Description:
This study compares the susceptibility to Haemonchus contortus infection in two breeds of sheep endemic to the Canary Islands, the Canaria Hair Breed sheep and the Canaria sheep. Sheep were experimentally infected with 20,000 larvae of H. contortus and animals killed on days 7 and 28 post-infection. No difference between sheep breeds were detected in immature worm counts at days 7 or 28 post-infection. However, in comparison to the Canaria sheep breed, the Canaria Hair Breed sheep showed lower mean faecal egg counts, lower adult worm counts, lower number of eggs in utero and female worm stunting. Overall, these data suggest that the Canaria Hair Breed sheep has a greater resistance to H. contortus infection than Canaria sheep, and that this resistance may act at the level of the adult parasite.
Description:
The purpose of this study was to compare the sensitivity and specificity of an ELISA test to detect Fasciola gigantica antigens (coproantigens) in bovine feces, with fecal egg counting and an ELISA for detecting anti-F. gigantica antibodies in serum. Monoclonal antibodies to cathepsin L were generated and used to capture this antigen in feces of infected cattle. Blood, feces, and livers were collected from 150 cattle at an abattoir in Jakarta, Indonesia, for anti-Fasciola antibodies, coproantigen detection, and F. gigantica egg and worm counts. Fluke recovery varied from 1 to 426 per host, with a mean of 32 flukes. The results showed that the sensitivity and specificity of coproantigen detecting ELISA (95 and 91%, respectively) was better than the anti-F. gigantica antibody ELISA (91 and 88%, respectively) and to fecal egg counting (87 and 100%, respectively). The coproantigen ELISA was able to detect 100% of the cattle with >15 flukes. A survey of 305 cattle in central Java over a 10-mo period validated this test in the field, demonstrating a high prevalence of fascioliasis and establishing the test as a useful diagnostic method to determine patent F. gigantica infections in cattle.
Description:
Canaria Hair Breed (CHB) sheep are more resistant than Canaria sheep (CS) to experimental Haemonchus contortus infection. Protective responses appear effective against the adult stage of the parasite, not as commonly reported in other breeds against the larval stages. In this study we have quantified several abomasal immune cells and correlated these with parasitological variables for each breed. A significant negative correlation between CD4+ T cell numbers and worm burden or length at 28 dpi was seen only in CS sheep. Significant negative correlations for both abomasal eosinophils and
Description:
The availability of effective vaccines would add a valuable tool to the management of gastrointestinal nematode infections in livestock. While some experimental vaccines have shown protection in laboratory trials, few have been tested in the field. In the present study, eight month old sheep kept on pasture were treated with anthelmintic 8 weeks before vaccination with a larval surface antigen of the nematode parasite, Haemonchus contortus, under a commercially acceptable protocol, i.e. 2 immunizations using a commercial adjuvant; they were then given a controlled challenge infection 4 weeks later in indoor pens. Vaccination of sheep with 4 increasing doses of antigen resulted in significant reductions of 61% and 27% in cumulative faecal egg counts in the two highest dose groups, and a 69% reduction in worm burden in the highest dose group. Blood loss, as determined by packed cell volume, was also significantly reduced in the highest dose group of sheep. One outlier sheep showed an unusual increase in egg count without a concomitant increase in worm burden compared to the control sheep, indicating a vaccine-induced stress response. Antigen-specific serum antibody levels steadily increased in sheep while on pasture and decreased when transported to indoor pens. No difference in antibody levels could be detected between vaccinated and unvaccinated sheep, but all showed increased antibody levels compared to uninfected control sheep kept in indoors pens for 2–3 months, suggesting sheep were sensitized to the larval antigen either from low dose pasture contamination or cross reaction with pasture-related antigens. The results of these studies confirm the protective properties of the larval surface antigen and its protective effect when vaccinations are performed in the field.
Description:
Galectins are increasingly recognised as important mediators of immune homeostasis and disease regulation, but comparatively little is known about their role in parasite infection. This study investigates the interaction between two ovine galectins, galectin-11 and galectin-14, and the parasitic liver fluke, F. hepatica. Galectin-14 was found in eosinophils infiltrating the tissue surrounding infected bile ducts and secreted in the connective tissue, while galectin-11 was specifically induced in epithelial cells of bile ducts from infected sheep. Strong nuclear staining was observed for galectin-11. Both galectins were found to be secreted into the bile fluid of parasite infected sheep, and were also detected in the excretory/secretory products of adult flukes, following their removal from the ovine host. Recombinant galectin-14, but not recombinant galectin-11, was found to bind specifically to the surface tegument of adult flukes in a carbohydrate dependent manner. This study shows for the first time that both galectin-14 and galectin-11 are produced in liver tissue after chronic liver fluke infection and that they can directly interact with the parasite in the bile ducts. Galectin-11 may also be involved in epithelial cell turnover and cancerogenesis.
Generation of a Novel Bacteriophage Library displaying scFv antibody fragments from the natural Buffalo host to identify antigens from adult Schistosoma japonicum for diagnostic development
Description:
Sheep were sensitized by repeated infection with Haemonchus contortus L3, followed by a 12 week rest period, and an abomasal cannula was surgically implanted in all sheep. Seven of the sensitized sheep were subsequently challenged with 50 000 H. contortus L3 while 4 control sheep were challenged with saline. Biopsy samples were taken using a fibreoptic endoscope on days 0, 1, 2, 3, 5, 7 and 28 after challenge and leukocyte subpopulations quantified by (immuno)histology. Differential blood cell counts were performed on the same days. At the end of the trial, sheep showed significantly reduced worm burdens compared to unsensitized control sheep, confirming their resistance status. Both blood and tissue eosinophils, as well as tissue
Description:
Infections with gastrointestinal nematode parasites are a major problem for the sheep industry in Australia and New Zealand and have been the subject of intensive research to define mechanisms of resistance. The ability to take continuous biopsy samples of infected organs and cannulate both afferent and efferent lymphatics of draining lymph nodes has been particularly useful in illuminating the kinetics of immune responses at the site of infection. Distinct localized immune responses were shown to occur within and between sheep breeds at different sensitization regimes, as well as at different developmental stages of the parasite within the host. Using localized antibodies derived from mucus and lymph nodes, two major antigens have been identified on the infective L3 stage, which may be responsible for inducing protection and have potential as vaccine targets. Recent advances in sheep genomics also offer the potential of gaining further insight into the underlying genetics of resistance to nematode infections.
Description:
With a rising world population and economic development, the global demand for meat, milk and other animal products is increasing dramatically. Controlling parasitic diseases in livestock, in particular helminth infections, could rapidly improve productivity and resource utilization. There is a growing interest in indigenous ruminant breeds because these animals have adapted to survive with minimal maintenance in the presence of high exposure to parasite infection. Recent findings on the mechanisms of parasite resistance in indigenous breeds are discussed, and the possibility that such studies may lead to new insight into the immunity and control of parasites proposed. These findings have important implications for the preservation of poorly characterized local indigenous breeds.
Description:
In the current study, three independent trials directly compared Fasciola gigantica and Fasciola hepatica infection of ITT sheep. In all trials, F. hepatica infection resulted in higher worm burden recoveries and greater physiological damage to ITT sheep. Developmental differences of the two Fasciola species were also observed during the first twelve weeks of a primary infection, where the migration and growth of F. hepatica was more rapid than F. gigantica. Various immunological blood parameters were measured and indicated similar kinetics in the humoral and cellular responses during the time course of infection with each Fasciola species. In contrast to F. hepatica infection, we demonstrate an innate and adaptive comparative ability of ITT sheep to resist the early stages of infection with F. gigantica infection. Unraveling the mechanisms leading to this differential resistance may potentially lead to new methods for the control of fasciolosis and other human liver flukes.
Description:
Asian schistosomiasis is a zoonotic parasitic disease infecting up to a million people and threatening tens of millions more. Control of this disease is hindered by the animal reservoirs of the parasite, in particular the water buffalo (Bubalus bubalis), which is responsible for significant levels of human transmission. A transmission-blocking vaccine administered to buffaloes is a realistic option which would aid in the control of schistosomiasis. This will however require a better understanding of the immunobiology of schistosomiasis in naturally exposed buffaloes, particularly the immune response to migrating schistosome larvae, which are the likely targets of an anti-schistosome vaccine. To address this need we investigated the immune response at the major sites of larval migration, the skin and the lungs, in previously exposed and re-challenged water buffaloes. In the skin, a strong allergic-type inflammatory response occurred, characterised by leukocyte and eosinophil infiltration including the formation of granulocytic abscesses. Additionally at the local skin site, interleukin-5 transcript levels were elevated, while interleukin-10 levels decreased. In the skin-draining lymph node (LN) a predominant type-2 profile was seen in stimulated cells, while in contrast a type-1 profile was detected in the lung draining LN, and these responses occurred consecutively, reflecting the timing of parasite migration. The intense type-2 immune response at the site of cercarial penetration is significantly different to that seen in naive and permissive animal models such as mice, and suggests a possible mechanism for immunity. Preliminary data also suggest a reduced and delayed immune response occurred in buffaloes given high cercarial challenge doses compared with moderate infections, particularly in the skin. This study offers a deeper understanding into the immunobiology of schistosomiasis in a natural host, which may aid in the future design of more effective vaccines.
Description:
Asian schistosomiasis is a zoonotic parasitic disease infecting up to a million people and threatening tens of millions more. Control of this disease is hindered by the animal reservoirs of the parasite, in particular the water buffalo (Bubalus bubalis), which is responsible for significant levels of human transmission. A transmission-blocking vaccine administered to buffaloes is a realistic option which would aid in the control of schistosomiasis. This will however require a better understanding of the immunobiology of schistosomiasis in naturally exposed buffaloes, particularly the immune response to migrating schistosome larvae, which are the likely targets of an anti-schistosome vaccine. To address this need we investigated the immune response at the major sites of larval migration, the skin and the lungs, in previously exposed and re-challenged water buffaloes. In the skin, a strong allergic-type inflammatory response occurred, characterised by leukocyte and eosinophil infiltration including the formation of granulocytic abscesses. Additionally at the local skin site, interleukin-5 transcript levels were elevated, while interleukin-10 levels decreased. In the skin-draining lymph node (LN) a predominant type-2 profile was seen in stimulated cells, while in contrast a type-1 profile was detected in the lung draining LN, and these responses occurred consecutively, reflecting the timing of parasite migration. The intense type-2 immune response at the site of cercarial penetration is significantly different to that seen in naive and permissive animal models such as mice, and suggests a possible mechanism for immunity. Preliminary data also suggest a reduced and delayed immune response occurred in buffaloes given high cercarial challenge doses compared with moderate infections, particularly in the skin. This study offers a deeper understanding into the immunobiology of schistosomiasis in a natural host, which may aid in the future design of more effective vaccines.
Description:
The development of inhalable ‘nanomedicines’ based on biocompatible lipids and polymers is attracting increasing interest worldwide. Our understanding of how pulmonary inflammation impacts on lung distribution and clearance kinetics however, is limited. Similarly, there is limited information on how the inhaled delivery of biocompatible nanomaterials affects existing respiratory disease. We have addressed these knowledge gaps by describing and comparing the pulmonary pharmacokinetic behaviour of a 3H-labelled PEGylated liposome loaded with a model drug (ciprofloxacin) after intratracheal administration to healthy rats and rats with bleomycin-induced lung inflammation by following both 3H label and drug. Cell- and cytokine-based markers of lung inflammation were used to evaluate the response of healthy and inflamed lungs to the liposome. Liposomes were initially cleared more rapidly from inflamed lungs than from healthy lungs, but exhibited similar rates of lung clearance after 3 days. This was interesting given that mucociliary clearance was more efficient from healthy lungs, despite evidence of higher mucus retention in inflamed lungs and reduced association of the liposome with lung tissue. Although the plasma pharmacokinetics of ciprofloxacin did not differ between rats with healthy or inflamed lungs after pulmonary administration, the plasma pharmacokinetics of 3H-phosphatidylcholine suggested higher liposome bioavailability and more prolonged absorption from inflamed lungs. Concentrations of the pro-inflammatory cytokine IL-1β were increased in bronchoalveolar lavage fluid after a single pulmonary dose of liposomes to rats with inflamed lungs, but no other significant changes in lung inflammatory markers were identified in healthy or bleomycin-challenged rats. Pulmonary inflammation has a significant impact on the short term disposition, and longer term clearance kinetics and response of the lungs to inhaled drug-loaded PEGylated liposomes after a single pulmonary dose. [Display omitted] •Pulmonary inflammation had a significant impact on the lung disposition of liposome.•Systemic absorption of lipids, but not of drug, was increased in the inflamed lungs.•Lung inflammation reduced the mucociliary clearance of the liposome dose.•A single liposome dose was not found to exacerbate pre-existing lung inflammation.