Abstract: Objective To study the impact of chronic schistosomiasis on the protective immunity induced by vaccine against hepatitis B virus. Methods 24 patients with chronic or advanced schistosomiasis (experimental group) and 26 healthy volunteers (control group) all without hepatitis B virus infection were selected for the study. Sera of the subjects in the two groups were collected before inoculation and on the 35th day after inoculation with yeast-derived recombinant hepatitis B vaccine. The level of anti-Hbs, IL-2 and TNF-α in sera was examined by ELISA respectively. Results Anti-Hbs in both groups were negative before inoculation, with an average absorbance （A value） of 0.134 and 0.150 respectively. After inoculation, positive rate of anti-Hbs was 17% (4/24, average A value 0.145 ) in experimental group and 92% (24/26, average A value was 1.210) in control group. The vaccine against hepatitis B induced significantly higher level of anti-Hbs in healthy volunteers compared with that in schistosomiasis patients (P < 0.01). The level of IL-2 and TNF-α increased in both groups after inoculation without significant difference compared with the level before inoculation. Conclusion The results suggest that the protective immunity of patients with chronic schistosomiasis is deficient to the stimulation of hepatitis B virus and it may involve in a higher incidence of hepatitis B among schistosomiasis patients.

Key words: Chronic schistosomiasis, Hepatitis B vaccine, Anti-HBs, IL-2, TNF-α