간흡충 재감염의 특이 항원-항체 면역반응

Abstract

This study was undertaken to evaluate antigen-antibody immune reaction which was specific to re-infection in clonorchiasis. The antigens were crude extract antigen (CsW) and excretory-secretory product antigen (CsE) from adult C. sinensis. The changing patterns of anti-C. sinensis IgG antibodies were observed by ELISA. The component antigenic proteins in CsW and CsE were observed by SDS-PAGE and Western-blot. As a single-infection, rats were infected with 50 or 100 and rabbits were challenged with 150 or 450 C. sinensis metacercariae. In re-infection group, rats were infected primarily with 50 and secondly 50 on 2 weeks post-infection (PI) and rabbits were primarily 150 and secondly 300 metacercariae on 8 weeks PI. Twenty-two C. sinensis egg-positives who had raw eating of fresh water fishes over once a year were regarded as a reinfection-suspected human. Fourteen egg-positives without raw-fish history were as single-infection. After the re-infection, the specific IgG antibody titer was rising after 2 weeks post-re-infection (PRI). The titer was 100% higher than those of single-infection until 6 weeks PRI. After then titers became same level in three groups. In the rabbit, the titer in reinfection was increasing from 1 week to 13 weeks PRI 30% more than those of single-infection, and then decreased to be same in three groups. In human, the mean titer in reinfection was same to that in single-infection. In Western-blot using CsE, The 7 kDa antigen band appeared more dense in re-infection than single-infection in rabbit not in rat. However, the 5 kDa band of CsW was observed from 12 to 39 weeks PRI in the rats and from 1 to 13 weeks PRI in the rabbits only in re-infection. The 10 kDa band was seen in response to the infection or the re-infection, so a double-band was specific to re-infection. In human, the 5 kDa band appeared 12 in 22 (54.5%) re-infection, but 1 in 14 (7.1%) in single-infection. In addition, the 10 kDa band was positive as 77.3% in re-infection and 64.3% in single-infection. In conclusion, re-infection with C. sinensis has provoked substantial anti-C. sinensis IgG antibody and 5 kDa low-molecular antigen was not sensitized in primary infection but its immune reaction was observed only after re-infection by antigenic boosting in the animals. In human clonorchiasis, the 5 kDa antigen band was significantly detected in re-infection too. In this context, the 5 kDa antigen which was named 'K3 antigen' was helpful to diagnose reinfected cases in human clonorchiasis.