Use of Various Antigens in the Diagnosis of Experimental Toxocariasis

Keimyung Medical Journal 1999;18(2):256-266.

실험적 견회충증 진단에 있어서 여러가지 항원의 효용성

홍재훈; 주종윤

Abstract

Toxocariasis is produced by the migration of the Toxocara canis larvae in extra?intestinal tissues in unnatural hosts or under suitable conditions in natural hosts. Serodiagnosis and treatment may be difficult. The present study was performed to observe the specific reacting antigenic bands of crude extract Toxocara canis adult and larval worm and excre-tory-secretory matirials. Its reaction to the serum IgG antibody obtained from experimentally infected mice. For adult antigen; after homogenization with adult worm; the homogenate was extracted at 4 °C for 2 days and centrifuged at 20;000 g for 1 hr. The supernatant was used as adult antigen. For larval antigen; after homogenization with larvae using ultrasonic homogenizer; the homogenate was handled by same method as adult antigen. The supernatant was used as larval antigen. ES antigen was collected excretory-secretory materials of Toxocara canis larvae cultured in RPMI 1640. Infected sera were obtained from mice infected with Toxocara canis embryonated eggs (A group : infected with 100 embryo-nated eggs ; B group : 500 embryonated eggs). The control sera were obtained from non-infected mice. Serum levels of IgG antibody by ELISA using crude antigen increased from 14 day after infection in adult antigen and ES antigen. But it was not observed the difference between infected sera and non-infected sera in larval antigen. And it was observed very little difference of A group and B group. The best result extressed as positive/negative ratio could be obtained when ES antigen was used. So ES antigen will be able to represent a antigen. By SDS-PAGE in 4-20% linear gel; it was showed to difference of each other antigens. By immunoblot; serum antibody was recognized in ES antigen ; major protein bands with molecular weight of 65.6; 51; 33; 27 and 24.5 kDa bands respectively. Among them 24.5 kDa band reacted even in non-infected control sera. The result of reaction was similar between adult and larval antigen; but intensity of reaction was very weak. These results suggest that Toxocara canis ES antigen will be able to represent a antigen that can be used in the diagnosis of toxocariasis.

Key Words: Toxocariasis, ELISA, Immunoblot Toxocara canis