Abstract: 　Objective To investigate the change of specific antibodies IgG, IgG1 subclass and IgE in sheep infected with Echinococcus granulosus(E.g) during anaphylactic shock, and to observe antigen B reactivity against IgG antibody in E.g|infected sheep. Methods Antigen B and crude antigen were prepared with E.g cyst fluid (EgCF) from infected sheep. The enzyme|linked immunosorbent assay(ELISA) was used for detecting the level of specific IgG, IgG1 and IgE during anaphylactic shock in sheep induced by E.g. Results The level of specific IgG, IgG1 and IgE was significantly higher in the infected sheep after 6 months than that of the uninfected control group (P<0.01). The IgE level decreased rapidly after anaphylactic shock induced, especially when the sheep was dying. Following an antigen challenge the sheep showed a general decrease in total IgG and IgG1 subclass. The total IgG showed a slight change at the beginning,followed by a decrease 1 h after challenge. The decrease of IgG1 subclass was more significant than the total IgG in 40 min after challenge injection. The positive rate was 91% for antigen B and 32% for crude antigen of EgCF against IgG antibody in E.g|infected sheep. Conclusion The specific IgE plays a major role in the anaphylactic shock, while IgG and IgG1 antibodies are also important. Antigen B derived from sheep E.g cyst fluid appears to be useful in serodiagnosis of and monitoring on the infection status in sheep.

Key words: Echinococcus granulosus, sheep, anaphylactic shock, antibody, Antigen B