Kinetic and avidity of IgY anti-Toxocara antibodies in experimentally infected chickens

IgY Antibodies from Birds: A Review on Affinity and Avidity

IgY antibodies are found in the blood and yolk of eggs. Several studies show the feasibility of utilising IgY for immunotherapy and immunodiagnosis. These antibodies have been studied because they fulfil the current needs for reducing, replacing, and improving the use of animals. Affinity and avidity represent the strength of the antigen-antibody interaction and directly influence antibody action. The aim of this review was to examine the factors that influence the affinity and avidity of IgY antibodies and the methodologies used to determine these variables. In birds, there are few studies on the maturation of antibody affinity and avidity, and these studies suggest that the use of an adjuvant-type of antigen, the animal lineage, the number of immunisations, and the time interfered with the affinity and avidity of IgY antibodies. Regarding the methodologies, most studies use chaotropic agents to determine the avidity index. Studies involving the solution phase and equilibrium titration reactions are also described. These results demonstrate the need for the standardisation of methodologies for the determination of affinity and avidity so that further studies can be performed to optimise the production of high avidity IgY antibodies.

Human Toxocariasis: 2010 to 2020 Contributions from Brazilian Researchers

This is a review of the published contributions made by Brazilian researchers between 2010 and 2020 on the natural history of human toxocariasis and the effects of human toxocariasis on nonhuman paratenic hosts.

Chickens bred extensively as sentinels from soil contamination by Toxocara

Environmental contamination by Toxocara spp eggs can be verified by parasitological techniques, which are mostly laborious, have low sensitivity, and may require repeated tests to establish the contamination status of a certain area. Given the significance of this parasite as an agent of infections in humans, that may cause blindness, especially in children, broilers chickens created extensively were evaluated as possible markers of parasite environmental contamination, through the detection of anti-Toxocara serum antibodies. Eighteen 15-day-old Label Rouge broilers were released on a farm with a history of dogs with Toxocara infection. At 0, 15 and 30 days after the release birds blood samples were taken, as well as soil samples. At the end of the experiment the birds were slaughtered, and the gastrointestinal tract was collected for coprological exams. The presence of anti-Toxocara antibodies resulted in increased reactivity indexes with time, and at 15 days five of the birds were positive and at 30 days, seven birds showed seroconversion. Examination of the soil samples by the centrifugation-flotation method in hyper saturated zinc sulfate solution revealed contamination by embryonated or infertile eggs of Toxocara at all times of collection, as well as the presence of Ascaridia eggs at 15 days after release of birds. Examination of bird's stool samples at the end of the experiment demonstrated 100% infection by Ascaridia galli, however there was no correlation between the counts of this parasite and the ELISA reactivity indices for anti-Toxocara antibodies. The results obtained allow us to infer the possibility of using anti-Toxocara spp-specific antibodies determination in birds raised extensively, which could then serve as sentinels of environmental contamination by this parasite.

IgY antibody and human neurocysticercosis: a novel approach on immunodiagnosis usingTaenia crassicepshydrophobic antigens

Human neurocysticercosis (NCC) is a worldwide neglected disease caused byTaenia soliummetacestode and responsible for various complications and neurological disorders. This study aimed to evaluate the use of specific immunoglobulin Y (IgY) produced by laying hens immunized with a hydrophobic fraction ofTaenia crassicepsmetacestodes (hFTc) in NCC diagnosis. Egg yolk IgY antibodies were fractionated, purified and characterized. Enzyme-linked immunosorbent assay (ELISA) was carried out to evaluate the production kinetics and avidity maturation of anti-hFTcIgY antibodies throughout the IgY obtention process. Antigen recognition tests were carried out by Western blotting and immunofluorescence antibody test using purified and specific anti-hFTcIgY antibodies for detection of parasitic antigens ofT. crassicepsandT. soliummetacestodes. Sandwich ELISA was performed to detect circulating immune complexes formed by IgG and parasitic antigens in human sera. The results showed high diagnostic values (93.2% sensitivity and 94.3% specificity) for immune complexes detection in human sera with confirmed NCC. In conclusion, specific IgY antibodies produced from immunized hens with hFTcantigens were efficient to detectT. soliumimmune complexes in human sera, being an innovative and potential tool for NCC immunodiagnosis.

Frequency of anti-Toxocara antibodies in broiler chickens in southern Brazil

The aim of this study was to evaluate the presence of anti-Toxocara antibodies in naturally infected broiler chickens (n = 189) from the state of Paraná, southern Brazil. The chickens were reared in a semi-intensive system by small family farmers (n = 7). An enzyme-linked immunosorbent assay (ELISA) was performed to detect the presence of anti- Toxocara spp. IgY after serum adsorption with Ascaridia galli antigens. An overall seroprevalence of 67.7% (128/189; 95% CI = 61.1-74.4) was observed. The frequency of positive animals by farm ranged from 29.6% to 100%. The optical density and reactivity index values observed in ELISA test indicated the possible chronicity of infection of the evaluated chickens. Associations between the presence of antibodies and the area where the chickens were reared (p = 0.382) or the population density of dogs on the farm (p = 0.785) were not observed. This study shows a high prevalence of Toxocara spp. antibodies in broiler chickens reared in semi-intensive systems and provides evidence that chickens are a good indicator of environmental contamination by larva migrans agents. Further studies are necessary to assess the risk factors associated with poultry infection and the likelihood of toxocariasis transmission to humans via the ingestion of free-range chicken meat.

Anti-Toxocara spp. IgY antibodies in poultry sold in street markets from Feira de Santana, Bahia, Northeastern Brazil

Since 1950, the human infection by parasites of the genus Toxocara, characterized by migration and permanence of larvae of the parasite in the liver, lungs, eyes, and brain, have been reported. The route of infection is the ingestion of embryonated eggs present in soil and contaminated vegetables, however there are reports of human illness associated with ingestion of viscera of paratenic hosts, including birds. This work aimed to detect the presence of larvae in the tissues and antibodies in the serum of poultry sold in street markets of Feira de Santana, Bahia, Brazil. Over a period of ten months, 100 birds of four street markets in the city were acquired, being examined organs and muscle tissue for the presence of larvae and the serum for the presence of anti-Toxocara spp. antibodies by indirect enzyme-linked immunosorbent assay (ELISA). Helminth larvae were not found in the examination of pepsin digested tissues, but 80 (89.9%) of 89 bird sera examined presented anti-Toxocara spp. IgY antibodies. These results may indicate that birds are coming from contaminated environments, where man and other animals can also be infected.