A novel Schistosoma japonicum endonuclease homologous to DNase II

Background Recent advances in studies of the Schistosoma japonicum genome have opened new avenues for the elucidation of parasite biology and the identification of novel targets for vaccines, drug development and early diagnostic tools. Results In this study, we surveyed the S. japonicum genome database for genes encoding nucleases. A total of 130 nucleases of 3 classes were found. Transcriptional analysis of these genes using a genomic DNA microarray revealed that the majority of the nucleases were differentially expressed in parasites of different developmental stages or different genders, whereas no obvious transcriptional variation was detected in parasites from different hosts. Further analysis of the putative DNases of S. japonicum revealed a novel DNase II homologue (Sjda) that contained a highly conserved catalytic domain. A recombinant Sjda-GST protein efficiently hydrolysed genomic DNA in the absence of divalent iron. Western-blot and immunofluorescence assays showed that Sjda was mainly expressed on the teguments of female adult parasites and induced early humoral immune responses in infected mice. Conclusions A novel DNase II homologue, Sjda, was identified in S. japonicum . Sjda was mainly distributed on the teguments of adult female parasites and possessed a typical divalent iron-independent DNA catalytic activity. This protein may play an important role in the host–parasite interaction.