Abstract: Objective　To investigate the origin of Biomphalaria straminea in China, so as to provide insights into assessment of schistosomiasis mansoni transmission risk and B. straminea control. Methods　Guanlan River, Dasha River, Shenzhen Reservoir, upper and lower reaches of Kuiyong River, and Xinzhen River in Shenzhen, China, were selected as sampling sites. Ten Biomphalaria samples were collected from each site, and genomic DNA was extracted from Biomphalaria samples. DNA samples were obtained from 15 B. straminea sampled from 5 sampling sites in Minas Gerais State, Pará State, Federal District, Pernambuco State, and Sao Paulo State in Brazil, South America. Cytochrome c oxidaseⅠ(COI) and mitochondrial 16S ribosomal RNA (16S rRNA) genes were sampled using the above DNA templates, and the amplified products were sequenced. The COI and 16S rRNA gene sequences were downloaded from GenBank, and the sampling sites were acquired. All COI and 16S rRNA gene sequences were aligned and evolutionary trees of B. straminea were created based on COI and 16S rRNA gene sequences to identify the genetic similarity and evolutionary relationship between B. straminea samples from China and South America. Results　A total of 60 COI gene sequences with a length of 529 bp and 3 haplotypes were obtained from B. straminea sampled from China. There were 165 COI gene sequences of B. straminea retrieved from GenBank, and following alignment with the above 60 gene sequences, a total of 33 haplotypes were obtained. Phylogenetic analysis showed that the three haplotypes of B. straminea from China were clustered into one clade, among which the haplotype China11 and three B. straminea samples from Brazil retrieved from GenBank belonged to the same haplotype. Geographical evolution analysis showed that the B. straminea samples from three sampling sites along eastern coasts of Brazil had the same haplotype with China11, and B. straminea samples from other two sampling sites were closely, genetically related to China11. A total of 60 16S rDNA gene sequences with approximately 322 bp in length were amplified from B. straminea in China, with 2 haplotypes identified. A total of 70 16S rDNA gene sequences of B. straminea were captured from GenBank. Phylogenetic analysis showed that Biomphalaria snails collected from China were clustered into a clade, and the haplotype China64 and the haplotype 229BS from Brazil shared the same haplotype. The 49 16S rDNA gene sequences of B. straminea from 25 sampling sites in southern Brazil, which were captured from GenBank, were included in the present analysis, and the B. straminea from 3 sampling sites shared the same haplotype with China64 in China. Geographical evolution analysis based on COI and 16S rRNA gene sequences showed that B. straminea sampled from eastern coastal areas of Brazil shared the same haplotypes in two gene fragment sequences with Biomphalaria snails collected from China. Conclusions　The Biomphalaria snails in China are characterized as B. straminea, which have a low genetic diversity. The Biomphalaria snails in China have a high genetic similarity with B. straminea sampled from eastern coastal areas of Brazil, which may have originated from the eastern coastal areas of Brazil.

Key words: Biomphalaria straminea, Schistosoma mansoni, Molecular tracing, Mitochondrial 16S ribosomal RNA, Cytochrome c oxidaseⅠ, China, Brazil

摘要： 目的　了解我国藁杆双脐螺来源，为我国曼氏血吸虫病流行风险评估和双脐螺控制提供依据。方法　选择我国深圳市观澜河，大沙河，深圳水库，葵涌河上、下游，新圳河作为采样点，每个采样点采集10个双脐螺样本，提取螺样本基因组DNA。自南美洲巴西米纳斯吉拉斯州、帕拉州、联邦区、伯南布哥州、圣保罗州的5个采样点获得15个藁杆双脐螺DNA样本。对上述DNA样本的细胞色素 c 氧化酶亚基Ⅰ（cytochrome c oxidaseⅠ, COI）和线粒体16S核糖体RNA（16S ribosomal RNA, 16S rRNA）基因进行扩增和测序。同时，从GenBank中下载藁杆双脐螺COI和16S rRNA基因序列，并获取其采样点信息。将所有基因序列进行比对并构建进化树，分析我国和南美洲双脐螺样本的遗传相似度和谱系进化关系。结果　从我国双脐螺样本中共获得60个长度为529 bp的COI序列，其中3个为单倍型。从GenBank中获得165条藁杆双脐螺COI序列，与上述60条序列比对后，共获得33个单倍型。进化树分析显示，采自我国的双脐螺3个单倍型聚在一支，其中单倍型China11与GenBank中获得的来自巴西的3个样本属于同一单倍型。地理进化分析结果显示，巴西东部沿海3个采样点的样本有与我国China11相同的单倍型，另2个采样点的样本与China11亲缘关系较近。扩增我国双脐螺样本16S rDNA基因，共获得60条长度约为322 bp的序列和2个单倍型。从GenBank中获得70条藁杆双脐螺16S rDNA序列。系统进化树分析显示，我国双脐螺样本聚为一支，其中单倍型China64与来自巴西的229BS为同一单倍型。将GenBank中获取的来自巴西南部25个采样点的49个藁杆双脐螺16S rDNA序列纳入分析，发现其中3个采样点的藁杆双脐螺与我国China64有相同的单倍型。综合分析藁杆双脐螺COI和16S rRNA的地理系统进化关系，发现仅巴西东部沿海地带样本与我国双脐螺样本在两个基因片段序列上具有相同单倍型。 结论　我国双脐螺为藁杆双脐螺，遗传多样性较低，与来自巴西东部沿海地区的样本遗传学相似度很高，可能来源于巴西东部沿海地区。 　

关键词: 藁杆双脐螺, 曼氏血吸虫, 分子溯源, 线粒体16S核糖体RNA, 细胞色素 c 氧化酶亚基Ⅰ, 中国, 巴西