Objective   To analyze the genetic variation of rDNA-ITS2 of Schistosoma japonicum and Paragonimus skrjabini in order to avoid the cross reactions in immune diagnosis between schistosomiasis and paragonimiasis.   Methods   The 2 species of fluke were collected

and then the genomic DNA was extracted

to amplify the gene of rDNA-ITS2 by polymerase chain reaction (PCR) and then sequenced. Multiple sequences were aligned by Clusterx

the genetic distance was analyzed by MEGA4

and the phylogentic tree of rDNA-ITS2 genes of Schistosoma and Paragonimus constructed with MP and NJ method. The motifis of the rDNA-ITS2 gene sequences of Schistosoma and Paragonimus were analyzed with DNAsis.   Results   The results of phylogentic trees of rDNA-ITS2 genes of Schistosoma and Paragonimus were similar. The genetic distance between Schistosoma japonicum and Paragonimus skrjabini was longer

though there was 42.7% similarity between their rDNA-ITS2 gene. There were 3 same transcription factors in the sequences of Schistosoma japonicum as well as Paragonimus skrjabini

AP_2_CS6

bHLH_CS and CAP_site.   Conclusion   Though there are obviously differences between the Schistosoma japonicum and Paragonimus skrjabini at the level of gene

they have significantly similarity in transcription factors of rDNA-ITS2 sequences. It may provide valuable theoretical information for studies on cross-reacting antigen between Schistosoma japonicum and Paragonimus skrjabini at gene level.