Chou Shyun, Izawa Nobumoto, Ike Kazunori, Tokiwa Toshihiro
Laboratory of Veterinary Parasitology, School of Veterinary Medicine, Faculty of Veterinary Science, Nippon Veterinary and Life Science University, 1-7-1 Kyonancho, Musashino, Tokyo, 180-0023, Japan.
Bird and Little Animal Clinic FALCONEST, Senjunakaicho, Adachi, Tokyo, 120-0035, Japan.
Int J Parasitol Parasites Wildl. 2021 Jan 14;14:75-83. doi: 10.1016/j.ijppaw.2021.01.002. eCollection 2021 Apr.
The genus Allen, 1933 (Apicomplexa: Sarcocystidae), an avian coccidia, is characterized by monosporocystic and octasporozoic oocysts without Stieda and substieda bodies. Some members of , which infect several raptor species, exhibit high levels of pathogenicity, making eumonosporiosis the leading cause of death in captive-bred raptors. The host specificity of these species appears to be mesostenoxenous, as evidenced by unsuccessful transmission between different orders of avian hosts. However, several studies have detected spp. in taxonomically distant avian hosts, indicating that some of these species may be euryxenous. In the current study, diarrheic fecal examination of a captive-bred juvenile merlin (Falconiformes: Aves) in Tokyo, Japan, was conducted, and a large number of oocysts were morphologically and molecularly identified as (Yakimoff and Matschulsky, 1932), a coccidia species reported only in Strigiformes. This is a new recorded host for this coccidia. Phylogenetic analyses via Bayesian inference and maximum likelihood methods using concatenated genomic datasets consisting of nuclear 18S rDNA, nuclear 28S rDNA and mitochondrial cytochrome C oxidase subunit 1 gene, revealed a well-supported monophyletic clade of spp. belonging to the family Sarcocystidae Poche 1913, which largely corresponded to the avian host phylogram. Therefore, based on distinguishable oocyst morphology, a new subfamily, Eumonosporinae, within the family Sarcocystidae, is proposed, and a reconsideration of the definition of Sarcocystidae is suggested. Further molecular characterization of this emerging pathogen, as well as clarification of its complete life cycle, including cyst-forming ability, is required for more appropriate generic assessment.
艾伦属（1933年）（顶复门：肉孢子虫科）是一种禽类球虫，其特征是具有单孢子囊和八孢子生殖的卵囊，没有斯氏体和亚斯氏体。该属的一些成员感染多种猛禽物种，具有高度致病性，使单孢子虫病成为圈养繁殖猛禽死亡的主要原因。这些物种的宿主特异性似乎是中等狭食性的，不同禽类宿主目之间的传播未成功证明了这一点。然而，多项研究在分类学上相距甚远的禽类宿主中检测到了该属的物种，表明其中一些物种可能是广食性的。在本研究中，对日本东京一只圈养繁殖的幼年矛隼（隼形目：鸟类）进行了腹泻粪便检查，通过形态学和分子学方法鉴定出大量卵囊为雅基莫夫和马奇尔斯基（1932年）报道的仅在鸮形目中发现的一种球虫物种。这是该球虫的一个新记录宿主。使用由核18S rDNA、核28S rDNA和线粒体细胞色素C氧化酶亚基1基因组成的串联基因组数据集，通过贝叶斯推断和最大似然法进行系统发育分析，揭示了属于1913年波切肉孢子虫科的该属物种的一个得到充分支持的单系分支，这在很大程度上与禽类宿主系统发育图相对应。因此，基于可区分的卵囊形态，提出了肉孢子虫科内的一个新亚科——单孢子虫亚科，并建议重新考虑肉孢子虫科的定义。为了进行更恰当的类属评估，需要对这种新出现的病原体进行进一步的分子特征分析，并阐明其完整的生命周期，包括形成包囊的能力。
