Protozoan Parasite Research Articles

Leishmania donovani Modulates Macrophage Lipidome During Infection

ABSTRACTObligate intracellular protozoan parasite, Leishmania donovani, causative agent of visceral leishmaniasis, led to impaired macrophage functions. It is well documented that many of these changes were induced by parasite‐mediated reduction in macrophage cholesterol content. Leishmania‐mediated alteration in the other lipids has not been explored in detail yet. Here, we found that the expression of key cholesterol biosynthetic genes and total cellular cholesterol were reduced during L. donovani infection. Further, we have also identified that this reduction in the cholesterol led to increased membrane fluidity and inhibition of antigen‐presenting potential of macrophages. In addition to this, we studied the relative changes in different lipids in THP‐1‐derived macrophages during L. donovani infection through liquid chromatography‐mass spectrometry. We found that Sphingomyelin (16:0) and ceramide (20:1, 26:0 and 26:1) were significantly reduced in infected macrophages. We further observed that the majority of different sub‐classes of phospholipids were downregulated significantly. Overall ratio of phosphatidylcholine versus phosphotidylethanolamine was decreased which indicated the compensatory mechanism of cell in response to cholesterol reduction. The observed Leishmania‐mediated alteration in macrophage‐lipidome provided the novel insights into mechanism of host‐pathogen interactions.

Unveiling the mechanism of hesperidin-induced LdTopI-mediated cell death pathway in protozoan parasite Leishmania donovani

Unicellular protozoan parasite Leishmania donovani is the causative agent for visceral leishmaniasis (VL) or Kala-azar, a neglected fatal parasitic disease. The conventional treatment of VL consists of therapeutic agents having several shortcomings such as toxicity, high cost, efficacy variance and increased drug resistance. Therefore, there is a desperate need to develop an effective treatment against the parasite. Previous reports suggested that flavonoids can inhibit the enzyme Leishmania donovani DNA topoisomerase I (LdTopILS). Therefore, for the first time in this present study, we divulge HSP (one of the natural sources of flavonoids), as a potent natural antileishmanial compound with efficacy in BALB/c mice at 20 mg/kg of body weight, inhibits LdTopILS at 97 % of its activity at 160 μM in preincubation condition (competitively). It binds with free enzyme and does not allow it to bind with the substrate DNA. Moreover, HSP does not stabilize DNA-topoisomerase I cleavable complex. Thus, HSP acts a catalytic topoisomerase I inhibitor, which inhibits complete activity by binding with Lys269 and Thr411 of large subunit of the enzyme. On the other hand, HSP induces the topo I-mediated programmed cell death process by the formation of cellular reactive oxygen species, resulting in depolarization of mitochondrial membrane potential, followed by fragmentation of nuclear DNA. Therefore, the present study illuminates a natural flavonoid that in future might be a promising lead for the treatment of VL.

Molecular survey of Toxoplasma gondii B1 gene in pigs from various localities in Korea.

Toxoplasma gondii, a common protozoan parasite, poses significant public health risks due to its potential to cause toxoplasmosis in humans and can be contracted from pigs, which are considered its critical intermediate host. The aim of this study is to evaluate the prevalence of T. gondii in slaughtered pigs for human consumption, emphasizing the zoonotic implications and the need for improved biosecurity and monitoring practices in pig farming. A total of 1,526 pig samples (1,051 whole blood samples and 384 lung tissue samples from the local slaughterhouse and 91 aborted fetus samples from local farms) were collected throughout the whole country of Korea in 2020. Among them, 6 (0.4%) were found to be infected with T. gondii by nested PCR. When compared by sample type, the prevalence of T. gondii was significantly higher in the aborted fetus samples (2.2%, 2/91) than in the blood (0.3%, 3/1,051) and lung tissue samples (0.3%, 1/384). The B1 gene sequence of T. gondii was similar (97.9-99.8%) to that of the other T. gondii isolates. This study represents the first molecular genotyping survey of T. gondii in the lung tissue of fattening pigs and aborted fetuses in Korea. Our findings indicated the importance of adopting preventive measures including the implementation of rigorous farm hygiene protocols and the promotion of public awareness about the risks of consuming undercooked pork. By addressing the gaps in current control strategies and encouraging the One Health approach, this study contributes to the development of more effective strategies to mitigate the transmission of T. gondii from pigs to humans, ultimately safeguarding public health.

Characterization of Entamoeba fatty acid elongases; validation as targets and provision of promising leads for new drugs against amebiasis.

Entamoeba histolytica is a protozoan parasite belonging to the phylum Amoebozoa that causes amebiasis, a global public health problem. E. histolytica alternates its form between a proliferative trophozoite and a dormant cyst. Trophozoite proliferation is closely associated with amebiasis symptoms and pathogenesis whereas cysts transmit the disease. Drugs are available for clinical use; however, they have issues of adverse effects and dual targeting of disease symptoms and transmission remains to be improved. Development of new drugs is therefore urgently needed. An untargeted lipidomics analysis recently revealed structural uniqueness of the Entamoeba lipidome at different stages of the parasite's life cycle involving very long (26-30 carbons) and/or medium (8-12 carbons) acyl chains linked to glycerophospholipids and sphingolipids. Here, we investigated the physiology of this unique acyl chain diversity in Entamoeba, a non-photosynthetic protist. We characterized E. histolytica fatty acid elongases (EhFAEs), which are typically components of the fatty acid elongation cycle of photosynthetic protists and plants. An approach combining genetics and lipidomics revealed that EhFAEs are involved in the production of medium and very long acyl chains in E. histolytica. This approach also showed that the K3 group herbicides, flufenacet, cafenstrole, and fenoxasulfone, inhibited the production of very long acyl chains, thereby impairing Entamoeba trophozoite proliferation and cyst formation. Importantly, none of these three compounds showed toxicity to a human cell line; therefore, EhFAEs are reasonable targets for developing new anti-amebiasis drugs and these compounds are promising leads for such drugs. Interestingly, in the Amoebazoan lineage, gain and loss of the genes encoding two different types of fatty acid elongase have occurred during evolution, which may be relevant to parasite adaptation. Acyl chain diversity in lipids is therefore a unique and indispensable feature for parasitic adaptation of Entamoeba.

CysLT receptor-mediated NOX2 activation is required for IL-8 production in HMC-1 cells induced by Trichomonas vaginalis-derived secretory products.

Trichomoniasis is caused by a sexually transmitted flagellate protozoan parasite Trichomonas vaginalis. T. vaginalis-derived secretory products (TvSP) contain lipid mediators such as leukotriene B4 (LTB4) and various cysteinyl leukotrienes (CysLTs) which included LTC4, LTD4, and LTE4. However, the signaling mechanisms by which T. vaginalis-induced CysLTs stimulate interleukin (IL)-8 production in human mast cells remain unclear. In this study, we investigated these mechanisms in human mast cells (HMC-1). Stimulation with TvSP resulted in increased intracellular reactive oxygen species (ROS) generation and NADPH oxidase 2 (NOX2) activation compared to unstimulated cells. Pre-treatment with NOX2 inhibitors such as diphenyleneiodonium chloride (DPI) or apocynin significantly reduced ROS production in TvSP-stimulated HMC-1 cells. Additionally, TvSP stimulation increased NOX2 protein expression and the translocation of p47phox from the cytosol to the membrane. Pretreatment of HMC-1 cells with PI3K or PKC inhibitors reduced TvSP-induced p47phox translocation and ROS generation. Furthermore, NOX2 inhibitors or NOX2 siRNA prevented CREB phosphorylation and IL-8 gene expression or protein secretion induced by TvSP. Pretreatment with a CysLTR antagonist significantly inhibited TvSP-induced ROS production, CREB phosphorylation, and IL-8 production. These results indicate that CysLT-mediated activation of NOX2 plays a crucial role in ROS-dependent IL-8 production in human mast cells stimulated by T. vaginalis-secreted CysLTs. These findings enhance our understanding of the inflammatory response in trichomoniasis and may inform the development of targeted therapies to mitigate this response.

On the PhyloQuant protein expression profiles approach to the taxonomic problem.

Inferring evolutionary relationships among organisms has been a fundamental problem in evolutionary biology. The current phylogenetic molecular methods serve as the baseline model to test new evolutionary hypotheses with taxonomic purposes. Leishmaniinae trypanosomatids subfamily includes protozoan parasites of clinical importance to humans. They have an intricate taxonomic history defined by morphological elements, host range, and molecular phylogenies. Unraveling the increasing diversity of this group has shown limitations in reconstructing the true evolutionary relationships among Trypanosomatidae species. Toward the goal of inferring evolutionary relationships that help to resolve phylogenetic and taxonomic controversies among parasites of the subfamily Leishmaniinae, Mule etal. propose the method PhyloQuant as a valuable approach, based on differential protein expression obtained from high throughput mass spectrometry data. Employing a pioneering methodological approach, Mule etal. assess the taxonomic problem for species hypothesis within Leishmaniinae, from quantitative phenetic protein expression profiles, in contrast to the standard multilocus phylogenetic approaches.

Effect of micronutrient deficiency on protozoal infection in stunting toddler

<p class="pf0"><strong><em>Background: </em></strong><em>Stunting is a developmental disorder caused by chronic inadequate nutritional intake in toddlers, leading to deficiencies in various nutrients, including iron and zinc. This can weaken toddlers' immunity, making them more vulnerable to infectious diseases, such as intestinal protozoa. An infected digestive tract can interfere with absorbing nutrients and reduce appetite, causing the infection to persist and become chronic. Chronic infection triggers the formation of pro-inflammatory cytokines that affect bone growth, hindering growth and causing stunting.</em><em></em></p><p class="pf0"><strong><em>Objectives: </em></strong><em>This study confidently investigates the correlation between iron and zinc micronutrient intake and intestinal protozoan infection in stunting toddlers in Jember District.</em><em></em></p><p class="pf0"><strong><em>Methods: </em></strong><em>The research is observational and cross-sectional, with 568 stunting toddlers aged 0-59 months in Jember District, East Java as study subjects. Iron and zinc intake were collected through 2x24-hour food-recall questionnaire interview and processed using the Nutrisurvey software. Protozoan infection status in toddler feces samples was identified using direct smear and modified Ziehl-Neelsen methods. The data analysis method chosen was the Spearman correlation test.</em></p><p class="pf0"><strong><em>Results: </em></strong><em>The study found that stunted toddlers in Jember District had mostly deficient micronutrient intake. The average iron intake is 2.56±3.06 mg and the average zinc intake is 1.8±1.47 mg. Protozoan infection was found in this study has a prevalence of 15.7%, with identified species including Entamoeba histolytica (3.3%), Giardia lamblia (2.6%), Cryptosporidium parvum (3.2%), Blastocystis hominis (5.3%), and mixed infections (1.2%). The statistical analysis confirms that there is no significant correlation between the intake of micronutrients iron (p=0.91;r=0.005) and zinc (p=0.76;r=0.013) and intestinal protozoan infection in stunting toddlers in Jember District.</em></p><p class="pf0"><strong><em>Conclusions: </em></strong><em>Based on the data, protozoan infection may be caused by multiple factors, such as parenting practices and family socioeconomics. However, improving nutrition by education and giving additional supplementation are crucial to reduce the prevalence of malnutrition in toddlers.</em><em></em></p>

CRISPR screens identify genes essential for in vivo virulence among proteins of hyperLOPIT-unassigned subcellular localization in Toxoplasma.

The research field to identify and characterize genes essential for in vivo virulence in Toxoplasma gondii has been dramatically advanced by a series of in vivo clustered regularly interspaced short palindromic repeats (CRISPR) screens. Although subcellular localizations of thousands of proteins were predicted by the spatial proteomic method called hyperLOPIT, those of more than 1,000 proteins remained unassigned, and their essentiality in virulence was also unknown. In this study, we generated two small-scale gRNA libraries targeting approximately 600 hyperLOPIT-unassigned proteins and performed in vivo CRISPR screens. As a result, we identified several genes essential for in vivo virulence that were previously unreported. We further characterized two candidates, TgGTPase and TgRimM, which are localized in the cytoplasm and the apicoplast, respectively. Both genes are essential for parasite virulence and widely conserved in the phylum Apicomplexa. Collectively, our current study provides a resource for estimating the in vivo essentiality of Toxoplasma proteins with previously unknown localizations.IMPORTANCEToxoplasma gondii is a protozoan parasite that causes severe infection in immunocompromised patients or newborns. Toxoplasma possesses more than 8,000 genes; however, the genes essential for in vivo virulence were not fully identified. The apicomplexan parasites, including Toxoplasma, developed unique organelles that do not exist in other model organisms; thus, determining the subcellular location of parasite proteins is important for understanding their functions. Here, we used in vivo genetic screens that enabled us to investigate hundreds of genes in Toxoplasma during mouse infection. We screened approximately 600 parasite proteins with previously unknown subcellular localizations. We identified many novel genes that confer parasite virulence in mice. Among the top hits, we characterized two genes essential for in vivo virulence, TgGTPase and TgRimM, which are widely conserved in the phylum Apicomplexa. Our findings will contribute to understanding how apicomplexans adapt to the host environment and cause disease.

Insights into Peptidyl-Prolyl cis-trans Isomerases from Clinically Important Protozoans: From Structure to Potential Biotechnological Applications.

Peptidyl-prolyl cis/trans isomerases (PPIases) are present in a wide variety of microorganisms, including protozoan parasites such as Trypanosoma cruzi, Trypanosoma brucei, Trichomonas vaginalis, Leishmania major, Leishmania donovani, Plasmodium falciparum, Plasmodium vivax, Entamoeba histolytica, Giardia intestinalis, Cryptosporidium parvum, and Cryptosporidium hominis, all of which cause important neglected diseases. PPIases are classified as cyclophilins, FKBPs, or parvulins and play crucial roles in catalyzing the cis-trans isomerization of the peptide bond preceding a proline residue. This activity assists in correct protein folding. However, experimentally, the biological structure-function characterization of PPIases from these protozoan parasites has been poorly addressed. The recombinant production of these enzymes is highly relevant for this ongoing research. Thus, this review explores the structural diversity, functions, recombinant production, activity, and inhibition of protozoan PPIases. We also highlight their potential as biotechnological tools for the in vitro refolding of other recombinant proteins from these parasites. These applications are invaluable for the development of diagnostic and therapeutic tools.

An Investigation of Mucosal Leishmaniasis in the Military Health System.

Leishmaniasis is a protozoal infection with an increased risk of transmission to those serving in the U.S. Military due to theaters of operation in endemic regions. There has, in recent decades, been robust experience with old-world leishmaniasis in the Military Health System (MHS); however, new-world leishmaniasis, which may result in mucosal leishmaniasis, has been less studied. A total of 88 patients from 2012 to 2022 with diagnosis codes for "mucocutaneous leishmaniasis" or "leishmaniasis, unspecified" were identified in the Military Data Repository and reviewed. Within this cohort, upon medical records review, there were 2 cases of leishmaniasis that met inclusion criteria. Case 1 was a 28-year-old active duty male with recent travel to Belize who presented with a mucosal lip lesion that was biopsied and had inconclusive species confirmation but was thought to be either L. braziliensis or L. mexicana. The second case involved a 30-year-old active duty male with a history of travel to French Guiana who had a cutaneous lesion on his left hand that was identified as L. guyanensis, a causative species for mucosal leishmaniasis. Neither had evidence of any further mucosal involvement on otolaryngologic evaluation, and both subsequently received systemic therapy with a good clinical response. Although only 2 cases were identified over an 11-year period, this disease remains an important medical consideration when conducting military operations within Central and South America, as both cases had recent military-specific travel to areas endemic for leishmaniasis.

Insights Into the Evolution, Virulence and Speciation of Babesia MO1 and Babesia divergens Through Multiomics Analyses

Babesiosis, caused by protozoan parasites of the genus Babesia, is an emerging tick-borne disease of significance for both human and animal health. Babesia parasites infect erythrocytes of vertebrate hosts where they develop and multiply rapidly to cause the pathological symptoms associated with the disease. The identification of new Babesia species underscores the ongoing risk of zoonotic pathogens capable of infecting humans, a concern amplified by anthropogenic activities and environmental changes. One such pathogen, Babesia MO1, previously implicated in severe cases of human babesiosis in the United States, was initially considered a subspecies of B. divergens, the predominant agent of human babesiosis in Europe. Here we report comparative multiomics analyses of B. divergens and B. MO1 that offer insight into their biology and evolution. Our analysis shows that despite their highly similar genomic sequences, substantial genetic and genomic divergence occurred throughout their evolution resulting in major differences in gene functions, expression and regulation, replication rates and susceptibility to antiparasitic drugs. Furthermore, both pathogens have evolved distinct classes of multigene families, crucial for their pathogenicity and adaptation to specific mammalian hosts. Leveraging genomic information for B. MO1, B. divergens, and other members of the Babesiidae family within Apicomplexa provides valuable insights into the evolution, diversity, and virulence of these parasites. This knowledge serves as a critical tool in preemptively addressing the emergence and rapid transmission of more virulent strains.

Pharmacokinetics and tissue distribution of LN002, a new compound alternative oxidase inhibitor against Cryptosporidium in rats.

Cryptosporidiosis is considered a crucial zoonotic disease caused by widely distributing parasitic protozoa called Cryptosporidium spp. Nitazoxanide is the only FDA-approved drug but is only effective with a good immune response of the host. In addressing this unmet medical need, we previously identified a compound, namely, LN002, as a potent alternative oxidase inhibitor against cryptosporidiosis. To illustrate the pharmacokinetics, absolute bioavailability, and tissue distribution of LN002 in rats, rapid and sensitive high-performance liquid chromatography was developed and validated for the separation and detection of LN002 in plasma, tissue samples, and intestinal contents. In this study, a single dose of oral administration and intravenous injection of LN002 was used to determine the levels of LN002 in plasma, tissue samples, and intestinal contents by UHLC. Results of the study indicated that after intravenous administration of 1mg/kg LN002, the AUC0-24 h, T1/2,Vd, and Cl were 7024.86h·ng/mL, 10.91h, 1.69L/kg, and 0.11L/h/kg, respectively. After oral administration of a single dosage of 100, 200, and 400mg/kg LN002, the Tmax, Cmax, AUC0-24h, T1/2, F, Vd, and Cl/F in plasma of rats were 1h, 849.88-4033.21ng/mL, 2280.41-7498.10h·ng/mL, 17.96-18.83h, 0.27%-0.32%, 581.54-869.21L/kg, and 25.97-39.00L/h/kg, respectively. After oral administration of 200mg/kg, LN002 was extensively distributed in the main tissues of rats, and massive amounts of LN002 were distributed in the intestine and intestinal contents, indicating its potential as an effective anti-Cryptosporidium compound. After oral administration of a single dosage of 200mg/kg, LN002 has a low bioavailability and high levels in the intestine, which is crucial for the safe and effective treatment of cryptosporidiosis. Overall, the results of this study provide valuable data support for the future study of LN002.

Distribution of and Relationships between Epidemiological and Clinicopathological Parameters in Canine Leishmaniosis: A Retrospective Study of 15 Years (2009-2023).

Leishmaniosis is a vector-borne disease caused by protozoan parasites of the genus Leishmania, which are zoonotic and have an important impact on animal and public health globally. Between 2009 and 2023, blood samples from domestic dogs with clinical suspicion of leishmaniosis were received from 286 veterinary medical centres throughout mainland Portugal. An enzyme-linked immunosorbent assay (ELISA) was utilised to detect antibodies against Leishmania infantum antigens. Additionally, a complete blood count and tests for total proteins, urea, creatinine and alanine aminotransferase, as well as protein electrophoresis, were also performed. No significant relationship between sex and breed was observed. The age distribution was bimodal, with the highest prevalence of disease occurring at 2-5 years of age and a secondary peak occurring at 6 years or over (p < 0.001). No statistical correlation was observed between creatinine and urea across the ELISA serological groups. In contrast, both the gamma globulin levels (r = 0.45; p < 0.001) and the albumin/globulin ratio (r = -0.36; p < 0.001) exhibited moderate correlations with the ELISA. These findings support recent seroprevalence studies in dogs, with some geographical areas in Northern Portugal exhibiting the highest values, which may be the result of geographical shifts in parasite circulation due to climate change.

Impact of &lt;i&gt;Tritrichomonas&lt;/i&gt; spp. on the immune system of Muc2&lt;sup&gt;–/–&lt;/sup&gt; mice after antibiotic therapy

While pathogenic protists inhabiting the reproductive tract are well studied, the gastrointestinal (GI) tract contains a constitutive protist microbiota that is an integral part of the vertebrate microbiome. Currently, the effect of protozoan infections on the host immune system and their potential contribution to disruption of mucosal immune homeostasis are not well understood. Protists, along with bacteria and viruses, are permanent representatives of the human microbiota. The main attention of researchers is focused on studying their pathogenic role in gastrointestinal diseases. However, their role in symbiotic relationships with hosts is relatively little studied. It was previously shown that the closest human ortholog of mouse Trichomonas (Tritrichomonas spp.) is Trichomonas Dientamoeba fragilis, which can cause symptoms of inflammatory bowel disease. It is currently unclear whether Dientamoeba fragilis and other protist species such as Enteromonas spp., Entamoeba dispar are commensals, pathobionts, or pathogens of the human intestinal tract. Thus, information about the mutualistic relationships between protists, the gastrointestinal microbiota, and the immune system of mice can be used to understand host-protozoan relationships in humans. The data obtained allow us to evaluate the potential contribution of commensal protozoa in the formation of protective mechanisms of the mucous membrane of animals and humans. We have previously shown that antibiotic therapy leads to an increase in the number of Tritrichomonas spp. along with a reduction in bacteria in the gut of mice with a mutation in the Muc2 gene. A mutation in this gene leads to impaired formation of the intestinal mucosa in mice. Mice with a mutation in the Muc2 gene can be used as model to study human inflammatory bowel diseases (IBDs). In this work, we conducted a comparative study of the immunological status of Muc2–/– mice harboring Tritrichomonas spp. after antibiotic therapy for 2 weeks followed by gavage of Lactobacillus johnsonii into mice and mice without introduction of probiotic microorganisms (self-recovery). Analysis of the main populations of lymphocytes in the blood, spleen and lymph nodes showed that the introduction of Lactobacillus johnsonii after antibiotic therapy leads to a significant increase in the population of T-lymphocytes in the blood and spleen, and an increase in the number of helper T cells in the lymph nodes of Muc2–/– mice compared to mice without the addition of probiotic microorganisms.

Human Ocular Toxoplasmosis in Romania: History, Epidemiology, and Public Health: A Narrative Review.

Toxoplasmosis, caused by the protozoan parasite Toxoplasma gondii (T. gondii), presents a significant global health concern, particularly for immunocompromised individuals and congenitally infected newborns. Despite its widespread prevalence, there are limited data on T. gondii seroprevalence and ocular toxoplasmosis in Romania. This review aims to summarize the research accomplished on the prevalence and epidemiology of human ocular toxoplasmosis in Romania. Ocular toxoplasmosis, a leading cause of infectious posterior uveitis worldwide, involves complex interactions between host immune responses and parasite factors. Clinically, it presents as focal necrotizing retinitis, characterized by active focal retinal lesions with adjacent chorioretinal scarring, often accompanied by vitreous inflammation and anterior chamber reactions. Diagnosis relies on clinical examination supported by fundus photography, optical coherence tomography (OCT), and serological assays. The authors followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) standards, conducting a literature review on PubMed, Google Scholar, and Scopus. Our focus was on ocular toxoplasmosis in Romania, and we used keywords and specific MeSH terms. Finally, 17 articles met all the criteria, as summarized in the PRISMA diagram. This study underscores the need for improved diagnostic methods, increased research efforts, and comprehensive public health education to mitigate the burden of toxoplasmosis and ocular toxoplasmosis in Romania.

Identification of Potential Trypanosoma cruzi Trans-Sialidase Inhibitors by Computational Drug Repositioning Approaches

Chagas disease, caused by the parasitic protozoan Trypanosoma cruzi (T. cruzi), represents a worldwide public health issue. To date, there is no efficient treatment to combat this pathology, and the only drugs available are usually toxic to the patient. Through the enzyme trans-salidase, the parasite invades, infects, and multiplies intracellularly in the host cell. This protein has been considered an attractive target for developing or searching for compounds with potential trypanocidal activity. In this study, an in silico analysis was performed using a Food and Drug Administration-approved computational drug repositioning approach to identify compounds with anti-Chagas potential against two trans-sialidase proteins. Those compounds with potential inhibition were analyzed and selected through a molecular docking-based virtual screening. Forty-nine compounds were identified, of which forty-five are available on the market, and the rest were evaluated in silico. Our predicted results follow that these compounds are safe for human use and could be potential anti-trans-sialidase agents.

Crystal structure of glycerol kinase from Trypanosoma cruzi, a potential molecular target in Chagas disease.

Chagas disease is a neglected tropical disease caused by the protozoan parasite Trypanosoma cruzi. It bears a significant global health burden with limited treatment options, thus calling for the development of new and effective drugs. Certain trypanosomal metabolic enzymes have been suggested to be druggable and valid for subsequent inhibition. In this study, the crystal structure of glycerol kinase from T. cruzi, a key enzyme in glycerol metabolism in this parasite, is presented. Structural analysis allowed a detailed description of the glycerol binding pocket, while comparative assessment pinpointed a potential regulatory site which may serve as a target for selective inhibition. These findings advance the understanding of glycerol metabolism in eukaryotes and provide a solid basis for the future treatment of Chagas disease.

CCR2-dependent placental migration of inflammatory monocytes suppresses abnormal pregnancies caused by Toxoplasma gondii infection.

Toxoplasma gondii (T. gongii) is a zoonotic protozoan parasite that causes congenital toxoplasmosis, including fetal death, abortion, stillbirth, morphological abnormalities, and premature birth. Primary T. gondii infection in pregnant women results in congenital toxoplasmosis. C-C chemokine receptor (CCR) 2 is reportedly a critical host defense factor against T. gondii infection. However, details of the role of CCR2 in the host immune response to T. gondii in congenital toxoplasmosis remain unclear. Here, we infected pregnant CCR2-deficient mice with T. gondii, resulting in stillbirth, embryonic resorption, fetal morphological abnormalities, and preterm delivery at significantly higher rates than those in pregnant wild-type mice. Consistent with the severity of abnormal pregnancy, a large area of placental hemorrhage and a large number of T. gondii infections around the hemorrhagic area were observed in the placentas of CCR2-deficient mice. In addition, the accumulation of inflammatory monocytes in the placenta was reduced in CCR2-deficient mice during infection. We further confirmed that the adoptive transfer of inflammatory monocytes collected from wild-type mice into T. gondii-infected pregnant CCR2-deficient mice effectively suppressed placental damage and abnormal pregnancy. Collectively, CCR2 contributes to pregnancy maintenance by regulating the migration of inflammatory monocytes into the placenta of T. gondii-infected pregnant mice.

Seroprevalence of Toxoplasma gondii and Neospora spp. in horse population of Tehran, Iran

Neospora spp. and Toxoplasma gondii are two closely related protozoan parasites that are widely distributed throughout the world. Horses can act as intermediate hosts for both parasites and can acquire disease. Blood samples were taken from 487 clinically healthy horses from 17 different mechanized stables in Tehran, the capital of Iran, during September and November of 2022. IFAT and ELISA were employed to detect antibodies directed against Neospora spp. and T. gondii. The anti-N. caninum antibodies were detected in 52 of the horses (10.67%) based on IFAT and in 86 of the 487 horses (17.65%) based on the ELISA test. Also, antibodies against T. gondii were detected in 41 horses (8.42%) based on IFAT and in 63 of 487 horses (12.94%) based on the ELISA test. Also, in 6 of the horses (1.23%) based on IFAT and in 13 of the 487 horses (2.67%) based on the ELISA test, double positivity suggested co-infection with both parasites. Gender, age groups, and the presence of dogs for neosporosis, and age groups and the presence of cats for toxoplasmosis, could be considered factors having an influence on the seroprevalences (P < 0.05). The results proved the importance of the urgent implementation of stringent regulatory measures to prevent and control the spread of these parasites.

Zoonoses and pet owners: A survey on risk perception in Northern Italy

Veterinary and human medicine are focused on the issue of emerging and re-emerging diseases, which are especially represented by zoonosis that could be a threat for public health. Zoonotic risk may come from pets: some canine and/or feline viral, bacterial, parasitic, protozoal or mycotic diseases can be transmitted directly to humans. There are several strategies to prevent the transmission of such zoonosis, and among them vaccination plays an important role. Through a survey carried out in Northern Italy aimed to collect information regarding owners’ knowledge and perception of the zoonotic risks associated with three zoonoses (rabies, leptospirosis, and dermatophytosis), it was demonstrated that dog owners tend to adhere more consistently to their pets’ vaccination schedules and are more receptive to changes in vaccination scheduling compared to cat owners. This study also suggests that cat owners predominantly visit veterinarians for vaccination purposes, whereas dog owners seek veterinary services for a variety of reasons. The survey highlighted the ongoing need to enhance owners’ understanding of zoonoses affecting their pets and also the protective role of vaccines. Veterinarians should undertake the responsibility of educating, reassuring, and informing pet owners about the significance of vaccines for their pets and for public health.