目的 鉴定齐齐哈尔市家鸭感染的棘口吸虫种类，并分析其核糖体全基因组序列特征及亲缘关系。方法 2024年7月于齐齐哈尔市家鸭肠道中采集棘口吸虫，通过压片法观察其形态学特征。提取虫体DNA，PCR扩增内转录间隔区2（ITS2）序列进行虫种鉴定。扩增核糖体全基因组序列并进行特征分析，测序结果在NCBI进行BLAST比对以确定基因边界，使用基因重复序列计算器检查重复序列，用RNAstructure软件预测核糖体小亚基（18S）、5.8S核糖体基因（5.8S）和核糖体大亚基（28S）的二级结构，用Megalign软件进行序列相似性分析，并使用MEGA 7.0、Clustal X、Paup和Mrbayes软件进行序列对齐，并以18S、ITS、28S序列为标记基因，采用最大简约法构建系统进化树。结果 共收集到3条棘口吸虫。虫体呈长叶形，头领发达，有37枚头棘。PCR扩增的ITS序列长度为1 037 bp，其中ITS2序列为431 bp，与泰国和俄罗斯分离的宫川棘口吸虫（GenBank登录号分别为PQ821045、OP696595）序列一致性均为99.77%，鉴定为宫川棘口吸虫。PCR扩增的宫川棘口吸虫核糖体全基因组序列长度为9 522 bp，其中18S、ITS1、5.8S、ITS2、28S和基因间隔区（IGS）序列长度分别为1 989、444、162、431、3 858和2 638 bp。将18S、ITS和28S提交至GenBank数据库，获得登录号为PV455727；IGS序列提交至GenBase数据库，获得登录号为C_AA117515.1。ITS2、28S和IGS序列具有重复序列，重复序列最多的为28S序列。核糖体DNA（rDNA）序列与宫川棘口吸虫（GenBank登录号为OR509027）序列一致性最高，达99.3%。二级结构预测结果显示，18S rRNA二级结构由多个茎环结构组成，呈“三叶草”形状；5.8S rRNA二级结构相对较小且较为紧凑，通过内部碱基配对形成稳定的构象；28S rRNA二级结构比较复杂，呈“多臂结构”。系统进化树结果显示，进化树均分为两大分支，本研究中的序列与已报道的宫川棘口吸虫聚集在1个小分支。结论 齐齐哈尔市家鸭感染的棘口吸虫为宫川棘口吸虫，其核糖体基因组ITS2、28S和IGS序列有重复序列，且与其他研究中的宫川棘口吸虫和卷棘口吸虫具有较近的亲缘关系。

Objective To identify the Echinostoma species from domestic ducks in Qiqihar City and analyze the characteristics and phylogenetic relationships of the Echinostoma ribosomal whole-genome sequences. Methods Echinostoma parasites were collected from the intestines of domestic ducks in Qiqihar City on July 2024, and the morphological characteristics of Echinostoma parasites were observed using the squash method. The DNA of the parasites was extracted and the internal transcribed spacer 2 (ITS2) sequence was amplified by PCR for parasites species identification, the ribosomal whole-genome sequence was amplified and subjected to sequence characteristics analysis. The sequencing results were aligned those recorded in the NCBI database using the BLAST tool to determine gene boundaries, and the presence of repetitive sequences was checked using a gene repeat sequence calculator. The secondary structure of the 18S, 5.8S and 28S was predicted using the RNAstructure software, and sequence similarity analysis was performed using the Megalign software. Sequence alignment was conducted using the MEGA 7.0, Clustal X, Paup, and Mrbayes software, and phylogenetic trees were constructed using the maximum parsimony method with 18S, ITS, and 28S sequences as marker genes. Results Three Echinostoma were isolated, which appeared a long leaf-like shape and had a well-developed head collar that contained 37 collar spines. The ITS sequence had a length of 1 037 bp, and the ITS2 sequence was 431 bp in length, which shared a 99.77% similarity with the ITS2 sequences of E. miyagawai isolated from Thailand (GenBank accession number: PQ821045) and Russia (GenBank accession number: OP696595), confirming the species as E. miyagawai. The ribosomal whole-genome sequence of E. miyagawai was 9 522 bp in length, and the lengths of the 18S, ITS1, 5.8S, ITS2, 28S and intergenic spacer (IGS) sequences were 1 989, 444, 162, 431, 3 858 and 2 638 bp, respectively. The 18S, ITS and 28S sequences were submitted to the GenBank database, with the accession number of PV455727; and the IGS sequence was submitted to the GenBase databases, with the accession number of C_AA117515.1. Repetitive sequences were found in ITS2, 28S, and IGS sequences, with the highest number of repetitive sequences seen in the 28S sequence. The rDNA sequence showed the highest similarity (99.3%) with the ribosomal genome sequence of E. miyagawai (GenBank accession number: OR509027). The secondary structure of 18S rRNA was composed of multiple stem-loop structures, which appeared a clover-like shape, and the secondary structure of 5.8S rRNA was relatively small and compact and formed a stable conformation via internal base pairs, while the secondary structure of 28S rRNA was complicated and appeared a multi-arm structure. Phylogenetic analysis revealed that phylogenetic trees were clustered into two clades, and the sequences in this study clustered on a small branch with those reported for E. miyagawai. Conclusion The Echinostoma species infecting domestic ducks in Qiqihar City is identified as E. miyagawai, and its ribosomal genome ITS2, 28S, and IGS sequences contain repetitive sequences and show close phylogenetic relationships with other E. miyagawai and E. revolutum from previous studies.