Protozoan Parasite Research Articles

Occurrence of Trypanosoma evansi Infection in Rottweiler Dog from Cauvery Delta Region of Tamil Nadu, India: A Case Report

Trypanosomes are the extraerythrocytic haemoflagellate protozoan parasites of domestic and wild animals including dogs. A male Rottweiler dog was presented with the history of anorexia, cloudy eyes and vomiting for a week. The dog was examined both physically and clinically. Blood was collected and subjected to haematological and biochemical analysis. Echocardiography of the thoracic cavity and ultrasonography of the abdominal cavity were performed. Molecular confirmation of parasite was carried out by PCR and DNA was sequenced to identify strain variations. Upon clinical examination, the dog revealed emaciation with high fever, unilateral corneal opacity, anemia, enlarged lymph nodes and distended abdomen. Echocardiography of the thoracic cavity showed ventricular hypertrophy and cardiomyopathy. Ultrasonography of the abdominal cavity showed splenomegaly and renomegaly. Haematological findings revealed decreased haemoglobin and erythrocyte count and biochemical findings revealed increased BUN and creatinine, hypoglycemia and hypoalbuminemia. Wet film and blood smear examination revealed actively motile trypanosomes and massive infection of trypanosomes, respectively. Molecular confirmation of species was carried out by amplification of 227 bp partial VSG gene of Trypanososma evansi, subsequently sequenced and phylogenitically analysed. The infected dog was treated intramuscularly with diminazene aceturate @ 3.5 mg /kg b.wt along with the supportive therapy. The study described the occurrence and diagnosis of trypanosomosis in dog. Early diagnosis and timely treatment is the most reliable way to safeguard the companion animals. It is the first report on trypanosomosis in dog from Cauvery delta region of Tamil Nadu, India.

Prevalence and determination of species distribution of Eimeria in poultry from the Swabi district, Pakistan

Background and Aim: Coccidiosis, caused by protozoan parasites of the genus Eimeria, is a significant concern in poultry farming, leading to substantial economic losses worldwide. In Pakistan, poultry is a major component of the agricultural sector, with both broiler and egg-laying chickens playing crucial roles in meeting the country’s protein needs. Despite the importance of the poultry industry, there is limited data on prevalence and species distribution of Eimeria in different types of chickens in District Swabi, Khyber Pakhtunkhwa, Pakistan. This study aims to estimate the prevalence and determine the distribution of Eimeria species in broiler and egg-laying chickens in this region. Materials and Methods: Nine hundred fecal samples were collected from broiler (380) and egg-laying domestic chickens (520) in District Swabi, Pakistan. Microscopic analysis was used to identify Eimeria parasites in all samples. After microscopic examination for positive identification, Eimeria species were determined using polymerase chain reaction (PCR) assays. Results: Microscopic examination identified Eimeria oocysts in 44.4% (400/900) of the samples. Eimeria parasite infection significantly varied based on chicken type, age, and gender (p < 0.05). The study found that broiler chickens (52.63%, 235/450), young chickens (4–6 weeks) (55.5%, 285/500), and females (52.2%, 200/380) were more infected with Eimeria spp. than egg-laying domestic chickens (38.5%, 200/520), adults (above 6 weeks) (28.8%), and males (36.7%, 165/450). PCR indicated a distribution rate of 42.5% (170/400) Eimeria tenella, 26.25% (105/400) Eimeria acervulina, 20% (80/400) Eimeria maxima, and 11.25% (45/400) Eimeria mitis. None of Eimeria necatrix, Eimeria brunetti, or Eimeria praecox was found in the study. Conclusion: This study underlines the essential requirement for targeted interventions due to the prevalence and predominance of E. tenella among identified Eimeria species. Future research should focus on refined sampling strategies and investigate the clinical significance of these parasites for effective disease management in the local poultry industry. Keywords: coccidiosis, domestic chickens, Eimeria species, microscopic and molecular identification, Pakistan, prevalence.

Toxicological Impact of Malachite Green on Freshwater Fish: A Comprehensive Review

Triarylmethane dyes, such as malachite green, are widely used in the culinary, pharmaceutical, textile, and other sectors for a variety of purposes, including aquaculture parasiticides. It controls fungal attacks, protozoan infections, and some other diseases caused by helminthes on a wide range of fish and aquatic organisms. Nonetheless, the dye's purportedly harmful effects have raised a lot more questions about its usage. The exposure time, temperature and the concentration all raise the dye's toxicity. It has been linked to chromosomal breaks, mutagenesis, cancer,teratogeneity, and pulmonary toxicity. Multi-organ tissue damage is one of malachite green's histopathological consequences. Fish exposed to malachite green have notable changes in their blood's biochemical characteristics. Malachite green and its reduced form, leucomalachite green, have been found in a variety of tissues, including eggs and fries, as well as serum, liver, kidney, and muscles. Despite a wealth of information about malachite green's toxicity, several developing countries still utilize it as a parasiticide in aquaculture and other industries. Hence, there is a significant likelihood of malachite green disposition in the food chain. To counteract its toxicological effect, it is crucial to identify a substitute because of its high toxicity.

Prevalence and subtyping of Blastocystis sp. in ruminants in Southwestern, Iran.

Blastocystis is the most common gastrointestinal protozoan parasite of humans and many vertebrates. This study was carried out to investigate the prevalence and determination subtype (ST) of Blastocystis in domestic ruminants of Shahrekord County, southwestern Iran. In this descriptive cross-sectional study, 330 ruminant fecal samples (107 cows, 115 sheep, and 108 goats) were evaluated by parasitological methods (direct wet mount microscopic examination and formalin-ether concentration), Giemsa staining, In vitro xenic culture (The modified Dobell and Laidlaw culture method), polymerase chain reaction, and sequencing from 2018 to 2019, then data were analyzed using SPSS software version 21. The overall Blastocystis positive in ruminants was 14.2% and the frequency of Blastocystis sp. in cattle, sheep, and goats were 0.93%, 17.4%, and 24.1% respectively. Molecular diagnosis techniques revealed that ruminants were infected with four STs (genotypes) of Blastocystis including ST5(21.3%), ST7(2.1%), ST10(17.1%) and ST14(57.4%). Also, the STs identified in cows were ST10, and the observed STs in sheep were ST5 (40%), ST7 (3%), ST10 (5%), ST14 (45%), and one unknown subspecies. Goats were infected by ST5 (7.7%), ST10 (23.1%), and ST14 (69.2%). In this study, ST14 was identified as the most common subtype of Blastocystis sp. that was not common between humans and livestock, meanwhile, ST5 and ST7 are common between humans and animals accounted 21.3% and 2.1% of the positive cases, respectively, and reinforces the hypothesis that ruminants are reservoirs of blastocystosis in humans.

Identification and molecular characterization of a novel Babesia orientalis rhoptry neck protein 4 (BoRON4).

Babesia orientalis, a protozoan parasite transmitted by the tick Rhipicephalus haemaphysaloides, holds significant economic importance along the Yangtze River. Key factors in the host invasion process include rhoptry neck proteins (RON2, RON4, and RON5) and apical membrane antigen 1 (AMA1). However, the intricacies of the interaction between AMA1 and RONs remain incompletely elucidated in B. orientalis. To better understand these crucial invasion components, the RON4 gene of B. orientalis (BoRON4) was cloned and sequenced. RON4 is 3468 base pairs long, encodes 1155 amino acids, and has a predicted molecular weight of 130kDa. Bioinformatics analysis revealed a unique region (amino acid residues 109-452) in BoRON4, which demonstrates higher sensitivity to epitope activity. The BoRON4 gene was strategically truncated, amplified, and cloned into the pGEX-6p-1 vector for fusion expression. We successfully used the mouse polyclonal antibody to identify native BoRON4 in B. orientalis lysates. Furthermore, the corresponding BoRON4 protein band was detected in the water buffalo serum infected with B. orientalis, while no such band was observed in the control. Additionally, I-TASSER and Discovery Studio software were used to predict the tertiary structures of BoRON4 and its ligands, CH-PKA and CH-complex. These ligands can serve as lead compounds for the development of anti-babesiosis drugs. In conclusion, BoRON4 emerges as a promising candidate antigen for distinguishing water buffalo infected with B. orientalis from their normal counterparts. This study positions BoRON4 as a potential diagnostic antigen for babesiosis in water buffalo, contributing valuable insights to the field of parasitology.

Phytochemical Analysis and In Vivo Antimalarial Activities of Ethyl Acetate Fraction of Spilanthes filicaulis on Mice Subjected to Plasmodium berghei.

Background and Objectives: Malaria airs a life-threatening risk in Tropical African countries, stemming from infection by Plasmodium species. This region is richly endowed by nature with a wealth of diverse and largely unexplored plants that hold the potential for managing this protozoan parasite. The currently accessible over-the-counter drugs for disease management often present affordability challenges for the average person, exacerbated by the parasite's increasing resistance to them. This study investigated the phytoconstituents present in the ethyl acetate fraction of Spilanthes filicaulis (EFSF) and explored the antimalarial effects of EFSF on mice infected with Plasmodium berghei. Methods: Standard methods and gas chromatography-mass spectrometry (GC-MS) were used to identify phytoconstituents. Chloroquine phosphate-sensitive P. berghei (NK-65) was intraperitoneally inoculated into Swiss mice. The invivo antimalarial activity of EFSF was assessed at dose levels of 250, 500, and 750 mg/kg, using 4-day suppressive and curative antimalarial models. Parameters evaluated in the inoculated mice included rectal temperature (RT), body weight (BW), packed cell volume (PCV), level of parasitemia, and mean survival time (MST). Results: Steroids, alkaloids, flavonoids, tannins, saponins, terpenoids, and cardiac glycosides were the identified phytochemicals present in EFSF, and GC-MS alongside reveals the presence of 20 bioactive compounds predominantly fatty acids and alcohol esters. Significant prevention of reductions in RT, BW, and PCV was observed in the EFSF-treated groups dose dependently relative to the untreated group. In addition, EFSF-treated groups significantly (p < 0.05) suppressed parasitemia and exhibited chemosuppression of 79.46% and 77.38% in 4-day suppressive, whereas suppression of 59.74% and 58.66% in curative treatment, respectively, at 500 and 750 mg/kg thus consequently extending the MST of infected treated mice compared with the untreated group. Interpretation and Conclusion: Put together, the EFSF exhibited enhanced antimalarial efficacy against mice infected with P. berghei thus affirming that plants still maintain lead way as a potential source of novel antimalarial remedies.

E-pharmacophore and deep learning based high throughput virtual screening for identification of CDPK1 inhibitors of Cryptosporidium parvum

Cryptosporidiosis, a prevalent gastrointestinal illness worldwide, is caused by the protozoan parasite Cryptosporidium parvum. Calcium-dependent protein kinase 1 (CpCDPK1), crucial for the parasite's life cycle, serves as a promising drug target due to its role in regulating invasion and egress from host cells. While potent Pyrazolopyrimidine analogs have been identified as candidate hit molecules, they exhibit limitations in inhibiting Cryptosporidium growth in cell culture, prompting exploration of alternative scaffolds. Leveraging the most potent compound, RM-1–95, co-crystallized with CpCDPK1, an E-pharmacophore model was generated and validated alongside a deep learning model trained on known CpCDPK1 compounds. These models facilitated screening Enamine's 2 million HTS compound library for novel CpCDPK1 inhibitors. Subsequent hierarchical docking prioritized hits, with final selections subjected to Quantum polarized docking for accurate ranking. Results from docking studies and MD simulations highlighted similarities in interactions between the cocrystallized ligand RM-1–95 and identified hit molecules, indicating comparable inhibitory potential against CpCDPK1. Furthermore, assessing metabolic stability through Cytochrome 450 site of metabolism prediction offered crucial insights for drug design, optimization, and regulatory approval processes.

Electrochemical Detection of Ornidazole Using a WS2 /CNFs Sensor

In recent decades, pharmaceutical compounds, notably antibiotics, have played a significant role in preventing infections and illnesses that affect both animals and humans. However, the utilization of antibiotics in the pharmaceutical industry, farming and other applications has led to environmental concerns 1. Nitroimidazole, an oral drug, is commonly used as an antibacterial agent. An example of a drug in nitroimidazole family is ornidazole (ORZ, (1-(3-chloro-2-hydroxy) propyl-2-methyl- 5-nitroimidazole)), and it is used in treating and preventing various infections, including genitourinary tract, intestinal and protozoal infections. Ornidazole has a heterocyclic structure comprising of an imidazole-based nucleus with a nitro group (NO2)1 and have become a well-established group of antiprotozoan and antibacterial agents. Beyond immediate therapeutic benefits, ornidazole could persist in the environment, posing long-term risks such as potential mutagenic and carcinogenic effects. Moreover, excessive antibiotics such as antibiotics such as ORZ in the environment can lead to the development of antibiotic-resistant pathogens. The widespread use of antibiotics in medical treatment and agriculture contributes to water contamination as these substances find their way into water bodies through various pathways. There is escalating concern over pharmaceutical contaminants therefore highlighting the importance of monitoring and regulating antibiotic levels in the environment. This requires significant research and electrochemical methods portray possibilities for drug detection due to their advantages of high sensitivity, low cost, simplicity and selectivity.Recent developments have brought to the spotlight, two dimensional materials as promising candidates for environmental sensing, due to their unique characteristics and wide-ranging applications. In particular, Transition-metal dichalcogenides (TMDs), comprising of MX2 , with M a transition metal atom e.g. Mo, W etc. and X, a chalcogen atom S, Se or Te 2, have garnered attention for their exceptional features. These materials consist of M atoms closely sandwiched between two layers of X atoms, linked by strong in-plane covalent bonds, and further bonded by weak van der Waals forces between the layers. Among the TMDs, tungsten disulfide (WS2) exhibits exceptional properties, including high electronic conductivity, good chemical stability, large capacitance and surface area. Those inherent properties of WS2, make it a suitable material for various applications, especially in environmental sensing 3.This study explores the detection of ornidazole using a composite material of WS2 with functionalized carbon nanofibers (CNFs). Carbon nanofibers (CNFs) are featured for their equally outstanding electrical and mechanical properties that make them promising candidates for sensor applications. CNFs also provide a unique platform for developing sensitive and selective sensors. Their versatility allows for functionalization, enhancing chemical properties and enabling tailored interactions with target analytes. The study emphasizes how CNFs, with their notable properties, complement WS2 in the creation of innovative sensor structures to create composites with improved sensing capabilities for drug compounds. In this study, the WS2/CNF nanocomposite was synthesized using hydrothermal synthesis and subsequently dispersed in ethanol and water, and then drop casted on a glassy carbon electrode. Prior to synthesis, the CNFs were functionalized using a low cost, environmental friendly method, thus enhancing their chemical properties. Herein, the resulting WS2/CNF composite demonstrates its efficacy in detecting ornidazole, and shows excellent potential for the development of electrochemical sensors. Overall, the work here aims to highlight the ongoing progress of electrochemical sensor technology, emphasizing its crucial role in addressing the growing challenges associated with drug contamination in the environment.References(1) Ettadili, F. E.; Azriouil, M.; Matrouf, M.; Tahiri Alaoui, O.; Laghrib, F.; Farahi, A.; Bakasse, M.; Saqrane, S.; Lahrich, S.; El Mhammedi, M. A. Materials Framework Based Bio/Sensors for the Detection of Ornidazole and Metronidazole Antibiotics in Environment and Foodstuffs. Inorganic Chemistry Communications. 2022. https://doi.org/10.1016/j.inoche.2022.109416.(2) Manzeli, S.; Ovchinnikov, D.; Pasquier, D.; Yazyev, O. V.; Kis, A. 2D Transition Metal Dichalcogenides. Nature Reviews Materials. 2017. https://doi.org/10.1038/natrevmats.2017.33.(3) Santos, B. G.; Gonçalves, J. M.; Rocha, D. P.; Higino, G. S.; Yadav, T. P.; Pedrotti, J. J.; Ajayan, P. M.; Angnes, L. Electrochemical Sensor for Isoniazid Detection by Using a WS2/CNTs Nanocomposite. Sensors and Actuators Reports 2022, 4. https://doi.org/10.1016/j.snr.2021.100073.

Cell Death of P. vivax Blood Stages Occurs in Absence of Classical Apoptotic Events and Induces Eryptosis of Parasitized Host Cells.

Elucidation of pathways regulating parasite cell death is believed to contribute to identification of novel therapeutic targets for protozoan diseases, and in this context, apoptosis-like cell death has been reported in different groups of protozoa, in which metacaspases seem to play a role. In the genus Plasmodium, apoptotic markers have been detected in P. falciparum and P. berghei, and no study focusing on P. vivax cell death has been reported so far. In the present study, we investigated the susceptibility of P. vivax to undergo apoptotic cell death after incubating mature trophozoites with the classical apoptosis inducer staurosporine. As assessed by flow cytometry assays, staurosporine inhibited parasite intraerythrocytic development, which was accompanied by a decrease in cell viability, evidenced by reduced plasmodial mitochondrial activity. However, typical signs of apoptosis, such as DNA fragmentation, chromatin condensation, and nuclear segregation, were not detected in the parasites induced to cell death, and no significant alteration in metacaspase gene expression (PvMCA1) was observed under cell death stimulus. Interestingly, dying parasites positively modulated cell death (eryptosis) of host erythrocytes, which was marked by externalization of phosphatidylserine and cell shrinkage. Our study shows for the time that P. vivax blood stages may not be susceptible to apoptosis-like processes, while they could trigger eryptosis of parasitized cells by undergoing cell death. Further studies are required to elucidate the cellular machinery involved in cell death of P. vivax parasites as well as in the modulation of host cell death.

Tritrichomonas foetus testing in bulls.

To provide a video tutorial on how to perform preputial scraping for the testing of Tritrichomonas foetus in bulls. Postpubertal bulls. A preputial scraping device is inserted in the prepuce, and back-and-forth scraping movements are made to collect smegma and T foetus organisms. The sample is placed in an appropriate media and prepared for shipment to the diagnostic laboratory. Preputial sampling is an effective method for diagnosing T foetus in infected bulls. Bulls are the primary carriers of T foetus, a protozoan parasite responsible for bovine trichomoniasis. By sampling and testing bulls, veterinarians can identify infected animals and implement control measures to prevent the spread of the disease within herds. Trichomoniasis can lead to significant reproductive problems in cattle, including infertility, embryonic death, and abortions. Sampling bulls allows for the detection of infection, enabling prompt intervention to protect the reproductive health of the entire herd. Trichomoniasis outbreaks can result in substantial economic losses for cattle producers due to reduced conception rates, increased calving intervals, and decreased calf crops. Sampling bulls helps to mitigate these losses by identifying and removing infected animals from the breeding pool, thereby minimizing the spread of the disease and its associated reproductive inefficiencies. In many regions, T foetus testing in bulls is a regulatory requirement for cattle movement and trade. Sampling bulls and obtaining negative test results are often necessary for obtaining health certificates and complying with interstate or international movement regulations.

Abundance and Parasitic Load of Housefly (Musca Domestica) in Amansea Area of Anambra State, Nigeria

Houseflies (Musca domestica) are major transmitters of pathogenic organisms to humans worldwide. This study was carried out to determine the relative abundance of housefly and its parasitic load in four different sites in the Amansea area of Anambra state, Nigeria. The housefly samples were collected with the aid of fly trap and sweep net and analyzed using sedimentation methods. Data obtained was calculated and expressed as simple percentages while chi-square was used to test for differences in prevalence rates of parasites in the study areas. Out of the 259 houseflies examined, 74 were infested with a prevalence of 28.57%. Houseflies were more abundant in the abattoir 92(35.52) followed by market area 71(27.41%), refuse dump sites (19.69%) while holy family hostels recorded the lowest abundance (17.37) (P=0.000). Houseflies infested with parasites were mostly found in holy family hostel 31(68.89) while the market area had the least infested house flies 5(7.04%). Two protozoan parasites (Entamoeba histolytica and Entamoeba coli) and two nematodes (Strongyloides stercoralis and Ascaris lumbricoides) were the parasites seen from the microscopic examination of samples. E. histolytica (7.61%) and E. coli (5.43%) were the parasites seen in Abattoir while S. stercoralis (7.04%) was the only parasite in the market area. E. histolytica (17.78%) and A. lumbricoides (51.11%) were seen in holy family hostel while E. coli (11.76%), S. stercoralis (7.84%) and A. lumbricoides (31.37%) were the parasites recovered from the houseflies in the Refuse dump site. The infestation of houseflies in the area is a threat to human health due to their ability to act as mechanical vectors for transmission of infectious pathogens. Hence, proper disposal and prompt removal of waste by environmental officers should be prioritized in the area as well as mass education of the public on the health implications of poor hygiene and poor sanitary practices.

Endoparasites of rabbits and hares.

Nematode, cestode, protozoan, microsporidian, and pentastomid parasites affect domesticated and wild rabbits, hares, and jackrabbits of the genera Brachylagus, Lepus, Oryctolagus, Pentalagus, and Sylvilagus. Some endoparasite infections are of limited or no significance, whereas others have potentially profound consequences. Accurate identification of endoparasites of rabbits, hares, and jackrabbits is an important facet of the work of veterinary pathologists engaged in lagomorph pathology. Here I review endoparasites from the pathologist's perspective, focusing on pathogenesis, lesions, and implications of infection. Stomach nematodes Graphidium strigosum and Obeliscoides cuniculi are infrequently pathogenic but may cause gastritis and gastric mucosal thickening. Nematodes Passalurus ambiguus, Protostrongylus spp., Trichostrongylus spp., and Trichuris spp. are rarely associated with disease. Adult Capillaria hepatica (syn. Calodium hepaticum) nematodes and non-embryonated eggs cause granulomatous hepatitis in wild Oryctolagus cuniculus and Lepus europaeus, resulting in multifocal, off-white, hepatic lesions, which may be misdiagnosed as hepatic eimeriosis. When the rabbit is an intermediate host for carnivore cestodes, the space-occupying effects of Cysticercus pisiformis and Coenurus serialis may have pathologic consequences. Eimeria stiedai is a major cause of white-spotted liver in O. cuniculus, particularly in juveniles. Enteric coccidiosis is a noteworthy cause of unthriftiness in young animals, and frequently manifests as diarrhea with grossly appreciable multifocal off-white intestinal lesions. O. cuniculus is the natural host for the zoonotic microsporidian Encephalitozoon cuniculi. Infection may be acute and focused mainly on the kidneys, or it may follow a chronic disease course, frequently with neurologic lesions. A latent carrier status may also develop.

Visceral Leishmaniasis with Renal Involvement: A Case Report

Visceral leishmaniasis (VL) is widespread in tropical and temperate region. It is caused by the protozoan parasite leishmania species and is transmitted through the bite of infected female sandflies. It manifests as pancytopenia, hepatosplenomegaly and fever. Here, we present a case of 20-year-old male presented with difficulty in swallowing for 2 months, abdominal distention for 30 days and shortness of breath for 20 days along with progressive renal impairment. Clinical examination revealed hepatosplenomegaly and laboratory investigations confirmed pancytopenia, nephrotic range proteinuria, hematuria and hypocomplementemia. Bone marrow aspiration and biopsy was performed which showed leishmania donovani (LD) bodies. It’suncommon presentation makes it challenging for physicians as well as pathologist to make a timely diagnosis.

Printing amphotericin B on microneedles using matrix-assisted pulsed laser evaporation.

Transdermal delivery of amphotericin B, a pharmacological agent with activity against fungi and parasitic protozoa, is a challenge since amphotericin B exhibits poor solubility in aqueous solutions at physiologic pH values. In this study, we have used a laser-based printing approach known as matrix-assisted pulsed laser evaporation to print amphotericin B on the surfaces of polyglycolic acid microneedles that were prepared using a combination of injection molding and drawing lithography. In a modified agar disk diffusion assay, the amphotericin B-loaded microneedles showed concentration-dependent activity against the yeast Candida albicans. The results of this study suggest that matrix-assisted pulsed laser evaporation may be used to print amphotericin B and other drugs that have complex solubility issues on the surfaces of microneedles.

The clinical, hematological, and biochemical profiles of patients with complications due to Plasmodium vivax malaria: A case series

Malaria, a protozoal infection caused by the six species of the genus Plasmodium, is one of the most important diseases known to humankind, with most infections caused by either of the two species – Plasmodium vivax and Plasmodium falciparum. Previously, it was held that falciparum malaria was responsible for causing severe, life-threatening disease, with vivax malaria causing mild or uncomplicated infections. In this case series, the clinical, hematological, and biochemical profiles of eight patients with features of complications due to P. vivax malaria, along with their clinical course, response to treatment, and clinical outcomes have been described. Among these, the most common clinical features were fever, headache, and myalgias. Five patients had altered mental status, two were prostrated, two were hypotensive, and one had recurrent generalized seizures. Three patients had pancytopenia, two had both anemia and thrombocytopenia, and one had evidence of disseminated intravascular coagulation. Six patients had clinical jaundice, four had elevated transaminases, and four had acute kidney injury. All cases showed excellent response to anti-malarial therapy. Hence, this case series revealed that P. vivax is capable of causing severe, life-threatening organ dysfunction akin to those seen in P. falciparum malaria and that early diagnosis and treatment initiation are associated with positive patient end outcomes.

Toxoplasma infection induces an aged neutrophil population in the CNS that is associated with neuronal protection

BackgroundInfection with the protozoan parasite Toxoplasma gondii leads to the formation of lifelong cysts in neurons that can have devastating consequences in the immunocompromised. In the immunocompetent individual, anti-parasitic effector mechanisms and a balanced immune response characterized by pro- and anti-inflammatory cytokine production establishes an asymptomatic infection that rarely leads to neurological symptoms. Several mechanisms are known to play a role in this successful immune response in the brain including T cell production of IFNγ and IL-10 and the involvement of CNS resident cells. This limitation of clinical neuropathology during chronic infection suggests a balance between immune response and neuroprotective mechanisms that collectively prevent clinical manifestations of disease. However, how these two vital mechanisms of protection interact during chronic Toxoplasma infection remains poorly understood.Main textThis study demonstrates a previously undescribed connection between innate neutrophils found chronically in the brain, termed “chronic brain neutrophils” (CBNeuts), and neuroprotective mechanisms during Toxoplasma infection. Lack of CBNeuts during chronic infection, accomplished via systemic neutrophil depletion, led to enhanced infection and deleterious effects on neuronal regeneration and repair mechanisms in the brain. Phenotypic and transcriptomic analysis of CBNeuts identified them as distinct from peripheral neutrophils and revealed two main subsets of CBNeuts that display heterogeneity towards both classical effector and neuroprotective functions in an age-dependent manner. Further phenotypic profiling defined expression of the neuroprotective molecules NRG-1 andErbB4 by these cells, and the importance of this signaling pathway during chronic infection was demonstrated via NRG-1 treatment studies.ConclusionsIn conclusion, this work identifies CBNeuts as a heterogenous population geared towards both classical immune responses and neuroprotection during chronic Toxoplasma infection and provides the foundation for future mechanistic studies of these cells.

The 26 S proteasome in Entamoeba histolytica: divergence of the substrate binding pockets from host proteasomes

ObjectiveProteasomes are conserved proteases crucial for proteostasis in eukaryotes and are promising drug targets for protozoan parasites. Yet, the proteasomes of Entamoeba histolytica remain understudied. The study’s objective was to analyse the differences in the substrate binding pockets of amoeba proteasomes from those of host, and computational modelling of β5 catalytic subunit, with the goal of finding selective inhibitors.ResultsComparative sequence analysis revealed differences in substrate binding sites of E. histolytica proteasomes, especially in the S1 and S3 pockets of the catalytic beta subunits, implying differences in substrate preference and susceptibility to inhibitors from host proteasomes. This was strongly supported by significantly lower sensitivity to MG132 mediated inhibition of amoebic proteasome β5 subunit’s chymotryptic activity compared to human proteasomes, also reflected in lower sensitivity of E. histolytica to MG132 for inhibition of proliferation. Computational models of β4 and β5 subunits, and a docked β4-β5 model revealed a binding pocket between β4-β5, similar to that of Leishmania tarentolae. Selective inhibitors for visceral leishmaniasis, LXE408 and compound 8, docked well to this pocket. This functional and sequence-based analysis predicts differences between amoebic and host proteasomes that can be utilized to develop rationally designed, selective inhibitors against E. histolytica.

Prevalence and genotype analysis of Cryptosporidium and Giardia duodenalis from shelter dogs in South Korea

Cryptosporidium and Giardia duodenalis are common gastrointestinal protozoan parasites that cause diarrhea in humans and animals. Although dogs in animal shelters in South Korea can be reintroduced into human society as companions, no continuous investigations have been conducted on the prevalence and genetic characteristics of the protozoan parasites. In the present study, 34 5 fecal samples from dogs were obtained from animal shelters in six provinces between January and December 2022. The prevalence of Cryptosporidium and G. duodenalis were molecularly identified at the 18S rRNA gene. Cryptosporidium canis isolates were subtyped at the gp60 locus, and G. duodenalis assemblages were identified at the tpi, bg and gdh loci. Overall, 6.67% of the fecal samples tested positive for Cryptosporidium spp. and two species were identified: C. canis (5.51%) and Cryptosporidium parvum (1.16%). Significant regional differences in prevalence were identified for C. canis. Subtyping analysis of C. canis isolates revealed a predominance of the subtype families XXa and XXE over XXb, and XXc. G. duodenalis was detected in 17.68% of the samples, and significant regional differences were identified; its prevalence was also significantly highest in diarrhoeic animals. Molecular characterization of G. duodenalis reveal that most isolates belonged to the canine-specific assemblages C and D. The present results can contribute to further insights into the prevalence and genotypes of Cryptosporidium and G. duodenalis in shelter dogs in South Korea.

Interplay between DOT1L and HDAC1 regulates Leishmania donovani infection in human THP-1 cells

Leishmania donovani, a protozoan parasite, causes visceral leishmaniasis. The parasite modifies the global gene expressions of the host genome, facilitating its survival within the host. Thus, the host epigenetic modulators play important roles in host-pathogen interaction and host epigenetic modification in response to infection. Previously, we had reported that the host epigenetic modulator, histone deacetylase 1 (HDAC1) expression was upregulated on Leishmania donovani infection. This upregulation led to the repression of host defensin genes in response to the infection. In this paper, we have investigated the interplay between the host DOT1L, a histone methyltransferase, and HDAC1 in response to Leishmania donovani infection. We show that the expression of DOT1L is upregulated both at transcript and protein level following infection leading to increase in H3K79me, H3K79me2, and H3K79me3 levels. ChIP experiments showed that DOT1L regulated the expression of HDAC1. Downregulation of DOT1L using siRNA resulted in decreased expression of HDAC1 and increased transcription of defensin genes and thereby, lower parasite load. In turn, HDAC1 regulates the expression of DOT1L on Leishmania donovani infection as downregulation of HDAC1 using siRNA led to reduced expression of DOT1L. Thus, during Leishmania donovani infection, an interplay between DOT1L and HDAC1 regulates the expression of these two histone modifiers leading to downregulation of defensin gene expression.

Structural insights into trypanosomatid Mnk kinase orthologues (kMnks) suggest altered mechanism in the kinase domain

Mitogen-activated protein kinase (MAPK) interacting protein kinases (Mnk1 and Mnk2) mediated phosphorylation of the eukaryotic initiation factor eIF4E is an important translation initiation control, in Mnk-mediated oncogenic activity and other disease conditions. Thus, Mnk kinases are an important target for therapy. Trypanosomatids are a class of kinetoplastids, some of which are protozoan parasites and cause diseases in humans. While protein translation initiation is well understood in eukaryotes and prokaryotes, there is a lack of sufficient structural information of this process in trypanosomatids. Here, we report that trypanosomatids have one orthologue of Mnk kinase with low overall sequence homology but high homology in the kinase domain and an additional C-terminal domain containing putative calmodulin binding site(s). We show that while many of the domains and motifs are conserved, homology modeling/structure prediction, docking analysis and molecular dynamics simulation studies suggest that trypanosomatid kMnk kinases, kinase domains are present in DFG-in conformation as opposed to the auto-inhibited DFD-out conformation of un-phosphorylated human Mnk1. Furthermore, we observed that several regulatory features are different in trypanosomatid kMnk kinases. Our study indicates that mechanism and regulation in the kinase domain of trypanosomatid kMnks are likely to be altered, and that they can be important drug targets.