Hu Jun-Jie, Liu Ting-Ting, Liu Qiong, Esch G W, Chen Jin-Qing, Huang Si, Wen Tao
School of Biological Sciences, Yunnan University, Kunming, 650091, China.
Department of Biology, Wake Forest University, Winston-Salem, NC, 27106, USA.
Parasitol Res. 2016 Oct;115(10):3973-81. doi: 10.1007/s00436-016-5163-6. Epub 2016 Jun 11.
Despite the importance of worldwide goat production, little is known about the prevalence of Sarcocystis spp. in domestic goats (Capra hircus) in China. The aims of the present study were to determine prevalence of Sarcocystis spp. in domestic goats in Kunming, China, as well as to identify parasite species based on morphological characteristics and DNA sequence analysis. Only microscopic sarcocysts of Sarcocystis spp. were detected in 174 of 225 goats (77.3 %). By light and transmission electron microscopy, two species, i.e., Sarcocystis capracanis and Sarcocystis hircicanis, were identified. Two sarcocysts from each of the two species were randomly selected for DNA extraction; the 18S rRNA gene (18S rRNA), the 28S rRNA gene (28S rRNA), and the mitochondrial cytochrome c oxidase subunit 1 (cox1) were amplified by the polymerase chain reaction (PCR) and subsequently sequenced. The results were compared with other previously sequenced Sarcocystis species retrieved from GenBank. There was little sequence variation between two isolates of the same species. S. capracanis was most closely related with Sarcocystis tenella; 18S rRNA, 28S rRNA, and mitochondrial cox1 sequences shared identities of 95.7-99.1, 95.3, and 92.3-93.2 % with those of S. tenella, respectively. Thus, mitochondrial cox1 sequences seem to perform better than 18S rRNA sequences or 28S rRNA sequences for identification of the two species. S. hircicanis was most closely related to Sarcocystis arieticanis, i.e., 18S rRNA and 28S rRNA sequences of the former species shared 97.2-97.4 and 95.6-96.1 % identities with those of latter, respectively. Phylogenetic analysis inferred from the three genetic markers yielded similar results and indicated the two species were within a group of Sarcocystis species with canines as known, or presumed, definitive hosts.
尽管全球山羊生产很重要，但关于中国家养山羊（Capra hircus）中肉孢子虫属（Sarcocystis spp.）的流行情况却知之甚少。本研究的目的是确定中国昆明家养山羊中肉孢子虫属的流行情况，并根据形态特征和DNA序列分析鉴定寄生虫种类。在225只山羊中，仅在174只（77.3%）中检测到肉孢子虫属的微观包囊。通过光学显微镜和透射电子显微镜，鉴定出两种肉孢子虫，即山羊肉孢子虫（Sarcocystis capracanis）和山羊犬肉孢子虫（Sarcocystis hircicanis）。从这两个物种中各随机选取两个包囊进行DNA提取；通过聚合酶链反应（PCR）扩增18S核糖体RNA基因（18S rRNA）、28S核糖体RNA基因（28S rRNA）和线粒体细胞色素c氧化酶亚基1（cox1），随后进行测序。将结果与从GenBank检索到的其他先前测序的肉孢子虫物种进行比较。同一物种的两个分离株之间几乎没有序列变异。山羊肉孢子虫与柔嫩肉孢子虫（Sarcocystis tenella）关系最为密切；18S rRNA序列、28S rRNA序列和线粒体cox1序列与柔嫩肉孢子虫的序列同一性分别为95.7%–99.1%、95.3%和92.3%–93.2%。因此，线粒体cox1序列在鉴定这两个物种方面似乎比18S rRNA序列或28S rRNA序列表现更好。山羊犬肉孢子虫与绵羊肉孢子虫（Sarcocystis arieticanis）关系最为密切，即前者的18S rRNA序列和28S rRNA序列与后者的序列同一性分别为97.2%–97.4%和95.6%–96.1%。从这三个遗传标记推断的系统发育分析产生了相似的结果，并表明这两个物种属于以犬类作为已知或推测终末宿主的肉孢子虫物种组。
