attempt to induce immunity against toxocara canis infection in albino mice parasltological studies

ABSTRACT

This study aimed at preparation and fractionation of the crude second stage Toxocara canis larval antigens and the determination of the optimal dose of the crude and fraction that gave the highest percentage reduction in the larval counts. The crude antigen was prepared from the second stage larvae after hatching of the cultivated larvated eggs obtained from the uteri of adult worms collected from 250 stray puppies. The antigen doses given individually in each group with a total dose of 12.5, 25, 50 and 100 mg protein, respectively. The crude antigen was further fractionated by column chromatography using Sephadex G-200. The dose of each fraction was calculated from the crude optimal dose according to their proportion in the elution volume. All immunized mice were challenged two weeks after the last imunizing dose by 800 larvated eggs. Brain larval count was done 30 days post-challenge to determine the optimal dose giveng the highest percentage reduction. It was found that a total dose of 12.5 mg protein of the crude antigen and the fourth fraction gave the highest percentage reduction in the larval count. These two antigens were further used to study the effect of immunization on humoral antibody responses. This was done by determination of the serum antibody level by the indirect fluorescent antibody test 3, 7, 15, 30 and 60 days post-infection. The antibody responses early and higher in the immunized groups than those of the controls. The maximum antibody level was reached at 15 days post-infection in all groups