Parasitology Research最新文献

An in vivo mouse model of Clonorchis sinensis (C. sinensis) infection with or without the administration of autophagy inhibitor chloroquine (CQ) stimulation was established to assess the possible involvement of autophagic response during C. sinensis infection. Abnormal liver function was observed at 4, 6, and 8 weeks post-infection, as indicated by elevated levels of ALT/GPT, AST/GOT, TBIL, and α-SMA in the infected groups. These findings indicated that C. sinensis infection activated autophagy, as shown by a decreased LC3II/I ratio and accumulated P62 expression in infected mice. Interestingly, CQ administration exhibited dual and opposing effects during the infection. In the early stage of infection, the engagement of CQ appeared to mitigate symptoms by reducing inflammation and fibrotic responses. However, in the later stage of infection, CQ might contribute to parasite survival by evading autophagic targeting, thereby exacerbating hepatic impairment and worsening liver fibrosis. Autophagy in liver was suppressed throughout the infection. These observations attested that C. sinensis infection triggered autophagy, and highlighted a complex role for CQ, with both protective and detrimental effects, in the in vivo process of C. sinensis infection.

Lymphatic filariasis and onchocerciasis are neglected tropical diseases and cause significant public health problems in endemic countries, especially in sub-Saharan Africa. Since the human parasites are not viable in immune-competent mice, animal models have been developed, among them Litomosoides sigmodontis which permits a complete life cycle in BALB/c mice, including the development of patent infections with circulating microfilariae (Mf, the worm's offspring). To investigate the immunomodulatory properties of helminths in vitro, antigenic extracts can be prepared from different life cycle stages of the L. sigmodontis model, including adult worms, but the methods to prepare these antigens differ between research groups. This study analyzed whether different centrifugation methods during the preparation of an antigenic extract, the gender of used worms, or the different fractions (soluble or pellet) altered filarial-specific CD4⁺ T cell responses. These cells were isolated from pre-patent or patent/chronic infected mice, hence those without and those with Mf, respectively. Ex vivo immune responses were compared at these two different time points of the infection as well as the parasitic parameters. Worm burden and cell infiltration were elevated in the thoracic cavity (TC) and draining mediastinal lymph nodes at the pre-patent stage. Within the TC, eosinophils were significantly up-regulated at the earlier time point of infection which was further reflected by the eosinophil-related eotaxin-1 levels. Regarding the production of cytokines by re-stimulated CD4⁺ T cells in the presence of different antigen preparations, cytokine levels were comparable for all used extracts. Our data show that immune responses differ between pre-patent and patent filarial infection, but not in response to the different antigenic extracts themselves.

Naegleria fowleri is the etiological agent of primary amebic meningoencephalitis (PAM), a rapidly progressive acute and fulminant infection that affects the central nervous system, particularly of children and young adults, which has a mortality rate greater than 95%, and its symptomatologic similarity with other meningitis caused by virus or bacteria makes it difficult to make a quick and timely diagnosis that prevents the progression of the infection. It is necessary to know the antigenic determinants as well as the pathogenicity mechanisms of this amoeba to implement strategies that allow for better antiamoebic therapeutic and diagnostic targets that directly impact the health sector. Therefore, the aim of this work was to analyze some virulence factors as part of extracellular vesicle (EV) cargo secreted by N. fowleri. The EV secretion to the extracellular medium was evaluated in trophozoites fixed and incubated with anti-N. fowleri antibody while molecular identification of EV cargo was performed by SDS-PAGE, Western blot, and RT-PCR. Our results showed that N. fowleri secretes a wide variety of vesicle sizes ranging from 0.2 to > 2 μm, and these EVs were recognized by antibodies anti-Naegleropore B, anti-19 kDa polypeptide band, anti-membrane protein Mp2CL5, anti-protease cathepsin B, and anti-actin. Furthermore, these vesicles were localized in the trophozoites cytoplasm or secreted into the extracellular medium. Specifically in relation to small vesicles, our purified exosomes were recognized by CD63 and Hsp70 markers, along with the previously mentioned proteins. RT-PCR analysis was made through the isolation of EVs from N. fowleri trophozoite culture by concentration, filtration, and ultracentrifugation. Interestingly, we obtained PCR products for Nfa1, NPB, Mp2CL5, and CatB genes as part of exosomes cargo. This suggests that the molecules identified in this work could play an important role in communication as well as in infectious processes caused by this amoeba. Therefore, the study and characterization of the pathogenicity mechanisms, as well as the virulence factors released by N. fowleri remains a key point to provide valuable information for the development of therapeutic treatments, vaccine design, or biomarkers for a timely diagnosis against infections caused by protozoa.

Cryptosporidiosis, primarily caused by Cryptosporidium parvum, is a significant cause of diarrhea in pre-weaned dairy calves. To investigate the prevalence of Cryptosporidium among pre-weaned diarrheic dairy calves and identify potential sources of infection in northern China, 234 fecal samples from 18 farms in six regions were analyzed for Cryptosporidium. Furthermore, 217 bedding samples from both occupied and unoccupied calf hutches, heating lamp pens, and individual calving pens in eight farms in Beijing were also examined for the presence of the parasite. All samples were screened for Cryptosporidium spp. using nested PCR targeting the SSU rRNA gene fragment, and C. parvum was subtyped with nested PCR targeting the 60 kDa glycoprotein gene. The prevalence of Cryptosporidium was 33.3%, with C. parvum and C. bovis constituting 29.9% and 3.4% of cases, respectively. The positive rate of Cryptosporidium in 1- to 4-week-old calves ranged from 9.6 to 63.6%. Analysis of the gp60 fragment of C. parvum revealed four subtypes: IIdA15G1, IIdA17G1, IIdA19G1, and IIdA20G1. Besides the bedding samples in heating lamp pens, both C. parvum and C. bovis were detected in bedding samples throughout the other regions. A significant positive correlation between the detection rate of Cryptosporidium in fecal samples and that in the bedding materials of occupied calf hutches (R = 0.93, P = 0.002). These findings suggest that C. parvum is the predominant species among pre-weaned diarrheic dairy calves in northern China. Contaminated bedding materials may act as sources of infection for newborn calves.

Recent work has demonstrated that exposure to artificial light at night (ALAN) may alter mosquito feeding behavior and so must be considered a moderator of vector-borne disease transfer. Anopheles funestus mosquitoes are a primary malaria vector in sub-Saharan Africa, but no study to date has tested the impact of ALAN on their feeding behavior. Here we test if the exposure to commonly used household lights (compact fluorescent lights, light-emitting diodes, and incandescent lights) alters Anopheles funestus feeding. Mated, unfed female mosquitoes were exposed to a light treatment, at the onset of darkness, followed by a blood-feeding assay. The light treatments consisted of a 30-min light pulse of one of the three household lights, each in individual experimental containers, versus controls. All three household lights resulted in a reduction in the percentage of females taking a blood meal, but only mosquitoes exposed to incandescent light showed a statistically significant reduction in feeding of 19.6% relative to controls which showed a 42.8% feeding rate. Our results suggest that exposure to some household lights during the night may have an immediate inhibitory effect on Anopheles funestus feeding. By helping identify which light types lead to a suppression of feeding, the findings of this study could provide insight necessary to design household lights that can help minimize mosquito feeding on humans.

Integral membrane pyrophosphatases (mPPases) hydrolyze pyrophosphate. This enzymatic mechanism is coupled with the pumping of H + and/or Na + across membranes, which can be either K + -dependent or K + -independent. Inorganic proton-translocating pyrophosphatases (H + -PPases) can transport protons across cell membranes and are reported in various organisms such as plants, bacteria, and protozoan parasites. The evolutionary implications of these enzymes are of great interest for proposing approaches related to the treatment of parasitic of phytopathogenic diseases. This work presents a literature review on pyrophosphate, pyrophosphatases, their inhibitors and emphasizes H + -PPases found in various medically significant protozoan parasites such as Toxoplasma gondii, the causative agent of toxoplasmosis, and Plasmodium falciparum, the causative agent of malaria, as well as protozoan species that primarily affect animals, such as Eimeria maxima and Besnoitia besnoiti.

Haemoparasitic infections are frequently observed in dogs from tropical regions, including India. The present investigation combined microscopic blood smear examination and PCR assays to assess the occurrence of canine tick-borne diseases (CTBD) from suspected dogs in and around Hisar, Haryana. Using the Giemsa-stained peripheral thin blood smear examination, 15 (12.5%) of the 120 dogs were infected with CTBD, with 5.8%, 3.3%, 2.5%, and 0.8% dogs testing positive for Hepatozoon canis, Ehrlichia canis, Babesia vogeli, and Babesia gibsoni, respectively. Using the PCR assay, CTBD was found to be 64.16% (77/120) in examined dogs. Of the 77 PCR-positive canines, 56 were infected with a single haemoparasite, while 21 were infected with two or more species. H. canis was the most abundant tick-borne pathogen, representing 35%, followed by E. canis 25.8%, B. vogeli 20%, and B. gibsoni 2.5%. The most common co-infection was with H. canis along with E. canis (7.5%). The PCR assay was proven to be more efficient for detecting haemoparasites in dogs compared to blood smear examinations. The study suggests that canine tick-borne diseases are common in Haryana and recommends using PCR-based molecular tests in addition to conventional microscopic examination to diagnose these infections for effective treatment and management of infected canines.

In this study, we conducted post-mortem examinations of golden jackals (Canis aureus) and red foxes (Vulpes vulpes) from the northern region of the Republic of Srpska (Bosnia and Herzegovina) to detect the presence of Angiostrongylus vasorum. An epidemiological survey was conducted in the densest golden jackal population in the country. Over two time intervals, we examined a total of 30 jackals and 16 foxes. The presence of A. vasorum was confirmed in two jackals (6.6%) and one fox (6.25%). These findings strongly suggest that the spread of A. vasorum can be facilitated by the active expansion and migration of golden jackals in Southeastern Europe. The morphological and molecular detection of A. vasorum in jackals and foxes confirmed its presence and active circulation in wildlife, while the phylogenetic analysis of the ITS-2 gene indicated a low sequence distance from European isolates.

This study aimed to carry out a molecular screening for the presence of Giardia, Cryptosporidium, and/or Entamoeba in the feces of pet and stray/feral cats in Jordan. G. duodenalis was found in 27.9% (95% CI, 23.2-32.9) of the 348 sampled cats overall; E. histolytica was found in only 0.6% (95% CI, 0.1-2.1) of the cats, while none of the sampled cats had Cryptosporidium infections. The infection rate of G. duodenalis among indoor cats (32.3%) did not differ significantly from that among outdoor cats (24.1%). There were significantly more infections (p = 0.0004) geographically in the cold semiarid areas (67%) than in the cold desert areas (24%). Multilocus sequence typing analysis of amplicons based on the bg, tpi, and gdh genes revealed that the majority of G. duodenalis infections were zoonotic assemblage B (65.9%; 64 of 97 positive samples); followed by feline-specific assemblage F (18.5%, 18/97); cattle-specific assemblage E (5.2%, 5/97); and then assemblage C that was shared with canids (1.0%; 1/97). Within Giardia isolates, a substitution mutation (A/G) was found at position 297 of the complete protein coding sequence (cds) of tpi-assemblage B, which may represent a new spreading mutation within this gene among the cat population in Jordan. The results of the present study suggest that close human-cat interactions could play a role in zoonotic transmission of Giardia, but further research is needed to determine the possible contribution of cats to the transmission of other protozoa to humans.

Treatment failure with amodiaquine was reported in Dangassa, where red blood cell (RBC) polymorphisms are found and seasonal malaria chemoprevention (SMC) is underway. Here, we aimed at assessing the influence of RBC polymorphisms on SMC effectiveness. This was a secondary analysis of data from a study conducted in Dangassa. Children aged 5 to 14 years enrolled in an open randomized study were assigned either to receive SMC (intervention arm) or not (control arm). SMC was implemented from July to November. For all children, hemoglobin type and blood group were determined at enrolment in July, and parasitemia and hemoglobin level were monthly monitored by finger-prick. Overall, 166 children were enrolled among which 82 (49.40%) in the control arm and 84 (50.60%) in the SMC arm. The prevalence of HbAS was 10.24% (17/166) with 12.20% in the control and 8.33% in the SMC arm. O group was the most common overall (45%) and in the SMC arm (54%), but the control arm had more B (39.02%) than O (36.59%). In the SMC arm, no case of Plasmodium infection and malaria disease was observed in the 7 HbAS children while in Non-HbAS children, peaks of infection and disease prevalence were respectively observed in October (24.66%) and November (7.14%). For the SMC arm, in group O and Non-group O, Plasmodium infection cases were observed from August to December. Plasmodium infection and malaria disease were more frequently observed in HbAS children in the control arm than in the SMC arm. Further studies are needed to assess factors associated with the asymptomatic carriage of parasites during SMC in Dangassa. NCT04149106.