Parasites & Vectors最新文献

Background: Immune thrombocytopenia (ITP) is an acquired autoimmune disease characterized by a low platelet count (< 100 × 10⁹/L) induced by an autoimmune mechanism, which increases platelet clearing by macrophages. Antigen B (AgB) is a lipoprotein derived from Echinococcus granulosus larvae and has been observed to modulate host immunity. This study evaluated the mechanistic impact of AgB on macrophage polarization in the ITP mouse model.

Methods: This study analyzed blood samples acquired from pediatric patients with ITP and healthy controls. Furthermore, the levels of inflammatory cytokines in plasma, as well as macrophage surface markers and autophagy-related markers [microtubule-associated protein 1 light chain 3 (LC3) and sequestosome-1 (p62)] in peripheral blood mononuclear cells (PBMCs) were evaluated. Moreover, the ITP model was successfully established after immunization with an anti-CD41 antibody and treatment with AgB in vivo. Platelet counts and hemorrhagic symptoms were continuously examined, while plasma inflammatory cytokine levels and the expression of pertinent indicators in the spleen were assessed. RAW264.7 macrophages and lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages were treated with AgB to assess the expression of relevant markers in an in vitro experiment. The mechanism by which AgB regulates LC3 and p62 levels to inhibit LPS-induced macrophages was investigated. Lastly, autophagy inhibitors were administered to evaluate the specific stage of autophagy affected by AgB.

Results: AgB ameliorated hemorrhage and increased platelet counts in ITP murine models while decreasing the M1/M2 macrophage ratio. AgB therapy increased macrophage autophagic flux in vivo and in vitro. To elucidate the effects of AgB on various stages of autophagy, macrophages were treated with two autophagy inhibitors: 3-methyladenine (3-MA) and bafilomycin A1. This study revealed that AgB primarily acts by influencing the expression of LC3II/LC3I and p62, increasing the formation of autophagosomes and enabling lysosomes to identify and consume autophagosomes more accurately. AgB also inhibits macrophage polarization towards M1. These results suggested that AgB reduced hemorrhage in the ITP mouse model by regulating autophagy-mediated macrophage polarization.

Conclusions: This study showed that AgB alleviates ITP by restoring autophagy flux, inhibiting M1 macrophage polarization, and modulating immunity.

Background: The combination of lotilaner, moxidectin, praziquantel, and pyrantel pamoate (Credelio Quattro) is a novel systemic endectocide that provides month-long effectiveness in dogs after a single oral treatment. The safety of Credelio Quattro flavored chewable tablets was investigated when administered orally at the upper end of the recommended dosage range (20-41 mg/kg lotilaner, 0.02-0.04 mg/kg moxidectin, 5-10 mg/kg praziquantel, and 5-10 mg/kg pyrantel) and multiples thereof when administered long term.

Methods: The study was randomized and blinded, with parallel groups beginning in healthy 8-week-old Beagle dogs and continuing until they reached adulthood. A total of 32 dogs were randomized among four groups (8 dogs/group) to nontreated controls or to treated groups at target doses of 1×, 3×, or 5× the maximum dose. Treatment was administered on nine occasions to dogs in a fed state every 4 weeks, with the control group receiving placebo tablets. Assessment of safety was based on regular health observations, complete physical/neurological examinations, food consumption, clinical pathology evaluations (hematology, clinical chemistry, and urinalysis), body weight, and macroscopic and microscopic examinations of collected tissues.

Results: Credelio Quattro did not induce any serious treatment-related adverse effects based on health observations, physical/neurological examinations, food consumption, clinical pathology, body weight, or macroscopic and microscopic examinations. The only non-serious treatment-related effects of Credelio Quattro were a dose-dependent increase in the frequency of discolored feces, diarrhea, and vomiting (including hypersalivation associated with vomiting in two of the 5× dogs).

Conclusions: This study demonstrates that Credelio Quattro exhibits a wide safety margin when administered monthly to puppies and dogs at the maximum recommended commercial dose, with only transient gastrointestinal symptoms similar to other oral antiparasitic products observed. Therefore, Credelio Quattro may be safely administered to dogs each month in accordance with the approved label.

Background: Tick-borne Jingmenviruses are becoming an increasing arbovirus concern due to the rising number of reported infections in humans and animals, as well as their wide geographic distribution. The involvement of other hematophagous arthropods as vectors of Jingmenviruses is still unknown.

Methods: Mosquitoes were sampled in two different biotopes in Cameroon (Yaoundé and Garoua) during the rainy and dry seasons in 2022 and 2023. Metatranscriptomics Next Generation Sequencing was conducted using Illumina technology. Viral sequences detection revealed the presence of several contigs with high sequence identity to a human-derived Jingmenvirus (HdJV) previously discovered in plasma from an individual from Yaoundé, Cameroon. A draft viral genome was constituted for each Jingmenvirus-positive sample. Maximum likelihood phylogenetic reconstructions were used to position mosquito-associated viruses within the diversity of Jingmenviruses. Statistical analyses were conducted to estimate the prevalence of infected mosquitoes and the effect of different variables (region, season, year, mosquito species) on Jingmenvirus detection.

Results: HdJV was identified during the dry and the rainy seasons in four species of mosquitoes: Aedes albopictus, Culex quinquefasciatus, and Culex wansoni from Yaoundé, and Anopheles gambiae s.l. from Garoua. The overall prevalence of HdJV-infected mosquitoes was estimated to be 0.9% [0.4-1.7], and the unique variable significantly associated with HdJV detection was the sampling area: Yaoundé showed the highest prevalence (2.3% [0.9-4.7]) compared with Garoua (0.2% [0.01-0.8]). Mosquito-associated Jingmenviruses shared a high nucleotide identity (between 98.6 and 100% according to the segment) and clustered in the same clade in the phylogenetic analysis, indicating that they belong to the same viral species circulating in different mosquito species. The viral genome shared between 96.4 and 98.9% nucleotide identity with a HdJV detected in the plasma of a patient suffering from febrile illness originating from the same area, suggesting the possible involvement of mosquitoes as vectors of arboviral Jingmenviruses in human infections.

Conclusions: This finding provides new insights into the ecology and transmission dynamics of Jingmenviruses, highlighting mosquitoes as potential vectors, alongside ticks, in the zoonotic transmission of this virus group.

Background: Bovine babesiosis is a tick-borne disease that poses a significant economic threat to cattle industries in tropical and subtropical areas, and Babesia bovis is the most virulent causative agent of bovine babesiosis. This apicomplexan parasite infects erythrocytes of cattle, causing severe hemolytic disease, and animals that survive an acute infection become persistently infected for life. Adult cattle (> 1 year of age) are highly susceptible and often succumb to acute infection. Protective host immunity involves peripheral blood mononuclear cells (PBMCs) including monocytes, dendritic cells (DC), natural killer (NK), T cells, and B cells, all of which act to control the pathogen. Monocytes release the cytokines interleukin (IL)-1β and tumor necrosis factor (TNF) and nitric oxide, in addition to chemokines that attract immature DCs. NK cells release IL-12, IL-18, and interferon gamma (IFNγ). Mature DC migrate to secondary lymphoid tissues to present Babesia antigens to T cells. B cells will produce antibodies against Babesia.

Methods: In this study, we examined the transcriptional signatures of PBMCs from adult cattle (aged > 1.5 years) experimentally infected with the B. bovis virulent strain Vir-S74-T3Bo, during the acute phase of babesiosis, at 10 days post infection (dpi), using RNA Sequencing (RNA-Seq) technology.

Results: Transcriptional signatures evident during the acute phase of babesiosis were cytokines and chemokines, such as IL-0, TNF, IL-1B, IL-18, CSF1, CXCL10 and CXCL16; pattern recognition receptors, such as CD14, TLR and NOD2; complement components, such as C1R, C2, C3aR1, CFB, CFI and CFP; cell adhesion molecules, such as ICAM1/2 and SELL; and apoptosis markers, such as CASP, BAX and BAK. We identified 1766 upregulated and 1508 downregulated genes, with fold changes ranging from two- to 429-fold. We discuss our findings in the context of immune responses to acute disease as a mechanism for adult host survival, with a focus on the molecular functions and biological processes involved in the response to B. bovis infection.

Conclusions: In this RNA-Seq analysis, we identified genes that are up- and downregulated in response to acute B. bovis infection. Gene expression of IL-10, along with that of the inflammatory cytokines IL-1β, TNFα and IL-18, suggests a non-protective response to B. bovis at 10 dpi. These results enhance our understanding of the molecular interactions between Babesia and the host immune system.

Background: Invasive alien species (IAS) are rapidly altering ecosystems, undermining biodiversity, ecosystem processes, and interspecies interactions. Although IAS ecological and economic effects are well recognised, their impact on mosquito populations and the dynamics of infectious diseases is poorly understood. Plant-derived sugars are crucial for mosquito biology, supporting nectarivorous male survival and enhancing female blood feeding.

Methods: In this study, we investigated how Parthenium hysterophorus, a rapidly proliferating invasive weed, shapes the population structure and nectar-feeding behaviour of the mosquito vector in the Rift Valley area of Kenya. Across six villages, three heavily infested with P. hysterophorus and three uninfested controls, we collected 48,489 mosquitoes representing 35 species from two subfamilies (Anophelinae and Culicinae) and nine genera, including Anopheles, Aedes, Culex, Mansonia, and Coquillettidia. Mosquito plant feeding was confirmed using the anthrone test, and the ingested flora were identified via DNA barcoding of chloroplast markers, specifically matK, rbcL, and ITS2.

Result: Mosquito abundance was significantly higher in Parthenium-infested villages, particularly during the dry season (p < 0.001), despite similar species diversity across sites. Medically important vectors, including Mansonia africana, Coquillettidia metallicus, Culex pipiens, and Anopheles funestus, were notably more common in invaded habitats. Overall fructose positivity was significantly high in mosquitoes from Parthenium sites (p = 0.046), with females showing especially higher rates (28.1% vs 18.0%; p = 0.0038). DNA barcoding indicated a clear feeding preference for P. hysterophorus among Coq. metallicus, Mn. africana, and An. funestus, alongside other plants such as Lantana camara.

Conclusion: Our findings indicate that P. hysterophorus has a notable impact on mosquito population composition and stimulates sugar-feeding behavior among important vector species. This IAS acts as a sustainable nutritional source, potentially enhancing mosquito survival, extending vector activity in dry seasons, and heightening the risk of arboviral disease transmission. The findings highlight the critical need to integrate invasive plant management within comprehensive mosquito control strategies.

Background: NETosis is a conserved process that has been maintained throughout evolution in various species. However, in the cattle tick Rhipicephalus microplus, a process similar to NETosis, known as ETosis, has not been previously described.

Methods: In this work, we demonstrate, using fluorometry and confocal and electron microscopy, the chromatin release and the extracellular trap (ET) formation in tick hemocytes in response to various treatments.

Results: The treatments analysis showed greater chromatin release in zymosan A-, Escherichia coli-, and LPS-treated hemocytes. This was consistent with the expression of the peroxinectin gene (pxn), the myeloperoxidase (mpo) analog gene in vertebrates, which participates in NETosis activation. Furthermore, DNA fibers were observed in tick hemocytes under all treatments, and transmission electron microscopy (TEM) showed that hemocytes treated with zymosan A have a clear nuclear envelope disruption, with a unidirectional release of chromatin.

Conclusions: This work investigates the existence of ETosis in tick hemocytes, representing a significant step toward understanding the tick's immune response. In addition to this contribution, new areas of research are emerging to understand the molecular mechanisms that govern this process, which we are currently exploring.

Background: Aedes albopictus and Aedes aegypti are key vectors involved in the transmission of human pathogens worldwide. Epidemiological studies have demonstrated varying levels of arbovirus transmission by these mosquito vectors, leading to an increasing number of investigations that assess vector competence (the ability of an insect to become infected and subsequently transmit a pathogen) of Ae. albopictus and Ae. aegypti lines, to decipher the risks associated with each species. In this study, we evaluated the vector competence of Ae. albopictus and Ae. aegypti lines from the Southwestern Indian Ocean (SWIO) for three arboviruses: Zika virus (ZIKV), dengue virus serotype-1 (DENV-1), and chikungunya virus (CHIKV).

Methods: Ten mosquito lines (eight Ae. albopictus and two Ae. aegypti lines), collected from five islands within SWIO (the Seychelles, the Comoros, and the Mascarene archipelagoes), were exposed to epidemic strains of ZIKV, DENV-1, and CHIKV. Three vector competence parameters (infection rate [IR], dissemination efficiency [DE], and transmission efficiency [TE]) were assessed at different days post exposure (dpe) to infectious blood meals, using plaque forming unit (PFU) assays. In addition, viral loads were quantified in positive saliva. These parameters were then compared between mosquito lines, geographic origins, and dpe for each virus.

Results: None of the mosquito lines were competent for the ZIKV strain tested. In contrast, both Ae. albopictus and Ae. aegypti lines were competent vectors for the strains of DENV-1 and CHIKV tested, with transmission efficiencies reaching 35.4% for DENV-1 and 62.5% for CHIKV. For both mosquito species, statistical analyses revealed that dpe significantly influenced vector competence parameters, whereas the geographic origin of mosquito lines did not.

Conclusions: The observed vector competence patterns for the three tested viruses might partly explain their current epidemiology in the SWIO. This approach should involve a larger number of Ae. aegypti lines and should be extended to other ZIKV, DENV, and CHIKV strains, as well as to viruses not currently reported in the region, to better assess the risk of (re-)emergence of mosquito-borne viruses in the SWIO.

Background: Babesia spp. are widespread tick-borne intraerythrocytic protozoa, infecting a broad range of vertebrate hosts. Red foxes are reservoirs of Babesia vulpes, belonging to the Babesia microti-like group (clade I), and play an important role in the epidemiology of canine and wildlife babesiosis. Besides B. vulpes, another species of this genus was molecularly reported in red foxes from Israel and Iraq and provisionally named "Babesia sp. MML-2014"; however, no morphological description of this small Babesia species was provided, preventing a proper species naming.

Methods: Infection with piroplasmid species was detected and described by microscopy of stained blood smears in one red fox from Southern Italy. Molecular characterization of the Babesia sp. and differentiation from B. vulpes was performed through PCR amplification of nuclear (18S rRNA, ITS1-5.8S-ITS2) and mitochondrial (cytochrome c oxidase subunit 1, cox1) gene markers, followed by DNA sequencing and phylogenetic analysis. In addition, Ixodes kaiseri ticks collected from the infected fox were screened for piroplasmids by PCR.

Results: Sequence comparison of piroplasmids showed 98-99% identity with the undescribed Babesia sp. MML-2014 and phylogenetic analyses confirmed that this taxon belongs to the Western group (clade III) and is differentiated by B. vulpes. Morphological and morphometric analyses further demonstrated that Babesia sp. nov. is a distinct small piroplasm and is characterized by unique Maltese cross forms. Based on the above, we named Babesia banethi sp. nov. as a new taxon. In addition, Babesia sp. nov. DNA was detected in the intestine of one engorged I. kaiseri specimen.

Conclusions: This study provides genetic and morphological findings of B. banethi sp. nov. A morphological description with measurements of the parasite forms in red fox erythrocytes, differential diagnosis supplemented by genetic characterization, and the deposition of the holotype in suitable collections have been made in compliance with the ICZN guidelines.

Background: Members of the genus Trichinella are muscle-dwelling zoonotic parasites of global importance for public health, animal husbandry, and trade. Trichinella chanchalensis (T13) is the newest species in the genus, first described in the Yukon and the Northwest Territories, for which the geographical distribution remains unknown due to limitations of the gold standard test for genotyping (multiplex polymerase chain reaction [PCR]). Our primary objective was to determine whether T. chanchalensis was present in Alaska, using a new molecular method that enables the description of the prevalence, co-infection, host associations, and risk factors for Trichinella spp. infection in wild carnivores.

Methods: Trichinella spp. larvae were recovered through artificial digestion of muscle and genotyped using next-generation sequencing (NGS).

Results: Trichinella spp. larvae were detected in 53/157 (34%) animals, namely wolverines (Gulo gulo), arctic foxes (Vulpes lagopus), red foxes (Vulpes vulpes), coyotes (Canis latrans), wolves (Canis lupus), brown bears (Ursus arctos), and polar bears (Ursus maritimus), but not in black bears (Ursus americanus) or lynx (Lynx canadensis). Prevalence was highest in polar bears and wolverines, while intensity (larvae per gram, LPG) was highest in red foxes, arctic foxes, and wolves. Most animals (65%) harbored single infections with Trichinella nativa, followed by mixed infections of T. nativa and Trichinella T6 (33%). A single wolverine was infected with T. nativa, T6, and T. chanchalensis. Combining NGS with statistical methods, we found no evidence of competition between T. nativa and T6 in host muscles. Trichinella spp. infection (primarily T. nativa) was the highest in the Northwestern region, whereas T6 infection probability was higher in the Interior and Southern regions, suggesting differences in environmental resistance even among these three taxa. In a single, highly infected brown bear, we detected a rare case of Trichinella spiralis of foreign origin based on whole-genome sequencing, suggesting illegal importation and disposal of meat.

Conclusions: We report a new geographical record for T. chanchalensis and a rare finding of T. spiralis in North American wildlife, and demonstrate the utility of new NGS methods for describing the ecology of parasites maintained in wildlife hosts commonly presenting as co-infections.