Number Of Parasites Research Articles

Mathematical Modeling to Guide Experimental Design: T Cell Clustering as a Case Study.

Mathematical modeling provides a rigorous way to quantify immunological processes and discriminate between alternative mechanisms driving specific biological phenomena. It is typical that mathematical models of immunological phenomena are developed by modelers to explain specific sets of experimental data after the data have been collected by experimental collaborators. Whether the available data are sufficient to accurately estimate model parameters or to discriminate between alternative models is not typically investigated. While previously collected data may be sufficient to guide development of alternative models and help estimating model parameters, such data often do not allow to discriminate between alternative models. As a case study, we develop a series of power analyses to determine optimal sample sizes that allow for accurate estimation of model parameters and for discrimination between alternative models describing clustering of CD8 T cells around Plasmodium liver stages. In our typical experiments, mice are infected intravenously with Plasmodium sporozoites that invade hepatocytes (liver cells), and then activated CD8 T cells are transferred into the infected mice. The number of T cells found in the vicinity of individual infected hepatocytes at different times after T cell transfer is counted using intravital microscopy. We previously developed a series of mathematical models aimed to explain highly variable number of T cells per parasite; one of such models, the density-dependent recruitment (DDR) model, fitted the data from preliminary experiments better than the alternative models, such as the density-independent exit (DIE) model. Here, we show that the ability to discriminate between these alternative models depends on the number of parasites imaged in the analysis; analysis of about [Formula: see text] parasites at 2, 4, and 8h after T cell transfer will allow for over 95% probability to select the correct model. The type of data collected also has an impact; following T cell clustering around individual parasites over time (called as longitudinal (LT) data) allows for a more precise and less biased estimates of the parameters of the DDR model than that generated from a more traditional way of imaging individual parasites in different liver areas/mice (cross-sectional (CS) data). However, LT imaging comes at a cost of a need to keep the mice alive under the microscope for hours which may be ethically unacceptable. We finally show that the number of time points at which the measurements are taken also impacts the precision of estimation of DDR model parameters; in particular, measuring T cell clustering at one time point does not allow accurately estimating all parameters of the DDR model. Using our case study, we propose a general framework on how mathematical modeling can be used to guide experimental designs and power analyses of complex biological processes.

Cardiorespiratory nematodes and co-infections with gastrointestinal parasites in new arrivals at dog and cat shelters in north-western Spain.

Metastrongyloid and trichuroid cardiorespiratory nematodes of dogs and cats are considered emergent in several European countries, and an increase in the number and extent of endemic foci has been described. Since data on their prevalence are limited in this continent, faecal samples from new arrivals (365 dogs and 65 cats) at two animal shelters in North-western Spain were analysed using both floatation and Baermann techniques. In order to confirm the microscopic identification of Metastrongylidae first stage larvae, molecular characterization based on the sequence of the ITS-2 was performed. The possible influence of some variables such as the species, sex and age of the animals and the co-infection with other gastrointestinal parasites on the prevalence of cardiorespiratory nematodes was analysed. The most prevalent metastrongylid was Aelurostrongylus abstrusus (15.4%) followed by Angiostrongylus vasorum (4.1%) and Crenosoma vulpis (1.1%). Regarding trichuroids, Eucoleus aerophilus and/or Eucoleus boehmi eggs were detected in 28 dogs (7.7%) and four cats (6.2%). Almost all animals positive to cardiorespiratory nematodes (86.8%) were co-infected with gastrointestinal parasites. The prevalence of Metastrongylidae and respiratory trichuroids was significantly higher in dogs co-infected with Taenia spp. and Toxocara canis or Giardia duodenalis and Sarcocystis spp., respectively. In cats, a significant higher prevalence of Metastrongylidae nematodes was found in animals co-infected with Toxocara cati. Our results reveal that cardiorespiratory nematodes are common in companion animals from north-western Spain, showing higher prevalences than those previously reported from this country. This investigation represents the first report of C. vulpis, E. aerophilus and E. boehmi in dogs from Spain. The identification of a number of zoonotic parasites is of public health concern. Our results indicate that these nematodes should be included in the differential diagnosis of dogs and cats from north-western Spain showing respiratory or cardiac clinical signs.

Role of dense granule antigen 7 in vertical transmission of Neospora caninum in C57BL/6 mice infected during early pregnancy.

Neosporosis is a parasitic disease affecting the health of dogs and cattle worldwide. It is caused by Neospora caninum, an obligate intracellular apicomplexan parasite. Dogs are its definitive host, it mostly infects livestock animals, especially cattle that acts as intermediate host. It is necessary to have well-established models of abortion and vertical transmission in experimental animals, in order to determine basic control measures for the N. caninum infection. We evaluated the role of N. caninum dense granule antigen 7 (NcGRA7) in the vertical transmission of N. caninum using the C57BL/6 pregnant mouse model. We inoculated mice on day 3.5 of pregnancy with parental Nc-1 or NcGRA7-deficient parasites (NcGRA7KO). Post-mortem analyses were performed on day 30 after birth and the surviving pups were kept until day 30 postpartum. The number of parasites in the brain tissues of offspring from NcGRA7KO-infected dams was significantly lower than that of the Nc-1-infected dams under two infection doses (1×106 and 1×105 tachyzoites/mouse). The vertical transmission rates in the NcGRA7KO-infected group were significantly lower than those of the Nc1-infected group. To understand the mechanism by which the lack of NcGRA7 decreases the vertical transmission, pregnant mice were sacrificed on day 13.5 of pregnancy (10days after infection), although parasite DNA was detected in the placentas, no significant difference was found between the two parasite lines. Histopathological analysis revealed a greater inflammatory response in the placentas from NcGRA7KO-infected dams than in those from the parental strain. This finding correlates with upregulated chemokine mRNA expression for CCL2, CCL8, and CXCL9 in the placentas from the NcGRA7KO-infected mice. In conclusion, these results suggest that loss of NcGRA7 triggers an inflammatory response in the placenta, resulting in decreased vertical transmission of N. caninum.

In-vitro Study on the Anti-leishmania Effects of Silver Nanoparticles on Leishmanaia Major Promastigotes

Background and Objectives: Cutaneous leishmaniasis is one of the most important health-threatening diseases in Iran and other countries. Glucantime is currently used to treat this disease, but due to its side effects and high resistance, alternative therapies such as the use of nanoparticles have been considered by researchers. This study aims to investigate the anti-leishmania activity of silver nanoparticles on Leishmania major in vitro. Methods: This is an experimental study on the anti-leishmania activities of silver nanoparticles at different concentrations of 0.75-0.96 µg/ml after 24, 48 and 72 hours of exposure to 106 live Leishmania major promastigotes. The numbers of live parasites were counted by Trypan Blue on a neobar slide using optical microscope (Hemocytometer method). Glucantime and distilled water were considered as positive and negative controls, respectively. The half-maximal inhibitory concentration (IC50) was calculated by SigmaPlot™ software, v‌ersion 13. All reactions were done three times and their average was considered as final result. Results: All concentrations of silver nanoparticles had anti-leishmania activity, where the concentration of 96 µg/ml had the highest effect (100%) 72 hours after exposure. The IC50 was obtained 36.67, 27.2 and 21.08 µg/ml after 24, 48 and 72 hours of exposure, respectively. Conclusion: Silver nanoparticles have an inhibitory effect on the growth of Leishmania major in different concentrations. However, further in-vivo studies are needed to determine the effictivness of silver nanoparticles.

Vaccine co-display of CSP and Pfs230 on liposomes targeting two Plasmodium falciparum differentiation stages

A vaccine targeting multiple stages of the Plasmodium falciparum parasite life cycle is desirable. The sporozoite surface Circumsporozoite Protein (CSP) is the target of leading anti-infective P. falciparum pre-erythrocytic vaccines. Pfs230, a sexual-stage P. falciparum surface protein, is currently in trials as the basis for a transmission-blocking vaccine, which inhibits parasite development in the mosquito vector. Here, recombinant full-length CSP and a Pfs230 fragment (Pfs230D1+) are co-displayed on immunogenic liposomes to induce immunity against both infection and transmission. Liposomes contain cobalt-porphyrin phospholipid (CoPoP), monophosphoryl lipid A and QS-21, and rapidly bind His-tagged CSP and Pfs230D1+ upon admixture to form bivalent particles that maintain reactivity with conformational monoclonal antibodies. Use of multicolor fluorophore-labeled antigens reveals liposome binding upon admixture, stability in serum and enhanced uptake in murine macrophages in vitro. Bivalent liposomes induce humoral and cellular responses against both CSP and Pfs230D1+. Vaccine-induced antibodies reduce parasite numbers in mosquito midguts in a standard membrane feeding assay. Mice immunized with liposome-displayed antigens or that passively receive antibodies from immunized rabbits have reduced parasite liver burden following challenge with transgenic sporozoites expressing P. falciparum CSP.

Comparative efficacy of five brands of Arthemeter Combination Therapy (ACTS) purchased in Ekiti State, Nigeria

Malaria is one of the most severe public health problems and a leading cause of morbidity and mortality where children and pregnant women are the most affected groups. This may be as a result of resistant of malaria parasites which are mostly traceable to drug adulteration. In this study, Plasmodium berghei NK65, a rodent malaria parasite was used as a model organism to simulate human malaria parasite. The efficacy of five brands of arthemeter combination therapies (ACTs) purchased from pharmacy stores in Ekiti state were evaluated. The drugs were coded Art-Ar, Art-Ph, Art-Ki, Art- Na, and Art-Gy respectively. Twenty-one mice were constituted into seven different groups of three mice. Each mouse was inoculated inter-peritoneally with Plasmodium berghei NK65 and left for 7days for the parasite to manifest. The prepared drug solution was administered on five of the seven groups orally for 10 days, while the remaining groups were used as the positive and the negative control groups. One of the control groups was given chloroquine (positive) and the other normal saline (negative). The antimalarial efficacy of the drugs (ACTs) was determined by examining their influence on the increase or decrease in the number of parasites (parasitemia level). Giemsa stained thin blood smears from the tails were used to assess parasitemia level and the parasites clearance rate. Results show that the average parasite clearance rates were 14.1, 40.6, 25.3, 44.9 and 27.9 for Arthemeter coded as Art-Ar, Art-Ph, Art-Ki, Art- Na and Art-Gy respectively. All the brands significantly cleared all the parasites within 7-9days of the treatment, which shows that adulterated Arthemeter is not presently in the community studied. Therefore, arthemeter combination therapy is recommended as a drug of choice for the treatment of malaria fever in Ekiti State.

The repositioned drugs disulfiram/diethyldithiocarbamate combined to benznidazole: Searching for Chagas disease selective therapy, preventing toxicity and drug resistance.

Chagas disease (CD) affects at least 6 million people in 21 South American countries besides several thousand in other nations all over the world. It is estimated that at least 14,000 people die every year of CD. Since vaccines are not available, chemotherapy remains of pivotal relevance. About 30% of the treated patients cannot complete the therapy because of severe adverse reactions. Thus, the search for novel drugs is required. Here we tested the benznidazole (BZ) combination with the repositioned drug disulfiram (DSF) and its derivative diethyldithiocarbamate (DETC) upon Trypanosoma cruzi in vitro and in vivo. DETC-BZ combination was synergistic diminishing epimastigote proliferation and enhancing selective indexes up to over 10-fold. DETC was effective upon amastigotes of the BZ- partially resistant Y and the BZ-resistant Colombiana strains. The combination reduced proliferation even using low concentrations (e.g., 2.5 µM). Scanning electron microscopy revealed membrane discontinuities and cell body volume reduction. Transmission electron microscopy revealed remarkable enlargement of endoplasmic reticulum cisternae besides, dilated mitochondria with decreased electron density and disorganized kinetoplast DNA. At advanced stages, the cytoplasm vacuolation apparently impaired compartmentation. The fluorescent probe H2-DCFDA indicates the increased production of reactive oxygen species associated with enhanced lipid peroxidation in parasites incubated with DETC. The biochemical measurement indicates the downmodulation of thiol expression. DETC inhibited superoxide dismutase activity on parasites was more pronounced than in infected mice. In order to approach the DETC effects on intracellular infection, peritoneal macrophages were infected with Colombiana trypomastigotes. DETC addition diminished parasite numbers and the DETC-BZ combination was effective, despite the low concentrations used. In the murine infection, the combination significantly enhanced animal survival, decreasing parasitemia over BZ. Histopathology revealed that low doses of BZ-treated animals presented myocardial amastigote, not observed in combination-treated animals. The picrosirius collagen staining showed reduced myocardial fibrosis. Aminotransferase de aspartate, Aminotransferase de alanine, Creatine kinase, and urea plasma levels demonstrated that the combination was non-toxic. As DSF and DETC can reduce the toxicity of other drugs and resistance phenotypes, such a combination may be safe and effective.

Recruitment and Seasonal Occurrence of Parasites in Juvenile Invasive Round Gobies (Neogobius melanostomus) in the St. Lawrence River, Quebec, Canada

The round goby (Neogobius melanostomus) is an invasive species that has become one of the most abundant fish in the St. Lawrence River, Quebec, Canada over the past 15 yr. Since its introduction, the round goby has acquired a number of native parasites, yet little is known about the dynamics of parasite recruitment. To examine this question, young-of-the-year and juvenile round gobies were collected monthly from 2 localities in the river (Îles de la Paix, Île Dorval) from June through November 2012. At Îles de la Paix, round gobies (n = 180) were infected with 3 species of parasites, all larval stages (Diplostomum spp., Tylodelphys scheuringi, Neoechinorhynchus tenellus). Prevalence of the digenean Diplostomum spp. varied from 3.3 to 13.3%, and mean abundance from 0.03 to 0.53 from June through September, with a maximum in August. The digenean T. scheuringi was seen only in August, at a prevalence of 10.0% and a mean abundance of 0.53. The acanthocephalan N. tenellus was observed in June, August, and September, prevalence ranging from 3.3 to 10.0% and mean abundance from 0.03 to 0.27. Maximum infection for all 3 species occurred in August. All infected fish were ≥44 mm in total length (TL). Fish infected with more than 1 parasite species were >60 mm TL. No round goby (n = 178) was infected at Île Dorval. This study demonstrated that the invasive round goby starts to acquire parasite infections in the St. Lawrence River in the first year of life and may contribute to the transmission of some parasites within this ecosystem.

Experimental Study on Primary Bird Co-Infection with Two Plasmodium relictum Lineages-pSGS1 and pGRW11.

Simple SummaryCo-infections with several parasites in one host at the same time are common in the wild. It is conceivable that a host infected with several different parasites may be significantly more affected immunologically than a host infected with only one parasite. However, one plus one is not always two when talking about parasite infections. We followed the infection and some health parameters of twenty-four domestic canaries allocated to four groups: birds in two groups were infected with a single parasite (Plasmodium relictum genetic lineage pSGS1 or P. relictum pGRW11), in one group with both mentioned parasites, and birds in the fourth group were considered as the controls. After infection, the time of appearance of parasites in the blood and developed parasitemia did not differ between groups. Differences in hemoglobin levels and in the numbers of young red blood cells between the control and experimental groups were detected, but observed differences between the groups of infected birds were not statistically significant. This study shows that co-infection with two malarial parasites does not necessarily result in a greater number of parasites and more severe disease to the host.Background: Co-infections are common in the wild. Thus, studies focused on parasite interactions are essential. We aimed to (i) follow the development of two genetic lineages of Plasmodium relictum—pSGS1 and pGRW11—during single infections and co-infections and (ii) evaluate their impact on bird host health. Materials: Twenty-four domestic canaries were allocated to four groups: two groups were infected with parasites of a single genetic lineage, one group was infected with parasites of both genetic lineages, and one group was considered as the control group. Parasitemia, the number of polychromatophils, changes in body weight, and hemoglobin levels were all quantified up to 32 days post-infection. Results: Three birds infected with pSGS1 died within 20 days post-infection. The prepatent period and the peak of parasitemia did not differ significantly between groups. Differences in hemoglobin levels between the control and experimental groups were observed and there was an abnormal increase in the number of polychromatophils in infected birds. In all infected groups, correlations were detected between the number of polychromatophils and parasitemia (positive), and between the number of polychromatophils and hemoglobin levels (negative). Conclusion: This study shows that co-infection with two phylogenetically closely related P. relictum parasites does not alter overall parasitemia and does not cause higher virulence to the host.

Parasites, Bacteria and Viruses of the Edible Dormouse Glis glis (Rodentia: Gliridae) in the Western Palaearctic

An overview of the parasites, bacteria and viruses of Glis glis (Rodentia, Gliridae) inhabiting the Western Palearctic is given. A total of 85 articles published from 1895 to 2021 were reviewed and analysed in our study. According to the literature’s data, 104 species associated with G. glis are recorded: 4 viruses, 8 Protozoa, 6 Cestoda, 6 Trematoda, 4 Nematoda, 1 Heteroptera, 2 Anoplura, 39 Siphonaptera and 34 Acari. The most studied group is ectoparasites. To a lesser extent, parasitic worms in G. glis were studied. There is very little data about the dormouse protozoans and viruses. The most studied parasites, viruses and protozoans of G. glis are in Germany, where 21 species were noted. The largest number of parasites was found in the dormouse in Russia (22), but of two groups only: helminths and ectoparasites. Only 20 out of 104 parasite species recorded in G. glis are host-specific. Most parasites (60 species) found in G. glis have a Palaearctic and cosmopolitan distribution. Three viruses, six species of protozoa and three helminths have veterinary and medical significance as potential pathogens of dangerous zoonoses. Also, many species of fleas, mites and ticks found on G. glis are vectors of a number of dangerous vector-borne diseases in humans and domestic and wild animals.

Biological protection of sugar beet sowings from beet nematode

Goal. To identify the efficiency of the bionematicide Clariva 156, FS (spores of the bacterium Pasteuria nishizawae, strain Pn 1, 0.02 l/seed unit) against beet nematode in sugar beet sowings.
 Methods. Laboratory, field. The research was carried out in Vinnytsia region in the years 2017—2019. Small-scale experiments were established in a natural invasive background. To determine the number of beet nematodes, soil samples were taken and analyzed before sowing and before harvesting sugar beet, as well as after the development of the first generation of the parasite. The accounting of sugar beet yield was carried out by weighing all root crops from each plot and counted per hectare of sowing. The sugar content of roots was determined on the on-stream line Venema by the method of cold-water digestion.
 Results. The use of bionematicide Clariva 156, FS allowed to reduce the number of the first generation of beet nematode by 27.7—35.3% (1.5 times) compared to the density of its population before sowing sugar beet. It is noted that the decrease in the number of parasites in the soil in the first half of the growing season had a positive effect on crop productivity. In particular, in the treatments where the seeds were treated with the biological preparation Clariva 156, FS, root yield increased by 2.3—12.6 t/ha, and the sugar collection increased by 0.5—1.9 t/ha, compared to the treatments without nematicide.
 Conclusions. Given the widespread and significant damage caused by the beet nematode to sugar beet sowings, the problem of protecting this crop from heteroderosis is still relevant. Its solution begins with a nematological survey of fields and ends with the introduction of an integrated control system, an important element of which is the use of biological methods. The obtained results prove that treatment of sugar beet seeds with bionematicide Clariva 156, FS gives the chance to reduce number of the first generation of beet nematode in sugar beet sowings up to 35%.

Sexual and developmental variations of ecto-parasitism in damselflies.

The prevalence and intensity of parasitism can have different fitness costs between sexes, and across species and developmental stages. This variation could arise because of species specific sexual and developmental differences in body condition, immunity, and resistance. Theory predicts that the prevalence of parasitism will be greater in individuals with poor body condition and the intensity of parasitism will be greater in individuals with larger body size. These predictions have been tested and verified in vertebrates. In insects, however, contradictory evidence has been found in different taxa. Here, we tested these predictions on two species of Agriocnemis (Agriocnemis femina and Agriocnemis pygmaea) damselflies, which are parasitized by Arrenurus water mite ectoparasites. We measured body weight, total body length, abdomen area and thorax area of non-parasitized damselflies and found body condition varied between males and females, between immature females and mature females and between A. femina and A. pygmaea. Then, we calculated the parasite prevalence, i.e., the absence or presence of parasites and intensity, i.e., the number of parasites per infected damselfly in eleven natural populations of both species. In line to our predictions, we observed greater prevalence in immature females than mature females but found no difference in parasite prevalence between males and females. Furthermore, we found that parasite intensity was higher in females than males and in immature females than mature females. Our result also showed that the frequency and intensity of parasitism varied between the two studied species, being higher in A. pygmaea than A. femina. Our study provides evidence that parasitism impacts sexes, developmental stages and species differentially and suggests that variation may occur due to sex, developmental stage, and species-specific resistance and tolerance mechanism.

Areca catechu L. and Anredera cordifolia (Ten) Steenis supplementation reduces faecal parasites and improves caecal histopathology in laying hens

ABSTRACT Some studies have shown that the betel nut Areca catechu L and “binahong” leaves Anredera cordifolia (Ten) Steenis have anti-parasite and wound healing properties. This study evaluated the effect of A. catechu nut and A. cordifolia leaves powder supplementation on faecal parasite number and type, histopathology of the intestine, caecum, associated organs, some serum biochemistry, and egg production of laying hens. Twenty-four 54-week-old ISA-brown laying hens from local layer farmers were assigned randomly into 4-treatment groups: 1) without supplementation (T0), 2) supplemented with 0.25% (T0.25%), 3) 0.5% (T0.5%), 4) 1.0% (T1.0%). We carried out the supplementation for 18 days by administering A. catechu nut powder for 3-days, and subsequently, A. cordifolia leaves powder for another 3-days for 3-rounds to control the parasite larvae. Faecal parasite count and type were enumerated at the beginning and end of treatment. Egg production was recorded daily during the 18 days experiment. Blood was sampled at the end of the experiment to determine serum albumin, globulin, and transaminases. The intestinal tract, liver, and spleen samples were collected at the end of the study for histopathological examination. Faecal Ascaridia galli in control hens increased by 87.5% after 18 days of the experiment, while A. catechu nut and A. cordifolia leaves powder supplementation prevented such an increase. Supplemented hens have a better reduction of Railentina cesticillus compared to control birds. Supplementation improved intestinal and other tissue histopathology, especially in the caecum (free of erosion), improving serum albumin and transaminases without affecting egg production.

Prevalence and intensity of parasitic worm eggs of bali cow (Bos sondaicus Muller) feces from two different shed sanitations

Bali cow (Bos sondaicus Muller) is a cow that is widely maintained. Poor sanitation of cowshed is caused by cow feces that are not cleaned, and become a medium of transmission of gastrointestinal worm parasites. The study aimed to compare the prevalence, intensity and degree of infection of parasitic worm eggs in the feces of Bali cows from two different shed sanitation, from a shed with poor sanitation and a from shed with good sanitation. The eggs of parasitic worms are separated from feces by buoyant methods and by sedimentation methods. The results showed that 15 out of 16 samples of Balinese cows contained parasites with a total of 43 worm eggs. The number of parasites obtained from Bali cow feces samples from shed with poor sanitation is higher (31 worm eggs) than that obtained from a well-sanitized shed (12 worm eggs). The prevalence, intensity and degree of parasitic infection obtained from Bali cow feces samples from a shed with poor sanitation were higher than those obtained from a shed with good sanitation. The results showed that poor shed sanitation increased the chances of cows being infected with parasites so that the prevalence, intensity and degree of infection of parasitic worm eggs were also high.

Amphotericin B is usually underdosed in the treatment of experimental cutaneous leishmaniasis

Introduction: Amphotericin B is an effective drug for the treatment of the different clinical forms of leishmaniasis. However, there are reports of its ineffectiveness in animals experimentally infected with Leishmania spp. That is why, the objective of the present work was to evaluate the balance of activity-toxicity at amphotericin B doses over 1 mg/kg, so that its use as a positive control antileishmanial drug were adequate.
 Method: BALB/c mice were experimentally infected with L. amazonensis and treated with amphotericin B by intraperitoneal route at doses from 5 mg/kg to 12.5 mg/kg, beginning 21 days after infection. The size of the lesions and the body weight of the mice were measured for eleven weeks after the commencement of treatment. The number of parasites was also determined three days after the end of treatment.
 Results: Amphotericin B at 5 mg/kg retarded lesions growth but neither reduced lesion size nor the parasite load at lesion site. Doses of 7.5 mg/kg to 10 mg/kg, every 48 h for 14 days (7 doses) caused a significant reduction of lesion size and parasite load without evident loss of body weight and without signs of toxicity. Amphotericin B at 12.5 mg/kg was more effective but produced unacceptable toxicity.
 Conclusions: The results support the use of amphotericin B as a positive control drug in BALB/c mice experimentally infected with L. amazonensis at doses of 7.5 mg/kg to 10 mg/kg to achieve an effect comparable to that observed in clinical practice.

Larval Exposure to Parasitic Varroa destructor Mites Triggers Specific Immune Responses in Different Honey Bee Castes and Species.

Innate immune systems are key defenses of animals and particularly important in species that lack the sophisticated adaptive immune systems as found in vertebrates. Here, we were interested to quantify variation in innate immune responses of insects in hosts that differ in their parasite susceptibility. To do this, we studied immune responses in honey bees, which can host a remarkable number of different parasites, which are major contributors of declining bee health and colony losses. The most significant parasite of honey bees is the mite Varroa destructor, which has infested the majority of global honey bee populations, and its control remains a major challenge for beekeepers. However, a number of nonmanaged honey bees seem able to control Varroa infections, for example, the Eastern honey bee Apis ceranacerana or the African honey bee Apis mellifera scutellata. These bees therefore make interesting study subjects to identify underlaying resistance traits, for example, by comparing them to more susceptible bee genotypes such as Western honey bees (A. melliferaligustica). We conducted a series of interlinked experiments and started with behavioral assays to compare the attractiveness of bee larvae to mites using different honey bee genotypes and castes. We found that 6-day-old larvae are always most attractive to mites, independently of genotype or castes. In a next step, we compared volatile profiles of the most attractive larvae to test whether they could be used by mites for host selection. We found that the abundance of volatile compounds differed between larval ages, but we also found significant differences between genotypes and castes. To further study the expected underlaying physiological differences between potentially resistant and susceptible host larvae, we compared the larval hemolymph proteomes of the three honey bee genotypes and two castes in response to mite exposure. We identified consistent upregulation of immune and stress-related genes in Varroa-exposed larvae, which differed between genotypes and castes. Tolerant honey bee castes and genotypes were characterized by stronger or more distinct immune esponses. In summary, we provide first insights into the complex involvement of the innate immune system of tolerant honey bees against mite infestations, which could be used for future breeding purposes.

Parasite‐mediated sexual selection in a damselfly

AbstractSexual selection can improve population fitness and purge deleterious mutation from the gene pool by promoting condition‐dependent mate selection. One ecological factor that reduces individual condition is parasitism. Parasitism tends to increase hosts' mutation load and likely indicates inferior host genetic quality. Parasite‐mediated selection, therefore, should favour the mating success of parasite‐resistant individuals over parasitised individuals. We tested this hypothesis in male Agriocnemis pygmaea damselflies, which are parasitised by Arrenurus water mites. We calculated frequency (i.e. the proportion of parasitism) and intensity (i.e. the number of parasites per parasitised individual) of parasitism in free‐flying males and males in copula in seven natural populations. We predicted that males observed mating will be less likely to be parasitised than expected based on the frequency of parasitism in the population. We further predicted that parasite intensity would be lower in males caught in copula than single males. We found that parasitised males were significantly less likely to be found in copula than non‐parasitised males, independent of their occurrence frequency. However, there was no difference in the average parasite load between males captured in copula or free‐flying males. Our study shows that in addition to natural selection, sexual selection is a strong agent against parasitism and implies that it could promote local adaptation to counteract parasite driven extinction risks.

Improved efficacy of meglumine antimoniate incorporated in anionic liposomes against Leishmania infantum infecting canine macrophages.

Leishmaniasis is a zoonotic disease and several drugs have been used in the treatment, including meglumine antimoniate (AME). The chemotherapy reaches clinical cure but does not eliminate parasites, contributing to drug resistance. To improve AME efficacy we incorporated it in anionic liposomes. The antiparasitic activity and intracellular localization were investigated in canine macrophages infected with Leishmania infantum. Liposomes (L-AME) is composed of egg phosphatidylcholine, cholesterol, palmitoyl oleoyl phosphatidyl serine and α-tocopherol (4 : 3 : 0.4 : 0.07 mol%) plus AME. L-AME size, polydispersity, zeta potential and morphology were analysed as well as antileishmanial activity and intracellular localization in DH82 macrophages. Liposomes (360 nm) zeta potential range from -40 to -65 mV, had 23% encapsulation efficiency and were stable for 180 days at 4°C. Free AME was cytotoxic towards L. infantum infected macrophages (ID50 = 0.012 M) while L-AME did not reduce cell viability. L-AME colocalized with parasites inside macrophages in a time-dependent manner, and reduced the percentage of infected cells and the number of intracellular parasites, decreasing the infection index (75-80%) twice as compared with AME treatment. Liposomal AME is a promising delivery system for treating visceral leishmaniasis, improving meglumine efficacy against L. infantum and minimizing its cytotoxicity towards canine macrophages.

Microbial regulation of intestinal motility provides resistance against helminth infection

Soil-transmitted helminths cause widespread disease, infecting ~1.5 billion people living within poverty-stricken regions of tropical and subtropical countries. As adult worms inhabit the intestine alongside bacterial communities, we determined whether the bacterial microbiota impacted on host resistance against intestinal helminth infection. We infected germ-free, antibiotic-treated and specific pathogen-free mice, with the intestinal helminth Heligmosomoides polygyrus bakeri. Mice harboured increased parasite numbers in the absence of a bacterial microbiota, despite mounting a robust helminth-induced type 2 immune response. Alterations to parasite behaviour could already be observed at early time points following infection, including more proximal distribution of infective larvae along the intestinal tract and increased migration in a Baermann assay. Mice lacking a complex bacterial microbiota exhibited reduced levels of intestinal acetylcholine, a major excitatory intestinal neurotransmitter that promotes intestinal transit by activating muscarinic receptors. Both intestinal motility and host resistance against larval infection were restored by treatment with the muscarinic agonist bethanechol. These data provide evidence that a complex bacterial microbiota provides the host with resistance against intestinal helminths via its ability to regulate intestinal motility.

Toxoplasma gondii and Neospora caninum Infections in Stray Cats and Dogs in the Qinghai-Tibetan Plateau Area, China.

Simple SummaryDiseases caused by parasites have introduced serious threats to human health and the development of animal husbandry in the Qinghai–Tibetan Plateau Area (QTPA), such as toxoplasmosis caused by Toxoplasma gondii and neosporosis caused by Neospora caninum. However, information on the epidemiology of toxoplasmosis and neosporosis in stray cats and dogs which are the definitive hosts of T. gondii and N. caninum in the QTPA is limited. The aim of this study was to establish a detailed record of the seroprevalence of T. gondii and N. caninum-specific IgG and IgM antibodies in serum samples and the molecular epidemiology in feces from stray cats and dogs in the plateau area. The results revealed that stray cats and dogs in the QTPA, China present both T. gondii and N. caninum infection through the antibodies and antigen detection of the indirect ELISA tests and qPCRs. The present study suggests the prevalence of acute neosporosis and chronic re-emergence of toxoplasmosis in stray cats and dogs in the testing area. To the best of our knowledge, this is the first report of T. gondii and N. caninum infection in cats and dogs in the QTPA, and the first determination of N. caninum infection in cats in China. In conclusion, stray cats and dogs play key roles in the transmission and prevalence of T. gondii and N. caninum in the plateau area.Toxoplasma gondii and Neospora caninum belong to the Apicomplexan protozoa which is an obligate intracellular parasite, causing toxoplasmosis and neosporosis throughout the world. Cats and dogs are the definitive hosts of these two parasites. However, information on the epidemiology of toxoplasmosis and neosporosis in stray cats and dogs in the Qinghai–Tibetan Plateau Area (QTPA) is limited, and little is known about the diversity of the diseases. Therefore, the aim of this study was to perform indirect ELISA tests based on recombinant TgSAG1, TgGRA1, NcSAG1 and NcGRA7 proteins to establish a detailed record of the seroprevalence of T. gondii and N. caninum-specific IgG and IgM antibodies in serum samples and to develop qPCR amplification based on TgB1 and NcNc5 genes to conduct molecular epidemiology in feces from stray cats and dogs in the QTPA. In the current study, a total of 128 cat serum samples were analyzed through serological tests in which 53 (41.4%) and 57 (44.5%) samples were found positive for T. gondii specific-IgG and IgM antibodies, and 2 (1.6%) and 74 (57.8%) samples were confirmed positive for N. caninum specific-IgG and IgM antibodies, respectively. Out of 224 stray dog sera, 59.8% and 58.9% were recorded as positive against anti-Toxoplasma IgG and IgM antibodies, 17.9% and 64.7% were detected positive against Neospora IgG and IgM. On the other hand, 1 of 18 cat fecal samples was successfully amplified within the Ct value of 10 to 30 while no cat was positive for neosporosis. Moreover, a higher prevalence of toxoplasmosis in stray dogs (14.5%, 16/110) than of neosporosis (5.5%, 6/110) with different parasite numbers were found. Further analysis showed that no significant sex differences were found nor between the overall infection rates of T. gondii and N. caninum in this study. This study suggests that stray cats and dogs play key roles in the transmission and prevalence of T. gondii and N. caninum in the plateau area.