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At least 19 recordsLinked to original sources
PubMed1987

Species-specific and common epitopes on the secreted and surface antigens of Toxocara cati and Toxocara canis infective larvae.

It is widely accepted that the major cause of visceral larva migrans (VLM) in man is Toxocara canis infection. This has been largely based on the detection of antibodies to this species. We have compared the antigens of T. canis and Toxocara cati in order to establish whether assay for the former might be compromised by infection with the latter. Comparisons were made by radioiodination of the surface and excretory/secretory (ES) glycoproteins of the infective larvae of both species, immunoprecipitation with poly- and monoclonal reagents, and SDS-PAGE. The SDS-PAGE profiles of surface antigens of the two species showed few similarities, whereas that of the ES material indicated considerable homology. Serum from infected animals and a human VLM patient exhibited complete cross reactivity, although there was evidence in the mouse of a specific response to one of the components of T. cati ES. Testing of ES against a panel of monoclonal antibodies (MoAbs) confirmed the similarity; all but one of the MoAbs recognized several of the components of both sources of ES. The only exception was MoAb Tcn-2, which did not react with T. cati surface, somatic or ES antigens. This antibody is known to recognize a carbohydrate determinant which is widespread on T. canis glycoproteins. This species-specific determinant, therefore, represents a reversal of the consensus that peptide determinants tend to be the more specific. Finally, the MoAbs were used to examine the exposure of shared epitopes on the surface of intact larvae of T. cati. Again, fine differences in binding by anti-carbohydrate monoclonals were observed when the two species of Toxocara were compared, reflecting a distinction in exposure or orientation of surface molecules on these nematodes. Moreover, these epitopes were absent or variably present on the surface of freshly hatched larvae, and full exposure did not occur until about 24 h post-hatching. This delay in the presentation of epitopes might have implications for the process of infection in sensitized hosts. In conclusion, it is probable that the serological response in man to T. canis is, by current serological methods, indistinguishable in specificity from that induced by T. cati infection, and that the MoAb which we describe could be used to permit discrimination.

Animals↗
PubMed1986

Biochemical polymorphism in Parascaris equorum, Toxocara canis and Toxocara cati.

Vertical starch gel electrophoresis was used to resolve proteins encoded by 18 gene loci in ascaridoid nematodes. Estimates of genetic variability were made from population samples of the dog ascarid (Toxocara canis), cat ascarid (Toxocara cati), and the horse ascarid (Parascaris equorum). Levels of polymorphism and mean heterozygosity were high, which is not consistent with the hypothesis that the intestinal environment selects for monomorphism among endoparasites. Most observed allele frequencies conformed to Hardy-Weinberg equilibrium expectations as tested by chi2 goodness-of-fit, suggesting that the proteins evaluated are inherited in a Mendelian fashion and that these nematodes are mating at random. Subunit structures of the following enzymes, deduced from electrophoretic phenotypes of heterozygotes, corresponded to those of vertebrates: lactate dehydrogenase; malate dehydrogenase; 6-phosphogluconate dehydrogenase; phosphoglucomutase; esterase D; peptidase B; peptidase D; and mannose-6-phosphate isomerase. This observation substantiates the conservative nature of polypeptide subunit number across phylogenetically diverse groups of organisms.

Alcohol Oxidoreductases↗
PubMed1980

Studies on the incidence of Toxocara and Toxascaris spp. ova in the environment. 1. A comparison of flotation procedures for recovering Toxocara spp. ova from soil.

Seven different flotation fluids were assessed for their efficiency in recovering Toxocara canis ova from artificially seeded soil samples. Using the most efficient (a saturated solution of magnesium sulphate plus 5% potassium iodide) 25 g amounts of 234 environmental soil samples were examined for the presence of Toxocara spp. and Toxascaris ova. Twenty-six samples (11.1%) yielded ova of one or other species. There was no discernible pattern of distribution of positives with relation to the source of the samples. The maximum number of ova recovered in any one sample was 19. All the ova recovered from the environment were considered viable and potentially infective.

Animals↗
PubMed2002

Immunodiagnosis of ocular toxocariasis using Western-blot for the detection of specific anti-Toxocara IgG and CAP for the measurement of specific anti-Toxocara IgE.

A prospective multicentric study was carried out to assess both the performance of Western-blot (WB) detecting specific anti-Toxocara IgG and that of CAP measuring specific IgE titre for the immunodiagnosis of ocular toxocariasis. For 14 outpatients presenting ophthalmic symptoms (choroiditis, chorioretinitis, papillar oedema, hyalitis, retinal detachment and/or uveitis), samples of serum and aqueous fluid (AF) were sent to the Department of Parasitology, University Hospitals, Toulouse, France. All patients but two tested positive with WB on the serum; 13 WB tests were performed on the AF, 12 of which were positive. The two patients who had a negative WB serum result tested positive for the AF. Specific IgE detection was considered as a complementary test of WB. Two patients showed a greater specific IgE titre in the AF than in the serum, and one had a positive result in the AF, but not in the serum. These six patients were considered as clear cases of ocular toxocariasis. Western-blot coupled with specific anti-Toxocara IgE detection appeared therefore to be an accurate procedure for the immunodiagnosis of ocular toxocariasis, provided the testing was simultaneously performed on the serum and AF.

Adolescent↗
PubMed1995

Effect of various doses of infective Toxocara canis and Toxocara cati eggs on the humoral response and distribution of larvae in mice.

The effect of 5-2,500 infective Toxocara canis and 5-1,000 T. cati eggs on the humoral immune response and on the distribution of larvae in the organism was studied in paratenic hosts--inbred C57BL6/J mice. With each dose of T. canis eggs the maximal antibody level was recorded on day 56 post infection and was followed by a moderate decline that lasted until day 154 of the experiment. A correlation between the antibody level and the egg count was observed only with the infective dose of 5-50 eggs. A more rapid occurrence of antibodies was recorded in mice infected with a high dose of eggs. In those given 5 and 7 T. cati eggs the antibody level exceeded the extinction threshold value only from day 21 to day 84. Low doses of T. canis (n = 5) and T. cati (n = 7) eggs caused a comparable distribution of larvae in mice, and the larval recoveries on day 70 post infection ranged between 10.00% and 25.74%. Following a dose of 500 T. cati eggs, 22.28% of the larvae were recovered, although only 1.08% were localized in the brain. A dose of 1,000 T. canis eggs yielded 36.37% of the larvae, with as much as 28.13% being found in the brain.

Animals↗
PubMed1986

The relationship between toxocara ELISA absorbance values and toxocara ELISA titres: a comparative study.

Enzyme-linked immunosorbent assays (ELISAs) may be made by a variety of techniques at one or several serum dilutions which is very confusing for clinicians. This study compares the ELISA results from two centres on sera from 12 patients investigated for ocular toxocariasis by two common ELISA methods--the absorbance and titration techniques. With one exception, ELISA results by the two methods correlated well. For reasons outlined, the absorbance ELISA method is likely to remain the preferred method in New Zealand and Australia. Attention is drawn to the implications of the serum response to Toxocara canis larvae, and the need to evaluate ELISA results against clinical findings is emphasized.

Absorption↗
PubMed1997

Relationship between allergic manifestations and Toxocara seropositivity: a cross-sectional study among elementary school children.

Toxocara (the cause of visceral larva migrans in humans) and allergy have in common both elevated immunoglobulin E (IgE) levels and eosinophilia. In the present study, we investigated: 1) associations between Toxocara seropositivity and allergic manifestations; 2) risk factors for Toxocara infection; and 3) differences in Toxocara seroprevalence, allergic manifestations and the associations between these two, in children from urban and rural environments. Blood samples from 1,379 Dutch urban and rural elementary schoolchildren, were examined for Toxocara antibodies, eosinophil numbers, total IgE concentrations, and the occurrence of inhaled allergen-specific IgE. Questionnaires investigating respiratory health and putative risk factors for infection were completed. It was found that 8% of the children had Toxocara antibodies, occurring significantly less often in females than in males. The means of total serum IgE levels and blood eosinophils were significantly higher in the Toxocara-seropositive than in the seronegative group. Allergic asthma/recurrent bronchitis was found in 7% of the children, allergic reaction on animal contact in 4%, and IgE to at least one inhaled allergen in 16%. These variables were associated with Toxocara seroprevalence. Inhaled allergen-specific IgE and asthma/recurrent bronchitis occurred significantly less often in rural than in urban areas, and significantly less often among girls than among boys. Furthermore, occurrence of allergen-specific IgE increased significantly with age. No association existed between Toxocara seroprevalence and assumed risks, i.e. contact with pet animals and public playgrounds. In conclusion, our results indicate that allergic manifestations occur more often in Toxocara-seropositive children. A relationship with an already existing allergic condition is plausible.

Animals↗