Abstract: 　Objective To determine the phylogenetic position of Schistosoma sinensium in the genus Schistosoma using mitochondrial cytochrome C oxidase 1 (CO1) and NADH dehydrogenase 1(ND1) as molecular markers. Methods The genomic DNA of adult worms were extracted by the GNTK method. The target regions were amplified by PCR using specific primers. The PCR products were purified before ligation into the plasmid Zero-Blunt. Recombinant plasmids were amplified in E.coli, extracted and purified using routine methods and then sequenced using M13 primers (F/R) on a Licor long read autosequencer. Sequences of related schistosomes were retrieved from GenBank and aligned with our data in the sequence editor ESEE. Gene trees were constructed in PHYLIP and MEGA using both maximum parsimony and neighborjoining methods. For parsimony analysis, all characters were treated as unordered and with equal weights. At least 3 000 cycles of bootstrapping were carried out. For analysis in MEGA, all gap columns were deleted. The third position of codon was included. Results The nucleotide and amino acid sequences of CO1 and ND1 of S.sinensium were obtained. Conclusion The phylogenetic trees from these molecular data suggested that S.sinensium belongs to the Asian schistosome group, and the results coincided with the previous rDNA (ITS2 & LSU) analysis results.

Key words: Schistosoma sinensium, cytochrome C oxidase 1(CO1), NADH dehydrogenase 1 (ND1), phylogenetic analysis