Vaccination with ultraviolet-attenuated cercariae of Schistosoma japonicum induced protectiveimmunity against challenge infection in experimental animal models.Our preliminary study on the transcrip-tion levels of IFN-γ and IL-4 in splenic CD4~+ T cells revealed that attenuated cercariae elicited predomi-nantly a Th1 response in mice at the early stage,whereas normal cercariae stimulated primarily Th2-dependent responses.Further analysis on the gene profile of the skin-draining lymph nodes demonstratedthat the levels of IFN-γ were significantly higher in vaccinated mice than those in infected mice at day 4,7and 14 post-vaccination or post-infection.However,for IL-12 and IL-4,the potent inducers of Th1 andTh2 responses,respectively,as well as IL-10,there were no differences over the course of the experimentbetween the infected and vaccinated mice.To explore the underlying factors that may potentially contributeto elevated IFN-γ in vaccinated mice,the mRNA profiles of the skin-draining lymph nodes at day 4 post-exposure were compared using oligonucleotide microarrays.Within the 847 probe sets with increased signalvalues,we focused on chemokines,cytokines and relevant receptors,which were validated by semi-quantitativeRT-PCR,A comprehensive understanding of the immune mechanisms of attenuated cercariae-inducedprotection may contribute to developing efficient vaccination strategies against S.japonicum,especiallyduring the early stare of infection. Vaccination with ultraviolet-attenuated cercariae of Schistosoma japonicum induced protective immunity against challenge infection in experimental animal models. Our preliminary study on the transcrip- tion levels of IFN-γ and IL-4 in splenic CD4 ~ + T cells revealed that attenuated cercariae elicited predomi- nantly a Th1 response in mice at the early stage, while normal cercariae stimulated primarily Th2-dependent responses. Further analysis on the gene profile of the skin-draining lymph nodes demonstrated that the levels of IFN-γ were significantly higher in vaccinated mice than those in infected mice at day 4,7 and 14 post-vaccination or post-infection. Despite, for IL-12 and IL-4, the potent inducers of Th1 and Th2 responses, respectively, as well as IL-10, there were no differences over the course of the experiment between the infected and vaccinated mice. To explore the underlying factors that may potentially contribute to elevated IFN-γ in vaccinated mice, the mRNA profiles of the skin-drainin g lymph nodes at day 4 post-exposure were compared using oligonucleotide microarrays. Whith the 847 probe sets with increased signalvalues, we focused on chemokines, cytokines and relevant receptors, which were validated by semi-quantitative RT-PCR, A comprehensive understanding of the immune mechanisms of attenuated cercariae-inducedprotection may contribute to developing efficient vaccination strategies against S.japonicum, especiallyduring the early stare of infection.