is an effective tool for diagnosing trypanosome infection in badgers and suggests that it could be widely used in wildlife species with unknown trypanosomes or mixed infections. The relatively high prevalence observed in these badgers raises the possibility that a significant proportion of UK badgers are naturally infected with trypanosomes.

Electronic supplementary material

The online version of this article (doi:10.1186/s13071-015-1088-7) contains supplementary material, which is available to authorized users.

Mycobacterium avium-intracellulare: a rare cause of subacromial bursitis

Septic subacromial bursitis is an uncommon disorder with only a few reported cases in the literature. The most common causative organism is Staphylococcus aureus. We report the case of a 61-year-old female with a septic subacromial bursitis where the causative organism was found to be Mycobacterium avium-intracellulare (MAI). The diagnosis was only made following a biopsy, and we use this case to highlight the importance of recognising the need to consider a biopsy and aspiration in atypical situations.

Toxoplasma gondii: prevalence in species and genotypes of British bats (Pipistrellus pipistrellus and P. pygmaeus)

Few studies have investigated Toxoplasma gondii infections in bat populations and none have reported its presence in protected British bat species. Using a collection of dead/euthanased bats collected from Lancashire, UK, two species of bats (Pipistrellus pipistrellus and Pipistrellus pygmaeus) were tested using a highly sensitive SAG1-PCR method specific for detection of T. gondii DNA (n=77; 71 P. pipistrellus and 6 P. pygmaeus). Whilst some potential bias may exist in the sampling strategy, an overall prevalence of 10.39% (±6.06%; 95%CI) was detected. All P. pipistrellus, were also genotyped using eleven polymorphic microsatellite loci to determine their local population structure. The programme STRUCTURE revealed that the majority of individuals (83%) were derived from one interbreeding population, and the remaining individuals (17%) had mixed genetic origins. There was no significant difference in the frequency of T. gondii infection or geographical distribution between subclusters. As all British bats are insectivorous, the routes of infection with T. gondii remain elusive. However, the locally large and panmictic gene pool suggests that intraspecies transmission could be applicable.

Toxoplasma gondii infection in the peritoneal macrophages of rats treated with glucocorticoids

It is well known that toxoplasmosis can be life threatening to immunocompromised individuals such as AIDS and organ transplantation patients. Glucocorticoids (GCs) are widely used in the clinic for the treatment of autoimmune diseases and organ transplantation resulting in acute toxoplasmosis in these patients. However, the interaction and mechanism between the development of acute toxoplasmosis and GC therapy are still unknown. The aims of this study were to investigate the infection of Toxoplasma gondii in the peritoneal macrophages of rats treated with glucocorticoids. Our results showed that the growth rate of T. gondii RH strain was significantly increased in the peritoneal macrophages of rats treated with glucocorticoids in vivo. For instance, 242 (±16) tachyzoites were found in 100 macrophages from the rats treated with methylprednisolone (MP), while only 16 (±4) tachyzoites were counted in the macrophages from the non-treated control rats 24 h after infection (P < 0.01). We also demonstrated that a significant inhibition of nitric oxide (NO) production was detected in the macrophages collected from the rats post-treated with GCs with 12.90 μM (±0.99 μM) of nitrite production from the rats treated with MP, while 30.85 μM (±1.62 μM) was found in the non-treated control rats 36 h after incubation (P < 0.01). Furthermore, glucocorticoids could significantly inhibit the expression of inducible nitric oxide synthase mRNA and its protein in the rat peritoneal macrophages. Our results strongly indicate that the decrease of NO in the rat peritoneal macrophages is closely linked to the cause of acute toxoplasmosis in the host. Additionally, there was a significant increase in the number of cysts produced by the naturally cyst forming, T. gondii Prugniaud strain with an average of 2,795 (±422) cysts of the parasite being detected in the brains of the rats treated with dexamethasone, while only 1,356 (±490) cysts were found in the non-treated control animals (P < 0.01). As rats and humans are both naturally resistant to T. gondii infection, these novel data could lead to a better understanding of the development of acute toxoplasmosis during glucocorticoid therapy in humans.