Experimental parasitology最新文献

Biological control, which utilizes nematophagous fungi to reduce gastrointestinal nematode populations, may effectively diminish the need for chemical anthelmintic treatments. However, the limited knowledge surrounding the mass production of chlamydospores hinders the widespread use of biological products as alternatives to traditional anthelmintics. This study aimed to evaluate the development of liquid culture media for the large-scale production of the nematophagous fungi Duddingtonia flagrans using a systematic procedure, progressing from microplates to bioreactor. The liquid culture media were successfully validated in a 13 L bioreactor, achieving a yield of 2.18x10⁷ chlam/g per day, which is comparable to the standard process of solid-state fermentation (SSF). Moreover, the nematode predatory ability remained unaffected by the changes in scales and exhibited a superior efficacy of over 90%. Consequently, this study demonstrates that the submerged fermentation approach serves as a viable alternative for the mass production of nematophagous fungi like D. flagrans.

Visceral leishmaniasis (VL) is an opportunistic infection in HIV patients with higher relapse and mortality rate. The number of HIV-VL patients is comparatively higher in areas where both infections are endemic. However, the conventional chemotherapeutic agents have limited success due to drug toxicity, efficacy variance and overall cost of treatment. Therefore, it is crucial to discover and develop newer potent antileishmanial agents for successful eradication of the disease. Our previous report, for the first time showed the leishminicidal effect of amprenavir (APV) mediated by inhibition of L.donovani Topoisomerase I (LdTopILS). So, we intended to demonstrate the effect of APV in combination with ritonavir (RTV). The present study revealed that the complete catalytic inhibition of LdTopILS by APV (10 μM) in combination with RTV (5 μM), compare to APV (20 μM) as previously reported (Roy et al., 2021). Moreover, APV (5 μM) in combination with RTV (4 μM) exhibited promastigote inhibition with IC₅₀ values of 2.4 ± 0.6 μM at 12 h and 1.6 ± 0.7 μM at 24 h, respectively. The study was extended in animal model where the in vivo antileishmanial efficacy of APV-RTV in BALB/c mice demonstrated that treatment of APV in combination with RTV led to significant splenic and hepatic protection as compared to single dose of APV. Moreover, the antileishmanial activity of APV in combination with RTV was exerted via inhibition of LdTopILS at much lower concentration of APV and this inhibition of the enzyme induced programmed cell death in Leishmania parasites by generating oxidative stress within the cells. From the in vitro, ex vivo and in vivo studies, it was indicated that lower dose of APV in combination with RTV elevated the effective killing of the parasites as compared to the single higher dose of APV. Thus, the current study highlights repurposing of available protease inhibitors in combination, which might be exploited further for the therapeutic development against VL as well as HIV-VL co-infection.

Toxoplasmosis is a parasitic disease affecting a significant portion of the global population, whose etiology can be attributed to the protozoan organism Toxoplasma gondii. Despite its public health importance, an efficacious vaccine to prevent human toxoplasmosis remains unavailable. To this end, we designed an experimental toxoplasmosis vaccine using recombinant vaccinia virus vectors (rVacv) expressing the T. gondii rhoptry protein 4 (ROP4) antigen and evaluated its efficacy in a murine model. Intranasal vaccination with ROP4-rVacvs induced parasite-specific serum antibody responses as early as 3 weeks post-immunization, with subsequent immunizations elevating antibody responses to a greater extent. When challenged with T. gondii ME49 strain, significantly enhanced levels of mucosal IgA antibodies were detected in the intestines of immunized mice. Additionally, ROP4-rVacv immunization ensured that T cells and germinal center B cell populations were retained at high levels. These immune responses mitigated the severity of neuroinflammation, reduced tissue cyst formation, and ensured the survival of immunized mice. Our findings indicate that ROP4-rVacv could be a promising toxoplasmosis vaccine candidate.

Schistosomiasis stands as one of the most significant parasitic diseases on a global scale, with approximately 250 million infections worldwide. It is imperative to address this pressing issue by developing new antischistosomal drugs. Chalcones have emerged as a promising class of natural compounds, demonstrating noteworthy effects observed in in vitro experiments with Schistosoma mansoni, and demonstrating the ability to inhibit SmNTPDases and apyrase from potatoes. In this study, we focused on uvangoletin, a naturally occurring dihydrochalcone from Piper aduncum. We isolated uvangoletin from P. aduncum fruits and conducted in vivo experiments to evaluate the efficacy of uvangoletin against adult Schistosoma parasites. Furthermore, we explored the inhibitory effects of uvangoletin on potato apyrase and employed molecular docking analyses to investigate its interactions with apyrase from potato and the two isoforms SmNTPDase 1 and 2 through in silico studies. Uvangoletin (400 mg/kg, p.o.), exhibited significant in vivo antiparasitic effects against adult S. mansoni, leading to a decrease of 53.7% in worm burden and 54.3% in egg production. The treatment also reduced hepatomegaly and splenomegaly. In silico investigations and ADMET studies indicated that uvangoletin possesses favorable drug-like properties and may interact with key residues involved in apyrase and SmNTPDases activities. Furthermore, uvangoletin demonstrated a substantial reduction in potato apyrase activity. These results suggest the potential for exploring other dihydrochalcones as promising candidates for antischistosomal agents.

The aim of this study was to evaluate the efficacy of a single 20 mg/kg dose of lotilaner for treating rabbits with concomitant infection by P. ovis and L. gibbus. Fourteen rabbits with diagnoses of otitis and fur infection, caused respectively by P. ovis and L. gibbus, were included. Samples of otic crust were collected with tweezers, weighed and examined microscopically to identify ectoparasites, which were counted to determine the number of mites per gram of crust. Hair samples were collected from three areas of 1 cm² in different regions of the body, for examination under a stereomicroscope to determine occurrences of the mite L. gibbus. The animals in the treated group received a single oral dose of 20 mg/kg of lotilaner and were evaluated on days 0, +3, +7, +14, +21, +28 and + 35. Parasitological efficacy of 100% for controlling P. ovis was observed after seven days. Total clinical remission was reached 14 days after treatment. For L. gibbus, parasitological cure was obtained seven days after treatment. We concluded that a single dose of lotilaner was effective for controlling P. ovis and L. gibbus, leading to parasitological control and clinical improvement of the animals.

Toxoplasmosis which is caused by T. gondii, is common among humans and animals. T. gondii is a threat to the fetus and individuals with immune disorders, especially patients with acquired immunodeficiency syndrome (AIDS) and individuals who undergo organ transplants. Therefore, quick diagnosis and accurate differentiation of acute and chronic stages are essential. One of the important serological methods in differentiating stages of the disease and the time of acquiring the infection is evaluating the IgG avidity. In this systematic review and meta-analysis, keywords were searched in databases including PubMed, Science Direct, ProQuest, Scopus, and Google Scholar. Included studies were collected after checking the inclusion and exclusion criteria, and according to the PRISMA flow chart. Finally, the data were analyzed by StatsDirect statistical software and random-effects model. A total of 10 studies (26 datasets) were eligible for analysis. The random effects model estimated the prevalence of low IgG avidity in acute toxoplasmosis using in-house IgG avidity tests of 84% and chronic toxoplasmosis infection using in-house IgG avidity of 91%. The IgG avidity test can be a helpful diagnostic tool in differentiating between acute and chronic stages. Also, this review emphasizes that the use of recombinant or chimeric proteins is preferable to TLA in differentiating acute and chronic stages. It can be concluded that choosing more effective antigens (multi-epitope and multi-stage) and performing more detailed studies on the design of an avidity kit to differentiate the stage of infection is required.

In Leishmania, the nucleotide-sugar UDP-galactose can be synthesized by a salvage pathway, the Isselbacher route, involving phosphorylation of galactose and the action of UDP-sugar pyrophosphorylase. The first enzyme of the pathway, galactokinase, has yet to be studied in this parasite. Here, we report a molecular and biochemical characterization of this enzyme in Leishmania mexicana. We showed that recombinant galactokinase (LmxGALK) phosphorylates galactose in the presence of ATP with K_m values of 0.077 mM for galactose and 0.017 mM for ATP. We proved by immunodetection that GALK is expressed in promastigotes and amastigotes of L. mexicana, L. braziliensis and L. infantum. In agreement with the presence of a type 1 peroxisome-targeting signal sequence present at the C-terminus of LmxGALK, the protein is localized mostly within glycosomes as shown by selective membrane permeabilization with digitonin, differential centrifugation, and immunofluorescence. Indeed, LmxGALK enzymatic activity was measured in the fractions corresponding to the homogenate and glycosomes, proving that it is active in promastigotes. In addition, it was shown that galactose cannot serve as an important carbon source for sustaining parasite growth, as cultures of promastigotes from three Leishmania species in LIT medium containing either no sugar or supplemented with D-galactose (20 mM) grew to lower density compared to these cultured with D-glucose (20 mM). These results suggest that D-galactose is mainly used for UDP-galactose synthesis by the salvage route, functioning when glucose is depleted from the medium, similar to the conditions promastigotes experience in the gut of the insect vector during its life cycle.

A light and electron microscopic study of skin biopsies taken from 9 patients with ulcerative leishmaniasis of both sexes aged from 14 to 26 years in the territory of the Republic of Azerbaijan was carried out. Based on clinical, morphological and electron microscopic parameters, all patients were diagnosed with ulcerative cutaneous anthroponotic leishmaniasis (Leishmania (L.) tropica). Stained and unstained ultrathin (50-70 nm) sections were viewed and photographed using a JEM-1400 transmission electron microscope at an accelerating voltage of 80-120 kV. Analysis of data from light and electron microscopic studies at the ultrastructural level made it possible to describe the structure and identify the morphometric parameters of the amastigote form of the intracellular parasite. Besides, it was found that the distance between the plasmalemmas of the parasitophorous vacuoles and the parasite L. (L.) tropica is only 1 nm. This facilitates the passage of the necessary nutrients for the survival of this parasite. One of the important factors in the chronic course and relapse of leishmaniasis caused by L.(L.) tropica is the penetration of the amastigote stage into the cytoplasm along with macrophages, and also into fibroblasts with low phagocytic activity. Pathological changes (deformed nucleus, damage to plasmalemma, focal destruction of the cytoplasm structures, vacuolization, etc.) in the parasite L. (L.) tropica, localized in macrophages, were identified and described.

Leishmania (Viannia) braziliensis is associated with distinct clinical manifestations such as cutaneous, mucocutaneous, and disseminated leishmaniasis. One factor related to this clinical spectrum is the structure of parasite populations. This study investigates in vivo binomial BALB/c-L. (V.) braziliensis exploring the phenotypic variability of subpopulations (Thor03, Thor10 and Thor22) of Thor strain, which have previously been described as causing distinct pattern infection in vitro. In the third week after infection, differences were observed in the development curves of the lesions, with larger lesions in the Thor03 and Thor10. At this point, lymph nodes of mice infected with the Thor03 and Thor10 exhibited lower IL-12 and TNF values compared to infection with the Thor strain and Thor22. The infection with the Thor10 showed highest values of the cytokine IL-10 compared to those infected with the Thor strain, Thor03 and Thor22. In addition, no statistical differences in parasite load wer observed in the footpad in seventh week post inoculation. In contrast, the higher parasite load values were observed in the lymph nodes for Thor03, Thor10 and Thor22 subpopulations. The data obtained here show these subpopulations cause transient and non-severe footpad lesions with parasite persistence in draining lymph nodes, although some mice developed non-healing lesions. Parasites isolated from the paws and lymph nodes of these animals were unable to establish persistent lesions in subsequent experimental infection assays. Collectively, these findings highlight consistent differences of infectionevolution and host immune response modulation, during infection among the Thor03, Thor10 and Thor22 subpopulations , all derived from a single strain.

It is not well understood how type 1 diabetes (T1D) and concomitant acute schistosomiasis mansoni affect pancreatic architecture. Male Swiss mice were administered streptozotocin (single 100 mg/kg i.p.) and thirty days later infected with 80 Schistosoma mansoni cercariae. Mice were divided into groups (n = 5): A (healthy control), B (infected), C (uninfected diabetic), and D (diabetic + infected) and euthanized at week 9 post-infection. Blood glucose levels, biometry, stereology, and pancreatic histology were evaluated. Groups C and D showed hyperglycemia (>200 mg/dL). Group B had a higher (+79%) pancreatic mass than A. The endocrine pancreas showed fewer islets of Langerhans (-62%; -50%) and a smaller islet area (-36%; -30%) in C and D, respectively, compared to A. Group D had a smaller (-37%) islet area than B. The volume density of the islets was reduced (-33%) in group C compared to A. Within the exocrine pancreas, the volume density of the pancreatic parenchyma was reduced in groups B (-29%) and D (-26%), and increased in C (+15%) compared to A. Group D was reduced (-35%) compared to C. Group D showed generalized pancreatitis, including disrupted tissue with multiple nuclei of destroyed acinar cells and lost connective tissue and acinar cells with a paucity of zymogen granules. Pancreatic stellate cells were found around areas of distorted architecture. Paired adult worms were found within the pancreatic vessels. In conclusion, concomitant T1D and schistosomiasis mansoni promote extensive exocrine and endocrine changes in the pancreas, whereas pancreatic involvement begins in acute schistosomiasis.