Species identification of diphyllobothriosis causative agent Dibothriocephalus nihonkaiensis found in the summer chum O. keta during spawning migration in the Amur River

The purpose of the research is the species identification of Dibothriocephalus spp. plerocercoids in the summer chum Oncorhynchus keta caught in the Amur River based on analysis of a cytochrome c-oxidase subunit 1 (COX1) gene fragment of mitochondrial DNA. Materials and methods. Using the method of partial helminthological dissection, 64 specimens of the summer chum ( Oncorhynchus keta ) caught in the Amur River in the Ulchsky District of the Khabarovsk Territory were examined. DNA was extracted from fragments of Dibothriocephalus spp. plerocercoids found, and a fragment of the gene encoding mitochondrial cytochrome c-oxidase subunit 1 ( COX1 ) of D. nihonkaiensis was amplified. The amplification products were sequenced using a Sanger sequencing method. The resulting nucleotide sequences were analyzed with the online BLAST algorithm. Results and discussion . Type F plerocercoids were detected in 38 summer chums O. keta . The COX1 gene fragment nucleotide sequences (579 base pairs) obtained by sequencing showed 98.55 to 100% similarity in the analyzed region to the D. nihonkaiensis reference sequences registered in GenBank. These studies confirmed that the summer chums O. keta caught in the Amur River were infected with diphyllobothriosis causative agent D. nihonkaiensis .