Masuda Aya, Sumiyoshi Toshiaki, Ohtaki Tadatoshi, Matsumoto Jun
Department of Veterinary Medicine, College of Bioresource Sciences, Nihon University, 1866 Kameino, Fujisawa, Kanagawa 252-0880, Japan.
Parasitol Int. 2018 Dec;67(6):702-705. doi: 10.1016/j.parint.2018.07.005. Epub 2018 Jul 18.
Blastocystis is an intestinal protist, commonly found in the human population and in a wide range of animals globally. Currently, isolates from mammalian and avian hosts are classified into 17 subtypes (STs) based on phylogeny of the small subunit rRNA gene (SSU rDNA), of which ten (ST1-9, 12) are reported in humans. ST10 is a major ST reported from livestock cattle. However, other STs including ST1, 3, 4, 5, and 6, which have the potential to be transmitted to humans, are also reported from cattle in several countries. Although a survey has been conducted previously in western Japan for livestock cattle, there is no information available regarding other parts of Japan. Therefore, this study surveyed the prevalence of Blastocystis and its STs in cattle from Kanagawa prefecture, eastern Japan. Fecal specimens, collected from 133 dairy cattle on four different farms, were subjected to a short-term xenic in vitro culture and Blastocystis were identified by microscopic examination. Seventy-two cattle were positive for Blastocystis (54.1%). Direct sequences for the partial SSU rDNA were obtained for 45 samples. Based on nucleotide sequence homology search and phylogenetic analysis, 44 isolates were identified as ST14 and one as ST10. Our study confirms the presence of these STs in dairy cattle in Japan for the first time. The STs identified here, ST10 and ST14, support previous findings that Bovidae may be the natural host for both STs.
芽囊原虫是一种肠道原生生物，在全球人类及多种动物中普遍存在。目前，基于小亚基核糖体RNA基因（SSU rDNA）的系统发育，来自哺乳动物和鸟类宿主的分离株被分为17个亚型（STs），其中有10种（ST1 - 9、12）在人类中被报道。ST10是在肉牛中报道的主要亚型。然而，包括ST1、3、4、5和6在内的其他亚型也在多个国家的牛中被报道，这些亚型有可能传播给人类。尽管此前在日本西部对肉牛进行过调查，但日本其他地区尚无相关信息。因此，本研究调查了日本东部神奈川县牛群中芽囊原虫及其亚型的流行情况。从四个不同农场的133头奶牛采集粪便样本，进行短期异养体外培养，并通过显微镜检查鉴定芽囊原虫。72头牛的芽囊原虫检测呈阳性（54.1%）。对45个样本进行了部分SSU rDNA的直接测序。基于核苷酸序列同源性搜索和系统发育分析，44个分离株被鉴定为ST14，1个为ST10。我们的研究首次证实了这些亚型在日本奶牛中的存在。这里鉴定出的ST10和ST14亚型，支持了之前关于牛科动物可能是这两种亚型天然宿主的研究结果。
