Abstract: Objective To explore sequence differentiation of ITS and 28S rDNA-LSU of Orientobilharzia turkestanicum from bovine and caprine hosts. Methods Adult worms of O. turkestanicum from the naturally infected cattle, sheep, cashmere goat and goat were collected and identified morphologically as O. turkestanicum according to existing keys and descriptions. The genomic DNA was extracted from parasites of different hosts. The internal transcribed spacer （ITS, contains ITS-1, 5.8S nuclear ribosomal DNA, ITS-2） and 28S nuclear ribosomal DNA-LSU were amplified by PCR, sequenced and analyzed by Chromas and DNASTAR softwares, and the RNA secondary structure of 28S rDNA-LSU was analyzed by DNAMAN software. Results ITS-1, 5.8S rDNA, ITS-2 and 28S rDNA-LSU of O. turkestanicum from bovine and caprine hosts were 384, 159, 331 and 1 304 bp, respectively. ITS-1 and 5.8S rDNA of O. turkestanicum from different definitive hosts were identical; ITS-2 of O. turkestanicum from cattle, sheep and cashmere goat were identical, with one nucleotide variation compared with that of goat; 28S rDNA-LSU of O. turkestanicum from sheep and cashmere goat were identical, with two nucleotides variation compared with that of cattle and goat. The RNA secondary structure of 28S rDNA LSU of O. turkestanicum from caprine hosts were identical or similar, but with large variation compared with that of cattle. Conclusion The rDNA sequence from different definitive hosts shows nucleotide variations to some extent and the RNA secondary structure of 28S rDNA-LSU from caprine hosts shows large variation in comparison to that of bovine.

Key words: Orientobilharzia turkestanicum, ITS, 5.8S rDNA, 28S rDNA-LSU, Sequence analysis