Identification and phylogenetic analysis of Parascaris equorum isolated from the Qinghai-Tibetan Plateau area

Zhang Qinqin; Jian Yingna; Zhouzai Cairang; Zhang Xueyong

doi:10.20154/j.cnki.issn1672-9692.2025.01.004

Abstract：The purpose of this study is to provide reference for the classification,identification,population genetic evolution analysis and molecular epidemiological investigation of Parascaris equorum.The morphological characteristics of the suspected Parascaris equorum adult isolates were observed,and the common primers of cox1 gene were used for PCR amplification and sequencing.Further PCR amplification and sequencing were performed using mitochondrial cox1 and nad1 specific gene primers of Parascaris equorum.The two gene sequences were compared with the corresponding gene sequences of Parascaris equorum listed in GenBank to analyze their homology,and the evolutionary tree was constructed to analyze the genetic evolutionary relationship.The results showed that the isolated strains were large,about 19 cm in length,nearly cylindrical,thin at both ends,yellowish-white,with three lips around the mouth.After PCR amplification,the target band appeared at about 450 bp,and the homology between the gene sequence and the cox1 gene sequence of Parascaris equorum was 98.0%.Preliminary results indicated that the nematode belonged to Parascaris equorum.PCR results showed that about 1 052 bp(cox1)and 660 bp(nad1)target bands were amplified,respectively.The homology analysis showed that the homology between the two target gene sequences and the corresponding gene sequences recorded by GenBank was 99.69%and 99.51%,respectively.The results of the evolutionary tree showed that the two genes of this strain were in the same branch as that of Parascaris equorum from different hosts.The results showed that the isolated nematode was successfully identified as Parascaris equorum adult,and its mitochondrial gene homology and genetic evolution relationship were analyzed,which laid a foundation for the classification,identification,population genetic evolution analysis and molecular epidemiological investigation of Parascaris equorum.