Abstract:

In order to identify the species of nematodes isolated from dolphin fecal samples, the morphology of the isolated nematodes is first identified. The parasite's body length was observed to be 120-140 mm long, with a cylindrical shape and slender ends. Its appearance was milky white and translucent, and its internal structure was observed to be yellowish under the microscope. It can be seen that the front end of the esophagus is thin and gradually expands backwards. We extracted the genomic DNA of the isolated worm and amplified the 28S rRNA D2-D3 gene and ITS gene fragments by PCR for molecular identification. The PCR results showed that the amplification products of the 28S rRNA D2-D3 gene and ITS gene were 797 and 840 bp, respectively. BLAST alignment results showed that the sequence similarity between the 28S rRNA D2-D3 gene (GenBank accession number OR345165) and the Anisakis typical (GenBank accession number HF911524.1) was 95.36%. The sequence similarity between the ITS gene (GenBank accession number OR345164) and the Anisakis typical (GenBank accession number MF668919.1) was 97.11%, with a 91.90% sequence identity between the ITS-1 region and the Anisakis typical (GenBank accession number MF668919.1). There is a 94.97% sequence identity between the ITS-2 region and the Anisakis typical (GenBank accession number JN968938.1) and a 100.00% sequence identity between the 5.8S rRNA region and the Anisakis typical (GenBank accession number OQ244221.1). Phylogenetic analyses based on the ITS gene and the 28S rRNA D2-D3 gene showed that the parasite samples isolated in this study were genetically closest to the Anisakis typical, and on the same branch.In summary, the isolated parasite samples obtained from this study should be the larvae of Anisakis typical based on microscopic examination and molecular analysis.

Key words: Anisakis, zoonosis, morphological observation, molecular identification, phylogenetic tree